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Issue 1, Volume 3,
January 2008
Title of the Paper: A Method of
Error Compensation on Sensors Based On Neural Networks Algorithm
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Authors: Zhu Wei,
Zeng Zhe-Zhao, Huang Dan
Abstract: To improve the error compensation precision on sensors, a method of
the error compensation on sensors based on the neural network algorithm is
proposed. The convergence of the algorithm is researched. The theory gist to
select learning rate is provided by the convergence theorem. To validate the
validity of the algorithm, the simulating example of the error compensation
on sensor was given. The result shows that the error compensation approach on
sensors using the neural network algorithm has a very high accuracy. Thus,
the method of the error compensation proposed is effective.
Keywords: Neural
networks; sensor; error compensation; algorithm; convergence
Title of the Paper: Transmission Cost
Allocation Schemes in Competitive Power Systems
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Authors: Adel Ali Abou
El-Ela, Ragab Abdel-Aziz El-Sehiemy
Abstract: This paper presents different flow-based transmission cost
allocation (TCA) schemes for distributing the transmission usage costs to
system individuals. Different independent system operator (ISO) visions are
suggested using the proportional rata method. In addition to the suggested
schemes, three other approaches are proposed. The first proposed approach
generalizes the equivalent bilateral exchanges (EBE) concepts presented in
[2] for lossy networks through multi-stage
procedure. The second proposed approach is based on modified sensitivity
factors (MSF). These MSF factors are developed from the actual measurements
of power flows in transmission lines and the power injections at different
buses. The proposed approaches exhibit desirable apportioning properties and
are easy to implement and understand. Case studies based two test systems
5-bus test system and the IEEE 14-bus test systems are carried out to show
the proposal's capability for flow-based TCA schemes.
Keywords: transmission
cost allocation, deregulated, modified sensitivity factors, bilateral
exchanges
Issue 2, Volume 3,
February 2008
Title of the Paper: Design and
Experimental Investigation of a Three-Phase APF based on Feed-Forward plus
Feedback Control
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Authors: Yang Han, Mansoor,
Gang Yao,
Li-Dan Zhou, Chen Chen
Abstract: An effective control scheme for three-phase three-wire active power
filter is proposed in this paper. Conventionally, the majority of existing
APF control strategies in literature adopts feed-forward control scheme,
which results in switching notches (sharp-rising or falling ripples) in the
source-side currents at conduction instants of diode/thyristor
rectifier load. The proposed method utilizes feedback control plus
feed-forward control structures to achieve a smooth filtering performance.
The feedback loop minimizes the steady-state error using two separate PI
regulators in d-axis and q-axis respectively. The feed-forward loop serves
the purpose of load disturbance rejection and it significantly enhances
performance of active power filter by using synchronous frame adaptive neural
network (SADALINE) algorithm. The proposed method overwhelms many existing
compensation schemes in terms of simplicity, robustness and ease of
implementation using DSP. The effectiveness of the proposed control scheme
has been substantially confirmed by experimental results.
Keywords: harmonic
contamination, active filter, power quality, SADALINE
Title of the Paper: Forecasting of Time
Series of Wind and Solar Energy by Using AMeDAS
Data
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Authors: Katsuhiro Ichiyanagi,
Kengo Taniguchi, Hiroyuki Nakano, Kazuto Yukita, Yasuyuki Goto, Katsunori Mizuno, Fujihiro Yamada, Nobuyuki Yamamoto,
Shigeyuki Sugimoto
Abstract: The forecasting of time series of the wind and solar energy is
necessary for the prevention from global warming. This paper explains the
technique of time series forecast of the wind power energy and solar energy
by using ten minutes intervals meteorological data obtained by AMeDAS(Automated
Meteorological Data Acquisition System). We discuss an application of a
neural network for forecasting to time series of wind velocity and solar
energy. Furthermore, the pattern matching is used to choose the training data
of the neural network. It is found from our investigations that forecasting
accuracy of the time series of wind velocity and solar energy is improved by
utilization the pattern matching of the weather map data.
Keywords: forecasting，wind velocity，solar
energy, neural network，pattern matching,
weather map, AMeDAS, wind power
Title of the Paper: Identification of
Wheeling Paths by an
Extended Sensitivity Analysis
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Authors: Hiromu
Hamada, Marta Marmiroli, Ryuichi
Yokoyama
Abstract: This paper proposes a practical method for identifying wheeling
paths in deregulated electricity markets based on an extended sensitivity
analysis. Using this method, it becomes possible to fix the proper and fair
wheeling rate according to the degree of responsibility of each power flow
transaction. Moreover, a wheeling rate based on the real power flow
responsibility is also an important signal to new power suppliers in the
markets. In order to show the validity of the proposed method, a series of simulations
on the IEEE 30 bus test system were conducted.
Keywords: Electricity
market, Route coloring, Sensitivity analysis, Wheeling, Pricing, Deregulation
Title of the Paper: Dielectric
Properties of Mixtures between Mineral Oil and Natural Ester from Palm Oil
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Authors: Suwarno, Irawan Surya Darma
Abstract: This paper reports experimental results on dielectric properties of
mixture between conventional mineral oil and a natural ester made from palm
oil. The experiment was done in attempt to find new type of liquid insulating
material which excellent in dielectric properties and friendly to
environment. The sample used are mixtures between
mineral transformer oil (Shell Diala B) and methyl
ester from palm oil. The content of ester in the mixture ranged from 0 to 100
%. The breakdown voltage, losses factor and dielectric constant as function
of ester content and temperature were investigated. The values of acidity,
viscosity and gassing tendencies are also presented. The experimental results
showed that increasing the ester content in the mixtures enhanced the
breakdown voltage and slightly increased the losses factor. A higher increase
of dielectric losses factor was observed at higher temperature. The
dielectric constant of the mixture was stable in the range of temperature
from room temperature up to 100oC. Acidity as well as viscosity increased
with the ester content. The viscosity decreased with temperature. Dissolved
gas analysis indicated that the total combustible in the mixture are
considerably lower than that threshold value for normal condition according
to IEEE C57.104. Comparing the experimental results and values of several
properties in standard such as ASTM D 3487, ASTM D 1289 and IEEE C57.104, the
composition of 50 % ester content is a good mixture to be used as
biodegradable insulating liquid.
Keywords: mineral oil,
methyl ester, temperature, ester content, dielectric properties, dissolved
gas analysis
Issue 3, Volume 3,
March 2008
Title of the Paper: Novel Decentralized
Pole Placement Design of Power System Stabilizers Using Hybrid Differential Evolution
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Authors: Yung-Sung Chuang,
Shu-Chen Wang, Chi-Jui Wu, Pei-Hwa Huang
Abstract: This paper is used to investigate a novel decentralized pole
placement design of lead-lag power system stabilizers using hybrid differential
evolution (HDE). Since only local speed deviations are used as the feedback
signals, the decentralized stabilizers could be easily implemented. It wants
to place the electromechanical modes within a designated region to have
enough damping. Participation factors are used to select the site and number
of stabilizers. If all electromechanical modes have been moved to the
specified region at the convergent step, the objective function will reach a
minimal value. The objective function is chosen to ensure the real parts and
damping ratios of electromechanical modes. A test power system is used to
reveal the goodness of this method. Several operating points can be
considered simultaneously in the determination of stabilizer parameters to
let the stabilizers work well under a wider range of operating conditions.
The computation time and convergence characteristic of this approach are
better, compared to the differential evolution and genetic algorithm. The
coherency measures are also proposed to evaluate the relative behaviours between any pair of generators of the system
with and without stabilizers.
Keywords: Power system
stabilizer, Electromechanical mode, Pole placement, Hybrid differential
evolution, Power system dynamics, lead-lag power system stabilizers.
Title of the Paper: Bi-objective
Intelligent Optimization for Frequency Domain
Parameter Identification of a Synchronous Generator
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Authors: P. Pao-La-Or,
T. Kulworawanichpong, A. Oonsivilai
Abstract: This paper describes an intelligent approach to estimate parameters
of a direct-axis equivalent circuit of a synchronous generator from frequency
response data using bi-objective intelligent optimization methods, genetic
algorithms and adaptive tabu search. The genetic
algorithms and adaptive tabu search are capable of
finding a global minimum within a given search interval. The sum square error
of magnitude and phase of the d-axis equivalent circuit transfer function to
formulate a bi-objective optimization problem is minimized to best fit the
measured data extracted from the frequency response test of the machine. As a
result, exploitation of the bi-objective optimization based on genetic
algorithms and adaptive tabu search give very good
results than those of using either the magnitude or the phase as a single
objective. This confirms the effectiveness of the intelligent approach for
solving bi-objective optimization problems described in this paper.
Keywords: Parameter
Identification, Genetic Algorithms, Adaptive Tabu
Search, Bi-objective Optimization, Synchronous Generator, Frequency Response
Title of the Paper: Closed-Form
Analytical Investigation of Space-Vector
PWM Inverter Fed Induction Motor Drive under
DC-Bus Voltage Pulsation
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Authors: Jiri
Klima
Abstract: Voltage sag or unbalance conditions at the
input rectifier stage of the ac-dc-ac rectifier-inverter induction motor
drive can cause the significant amounts of harmonic voltage at twice the line
frequency 2f1. This voltage ripple can have a degrading effect on the
induction-machine performance characteristics. This paper presents an
analytical closed-form mathematical model and analysis of the impact of
DC-bus ripple voltage of the three-phase voltage source inverter (VSI) with
the space-vector PWM (SVPWM) on the induction machine phase voltages,
currents and torque pulsations. The analytical expressions for the voltage
and current space-vectors as a function of the DC-bus voltage pulsation are
derived. From the current space vectors the torque behavior is estimated,
again as a function of DC-link voltage pulsation. Next, it is shown, that
DC-link voltage ripple components may cause large torque pulsation. The
proposed analytical method is based on the mixed p-z approach [13], enabling
presentation of the results in lucid and closed-form. To verify the
effectiveness of the proposed analytical model, experimental results based on
laboratory setup were performed.
Keywords: PWM inverter,
mathematical model, induction motor, torque pulsation.
Title of the Paper: Consideration of
Uncertainty Factors in Search for High Risk Events of Power Systems Caused by
Natural Disasters
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Authors: Tetsushi
Miki
Abstract: Power systems become large and complex, so the occurrence rates of
a great deal of energy loss caused by faults become high. In this situation,
the development of the efficient search method for high risk events of power
systems is strongly required. Risk is defined as the product of energy loss
and its occurrence rate, considering that the goal of power systems is the
stable supply of power. This paper presents the developed method which can
search accurately and efficiently high risk events of power systems caused by
natural disasters in more safety side by considering uncertainty factors
occurred in power systems. It was applied to the model system composed of 3
generators and 9 buses. The results of application have clarified its
effectiveness.
Keywords: Power Systems,
Transient Stability, Risk, Natural Disasters, Critical Fault Clearing Time
Title of the Paper: Minimization of
Shaft Torsional Oscillations by Fuzzy Controlled
Braking Resistor Considering Communication Delay
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Authors: Mohd.
Hasan Ali, Minwon Park,
In-Keun Yu
Abstract: This paper analyzes the effect of the fuzzy logic-controlled
braking resistor (BR) on minimizing shaft torsional
oscillations of the generators in a multi-machine power system. The influence
of communication delay associated with the fuzzy controller input calculation
on minimizing shaft torque oscillations is investigated. Global Positioning
System (GPS) is proposed for the practical implementation of the calculation
of the input of the fuzzy logic controller. Communication delays may affect
the control system, and consequently the performance of minimizing shaft torsional oscillations also. A prediction function is
proposed to reduce the negative effect caused by the communication delay on
minimizing shaft torsional oscillations. Simulation
results of a balanced fault at different points in the power system show that
the fuzzy logic-controlled braking resistor can minimize the shaft torsional oscillations of synchronous generators well.
Moreover, the communication delay has an influence on minimization of shaft
torque oscillations. Also, the negative effect caused by the communication
delay on minimizing shaft torsional oscillations
can be reduced by the prediction method.
Keywords: Braking
resistor, Communication delay, Fuzzy controller, Global positioning system
(GPS), Minimizing shaft torsional oscillations,
Prediction function, TKED.
Title of the Paper: Analysis of Partial
Discharge in Insulation Oil using Acoustic Signal Detection Method
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Authors: Gyung-suk
Kil, Dae-won Park, Il-kwon
Kim, Su-yeon Choi
Abstract: This paper dealt with the frequency analysis of acoustic signal
produced by partial discharge (PD) in insulation oil and the positioning of
PD occurrence to apply to diagnose oil insulated transformers. We assembled
three types of electrode system; the needle-plane, the plane-plane, and the
void to simulate partial discharge in insulation oil. A low-noise amplifier
and a decoupler were designed to detect acoustic
signal with high sensitivity. The frequency ranges of acoustic signal were 70
kHz~210 kHz in the needle-plane, 65 kHz~260 kHz in the plane-plane, and 60
kHz~270 kHz in the void electrode system. Their peak frequencies were 133
kHz, 132 kHz and 128 kHz, respectively. The position of PD occurrence was
calculated by the time difference of arrival (TOA) using four acoustic
emission (AE) sensors and we could find the position within the error of 3%
in the experimental apparatus.
Keywords: Acoustic
signal, Partial discharge (PD), Oil insulated transformers, Diagnosis,
Electrode system, Frequency analysis, Position, Time difference of arrival
(TOA)
Title of the Paper: A Prototype of a
Linear Switched Reluctance Motor with a New Design Methodology
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Authors: D. S. B. Fonseca, C. P. Cabrita, M. R. A CaladoI
Abstract: A new and original optimized desighn
methodology concerning a Linear Switched Reluctance Machine (LSRM), with a
new topolgy and for light electric traction applications , is proposed in this paper. This methodolgy is based on the systematic use of a simple
geometric design process, and a fast simulation methodolog
is used to evaluate the performance of each one of the several design
process, and a fast simulation methodology is used to evaluate the proformance of each one of several design machines.
Keywords: Linear Switched
Reluctance Machines, Traction Foces Evaluation,
Machine Simulation, Oprimised Design.
Title of the Paper: The influence of
the Effect of Grounding and Corona Current to the Field Strength the Corona
Onset and the Breakdown Voltage of Small Air Gaps
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Authors: Leandros
A. Maglaras, Athanasios
L. Maglaras, Frangiskos
V. Topalis
Abstract: In the present paper the values of the field strength at
Corona onset and
Breakdown in small air gaps in connection to the effect of grounding is
investigated. The effect of grounding is occurred due to the fact that in air
gap arrangements one electrode is usually grounded. The field distribution is
analyzed with the Finite Element Method. The corona onset and the breakdown
voltage are experimentally measured. The maximum value of the field strength
at corona onset and breakdown are calculated for the different arrangements
with one electrode grounded and with the electrodes symmetrically charged,
and are compared. It is resulted that the effect of grounding influences the
field distribution, the corona onset, and the breakdown voltage of small air
gaps greatly. The effect is intense in the non-symmetrical rod-plate air gaps
and less significant in the symmetrical ones, rod-rod and sphere-sphere. The
values of the corona onset and the breakdown voltages are much higher in the
arrangement with one electrode grounded, and in the rod-plate air gaps with
the rod grounded. The correspondent values of the field strength are almost
equal for the two different cases. In longer air gaps the corona current
suspends the breakdown, the effect of grounding is vanished, and the field
strength at breakdown is higher in the arrangement with the plate grounded.
Relations between the field strength, the gap length and the rod’s diameter,
as well as between the corona current and the breakdown voltage and field
strength arise. The principle of action-reaction is valid.
Keywords: Field Strength,
Field Factor, Electric Breakdown, Corona
Onset, Corona
Current, Finite Element Method, Grounding Effect.
Title of the Paper: Behavior of the
Lead Acid Battery after the Rest Period
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Authors: Septimiu
Mischie, Liviu Toma
Abstract: This paper presents the characteristics of a lead acid battery
regarding the charge that it can release. It is desired to determine the
effect of the rest period on the charge released by the battery. For this
purpose a series of experiments that contain at least one rest period are
presented. In each of them the charge released is counted, depending on the
time when the rest period is started. It is pointed out that, every battery
can release a charge close to its theoretical capacity if the discharge
contains rest periods.
Keywords: Lead acid
battery, Charge released, Rest period, Charge available
Issue 4, Volume 3,
April 2008
Title of the Paper: Semiconductor
Devices and Their Use in Power Electronic Applications
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Authors: N. Y. A. Shammas,
S. Eio, D. Chamund
Abstract: Power semiconductor devices are the key electronic components used
in power electronic systems. The solid-state power electronic revolution
started with the invention of the thyristor or Silicon
Controlled Rectifier (SCR) in 1956, and many power semiconductor devices have
been produced since then. Advances in semiconductor technology have improved
the efficiency of electronic devices which resulted in reduced cost, weight
and size of power electronic systems. Power Integrated Circuits (PIC) have
been developed as a result of recent advances in integration technology,
which led to a significant improvement in reliability of power modules. This
has extended the use of power converters for portable, aerospace and
automotive applications. Thyristors and Insulated
Gate Bipolar Transistors (IGBT’s) have been used
extensively in power electronic circuits. Power diodes are some of the
important devices for inverter and freewheeling applications. Diode reverse
recovery under high di/dt operating conditions may
result device and circuit failure. In this paper, detailed study and progress
made in power semiconductor devices, their characteristics, packaging,
thermal issues and different high power application are given.
Keywords: Power
Semiconductors Devices, Thermal Effects, Device Packaging, Power
Applications.
Title of the Paper: Minimum Energy and
Minimum Time Control of Electrical Drive Systems
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Authors: Corneliu
Botan, Vasile Horga, Florin Ostafi, Marcel Ratoi
Abstract: A comparison between time optimal control and minimum energy
control for electrical drives is performed. The drives with DC, PMSM or
induction motors are considered. A simple strategy using the currents as
control variables is proposed. A unified theoretical approach for optimal
control of electrical drives with different motor types is indicated.
Simulation and experimental results are presented.
Keywords: Electrical
drives, Optimal control, Energy, Time, AC, DC motors
Title of the Paper: Energy
and CO2 Emission Assessment of Cooling Generation Alternatives: A
Comprehensive Approach based on Black-Box Models
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Authors: Pierluigi
Mancaella, Gianfranco Chicco
Abstract: Nowadays, cooling production is increasingly required to satisfy
more and more demanding life standards, in particular for air conditioning
applications in urban areas. Energy efficiency improvement and greenhouse gas
emission reduction are primary tasks at the present stage of evolution of the
energy generation systems. In this respect, different alternatives available
for cooling generation, fed either electrically or by gas (absorption or
engine-driven chillers), can bring about different environmental impacts in
dependence on the specific generation framework. This paper presents a
comprehensive unified energy and environmental model for cooling generation
assessment. The approach proposed is based upon formulation of synthetic
black-box models that characterize the relevant energy system components.
Specific indicators are defined to represent the cooling energy saving and
CO2 emission reduction obtainable from natural gas direct-fired chillers with
respect to traditional compression electric chillers. By using these novel
indicators, break-even conditions are worked out to identify the limits of
convenience of different cooling generation technologies. Numerical examples
are provided to assess the potential benefits of the various solutions in
different countries. Specific discussions refer to considering power system
average or marginal operational characteristics.
Keywords: Absorption
chillers, Compression chillers, Electric chillers, Emission reduction, Energy
saving, Engine-driven chillers, Environmental impact assessment, Greenhouse
gases, Natural gas.
Title of the Paper: Electronic
Communities - Catalysts or Rotten Apples of Traditional Agents of
Socialization for 'Generation-Y'?
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Authors: Jurica
Pavicic, Niksa Alfirevic, Nino Gabelica
Abstract: Whoever considers himself/herself a young person will have to cope
with more or less acceptable social challenges to distinctive social
identities based upon age differentiation. Clearly
different from those they consider to be older, young people and various
'wannabes' face the contemporary community sociology phenomenon of electronic
communities. As such communities are derived from patterns of modern
electronic communication, possession of advanced computer skills is a
valuable social asset for young people who are quite 'at home' in
communicating/expressing themselves using interactive media and messaging.
The issue of being 'at home' in interpreting the social world in terms of
electronically mediated interaction is often mixed (or even confused) with
the (in)ability to apply 'traditional' forms of
social interaction and socialization. Therefore, it is important to ask
whether contemporary theories/models of the electronic community apply to the
identification and socialization of the generation acquainted with
information technology at a very early age (the so-called 'Generation Y'). It
is believed that some new patterns in socialization/community building may be
identified by analyzing the interactions among the 'offline' and 'online'
social worlds/experiences of 'Generation Y' and even extended to a wider
group, as society as a whole reflects the behavior and fundamental
characteristics of youth culture.
Keywords: Electronic
communication, youth culture, agents of socialization, mobile communication,
virtual community
Title of the Paper: Design of a New
Micro Direct Methanol Fuel Cell Utilizing MEMS Technology
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Authors: Xiuling
Ji, Wenzhong Lou
Abstract: In this paper, a special micro DMFC using MEMS technology is
designed to work in circumrotating condition, which providing power using
inertia over-load. The designed cell is a cylinder, anode channel is inside,
cathode is outside and exposes to the air. When the overload exceeds the
critical value, the liquid inside reserve tank will splash and comes into the
two electrodes, and then the cell will be activated. The voltage, current
density and work time of DMFC are calculated, fuel tank and active system are
designed to satisfy the working condition, and the DMFC performance of
serpentine and parallel flow fields is analyzed preliminary. A current
collector open ration of 70% is chosen in the design of the DMFC, and effect
of the open ratio on the performance of the DMFC is analysed
simultaneously. Furthermore, cathode and anode plates are fabricated using a
MEMS technology--3D KOH- etching. Although there are many experimental works
to do to testify its performance, it is true that the flow field simulation
is authentic and the primary design is feasible.
Keywords: μDMFC, MEMS, design, KOH-etching, flow fields,
circumrotating
Title of the Paper: Fast Evaluation of
Available Transfer Capability (ATC) Considering Integral Square Generator Angle (ISGA)
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Authors: M.M. Othman, N. Mat, I. Musirin, A. Mohamed, A.
Hussain
Abstract: One of the concepts in restructuring the electric power industry is
the ability to accurately and rapidly quantify the power transfer so-called
as the available transfer capability (ATC). Accurate identification of ATC
provides vital information for both planning and operation of the bulk power
market in reserving transmission services. There are various methods used to
determine ATC such as the DC power flow, AC power flow, optimal
power flow and sensitivity techniques. These methods considered the
transmission line and voltage limits as the constraints for ATC computation.
This paper presents the determination of power transfer between two buses
that takes into account the dynamic security constraint. The dynamic security
constraint based transient stability has been found to be one of the limiting
factors in determining the power transfer so-called as the available transfer
capability (ATC). The multi-machine integral square generator angle (ISGA)
index is used to measure the severity of stable and unstable transient events
during the occurrence of line outage and it is considered as the dynamic
security constraint of the ATC assessment. The determination of ATC
considering dynamic security constraint has been performed on the 6 bus and
11 bus systems. Comparative study has been made between the cubic-spline interpolation technique and recursive AC power
flow method in determining the value of ATC.
Keywords: Cubic-spline interpolation technique, recursive AC power flow
method, integral square generator angle, available transfer capability and
line outage.
Title of the Paper: Voltage Profile
Improvement Using Unified Power Flow Controller via Artificial Immune System
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Authors: Ismail
Musirin, Nur D. M. Radzi, Muhammad M. Othman, Mohamad K. Idris, Titik K. A. Rahman
Abstract: Voltage profile is one of the concerned issues in power system
studies. This is due to the fact that voltage profile decay can be
experienced by the system when system is subjected to load increment or
disturbances. Unscheduled increment of load variation in a power transmission
system has driven the system to be stressful, leading to potential cascading
trip on the entire system. Thus, close monitoring of load variation in a
power network can help to avoid the system operating close to its maximum
capacity. In addressing this phenomenon, special scheme can be implemented
such as reactive power compensation; installation of flexible AC transmission
system (FACTs) devices and capacitor placement.
Identification of the optimal value of compensating capacitors required
proper optimization technique; able to search the optimal solution with less
computation time. This paper presents the voltage profile improvement using
unified power flow controller (UPFC) approach based on artificial immune
system (AIS). In this study, AIS optimization engine is developed for voltage
profile improvement which utilized UPFCs as the
control variables embedded into the system’s data. Implementation on the IEEE
Reliability Test System (RTS); considering several variations in the AIS
properties indicated AIS potential in solving voltage control problems.
Verification through comparison of results using evolutionary programming
utilizing the similar system data indicated that AIS is feasible to solve
voltage depreciation problems.
Keywords: Artificial
immune system, fitness, objective function, optimization, UPFC, voltage
profile.
Title of the Paper: Methodological
Approach for Ground Contamination Assessment and Remediation of Brownfields
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Authors:
M. G.
Brito,
C. N.
Costa, D. Vendas
Abstract: A methodology is presented for ground contamination assessment and
remediation of brownfields, emphasizing the
application of geostatistical models in sequential
stages of site investigation. The methodology is applied to a former
industrial area in Barreiro
(Portugal), in the left
margin of Tagus
River, 7km south of
Lisbon. The area, where heavy industry
(chemical, metallurgical, etc.) operated during the last century, is
presently submitted to environmental requalification
planning for urban redevelopment.
Keywords: ground
contamination, site assessment, remediation, geostatistics,
brownfields, heavy metals
Title of the Paper: Role of Reactive
Power Source on Power Quality of Three-Phase Self-Excited Induction Generator
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Authors: Sudhir
Sharma, K. S. Sandhu
Abstract: Traditional wind turbines are equipped with induction generators.
Induction generators are preferred because they are inexpensive, rugged, and
require very little maintenance. Unfortunately, induction generators require
reactive power from the grid to operate and/ or some capacitor compensations
are often used with self excited induction generators. Static capacitors are
generally employed to achieve the required performance in a self-excited
induction generator. Literature survey reveals that a little work has been
done to investigate the effects of capacitor bank selection on the voltage
profile of generator and its effect on the harmonics generated by induction
generator. In this paper an attempt is made to analyze the effects of
reactive source on the performance of machine and the effects of capacitor
bank on the harmonics were investigated using MATLAB/SIMULINK. Importance of
capacitor bank selection on quality of output power is highlighted through
simulated results as obtained.
Keywords: Induction
Generators, MATLAB, Reactive Power, Self-Excitation, Wind Energy, Excitation
capacitor, Harmonic Distortion.
Title of the Paper: Developing Power
Systems Reliability and Efficiency by Integrating Grid Computing Technology
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Authors: R. Al-Khannak, B. Bitzer
Abstract: The need for reliable, redundant, and clean power generation in
power systems is becoming more importance. This need requires
geographically-distributed power systems to be integrated as a single entity
where among the main features of this integration are large data base and
computing intensive. Hence the current power systems are not able to handle
this huge datasets required for that integration, Grid Computing is a gateway
to virtual storage media and processing power. This paper analyzes, describes
and simulates the integration of modern power systems into grid computing
technology. Paper begins by introducing grid computing as a technology,
defining selected middleware. Two power implementations are illustrated,
power load forecasting within traditional and grid computing based systems,
and real time power system controlling and monitoring with grid computing
technology integration to enhance power system reliability. Developed
reliable backup system strategy has been achieved by implementing grid
computing technology as an innovative integration benefit.
Keywords: Computational
grid, idle resource, grid computing, resource broker, job, node, grid
middleware.
Title of the Paper: Harmonic Distortion
and Reactive Power Compensation in Single Phase Power Systems using
Orthogonal Transformation Strategy
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Authors: W. Hosny, B.
Dobrucky
Abstract: The orthogonal transformation technique which was instigated by Akagi et al in 1984 for the investigation of the
instantaneous power in a three phase power system is extended in this paper
in order to derive novel compensating current expressions for a single phase,
shunt active power filter. This filter is used for a single phase power
supply feeding a non-linear load in order to compensate for the instantaneous
reactive power or the harmonic current distortion or for compensating of
both. The configuration of the active power filter utilised
in this investigation is included. In addition, the filter compensating
current control technique and methods implemented for the evaluation of the
filter ratings and size are included. An expression for the distortion power
equation for a single phase power supply feeding a non-linear load is derived
in the Appendix. This expression is extremely useful as an aid to design
active power filters which compensate for both of the reactive power and the
current higher harmonics. Experimental results demonstrated the effectiveness
of the novel expressions for the active power filter compensating currents
derived in this paper.
Keywords: Single phase
power systems, orthogonal transformation technique, harmonic distortion and
reactive power compensation
Title of the Paper: Optimal Size and
Location of Capacitors Placed on a Distribution System
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Authors: Ching-Tzong
Su, Cheng-Yi Lin, Ji-Jen Wong
Abstract: This paper proposes a study of reactive power compensation for
electric distribution systems to find out the optimal capacitive compensation
location and quantity. The most commonly used reactive power sources for
compensation in distribution systems are capacitor banks. The compensation
problem under study is an optimization problem. A new method-evolutionary
simulated annealing, with evolution strategies embedded in the simulation
annealing, is employed to solve a 36-bus distribution system composed of
radial-type and loop-type circuits, to find out the optimal capacitor
placement solutions. Lastly, according to the results of simulation, it
validates the proposed approaches and provides the way to promote the
power-supply quality of distribution systems.
Keywords: Capacitive
compensation, Radial-type, Loop-type, Evolutionary simulated annealing, Power
loss, Bus voltage
Title of the Paper: An Efficient
Particle Swarm Optimization for Economic Dispatch Problems With Non-smooth
cost functions
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Authors: K. Thanushkodi,
S. Muthu Vijaya Pandian, R. S. Dhivy Apragash, M. Jothikumar, S. Sriramnivas, K. Vinodh
Abstract: An efficient Particle Swarm Optimization (PSO) technique, employed
to solve Economic Dispatch (ED) problems in power system is presented in this
paper. With practical consideration, ED will have nonsmooth
cost functions with equality and inequality constraints that makes the problem, a large-scale highly constrained
nonlinear optimization problem.The proposed method
expands the original PSO to handle a different approach for solving those
constraints. In this paper, an efficient PSO technique is employed so that
faster convergence is obtained for the same results published in IEEE
Proceedings. To demonstrate the effectiveness of the proposed method it is
being applied to test ED problems, one with smooth and other with nonsmooth cost functions considering valve-point loading
effects. Comparison with other optimization techniques showed the superiority
of the proposed EPSO approach and confirmed its potential for solving nonlinear
economic load dispatch problems.
Keywords: Economic load
dispatch, Particle swarm optimization, Valve point loading effect
Issue 5, Volume 3,
May 2008
Title of the Paper: The Efficient
Offline Search System for High Risk Events of Power Systems Caused by Natural
Disasters
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Authors: Tetsushi
Miki
Abstract: Power systems become large and complex, so the occurrence rates of
a great deal of energy loss caused by faults become high. In this situation,
the development of the efficient search system for high risk events of power
systems is strongly required. Risk is defined as the product of energy loss
and its occurrence rate, considering that the goal of power systems is the
stable supply of power. This paper presents the offline search system which
can search accurately and efficiently high risk events of power systems
resulted from the loss of transient stability caused by natural disasters. It
was applied to the model system composed of 3 generators and 9 buses. The
results of application have clarified its effectiveness.
Keywords: Power Systems,
Transient Stability, Risk, Natural Disasters, Critical Fault Clearing Time
Title of the Paper: Control
of Maintenance Policies by Means of a Simulation Model. A Case Study in a
Hospital
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Authors: M. Carmen Carnero
Abstract: This paper describes a simulation model formed by means of Matlab software that enables the visualization of trends
in maintenance policies (Corrective, Preventive and Condition Monitoring),
taking into account specific initial conditions and different levels of efficiency
in the set-up of a Condition Monitoring Programme.
Once a maintenance policy has been set up, different factors must be
controlled to enable deficiencies to be detected early. The detection and
diagnosis of these irregularities is the reason for the development of the
simulation model of trends in maintenance policies. The model has been
applied to a Hospital where maintenance efficiency has an influence not only
on machines but also on people, by directly influencing the quality of the
patients´ welfare service. Considering the characteristics of the Condition
Monitoring Programme set up in the Hospital,
maintenance trends are simulated to forecast future behaviour
in relation with different alternatives, from the worst to the best possible
states.
Keywords: Preventive
Maintenance, Condition Monitoring, Corrective Maintenance, Simulation,
Control, Hospital.
Title of the Paper: Performance
Comparison Of UPFC In Coordination With Optimized POD And PSS On Damping Of
Power System Oscillations
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Authors: S. N. Dhurvey, V. K. Chandrakar
Abstract: This paper presents a new approach for determining the effective
control signals for damping of oscillations by performance comparison of
Unified Power Flow Controller in coordination with Power Oscillation Damping
Controller and Power System Stabilizer. For the analysis Modified Phllips-Heffron Model of Single Machine Infinite Bus
system is established with Unified Power Flow Controller. Impact of
additional damping controllers like Power Oscillation Damping Controller and
Power System Stabilizer are designed to achieve improved damping performance
of the Single Machine Infinite Bus system by selecting effective control
signals. The Power Oscillation Damping Controller parameters are optimized by
using Nonlinear Control design Blockset (NCD).
Investigations reveal that coordinated tuning of Unified Power Flow
Controller with optimized POD parameters provide the robust dynamic
performance. Eigen value analysis provides the
quantitative measure for the comparative performance of additional damping
signal with effective control signals.
Keywords: FACTS, UPFC,
POD, PSS, Damping of oscillations
Title of the Paper: Fuzzy Logic
Controlled Adaptive Active Power Filter for Harmonics Minimization and
Reactive Power Compensation under Fast Load Variation
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Authors: A. Ghasemi,
S. S. Mortazavi, R. Kianinezhad
Abstract: This paper describes the application of a new fuzzy based control
strategy to a three-phase shunt active power filter for harmonics
minimization and reactive power compensation required by a variable
non-linear load. To improve dynamic behaviour of
shunt active power filter and make it robust under wide range of load
variations, the value of load current is considered as an input of fuzzy
controller. The proposed scheme is extensively tested for wide range of
variable load current under stochastic conditions and results are found to be
quite satisfactory to improve dynamic behaviour of
shunt active power filter and mitigate harmonics from the utility current.
Keywords: Shunt active
power filter, Adaptive control, Harmonics compensation, Fuzzy logic
controller, Power quality, Power factor correction
Title of the Paper: Load Flow Models
for the Static Var Compensator Distribution D-SVC
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Authors: Larbi
Boumediene, Mounir Khiat, Mustapha Rahli
Abstract: During the last decade power system have been equipped with complex
components such as Distribution Static Var
Compensators (D-SVCs). These components have
introduced new possibilities to control power systems,
D-SVCs can almost continuously change the amount of
reactive power from capacitor banks. The behavior of these new components is
different from 'old' technologies since they contain power electronics and
detailed representations of them are non-linear. Due to their complexity they
are difficult also to simulate. When studying power systems including such
components, the analyzer must decide whether it is necessary to include a
detailed model of them or not, i.e. to represent each event that takes place, or ignore them. In this paper, the load
flow models for the static Var compensator
distribution (D-SVC) are presented. These models are incorporated into
existing load flow harmonic (LFH). The models of the D-SVC are based instead
on the variable shunt susceptance concept. The
D-SVC state variables are combined with the bus voltage magnitudes and angles
of the network. Two examples are examined in the principal content of this
paper; both of them contain nonlinear loads. Conclusion is made concerning
the application of harmonic power flow studies.
Keywords: Static Var compensator in distribution (D-SVC), load flow
harmonic (LFH), conventional load flow (CLF), fundamental load flow (FLF),
harmonic.
Title of the Paper: Required Energy
Calculation by Hot Rolling of Tubes and of the Main Drive Motors Power for a Stretch
Reducing Mill
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Authors: Macrea
Dorian, Costin Cepisca, Sorin Dan Grigorescu
Abstract: This work shows the methodology regarding the calculation of the
deformation resistance and of the required energy and power for hot reducing
of tubes on a stretch reducing mill (SRM) with the final aim of an optimal
sizing of the mill drives. Effective calculations are shown as methodology
examples for the case of stretch reducing of a
Ö123x3.9mm blank into a Ö 49x3.25mm tube. In order to evaluate the validity
and accuracy of the suggested calculation methodology, the calculation
results regarding the required reducing energy have been compared with the
experimental data collected at a SRM in operation on which the research has
been performed as well as with the experimental data presented in the
literature.
Keywords: stretch
reducing mill, hot reducing tubes, energy, drive motor
Title of the Paper: Evaluation of the
Westinghouse cycles
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Authors: Miroslava
Smitkova, Frantisek Janicek
Abstract: Hydrogen is industrially produced mainly from fossil fuels e.g. by
natural gas steam reforming, coal gasification and as a by-product of naphtha
reforming. A variety of technologies can be used for hydrogen production. In
the long term, with respect of a lack of fossil fuels, hydrogen produced from
water can play a very important role in the energy system. The goal of the
water splitting thermo-chemical cycle is the replacement of thermal
decomposition of water with several partial reactions. This paper deals with
the one of most promising water splitting thermo-chemical cycle – the
Westinghouse cycle. Simulation, optimization and overall evaluation
(including calculation of efficiency and life cycle analysis) of the
Westinghouse cycle were preformed and main obtained results are reported.
Keywords: hydrogen,
hydrogen production, water splitting thermo-chemical cycles, Westinghouse
cycle, life cycle analysis, solar energy
Title of the Paper: Energy Comparison
of MPPT Techniques for PV Systems
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Authors: Roberto Faranda, Sonia Leva
Abstract: Many maximum power point tracking techniques for photovoltaic systems
have been developed to maximize the produced energy and a lot of these are
well established in the literature. These techniques vary in many aspects as:
simplicity, convergence speed, digital or analogical implementation, sensors
required, cost, range of effectiveness, and in other aspects. This paper
presents a comparative study of ten widely-adopted MPPT algorithms; their
performance is evaluated on the energy point of view, by using the simulation
tool Simulink®, considering different solar
irradiance variations.
Keywords: Maximum power
point (MPP), maximum power point tracking (MPPT), photovoltaic (PV),
comparative study, PV Converter.
Title of the Paper: Stability
Enhancement for Multi-machine Power System by Optimal PID Tuning of Power
System Stabilizer using Particle Swarm Optimization
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Authors: Anant
Oonsivilai, Boonruang Marungsri
Abstract: This paper demonstrates the superior effectiveness of utilizing the
artificial search technique to ascertain parameters optimization of power
system stabilizer (PSS), contemplating proportional-integralderivative
controller (PID) for a multi-machine power system, compared to the customary
Ziegler-Nichols method. As the PID - PSS parameters are also tuned by the
Ziegler-Nichols method at the same operating point. Its effectiveness is
presented using four machines power system. Acquire settings of PID - PSS
which meliorate damping frequency of system are optimized by minimizing an
objective function using Particle Swarm Optimization, an artificial search
technique. The results convey eminent efficiency of the proposed PSO based
PID controller.
Keywords: Power system
stabilizer, PID tuning, Multi-machine power system, Particle Swarm
Optimization, Artificial intelligent search technique
Title of the Paper: An Innovative
Decision Support System for Strategic Investments in Power Sector
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Authors: Gabriela Prelipcean, Mircea Boscoianu
Abstract: Energy infrastructure investments occur in a highly dynamic
context, with many different risks. In project investment evaluation,
governments, investors and financial intermediaries are interested in a
methodology that include the risks and uncertainties in power sector (due to
changing energy price in competitive energy markets, uncertain future carbon
price, uncertain government policy on climate change, and uncertain international
regime on climate change mechanism). The risk of political shocks associated
with high uncertainties and volatility in the aftermath of global markets
turbulences could dramatically change the investment conditions and
technology selection in strategic energy sector. The analysis of the impact
of these policies on power investment is based on Real Options Analysis (ROA)
inspired from Dixit, Pindyck
(1994) optimization and Yang, Blyth
(2006) model combined with neural networks (NN).
Keywords: Discounted cash
flow (DCF), Real option analysis (ROA), Neural networks (NN), Price
uncertainty, Volatility, Flexibility.
Title of the Paper: Dynamic Analysis of
Electric Arc: From the Single-Phase State Approach to the Three-Phase Clarke
Approach
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Authors: Francesco Della Torre, Sonia Leva, Adriano
Paolo Morando
Abstract: In the present paper the analysis based on state equations method
is applied to the transient study of interrupted single- and three-phase
networks. The proposed approach is independent on the mathematical model
adopted to represent the electric arc. In the three-phase case, the Clarke
transformation allows us to perform the energy analysis of the three-phase
electric arc during any balanced or unbalanced transient conditions. The
Clarke energy balance related to the imaginary power concept permits to
design the breaker under study without the use of empirical coefficients
normally adopted in literature.
Keywords: Circuit
breakers, Switching transients, Transient analysis, Clarke Approach.
Title of the Paper: Modelling
Saturated Induction Machines with a View to On-line Dynamic Security Analysis
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Authors: Lucian Lupsa-Tataru
Abstract: During the dynamic processes, the induction machine, as component
part of interconnected power systems, is now exposed to large variations of
magnetic stress. To perform an analysis in on-line mode, when the time
required for the computation is a crucial consideration, these variations
have to be taken into account by means of a dynamic model that has to combine
accuracy with structural simplicity. Various dynamic d-q axis models of
induction machine, derived with the purpose of synthesis of the
vector-controlled system or with a view to off-line study, come to be
inappropriate for the on-line dynamic security assessment. This is mainly due
to models complex structure, which incorporates additional
saturation-dependent parameters. The approach in literature, wherein the
concept of dynamic (differential) inductance predominates over, will be
avoided by reconsidering the winding flux linkage state-space model of induction
machine. An auxiliary algebraic equation suitable for a solving in relation
to magnetizing inductance will be formulated to complete the original
structure of flux linkage state-space model. It will be shown that the
employment of the well-established Frölich model to
describe the machine magnetizing curve makes feasible the magnetizing
inductance expressing in terms of only winding flux linkages. Besides, we
will advance the procedure of computing the magnetizing inductance when a
magnetizing curve piecewise representation based on Frölich
type model is employed. The derivation will be carried out without altering
the structural equations of the generalised d-q
axis mathematical model of induction machine.
Keywords: Modelling, Dynamic Security Analysis, Induction Machine,
Main Flux Saturation, Flux Linkage State-space Model, Frolich
Model.
Issue 6, Volume 3,
June 2008
Title of the Paper: Reengineering of
Distribution lines for Power Loss Reduction-Bhiwandi
Case Study
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Authors: Shrirang
Karandikar, Ashok Ghatol
Abstract: The Indian Power sector is currently undergoing sea change.
Increased efficiency in the sector can help in the task of achieving the
national perspective of power to everyone by the year 2012. The transmission
and distribution losses world wide when compared shows that in the developing
nations these are very high as compared to developing nations. Therefore this
is definitely the matter of concern to the developing nations. The
distribution system performance is normally controlled by either voltage
regulation at the farthest end of the distribution line or thermal limitation
of the current carrying conductor of such distribution line. The case study
presented here is carried out in the Bhiwandi city
which is textile hub of the state of Maharashtra in
India.
The Bhiwandi city is near Mumbai and has large
concentrated load of industry mainly related to Textile business. The
reengineering of the distribution system carried out has yielded the results
and the distribution system losses have reduced from highest in the state to
below state average.
Keywords: Distribution
lines, Overload, ASCR Conductor, Power Losses, Reliability, Controlling
carbon emission.
Title of the Paper: Evaluation of the
Westinghouse Cycles
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Authors:
Miroslava Smitkova, Frantisek Janicek
Abstract: Hydrogen is industrially produced mainly from fossil fuels e.g. by
natural gas steam reforming, coal gasification and as a by-product of naphtha
reforming. A variety of technologies can be used for hydrogen production. In
the long term, with respect of a lack of fossil fuels, hydrogen produced from
water can play a very important role in the energy system. The goal of the
water splitting thermo-chemical cycle is the replacement of thermal
decomposition of water with several partial reactions. This paper deals with
the one of most promising water splitting thermo-chemical cycle – the
Westinghouse cycle. Simulation, optimization and overall evaluation
(including calculation of efficiency and life cycle analysis) of the
Westinghouse cycle were preformed and main obtained results are reported.
Keywords: hydrogen,
hydrogen production, water splitting thermo-chemical cycles, Westinghouse
cycle, life cycle analysis, solar energy
Title of the Paper: Dynamic Analysis of
Electric Arc: From the Single-Phase State Approach to the Three-Phase Clarke
Approach
DOWNLOAD
FULL PDF
Authors: Francesco Della Torre, Sonia Leva, Adriano
Paolo Morando
Abstract: In the present paper the analysis based on state equations method
is applied to the transient study of interrupted single- and three-phase
networks. The proposed approach is independent on the mathematical model
adopted to represent the electric arc. In the three-phase case, the Clarke
transformation allows us to perform the energy analysis of the three-phase
electric arc during any balanced or unbalanced transient conditions. The
Clarke energy balance related to the imaginary power concept permits to
design the breaker under study without the use of empirical coefficients
normally adopted in literature.
Keywords: Circuit
breakers, Switching transients, Transient analysis, Clarke Approach.
Title of the Paper: Energy Comparison
of MPPT Techniques for PV Systems
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FULL PDF
Authors: Roberto Faranda,
Sonia Leva
Abstract: Many maximum power point tracking techniques for photovoltaic
systems have been developed to maximize the produced energy and a lot of
these are well established in the literature. These techniques vary in many
aspects as: simplicity, convergence speed, digital or analogical
implementation, sensors required, cost, range of effectiveness, and in other
aspects. This paper presents a comparative study of ten widely-adopted MPPT
algorithms; their performance is evaluated on the energy point of view, by
using the simulation tool Simulink®, considering
different solar irradiance variations.
Keywords: Maximum power
point (MPP), maximum power point tracking (MPPT), photovoltaic (PV),
comparative study, PV Converter.
Title of the Paper: Investigation on
Leakage Current Waveforms and Flashover Characteristics of Ceramics for
Outdoor Insulators under Clean and Salt Fogs
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Authors: Suwarno
Juniko P
Abstract: Outdoor insulators play an important role in high voltage
transmission lines. Since long time ago, ceramic insulators are widely being
used in power systems at medium, high and extra high voltage levels. During
operation, the insulators may severe a certain degree of pollution which may
reduce their performances such as surface resistance and flash over voltages.
Under these conditions a large leakage current (LC) may flow on the surface
and degradation may take place. In long term the degradation may lead to the
flash over of the insulators. This paper reports the experimental results on
the leakage current characteristics of ceramics under various simulated
environmental conditions. The samples used are blocks of ceramics with
dimension of 250 x 50 x 20 mm3. The samples were made from same materials for
outdoor ceramic insulators. The samples were put in a test chamber with
controlled humidity and artificial pollution conditions. AC voltage with
frequency of 50 Hz was applied. The tests were conducted according to IEC
60-1 (1989) and IEC 507 (fog test). The LC waveforms up to flash over were
measured. The magnitudes as well as harmonic content of the LC were analyzed.
The correlation between LC waveforms and dry band arching phenomenon was also
elaborated. Experimental results showed that for clean insulators leakage
current was much smaller than polluted insulators. The waveform distortion
was observed particularly at positive half cycle when applied voltage was
increased to higher than 20 kV. This indicated that electric discharges
initiated from air proximity of the sample surface. For kaolin-salt polluted
insulators, the LC amplitude was much higher than clean insulators. LC
waveform distortion started at 10 kV. Unbalance distortion of LC waveforms
was observed similar to those of clean samples. However, for kaolin-salt
polluted samples, the distortion was observed mainly at negative half cycles
which indicated that the electric discharges were initiated from the
salt-kaolin layer embedded on the sample surface. Observation of LC waveforms
during the process of flashover revealed that THD of increased with the
applied voltage.
Keywords: outdoor
insulator, ceramics, leakage current, harmonic, dry band, flashover
Title of the Paper: Stability
Enhancement for Multi-machine Power System by Optimal PID Tuning of Power
System Stabilizer using Particle Swarm Optimization
DOWNLOAD
FULL PDF
Authors: Anant
Oonsivilai, Boonruang Marungsri
Abstract: This paper demonstrates the superior effectiveness of utilizing the
artificial search technique to ascertain parameters optimization of power
system stabilizer (PSS), contemplating proportional-integralderivative
controller (PID) for a multi-machine power system, compared to the customary
Ziegler-Nichols method. As the PID - PSS parameters are also tuned by the
Ziegler-Nichols method at the same operating point. Its effectiveness is
presented using four machines power system. Acquire settings of PID - PSS
which meliorate damping frequency of system are optimized by minimizing an
objective function using Particle Swarm Optimization, an artificial search
technique. The results convey eminent efficiency of the proposed PSO based
PID controller.
Keywords: Power system
stabilizer, PID tuning, Multi-machine power system, Particle Swarm
Optimization, Artificial intelligent search technique
Title of the Paper: Energy
Saving through Solar Lighting Systems
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Authors: Roberto Faranda, Kim Fumagalli
Abstract: Among the energy expenses for a building, the lighting system can
contribute up to 50% of the total electrical consumption, and especially
large quantities of energy are used in schools and office buildings. One
possible method to reduce such consumption is to exploit solar, or natural,
light. Through natural light, it is possible to illuminate indoor
environments while maintaining appropriate illuminance
levels necessary for indoor activities. Indeed, it is a mistake to search for
the maximum energy savings, if this creates a possible disturbance to a
person’s visual health in the office. Moreover, it is important to highlight
that the light quantity is not enough to evaluate the working comfort; the
light quality must also be held in consideration. Therefore, for optimal
energy savings, the most favorable combination of the elimination of energy
waste, the light quality, and the light quantity must be assessed.
Keywords: Natural light,
solar light, energy saving, Daylighting, energy
certification, insulation
Title of the Paper: Generation
Reliability Assessment in Power Pool Market Using MCS and Intelligent Systems
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Authors: H. Haroonabadi, M.-R. Haghifam
Abstract: Deregulation policy has caused some changes in the concepts of
power systems reliability assessment and enhancement. In this paper,
generation reliability is considered, and a method for its assessment using
intelligent systems is proposed. Also, because of power market and
generators’ forced outages stochastic behavior, Monte Carlo Simulation is
used for reliability evaluation. Generation reliability,
merely focuses on interaction between generation complex and load. Therefore,
in this research, based on market type and its concentration, reserve margin,
and various future times, a Neuro-Fuzzy system is
proposed for evaluation of generation reliability which is valid and usable
for all kinds of power pool markets. Finally, the proposed method is assessed
on IEEE-Reliability Test System with satisfactory results. It will be shown
that if market becomes more concentrated or price elasticity of demand
increases, reliability will improve.
Keywords: Generation
reliability, Power pool market, Monte Carlo simulation, Intelligent systems.
Title of the Paper: Application of
Adaptive Tabu Search for Optimum PID Controller
tuning AVR System
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Authors: Anant
Oonsivilai, Padej Pao-La-Or
Abstract: This paper postulates the ascertainment of offline, optimal
proportional-integral-derivative (PID) controller parameters of an automatic
voltage regulator (AVR) system using Adaptive Tabu
Search (ATS) algorithm. By minimizing the performance index such as
integrated absolute error (IAE), the integral of squared error (ISE), and the
integral time absolute error (ITAE) employed method, the parameters of this
PID controller is acquired. For significant contrast, the classical tuning
proposed by Ziegler and Nichols is applying compared with demostrated
method. The performance of the proposed tuning mechanism had been
demonstrated and analysed in efficient and robust
in improving the step response of an AVR system with application to control
of synchronous generator excitation system by selecting the suitable
performance index.
Keywords: Optimal
control, AVR, Excitation system, PID controller, Adaptive Tabu
Search 1 Introduction .
Issue 7, Volume 3,
July 2008
Title of the Paper: Identification of
Wheeling Paths and MW- Redispatching for Transmission Loading Relief by Extended
Sensitivity Analysis
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Authors:
Hiromu Hamada, Kaoru Koyanagi, Ryuichi Yokoyama
Abstract: - This paper proposes the practical method for MW- redispatching and identifying wheeling paths taking
transmission line constraint into account based on an extended sensitivity
analysis. Because the decision for the MW- dispatch/ scheduling is requested
to be very fast, the method proposed here brings the efficiency of
computations by utilizing the existing practical approaches for obtaining the
optimal solution. So, in this paper, a method of MW- redispatching
by using the practical sensitivity-based technique, which is used for identifying
the wheeling paths in overloaded states is proposed. By the proposed method, the
MWredispatching problem without using OPF solutions
can be solved. On the other hand, in deregulated electricity markets, appropriate
and efficient levying of the wheeling rate is one of the critical issues. It
is obvious that if wheeling paths from suppliers to customers could be
identified appropriately, it becomes possible to set up the proper and fair
wheeling rate according to the degree of power flow in each wheeling path. Until
now, we have reported that it is possible to identify paths of the wheeling
in any situation effectively by making use of the sensitivities calculated by
an extended sensitivity analysis. In the previous research based on the
sensitivity analysis, constrains on transmission lines have not been taken
into consideration. Then, in this paper, the method of identifying wheeling
paths is presented taking transmission line constrains into account based on
an extended sensitivity analysis. In order to show the validity of the
proposed method, a series of simulations on the IEEE 30-bus test system are
conducted and numerical results are demonstrated.
Key-Words: - Wheeling
path, Sensitivity analysis, Wheeling
rate, Congestion management, Deregulation, Electricity market.
Title of the Paper: Complete Dynamic Behaviour Mathematical Modelling
of Hydromechanical Equipment. Case study: Hydro
Power Plant Raul Mare-Retezat, Romania
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Authors: Flavius Dan Surianu, Constantin Barbulescu
Abstract: - The paper is presenting an application of “HYDRO” mathematical
model for simulating the dynamics of hydraulic equipment in the special case
of the fast loading with electric power of Raul Mare-Retezat,
hydro power plant, Romania.
Based on the mathematical model described in the paper, a software
application is developed in Delphi
environment. This software tool is designed for studying the behavior of the
model in the event of perturbations. The results of the mathematical
simulation are compared with those experimentally obtained through SCADA
monitoring system with which the hydro-power plant is equipped.
Key-Words:
- Hydro power plant, Dynamic behaviour, Mathematical
model, Hydraulic parameters, Hydro mechanical equipment, Hydro turbine.
Title of the Paper: Evaluation of
Transmission Cost Allocation Methods using a Specially Designed Software
Application
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Authors: Flavius Dan Surianu, Constantin Barbulescu
Abstract: – The current paper presents an evaluation of transmission cost
allocation methods. The case study used is represented by the power system
based on the South-West side of the Romanian National Power System. The
evaluation is carried-out using a software tool specially designed for this
purpose. It was elaborated at “Politehnica” University of
Timisoara, within
the Power Engineering Department. The algorithm is implemented in Matlab software. Two operating regimes are evaluated. The
base case for the power system mentioned previously and a congested regime, for
the same power system, is analyzed from the transmission cost allocation
mechanism point of view. There are evaluated three transmission cost
allocation methods: zonal allocation method, postage stamp method and locational marginal prince method. The algorithm of the
software and the obtained results are presented and analyzed.
Key-Words:
– power system, cost allocation method, tool, software, generating unit, load,
power flow, marginal cost.
Title of the Paper: Ancillary Services
Management in an Open Market Environment
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Authors: Nikola
Svigir, Igor Kuzle, Darjan Bosnjak
Abstract: - In accordance with accepted package of Energy laws in 2001 and
their harmonization with Directive 2003/54/EC in 2004 beginning the process
of opening and liberalization of electric power sector in the Republic of
Croatia. The Energy law stipulates the
following activities of the power sector generation of electricity (apart
from electricity generation for eligible customers): transmission of
electricity, distribution of electricity, retail supply of electricity (apart
from retail supply of electricity for customers free to chose the supplier) as
well as organization of the electricity market. This article gives an
overview of ancillary services and describes ways to measure, estimate and
allocate costs for some ancillary services. Also, there is a description of the
current situations in some countries in southeast Europe.
Key
Words: - Ancillary Services, Deregulation, Electricity Market, Frequency
Regulation, Reactive Power Regulation, Reserves, Transmission System Operator.
Title of the Paper: Improving of
Transient Stability of Power Systems By supplementary Controllers of UPFC
Using Different Fault Conditions
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Authors: A.
Kazemi, F. Mahamnia
Abstract-- Long distance AC transmission is often subject to stability problems , which limits the transmission capability. Large
interconnected power systems often suffer from weakly damped swings between synchronous
generators and subsystems. This paper presents two methods ,
based on the use of nonlinear system model , to improve transient stability
and damping of power swings using UPFC. A state- variable control strategy
has been derived using local available signals of real and reactive power. The
results of simulation tests of two control methods, undertaken using a small
multi-machine system model, have been presented. The simulations show that
the methods make good results in different fault places and clearing time. The
results present that controlling series part of UPFC can improve transient
stability by state-variable control method, but simultaneous control of shunt
and series part of UPFC can damp voltage oscillations by direct Lyapunov method.
Key-Words:
Transient stability, Local measurement, Flexible ac transmission systems (FACTS) , UPFC , Power oscillations damping.
Issue 8, Volume 3,
August 2008
Title of the Paper: Improvement of
Technological and Electric Performances for Plate-Type Electrostatic
Precipitators with Three Sections
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Authors: Gabriel Nicolae Popa, Victor Vaida, Angela
Iagar, Corina Maria Dinis
Abstract: The plate-type electrostatic precipitators have long been used by
industry applications as the preferred method for controlling pollution with
dust particles. The paper analyze the collection efficiency, for electrostatic
precipitators with three sections (still, there is in industry applications),
when are used different voltage supplies of electrostatic precipitators
sections, the gas particles mass distributions, element average V-I curves,
onset Corona voltage, spark discharge voltage, current density, collection
efficiency, the inlet and the outlet dust concentration for different
energization of sections. It’s been performed an analysis of the total
harmonic distortion coefficient of the current absorbed by the source, the
supply voltage, the apparent and active power (for fundamental and harmonics),
and the power factor (global, fundamental’s and deforming) in situation when
the current’s value from the ESP field was superiorly limited.
Keywords:
Pollution, Electrostatic precipitators, Collection efficiency, Total harmonic
distorsion
Title of the Paper: Analysis of Wind
Potential and Energy Production in Naxos Island, Greece
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Authors: Ioannis Fyrippis, Petros J. Axaopoulos,
Gregoris Panayiotou
Abstract: A remote location in the northeastern part of Naxos Island, Greece,
has been investigated with respect to wind power potential, using real data
collected from a measurement mast. The obtained wind characteristics were
statistically analyzed using the Weibull and Rayleigh distribution functions.
The results from this investigation showed that the selected site falls under
Class 7 of the international system of wind classification as the mean annual
wind speed recorded in the area was 7.4 m/s and the corresponding annual mean
power density was estimated to be 420 W/m2. Furthermore, the prevailing wind
directions characterizing the area were the northeastern and the
north-northeastern. From the statistical analysis of these results, it was
revealed that the Weibull model fitted the actual data better. This remark was
further enhanced by the evaluation of the performance of these two
distributions. Finally, the expected energy production from two potentially
installed wind turbines of 1 MW and 2.5 MW has been determined, based on the
available wind potential. The resulting annual energy production is 4 GWhe and
8 GWhe for the wind turbine of 1 MW and 2.5 MW respectively.
Keywords:
Wind potential, Wind speed, Wind power density, Weibull and Rayeigh
distribution, wind turbine, Greece
Title of the Paper: Flat Facet Parabolic
Solar Concentrator with Support Cell for One and More Mirrors
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Authors: Ernst Kussul, Tatiana Baidyk, Oleksandr
Makeyev, Felipe Lara-Rosano, Jose M. Saniger, Neil Bruce
Abstract: Parabolic dish solar concentrators are very expensive devices with a
cost of up to a half of the total cost of a solar power station. The specific
technology of parabolic mirror manufacturing makes the decrease of the cost
very problematic. Even in mass production the cost of a parabolic mirror is
estimated as $500 per square meter. There is another way to make a parabolic
concentrator by approximating a parabolic surface with large number of small
flat mirrors. We created a small prototype of this type of solar concentrator
which contains 24 flat mirrors in the form of equilateral triangles with side
length of 50mm. This prototype has special nuts to adjust the positions of the
nodes in the points of connections of the apexes. These nuts make it possible
to approximate the parabolic shape in an easy and inexpensive way.
Keywords:
Solar Concentrator, Flat Mirrors, Recognition System
Issue 9, Volume 3,
September 2008
Title of the Paper: Design and Testing
of a Steam-Resistant Insulation System for the Stator of a Low-Voltage
Turbo-Generator Taking Thermal Aspects into Account
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Authors: V. Sihvo, J. Nerg, J. Pyrhonen
Abstract: Traditional insulating materials used in low-voltage machines cannot
normally withstand steam because of the simultaneus presence of high
temperature and humidity. In order to find a steam-resistant insulation system
that includes magnet wire, groundwall and phase insulations and impregnating
resin, accelerated aging tests were carried out applying small-scale models.
Eight different insulation systems were constructed on these models, and seven
different wire insulations were tested. The specimens were immersed in hot,
pressurized water, which influenced the material instead of steam. Suitable
materials for each part of the insulation system of a low-voltage,
random-wound machine were found. Taking into account the thermal
conductivities of each insulating material, the heat transfer of the machine
was calculated for all the tested insulation systems.
Keywords:
AC Machines, Induction machine, Insulation, Magnet Wire, Water
Title of the Paper: Economic Load
Dispatch with Emission Constraints using Various PSO Algorithms
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Authors: K. Sathish Kumar, V. Tamilselvan, N. Murali,
R. Rajaram, N. Shanmuga Sundaram, T. Jayabarathi
Abstract: This paper develops an efficient and clear insight view about the
application of various PSO algorithms to the economic load dispatch problem
with emission restrictions as the constraint. Solution acceleration techniques
in the algorithm which enhance the speed and robustness of the algorithm are
developed. The power and usefulness of the algorithm is demonstrated through
its application to a test system.
Keywords:
Economic dispatch, Combined Emission and economic dispatch (CEED),Particle
swarm optimization(PSO), Dispersed particle swarm optimization(DPSO),New
particle swarm optimization(NPSO)
Title of the Paper: Simulation of
Electric Field and Potential Distributions on Silicone Rubber Polymer
Insulators under Contamination Conditions Using Finite Element Method
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Authors: Boonruang Marungsri, Winai Onchantuek
Abstract: This paper presents the simulation results of electric field and
potential distributions along surface of silicone rubber polymer insulators
under clean and contamination conditions. In former experimental research,
silicone rubber polymer insulators having near the same leakage distance are
subjected to 15 kV during 50 test cycles of artificial salt fog ageing test.
After 50 test cycles, alternate sheds silicone rubber polymer insulator showed
better contamination performance than straight sheds silicone rubber polymer
insulator. Severe surface ageing was observed on the straight sheds insulator.
The objective of this work is to elucidate that electric field distribution
along straight sheds insulator higher than alternate shed insulator in salt
fog ageing test. Finite element method (FEM) is adopted for this work. The
simulation results confirmed the experimental data, as well.
Keywords:
Electric field distribution, potential distribution, silicone rubber polymer
insulator, straight sheds, alternate shed, clean condition, contamination
condition, finite element method
Issue 10, Volume 3,
October 2008
Title of the Paper: Practical Operation
Control and Planning of NAS Battery
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Authors: Yusuke Hida, Ryuichi Yokoyama, Kenji Iba,
Kouji Tanaka
Abstract: The role of the battery energy storage system (BESS) has become
essential in modern power systems. Among various types of BESS, NAS (Sodium
and Sulfur) battery is one of the most promising products. NAS battery system
is a commercial product implemented widely in Japan. A practical strategy and
planning of NAS battery operation is proposed in this paper. In Planning, a
load forecast using past cases is introduction. In strategy, two important
parameters are evaluated to get a satisfactory performance of the load
following operation of NAS battery. The first one is the amount of reserve
(margin) and the second one is the trigger of release. The amount of margin is
defined as a percentage of “charged battery energy”. A predetermined threshold
is used to control the battery energy use in this paper. By a series of
computational simulations, it is verified that the load-following operation
introduced by this strategy yields flexible and cost-benefit effectiveness.
Keywords: NAS Battery, Energy Storage System, BESS, Load Following Operation,
Load Forecast
Title of the Paper: Evaluation and
Simulation of a Commercial 100W Polymer Electrolyte Membrane Fuel Cell (PEMFC)
Stack
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Authors: Gregoris Panayiotou, Petros Axaopoulos,
Ioannis Fyrippis
Abstract: In this study the performance of a commercial air-breathing 100 W
Polymer Electrolyte Membrane Fuel Cell (PEMFC) stack is experimentally and
theoretically evaluated using a widely known commercially available generic
mathematical model of the Transient System Simulation Software (TRNSYS). The
simulation results were compared with the experimental data to investigate the
convergence between them and to validate the model in order of establishing
confidence in the model when used with rather small FC stacks. The PEMFC stack
used in this project is a commercial product named H-100FC. The conclusions
coming out of this study show that the simulation results are in good
agreement with the experimental data and consequently this model can be
reliably used to simulate sub kilowatt PEMFC s. A series of interventions for
the improvement of the performance of this commercial PEMFC stack is proposed.
Keywords: PEMFC, Fuel Cell, Experimental, Commercial, Sub-kilowatt,
Simulation, TRNSYS
Title of the Paper: Alternative
Technique of Classifying PMUs at Optimal Environment in Power System
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Authors: Kenedy A. Greyson, Anant Oonsivilai
Abstract: This paper presents an alternative technique of classifying
measuring units in a measuring optimal environment of a power system. Each
measurement is given a certain weight depending on its effect on state
estimation solution. The technique used is to fit curve fitting to determine
the optimal approximation in the absence of other measurements. Absence of
measurement may be due to the lack of communication links, being identified as
a bad measurement and that it has to be removed, or for any other reason that
may apply. To obtain the measurement unit placement, singular value
decomposition (SVD) technique was used to solve the problem of minimum number
of measurements placement while maintaining accuracy as well as network
observability. The relative error is used to compare the change in estimated
solution related to the true value. Finally, the critical and non critical
measurements are identified in the system. The proposed method is applied to
determine the measurement weights of the measurements weights of optimal PMU
weights in state estimator solutions for the IEEE 14-bus, IEEE 30-bus and
Tanzania Electric Supply Company (TANESCO) systems.
Keywords: Measurement placement, accuracy, weight, state estimation,
coefficient of determination
Title of the Paper: Electromagnetic
Field Distribution of Phase-Sequence Orientation of a Double-Circuit Power
Transmission Line Based on Finite Element Method
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Authors: P. Pao-La-Or, A. Isaramongkolrak, T.
Kulworawanichpong
Abstract: This paper proposes a mathematical model of electric and magnetic
fields caused by high voltage conductors of electric power transmission
systems by using a set of second-order partial differential equations. This
study has considered the effect of conductor phase-sequence orientation on
electromagnetic fields emitted around a double-circuit, extra high-voltage,
power transmission line. Five typically-used phase-sequence orientations in
Thailand and one three-phase fault for 500-kV double-circuit transmission
lines are examined. Computer-based simulation utilizing the two dimensional
finite element method in the time harmonic mode, instructed in MATLAB
programming environment with graphical representation for electric and
magnetic field strength have been evaluated. The simulation results showed
that the phase-sequence orientation is one among key factors to influence the
electromagnetic field distribution around the transmission line.
Keywords: Phase-sequence, Electric Fields, Magnetic Fields, Finite Element
Method (FEM), Transmission Line, Computer Simulation
Issue 11, Volume 3,
November 2008
Title of the Paper: Harmonic Detection
Algorithm based on DQ Axis with Fourier Analysis for Hybrid Power Filters
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Authors: K-L. Areerak
Abstract: The paper presents the DQ axis with Fourier analysis (DQF) algorithm
to identify harmonic quantities for hybrid power filters. This algorithm is a
combination of the advantages of DQ axis method and sliding window Fourier
analysis (SWFA). This paper also presents the harmonic elimination by using
the DQF algorithm for both three-phase balanced and unbalanced systems. The
results show that the unbalanced system becomes a balanced condition with
successfully reducing the quantity of system harmonic components after
completely harmonic elimination by using the proposed algorithm. The results
confirm that the DQF algorithm is flexible and suitable in terms of design for
hybrid power filters.
Keywords: Harmonic elimination, harmonic detection, hybrid power filter, DQ
axis with Fourier
Title of the Paper: Study of Influence
of an Overhead Ground Wire on Electric Fields around the HV Power Transmission
Line Using 2D and 3D Finite Element Method
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Authors: P. Pao-La-Or, A. Isaramongkolrak, T.
Kulworawanichpong
Abstract: This paper has proposed a mathematical model of electric fields
caused by high voltage conductors of electric power transmission systems by
using a set of second-order partial differential equations. This study has
considered the effect of the overhead ground wire on electric fields emitted
around the high voltage transmission line. Comparison among two test cases,
with and without the overhead ground wire, has been illustrated.
Computer-based simulation utilizing the two-dimensional (2D) and
three-dimensional (3D) finite element method in the time harmonic mode,
instructed in MATLAB programming environment with graphical representation for
electric field strength has been investigated. The simulation results show
that the transmission system having the overhead ground wire can remarkably
reduced the intensity of the electric field strength.
Keywords: Overhead Ground Wire (OHGW), Electric Field Strength, Finite Element
Method (FEM), Transmission Line, Computer Simulation
Title of the Paper: An Efficient
Particle Swarm Optimization (EPSO) for Economic Dispatch Problems With
Transmission Losses for Both Smooth and Non-smooth Cost Functions
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Authors: S. Muthu Vijaya Pandian, K. Thanushkodi
Abstract: An Efficient Particle Swarm Optimization (EPSO) technique, employed
to solve Economic Dispatch (ED) problems including losses in power system is
presented in this paper. With practical consideration, ED will have nonsmooth
cost functions with equality and inequality constraints that make the problem,
a large-scale highly constrained nonlinear optimization problem. The proposed
method expands the original PSO to handle a different approach for satisfying
those constraints. In this paper, an Efficient Particle Swarm Optimization (EPSO)
technique is employed so that faster convergence is obtained for the same
results published in IEEE Proceedings. To demonstrate the effectiveness of the
proposed method it is being applied to test ED problems, one with smooth and
other with non smooth cost functions considering valve-point loading effects.
Comparison with other optimization techniques showed the superiority of the
proposed EPSO approach and confirmed its potential for solving nonlinear
economic load dispatch problems with losses.
Keywords: Economic load dispatch, Particle swarm optimization, Valve point
loading effect
Title of the Paper: Comparison of Output
Current Harmonics of Voltage Source Inverter used Different PWM Control
Techniques
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Authors: Mehmet Yumurtaci, Seydi Vakkas Ustun, Secil
Varbak Nese, Hasan Cimen
Abstract: Induction motor driver circuits are harmonic sources because of
their semiconductor switching power components. Harmonics are provided by
inverter, are inevitable, so optimization of these is made. For this purpose,
more fast and had less switching losses ones of used semiconductor power
switching components are preferred, also PWM (Pulse Width Modulation)
techniques used in inverter are developed. In this paper, Sinus PWM (SPWM),
Square Wave PWM, Carrier Based SVPWM and Space Vector PWM (SVPWM) techniques
are implemented using dsPIC30F2010 micro controller which is one of DSP
(Digital Signal Processor) controllers developed for motor control. Output
current harmonics of open loop voltage source inverter for different PWM
techniques are measured by harmonic analyzer. Comparison of PWM techniques is
made with obtained measurement results and it is shown that minimum current
harmonic is produced by SVPWM technique with experimental results.
Keywords: Square Wave PWM, SPWM, Carrier Based SVPWM, SVPWM, Harmonic, DSP,
VSI
Issue 12, Volume 3,
December 2008
Title of the Paper: Estimation of Load
Diagrams in MV/LV Substations
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Authors: J. N. Fidalgo
Abstract: Efficient power systems planning and exploration require the
estimation of load diagrams at the different levels of the distribution
networks. In particular, the planning of new MV/LV substations requires the
assessment of their expected load curves under different exploration
scenarios. The deregulation process and environment preservation constraints
also compel the need of higher efficiency levels in network investments. This
paper describes the methodologies adopted for the estimation of load curve
diagrams in MV/LV substations. The assessment process is based on billing data
(monthly energy consumption, hired power contracts, activity codes and weekday
type), which is the unique information generally available at this level of
the network. The most common approaches use measurements in typical classes of
consumers defined by experts to construct inference engines that, most of the
times, only estimate peak loads. In this paper, two different approaches are
tested. The first one is based on the definition of classes using a clustering
algorithm and uses Artificial Neural Networks (ANN) for the estimation of the
MV/LV substation load curve. In the second one, an ANN is trained to output
directly the load diagram estimated for each individual consumer. This article
describes the adopted methodologies and presents some representative results.
Performance attained is discussed as well as a method to achieve confidence
intervals.
Keywords: Load estimation, Clustering, Artificial neural networks,
Distribution networks
Title of the Paper: Steady Sate Analysis
of Self-Excited Induction Generator using Phasor-Diagram Based Iterative Model
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Authors: Kanwarjit Singh Sandhu, Dheeraj Joshi
Abstract: Induction generators in self excited mode are found to be suitable
for remote and windy locations. Prior to installation there is a need to
predict the behaviour of machine under all possible operating conditions. This
is possible through steady state modeling of such generators. Steady state
analysis of self excited induction generator (SEIG) needs an estimation of
generated frequency and magnetizing reactance under all possible operating
conditions. So far most of the researchers have used loop impedance, nodal
admittance or iterative techniques to determine the steady state performance
of such machines. In this paper a new model based upon phasor diagram of
induction generator has been proposed to analyze the behaviour of self excited
induction generator. Modeling results in a third order equation in generated
frequency and a simple expression for magnetizing reactance. Complete
mathematical analysis to derive the different expressions is presented here.
Computed results have been compared with experimental results on test
machines. Closeness between the two proves the validity of proposed modeling.
Keywords: Non-conventional sources, Renewable energy, Steady state analysis,
Self-excited induction generator (SEIG), Wind energy
Title of the Paper: Comprehensive
Analysis of Electrical Distribution Network Operation – An Approach of
Electrical Load Modelling
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Authors: Jako Kilter, Mati Meldorf
Abstract: The electrical distribution network operation depends considerably
on network busloads, which are formed by active and reactive power of the
substations. Therefore, the network operation variables such as power flows,
currents, voltages, etc. change similarly as do loads. It is possible to
notice periodicity, temperature dependency, stochasticity etc. This paper
describes the distribution network monitoring methodology based on the
mathematical model of load, i.e. in described approach, the network busloads
are modeled using the mathematical model of load and afterwards, modeled load
values in different conditions are used for network monitoring. Monitoring is
understood as network operation forecasting, simulation, and analysis. Success
of monitoring is guaranteed by an adequate mathematical model, which describes
the changes of the load during the entire observable period, both in the past
and in the future. The results, obtained through network monitoring process
could be used for long- and short-term planning and dispatching, considering
adequate changes in time, temperature dependency, probable deviations of the
state variables etc. Based on the results it is possible to assess network
operation and possible future scenarios and their effect on the network and
apply appropriate solutions to enhance system reliability and security. An
application of network analysis, modelling and estimation but also validation
of results with real measurements obtained from real distribution network is
presented.
Keywords: Busloads, distribution network, mathematical model of load, load
monitoring, network operation monitoring, SCADA, state estimation
Title of the Paper: Monte Carlo
Simulation for Voltage Stability Index Evaluation
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Authors: T. Ratniyomchai, T. Kulworawanichpong
Abstract: This paper presents an alternative approach to evaluate voltage
stability indices in electric power systems by using Monte Carlo simulation
(MCS). Fast voltage stability index (FVSI), line stability index (Lmn) and
line stability factor (LQP) are used as indicators to determine the capability
of reactive power loading at a given bus position. Conventionally, loading the
test bus with pure reactive power is not realistic because power system load
changes randomly at every load bus in both real and reactive powers. In this
paper, MCS was introduced to simulate load increment of all load buses with
appropriate random numbers and their probability. From this approach, all the
indices mentioned above can be calculated repeatedly with a large number of
trials. To evaluate its use, a small fivebus, and the standard IEEE 30- and
57-bus test systems were employed for demonstration. As a result, comparing
among these indices, the weakest bus of the test system can be identified with
some degree of confidence.
Keywords: Fast voltage stability index, line stability index, line stability
factor, Monte Carlo simulation
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