|
Issue 1, Volume 7,
January 2012
Title of the Paper: Application of Ant
Colony Algorithm to the Analysis of High Frequency Equivalent Circuit of DC
Motor
DOWNLOAD
FULL PDF
Authors: Jinfeng Liu,
Xudong Wang, Nan Jiang
Abstract: The Electromagnetic Compatibility (EMC) of direct current (DC) motor
windings is a system model which is able to reflect the functional characters
of the system in the whole EMC specified frequency(150KHz~30MHz). For most
motor designing process, it always evaluated the inductance of windings in
lower or working frequency; however, when analyzing the conducted
interference, it is necessary to take some parameters in high frequency into
account in building up the EMC model, such as the noticeable distributed
capacitance among the windings or between windings and shells. Past research
neglected the common-mode current generated by the high frequency interference
through motor bearings coupled with shells, since the parasitic capacitance of
rotor core comes from armature windings supplied sufficient paths. In EMC
modelling for DC motor problem, first test the impedance of windings by
experiments, then generate the equivalent circuit with total parameters. At
present, it is a difficulty that how to choose the parameters. Most
researchers preferred to adopt analytical calculation, however, it could not
reflect the essence of the model since it requires many simplification. As a
result, this paper adopted ant colony algorithm (ACA) with positive feedback
to intelligent search and global optimize parameters of equivalent circuit.
Simulation result showed that impedance of equivalent circuit calculated by
this algorithm was the same as experimental result in the whole EMC frequency.
In order to further confirm the validity of ACA, PSPICE circuit simulation was
adopted to simulate the spectrum of common mode Electromagnetic Interference
(EMI) of equivalent circuit. The simulation result accorded well with the
experiment result received by EMI receiver. So it sufficiently demonstrated
correctness of ACA in the analysis of high frequency equivalent circuit.
Keywords: Ant colony
algorithm, Motor windings, EMC, Conducted interference, Common mode EMI,
PSPICE simulation, EMI receiver
Title of the Paper: Optimal Capacitor
Placement to Reduce Losses in Distribution System
DOWNLOAD
FULL PDF
Authors: Anwar S.
Siddiqui, Farrukh Rahman
Abstract: Distribution system provides a final link between the high voltage
transmission system and the consumers.To improve the overall efficiency of
power system, the performance of distribution system must be improved. An
important method of controlling bus voltage is by shunt capacitor banks at the
buses at both transmission and distribution levels along lines or substation
and loads. The problem of capacitor allocation in electric distribution
systems involves maximizing “energy and peak power (demand) loss reductions”
by means of capacitor installations. As a result power factor of distribution
system improves. A 10 bus radial distribution system is taken as model. The
load flow program is executed using Fuzzy Logic toolbox of MATLAB. Fuzzy logic
based technique is used for determination of suitable location of capacitor
placement. Shunt capacitors to be placed at the nodes of the system will be
represented as reactive power injections. Fuzzy techniques have advantages of
simplicity, less computations & fast results.
Keywords: Power System,
shunt capacitor banks, bus voltage control, Capacitor Placement
Title of the Paper: System Frequency
Regulation Investigation in Doubly Fed Induction Generator (DFIG)
DOWNLOAD
FULL PDF
Authors: Xue Yingcheng,
Tai Nengling
Abstract: The conventional decoupling control in the variable-speed doubly fed
wind turbines has little support to the system frequency. The characteristics
of doubly fed induction generator (DFIG) wind turbines and conventional plant
are compared. The contributions of DFIG to system inertial response and
frequency regulation are investigated. The influence of auxiliary loop
parameters on the inertial response is illustrated. The paper also introduces
a novel algorithm to enhance the participation of DFIG in existing frequency
regulation mechanisms. The proposed approach takes advantage of the fast
response capability associated with DFIG. The control system consists of four
functional modules, i.e. frequency control, rotational speed delay recovery,
speed protection and coordination control with conventional generators.
Simulation results show that the control strategy has a fast response speed to
the transient frequency error. It proves that wind farms can participate in
the system frequency regulation to a certain extent.
Keywords: DFIG, inertial
response, wind turbine generators, Frequency regulation, power control
Title of the Paper: Aggregate Static
Power Load Modeling in Coalmine
DOWNLOAD
FULL PDF
Authors: A. O. Pei, M.
U. Long-Çua
Abstract: In order to overcome the defects of the traditional static load
modeling in coalmine, a new modeling method is proposed in this paper. First,
a new clustering method based on improved PSO algorithm is presented to
classify the load data in order to reduce the number of load model before
modeling. Second, RBF neural network based on improved PSO algorithm is put
forward to establish aggregate load model. Finally, verified by an example,
the method in this paper can greatly improve the accuracy of the model
compared with traditional static load model.
Keywords: aggregate static
load model, particle swarm clustering algorithm, subtractive clustering
algorithm, K-means clustering algorithm, radial basis neural network, power
grid in coalmine
Title of the Paper: Comparing
Efficiency of PSO with GA in Transmission Expansion Planning Considering
Network Adequacy
DOWNLOAD
FULL PDF
Authors: Meisam Mahdavi,
Amir Bagheri, Elham Mahdavi
Abstract: The lines adequacy of the network is necessary to provide load
demands when the network is expanding, because its lack caused by load
interruption. In this paper, in order to take the transmission lines condition
after expansion into account from the line loading view points, the adequacy
of the transmission network is considered for the solution of the STNEP
problem. To obtain the optimal network arrangement, a discrete particle swarm
optimization (DPSO) algorithm is being used for minimizing the network
construction and operational cost and compared with genetic algorithm (GA).
The particle swarm optimization is a recently developed evolutionary algorithm
based on the swarm behavior in the nature and has a strong ability to find the
most optimistic results. The motivation for using the DPSO technique is to
reduce design effort and find an optimum planning network. The effectiveness
of the proposed idea is tested on the Garver's six-bus network and an actual
transmission network of the Azerbaijan regional electric company in Iran. The
evaluation results evaluation reveals that the annual worth of the network
adequacy has a considerable effect on the network arrangement. In addition,
the obtained network, based on the DPSO algorithm, has lower investment cost
and higher adequacy rate. To verify the results, expansion cost index on
adequacy rate for IEEE Garvers network has been compared with GA results.
Keywords: DPSO, GA, STNEP,
Network adequacy, Optimization problem, Transmission lines
Issue 2, Volume 7,
April 2012
Title of the Paper: Synchronised Linear
Ramp-Pulse Based Triggering Pulse Generation ON/OFF Control for Solid-State
Switches: Capacitor Switching Applications
DOWNLOAD
FULL PDF
Authors: K. Subramanian,
K. K. Ray
Abstract: This paper describes a newly developed triggering circuit, has been
use to turn on and off the solid-state switches, such as TRIAC switched
capacitors applications. A linear ramp signal based synchronization technique
has been propose and implemented successfully, for the capacitor switching
operation of a simple power system. This scheme enables the firing circuit to
adjust itself against any phase and/or sequence alterations. This feature
leads to elimination of the phase locked-loop (PLL) control, are commonly used
to synchronize the pulse generations with respect to the system the supply
frequency. Those pulses are, to control the converter / inverter operation of
an industrial drives and the FACTS controllers also. The proposed circuit has
been constructing and tested experimentally in the laboratory. The simulation
work completed using Or CARD software. The result shows a good agreement with
the theoretical waveforms.
Keywords: linear ramp
signal, synchronization, capacitor switching
Title of the Paper: Application of
Fuzzy Principles in Evaluating Quality of Manufacturing Process
DOWNLOAD
FULL PDF
Authors: Hrehova Stella,
Vagaska Alena
Abstract: The article deals with the possibility of using artificial
intelligence elements in order to evaluate the quality of a manufacturing
process. There are described selected indexes of a production process quality
evaluation based on statistical process control (SPC), their interpretation
and evaluation by means of fuzzy sets, which enable us to work with
inaccurate, incomplete or vague information about a monitored and reviewed
phenomenon. There are described possibilities of using program system Matlab
and its toolboxes Simulink and Fuzzy Logic to evaluate quality of the
manufacturing process based on fuzzy principles.
Keywords: SPC, quality,
manufacturing, process, fuzzy, Matlab
Title of the Paper: Lightning Surge
Response Improvement by Combinations of Varistors and Gas Discharge Tubes
DOWNLOAD
FULL PDF
Authors: Hitoshi Kijima,
Kazuo Murakawa
Abstract: This paper proposes a new methodology for protecting power
apparatuses against overvoltage or overcurrent caused by lightning surge.
Surge Protective Devices (SPDs) are used for protecting apparatuses against
overvoltage or overcurrent caused by lightning surge. SPDs are mainly divided
into two categories. One is clamping type and the other is switching type.
Typical clamping type SPD is a variable resitor (varistor). Typical switching
type SPD is a Gas-filled Discharge Tube (GDT). Both varistors and GDTs have
problems when using them alone. Therefore both a GDT and a varistor are
normally connected in series or parallel. However these simple connections of
them have still problems. This paper proposes a lightning surge response
improvement by combinations of both varistors and GDTs in order to solve the
problems of them. It is that three or more GDTs are connected in series and
two or more varistors are connected in parallel. This new methodology has
already beeing filed as patents in many countries. The proposed methodology
could solve the problems of conventional combinations of a GDT and a varistor.
Keywords: Surge protective
device, Varistor, Gas discharge tube, Lightning surge, Overvoltage,
Overcurrent
Title of the Paper: Optimal Power
System Stabilizer Based Enhancement of Synchronizing And Damping Torque
Coefficients
DOWNLOAD
FULL PDF
Authors: Ali M. Yousef,
Ahmed M. Kassem
Abstract: Design of power system stabilizer for enhancement power system
stability is proposed. The effect of the proposed PSS on the synchronizing and
damping torque coefficients is proved. To study the effectiveness of the
proposed linear quadratic regulator (LQR) power system stabilizer, a sample
power system in a linearized model is simulated and subjected to different
operating conditions. The Linear Quadratic Gaussian (LQG) power system
stabilizer is proposed. The power system dynamic responses after applying a
variety of operating points with the proposed LQG-PSS stabilizer are plotted.
The output of such stabilizer is fed directly to the automatic voltage
regulator (AVR) of the synchronous machine. The input to such stabilizer are
four state variables, two are accessible which are the deviation of the speed
(Äù) and rotor angle (Ää). The other two inaccessible states that are the
deviation of the Voltage proportional to q-axis flux linkage. (ÄE'_q) and the
Generator field voltage (ÄE_fd). An observer has been designed to access the
two inaccessible states. Further, the effect of connecting the proposed power
system stabilizer on synchronizing and damping torque coefficients is
tabulated. A comparison between the effect of the power system stabilizer
based on either LQR approach, the proposed LQG stabilizer in terms of either
power system responses or its eigenvalues due to different load condition is
reported.
Keywords: Power Systems,
LQR Control, LQG Power System Stabilizer
Title of the Paper: Optimizing the
Inspection Routine for the Detection of Electrical Energy Theft in AES
Eletropaulo in São Paulo, Brazil
DOWNLOAD
FULL PDF
Authors: L. J. Hernandes
Jr., L. C. Duarte, F. O. Morais, E. C. Ferreira, J. A. Siqueira Dias
Abstract: This work describes the development of a non-invasive and low-cost
process that allows for the improvement of the energy theft inspection
routine, increasing the field inspection team productivity and reducing the
customer's embarrassment in cases where no irregularity is found. This new
process is based on the development of an electronic Ah meter device that can
be installed on the customer's pole input connections to the power lines.
Using the recorded Ah value in the device, it is possible to estimate, within
a margin of error, the energy consumption of the customer during a small
period, typically one week. This energy value is compared to the customer's
regular energy meter reading for the same period. A comprehensive statistical
study performed with a database of more than 80000 customers in distribution
area of the utility company AES Eletropaulo in São Paulo, Brazil concludes
that the comparison between these readings can clearly indicate when tampered
or defective meters are found.
Keywords: Electrical
energy theft, fraud inspection routine, electricity tariffs, sustainable
development, emergent countries, energy efficiency, illegal energy consumers
|
