International Review on Modelling and Simulations - Papers (Part A)
Algorithms, Schemes and Techniques of Space-Vector Modulation for Dual-Inverter
Systems with Symmetrical Multilevel Phase Voltage
Vol. 5. n. 5, pp. 1877-1886
Abstract - Basic
schemes of synchronized space-vector-based pulsewidth modulation (PWM)
have been applied for control of dual-inverter fed open-end winding
motor drive supplied by two dc-sources with non-equal voltages. It has
been shown, that algorithms of synchronized PWM provide continuous phase
voltage symmetry for any ratio (integral or fractional) between the
switching and fundamental frequencies of two inverters, and also for any
ratio between voltages of two dc-sources of dual-inverter systems.
MATLAB-based simulations illustrate behavior of dual-inverter systems
with synchronized PWM. Spectra of multilevel phase voltage of open-end
winding drives with both continuous and discontinuous schemes of
synchronized PWM do not contain even harmonics and sub-harmonics during
the whole control range, including the zone of overmodulation, which is
especially important for the medium-power and high-power systems.
Keywords: Cascaded Voltage Source Inverters, Modulation Strategy, Voltage Synchronization .
Vol. 5. n. 5, pp. 1887-1893
Abstract - This
paper presents a modified bacterial foraging algorithm (MBFA) to solve
large –scale OPF with consideration of practical generators constraints.
The basic bacterial foraging algorithm (BFA) is an evolutionary
optimization technique inspired by the foraging behavior of the E. coli
bacteria. The original BFA has been successfully used for small scale
optimization problems. On the other hand, when it is applied to larger
constrained problems, it shows poor convergence characteristics. To
overcome these difficulties due to the complexity and
high-dimensionality of the search space of the problem, important
modifications are introduced to enhance the performance of the BFA. The
strategy of the OPF problem is decomposed in two sub-problems, the first
sub-problem related to active power planning to minimize the fuel cost
function, and the second sub-problem designed to make corrections to the
voltage deviation and reactive power violation based in an efficient
reactive power planning of multi Static VAR Compensator (SVC). Numerical
results on test systems IEEE 30-Bus compared with results of others
competitive global approach. The results show that the proposed approach
can converge to the optimum solution, and obtains the solution with high
Keywords: FACTS Devices, Modified Bacterial Foraging Algorithm, Optimal Power Flow, Shunt Compensators.
Comparing Space Vector Pulse Width Modulation Switching Strategies in
Three-Level NPC Inverter from Power Quality Point of View
Vol. 5. n. 5, pp. 1894-1909
Abstract - Voltage
source inverter (VSI) can produce single and three-phase (3P) AC
voltages from a constant or variable DC voltage. There are many ways to
control the VSI output voltage. Each control way produces some harmonics
at the VSI output voltage. The space vector pulse width modulation (SVPWM)
may be more effective than other modulation methods, e.g., harmonic
injection, phase shifting, multi career pulse width modulation, in
decreasing the low order harmonics (LOH). Different switching strategies
(SSs) of power electronic devices in SVPWM have some specific advantages
and disadvantages with regard to one another. In this paper, a
comparative study between different SVPWM SSs by considering some
objective functions such as total harmonic distortion (THD), power and
switching losses, the ratio of the harmonic components to the
fundamental component, distortion factor (DF) is carried out. It is also
shown that by selecting an optimized and appropriate SS for SVPWM, the
harmonic orders, which are the multiples of the frequency index (FI),
are eliminated. Then, to investigate the impact of variations of the
capacitors voltage and switching frequency (SF) on power quality
criteria, the most appropriate and optimized SS presented in this paper
is applied to a 3P three-level (3L) neutral-point-clamped (NPC) VSI to
supply a 3P load.
Keywords: SVPWM, Optimized SS, 3L NPC VSI, Power and Switching Losses, THD, DF.
Closed Loop Control of Soft Switched Interleaved Buck Converter
Vol. 5. n. 5, pp. 1910-1918
Abstract - Design,
Modeling and Simulation of a closed loop control is presented for
Interleaved Buck Converter with Soft Switching. The features of the
closed loop system are to reduce the switching losses and load current
sharing among the parallel connected converters. The control system of
the converter is designed using PWM technique.
Keywords: Buck Converter, Interleaved, Microcontroller, Resonant Component, Zero Current Switching.
Vol. 5. n. 5, pp. 1919-1926
Abstract - ThThis
paper presents a pioneering approach for the hardware implementation of
single phase cascaded multilevel inverters. Most of the recently
reported research activities on multi level inverters; the
implementations were obtained with digital signal processors or
microcontrollers. Nowadays, parallel programmable logic devices, such as
the field programmable gate array (FPGA) with embedded microprocessors,
have become powerful hardware options, offering low cost, high execution
speed, re-configurability and parallelism. This paper intends to present
an implementation methodology for selective harmonic elimination (SHE)
pulse width modulation (PWM) of cascaded single phase multilevel
inverter. In order to efficiently remove the dominant harmonics in the
output voltage profile, the accurate values of angles were calculated.
The entire system is modeled in Matlab / Simulink platform to verify the
calculated angle values and the implementation was carried out by FPGA.
The total harmonic distortion (THD) profile in the output voltage
waveforms for different modulation index values, variation of switching
angles with respect to the modulation index, operational behavior of
multilevel inverter and implementation issues are also analyzed. The
experimental results show a very close agreement to the simulation
Keywords: Cascaded Multi Level Inverter, Pulse Width Modulation, Selective Harmonic Elimination, Total Harmonic Distortion, Field Programmable Gate Array.
Space Vector Modulated Z-Source H-Bridge Asymmetric Multilevel Inverter with
Vol. 5. n. 5, pp. 1927-1933
Abstract - This
research paper presents elucidates a control method Space Vector
Modulated (SVM) Z - Source (or impedance-fed) Asymmetric Multilevel
Inverters (ZAMLI). The multilevel inverter is applied with multiple DC
sources to develop 2n+1-1 levels. Where n is the number of DC
sources used in an inverter and the output waveform has 15 levels. The
Z-source converter surmounts the conceptual and theoretical barriers and
limitations of the traditional voltage-source converter and
current-source converter and offers a new power conversion concept. By
this method of control, the full utilization of the dc link input
voltage and keeping the lowest voltage stress across the switches with
variable input voltage could be achieved using passive components. Space
vector pulse-width-modulation method is also applied to control the
boosting dc voltage. The proposed converter are applied with reduced
semiconductor switches, hence it reduces the circuit complexity,
switching losses, cost and increases the converter efficiency when
compared with traditional systems. A simulation model of conventional
multilevel inverter and Z-source asymmetric MLI has been built in MATLAB/SIMULINK
and its performance has been analyzed.
Keywords: Z-Source Asymmetric MLI (ZAMLI), Space Vector Pulse Width Modulation (SVPWM), Reduced Switches, Low Cost, THD.
Harmonic Reduction of Three-Phase Multilevel Inverter for Grid Connected
Photovoltaic System Using Closed Loop Switching Control
Vol. 5. n. 5, pp. 1934-1942
Abstract - In this
paper the application of closed loop switching control of grid connected
three phase multi level diode clamped multilevel inverter (DCMLI)
connected to a solar farm is discussed. The system is modeled in order
to obtain low harmonics distortion: closed loop controllers are used to
maintain the DC link capacitor voltage as constant. In order to extract
the maximum amount of power from the photovoltaic generator, an
intelligent control method for the maximum power point tracking (MPPT)
is proposed for the photovoltaic system under variable temperature and
insulation conditions. This method uses a fuzzy logic controller (FLC).
Sinusoidal pulse width modulation (SPWM) and space vector pulse width
modulation (SVPWM) techniques are employed to study the harmonic profile
of closed loop controlled inverter output voltage. The total harmonic
distortion (THD) for five and seven level of DCMLI in SPWM and SVPWM are
reported which reveals that they are less than the already proposed
three level inverter in terms of THD and the simulation results have
shown the effectiveness of the proposed scheme.
Keywords: PV Array MPPT, Diode Clamped Inverter, Fuzzy Logic Control, SPWM, SVPWM, THD.
Intelligent Controlled Bidirectional DC to DC Converter
Vol. 5. n. 5, pp. 1943-1950
Abstract - This work
deals with FPGA based implementation of a dual half bridge bidirectional
DC to DC converter and digital simulation of online trained neural
network controlled bidirectional DC to DC converter. Initially, a
mathematical model of the converter is developed using MATLAB Simulink.
The open loop characteristics of the mathematical model are verified. An
online trained neural network controlled closed loop converter using
mathematical model is designed. Online training of the neural network is
done with the help of PID controller. The PID parameters are tuned using
SISO tool. The neural network is trained using Back Propagation
Algorithm. Next, the converter circuit is constructed using MATLAB
Simulink. Operation of the converter in boost and buck mode are
verified. Using the same control loop, the output voltage regulation
characteristics of the converter system is obtained. The simulation
results of closed loop converter using PID and Neural Network (NN)
controllers are compared. A software program using the Hardware
Description Language, VHDL is developed for the generation of driving
pulses to MOSFET Switches. The converter is implemented using the
generated driving pulses. Implementation results of converter system are
Keywords: DC to DC Converter, Mathematical Model, Neural Network, Online Training, VHDL.
HVDC Light Systems: An
Vol. 5. n. 5, pp. 1951-1959
Abstract - Nowadays,
conventional thyristor-based High Voltage Direct Current (HVDC)
transmission systems hold the market in long distance bulk power
transmission. However, recent upgrades in power electronics technology
have led to Insulated Gate Bipolar Transistor (IGBT) based HVDC systems,
commercially known as HVDC Light systems becoming a feasible competitor.
In this paper, an overview of the existing research and recent
improvements in the area of HVDC Light technology is provided. Modeling
and control methods are reported and multilevel converter topologies are
also presented. A summary of recent HVDC Light installations worldwide
is included. Throughout the paper numerous areas of open research and
developments including, the integration of large-scale renewable energy
sources to the grid are also identified to promote future growth of this
Keywords: HVDC Light, HVDC Transmission, IGBT, Multilevel Converters, Voltage Source Converter Based HVDC, DC Circuit Breakers.
Vol. 5. n. 5, pp. 1960-1968
Abstract - Common
mode voltage produced by fast switching IGBT inverter may cause problems
like bearing damage and resultant current flow through these bearing
after break-down of lubrication films. In this paper three level back to
back converter is applied in doubly fed induction generator and new
space vector modulation (SVM) switching method is proposed which select
appropriate voltage vectors among 27 voltage vector of three-level
NPC_VSI to achieve three main goals:
Keywords: Space Vector Modulation (SVM), Neutral Point Clamped Voltage Source Inverter (NPC_VSI), Common Mode Voltage (CMV), Doubly Fed Induction Generator (DFIG).
A Solution Method to Optimize Power Converter Modeling for Real Time Digital
Vol. 5. n. 5, pp. 1969-1975
Abstract - This
paper presents the comparison various methods to analyse and solve a
power electronic system for real time applications. Performance
evaluation of each method has been presented based on various parameters
like convergence, accuracy, step size. These methods also have been
validated with the simple power electronic converter circuit and
comparison results are tabulated.
Keywords: Real Time, Decoupled, Switching Function, Zero Crossing.
Impedance Source Converter Based Stabilization of a Stand Alone Wind Generator Using Inverted Sine PWM
Vol. 5. n. 5, pp. 1976-1981
Abstract - This paper presents an effective technique for stabilization of magnitude and frequency of generated voltage in an isolated wind power generating system. The power controller consists of an Insulated Gate Bipolar Junction Transistor (IGBT) based Impedance Source Converter (ZSC) and a battery at its DC link. The controller is having bidirectional flow capability of active and reactive powers by which it controls the terminal voltage and frequency with varying wind speed and load conditions. Inverted sine carrier pulse width modulation (ISCPWM) switching strategy is used in impedance source converter. The proposed system is simulated in MATLAB using Simulink and Power System Block-set (PSB) toolboxes and the effectiveness is shown in the results.
Keywords: Self Excited Induction Generator, Wind Energy Conservation System, Impedance Source Converter, Inverted Sine Carrier PWM.
Elimination of Speed Kink in Brushless DC Motor Operating in Open Loop
Vol. 5. n. 5, pp. 1982-1986
It has been observed that speed waveform of Brushless
dc motors operated in open loop has a kink at nearly half the rated
speed. This is especially noticed when the motor is employed to drive
loads with low inertia. The speed kink in turn results in negative
excursions of DC link current. This work proposes two methods, diode
method and inductance method to avoid speed kink and negative excursions
of DC link current. The former method prevents the DC link current from
taking negative values where as in latter, the high frequency components
in DC link current is filtered out. Results show that in both cases the
kink in speed waveform is removed without compromising rise time.
Precisely, the overall performance of inductance method excel the diode
method and hence it is a more viable and effective method for overcoming
the speed kink in Brushless DC Motors.
Keywords: BLDC, Speed Kink, Insertion of Diode, Inductive Filtering.
A New Approach on Fault Discrimination for Diagnosis of Two-Winding Transformers
Using Transfer Function Method
Vol. 5. n. 5, pp. 1987-1994
Abstract - This
paper presents an algorithm to identify the type of changes in the
lumped model of an experimental two-winding transformer in order to be
used in diagnosis of transformers. This algorithm is based on transfer
function method and acquired from simulation results of a two-winding
transformer which is experimentally verified. The results of comparisons
Keywords: Transformer, Diagnosis, Monitoring, Transfer Function.
Parameters Calculation of Transformer Winding Detailed Model Based on Finite
Element Method to Study Partial Discharge
Vol. 5. n. 5, pp. 1995-2000
Abstract - The first
step to locate Partial Discharge in power transformers is to find a
model that can clearly explain the behavior of the winding in
high-frequency. The detailed model is one of the models used for the
study of PD. One of the fundamental problems of the described model is
to find its parameters. And the accuracy in calculating these parameters
has significant impact on reducing the simulation error and PD locating.
The current paper seeks to calculate the parameters of the detailed
model 20kv distribution transformer winding by using the finite element
method (FEM). Comparing the results of this model with pulse waveforms
obtained from the PD to the winding in the laboratory environment
demonstrates the validity and accuracy of this model.
Keywords: Partial Discharge, Power Transformers, Finite Element Analysis, Detailed Model.
Permanent Magnet Power Inductor Circuit and Physical Modeling
Vol. 5. n. 5, pp. 2001-2006
Abstract - This
paper presents a circuit model and a physical model for a 13mm ×14.8mm ×
7mm, 30A, ~ 890nH power inductor that utilizes a permanent magnet in
order to achieve high saturation current with small size. The presented
permanent magnet power inductor (PMPI) circuit model is derived and used
as a design guide.
Keywords: Power Inductor, Permanent Magnet, PMPI, Modeling, Simulation, DC-DC Converter.
Adaptive Neuro-Fuzzy Inference System (ANFIS) Based Simulation of Induction
Vol. 5. n. 5, pp. 2007-2016
Abstract - AC motor
drives are used in multitude of industrial and process applications
requiring high performances. In high performance drive systems the motor
speed should closely follow a specified reference trajectory regardless
of any load disturbances and any model uncertainties. The
controllability of torque in an induction motor with good transient and
steady state responses form the main criteria in the designing of a
controller. Though, PI controller is able to achieve these but with
certain drawbacks. The gains cannot be increased beyond certain limit so
as to have an improved response. Also it deteriorates the controller
performance. With the advent of artificial intelligent techniques, these
drawbacks can be mitigated. Base on the inability of conventional
control methods like PI, PID controllers to work under wide range of
operation. Artificial intelligent based controllers like ANN, Fuzzy
controller, ANFIS, expert system, genetic algorithm are widely used in
the industry. But, the main problem with the conventional fuzzy
controllers is that the parameters associated with the membership
functions and the rules depend broadly on the intuition of the experts.
In this paper Fuzzy and ANFIS based control of induction motor is done.
ANFIS performs better than the conventional and fuzzy and proves be more
Keywords: Adaptive Neuro-Fuzzy Inference System (ANFIS), Sugeno Fuzzy Controller, Hebbian Learning Genetic Algorithm, Expert System.
Control of Isolated Self-Excited Induction Generator with DTFC Strategy and DC
Voltage Fuzzy Controller Used in Wind Turbin
Vol. 5. n. 5, pp. 2017-2025
Abstract - This
paper presents a simple algorithm based on the direct torque and flux
control (DTFC) for Self-excited induction generators (SEIG) used in
isolated areas to generate electrical energy. The three-phase SEIG is
excited by a voltage source inverter connected to a single-capacitor on
the DC side. The limitation of having stand-alone SEIG is poor voltage
regulation, which occurs with change in speed and load condition. Hence,
there should be a control system that keeps the terminal voltage of the
SEIG and the DC bus voltage constant when the speed of the rotor and
also, the load on the SEIG are varied. The DTFC control with a Fuzzy
logic controller scheme has been presented to maintain the terminal
voltage of the generator and the DC bus voltage constant for variable
rotor speed and load. The proposed control scheme has shown very good
voltage regulation even with sudden application and removal of load on
the DC side.
Keywords: Self Excited Induction Generators (SEIG), DTFC, Fuzzy Logic Controller, DC Voltage Regulation, Wind Turbine.
Simulation and DSP Based Real Time Implementation of Closed Loop Variable Speed
Operation of a PMBLDC Motor Drive System
Vol. 5. n. 5, pp. 2026-2035
Abstract - Closed
loop variable speed operation of a Permanent Magnet Brushless DC (PMBLDC)
motor drive covering transient and steady state running conditions has
been investigated through extensive simulation using MATLAB/ Simulink.
The simulation schematic models the full drive system fed from a 6-pulse
voltage fed PWM inverter and implements a space vector based predictive
current controller for independent torque and speed control. The motor
operates as a prime mover coupled to a dc generator and the entire drive
is modeled using a set of related electromechanical equations. Hardware
implementation of the closed loop system consisting of a DSP controller
and power module covering speed and current feedback was carried out and
the results are presented. The results confirm the real-time capability
of the controller and associated DSP program in a practical operational
Keywords: Closed Loop Operation, PMBLDC Motor, Predictive Current Control, Real Time DSP Controller, Space Vector PWM.
Position Sensorless Direct Torque Control of Brushless DC Motor Drive Using
Four-Switch, Three Phase Inverter
Vol. 5. n. 5, pp. 2036-2041
Abstract - Today,
cost reduction is important matter in all of the systems. In brushless
dc (BLDC) motor drives, cost reduction can be achieved by elimination of
three Hall Effect position sensors and reducing the number of power
switches. On the other hand, in order to reduce the torque ripple,
direct torque control (DTC) method can directly control the inverter
states. To utilize simultaneous both advantages, reduction cost and
minimization torque ripple, we proposed a novel reduced-part position
sensorless DTC technique for a four-switch, three-phase BLDC motor drive
in the constant torque region. The performance of the proposed scheme is
verified via some simulations.
Keywords: Brushless Dc Motor Drives, Direct Torque Control, Four-Switch Inverter, Sensorless Control, Cost Reduction.
Improved Dynamic Performance of IPMSM Over Wide Speed Range Based on Numerical
Computation of id in the Field Weakening Region
Vol. 5. n. 5, pp. 2042-2048
Abstract - This
paper presents a high precision calculation of d-axis stator current, id
to improve the performance of interior permanent magnet synchronous
motor (IPMSM) drive over wide speed range for high performance
industrial drive applications. The Newton-Raphson method (NRM) is used
for computation of flux component of stator current, id.
Traditionally, the simplified equation is used to calculate id
in the flux weakening region in order to avoid complexity. The power
capacities of the motor and the inverter are considered in developing
the control algorithm. The efficacy of the proposed NRM based
computation of id for IPMSM drive is evaluated in simulation
at different operating conditions. The performance of the IPMSM drive
with the proposed NRM method is also compared with the conventional
calculation of id.
Keywords: Interior Permanent Magnet Synchronous Motor, Field Weakening Operation, Newton-Raphson Method, High Precision Computation, Motor Drives.
Torque Profile Analysis of In-Wheel Switched Reluctance Motor with Pole Shape
Vol. 5. n. 5, pp. 2049-2055
Abstract - Switched
reluctance motors are widely used in various applications due to its
inherent simplicity, robustness and fault tolerance. The design of outer
rotor type (in-wheel) Switched Reluctance Motor plays a vital role in
Electric vehicle. This work aims at the torque profile analysis of
proposed machine with the stator and rotor pole shape modifications.
Attempts have been carried out in the way of changing the stator and
rotor pole shapes to minimize the torque ripple and at the same time to
maximize average torque. Three possible models have been chosen for
analysis. The finite element analysis Package MagNet7.1.1 is used to
obtain the electromagnetic analysis for the three models. From the
static torque characteristics the average torque and percentage torque
ripple are obtained. The comparative study on the average torque and the
torque ripple for all the models are done. The machine chosen for study
is 120V, 5Hp, 1500rpm, 6/8 SRM. The best pole shape model with maximum
average torque and low torque ripple is obtained.
Keywords: Finite Element Analysis, In- Wheel SRM, MagNet7. 1.1, Pole Shapes.
Vol. 5. n. 5, pp. 2056-2065
Abstract - In this
paper different drive train models for wind generators has been studied
in detail. Simscape-the physical system modeling software in MATLAB/SIMULINK
has been used to verify the behavior of these models in a wind power
system. Physical system simulation using simscape is comparatively
easier than any other software that uses dynamic equations for the
purpose. The torque, speed and power output of a fixed speed grid
connected wind generator using various drive train models under changing
wind conditions has been compared and analyzed.
Keywords: Drive Train, Fixed-Speed Wind Generators, Simscape, Wind Gust, Wind Ramp, Wind Turbulence.
Self-Scheduling of a Plug-in Electric Vehicles Aggregator in Spinning Reserve
Vol. 5. n. 5, pp. 2066-2074
Abstract - Because
owners of private vehicles use their vehicles on some hours in a day and
their vehicles stay in parking lots without using in the rest of the
day, the batteries of plug-in electric vehicles (PIEVs) can be
considered as a source of energy storage. Probabilistic and non-linear
behavior of the PIEVs owners at time of connection to and disconnection
from the aggregator and probabilistic state of power market necessitate
the self-scheduling (SS) of the aggregator for participation in spinning
reserve (SR) market to confront with many uncertainties. In this paper,
the probabilistic behavior of the PIEVs fleet is modeled from the
aggregator’s point of view. Also, this paper takes the perspective of an
aggregator that manages the participation of PIEVs fleet in the SR
market and presents a mathematical model for optimal
charging/discharging of the PIEVs, based on probabilistic driving
patterns of the fleet and probabilistic electricity market prices.
Keywords: Plug-In Electric Vehicles (PIEVS) Aggregator, Self-Scheduling (SS), Spinning Reserve (SR) Market.
Vol. 5. n. 5, pp. 2075-2103
Abstract - In this
paper, we proposed the development of neural adaptive controls to ensure
the robustness of uncertain nonlinear multivariable systems. We used two
techniques: Robust neural adaptive control and neural indirect adaptive
control. The study of the stability and robustness of both techniques
was performed by Lyapunov theory. To validate these techniques and
discover their effectiveness, a simulation example was considered. The
simulation results obtained by these two control techniques have shown
the effects of disturbance compensation, good performance tracking data
paths and stability control systems. Comparative studies between these
two techniques show that the neural indirect adaptive control cannot
mitigate the effect of disturbances compared to the robust neural
Keywords: Neural Adaptive Control, Robust Neural Adaptive Control, Neural Indirect Adaptive Control, Lyapunov Theory, Uncertain Nonlinear Multivariable Systems.
Vol. 5. n. 5, pp. 2104-2118
Abstract - Balancing
identification plays a crucial role in structural dynamics and vibro-acoustic
system optimization. The followed approach is based on the “Modal
testing and Analysis” concept. The Eigen modes of the system model can
be visualized and allow a direct physical interpretation. Using the
modal models, design improvements can be predicted and the structure
optimized. The present paper not only review the test procedure and
system identification principles of modal analysis, but also discusses
the balancing practical problems with which engineers, performing modal
testing and analysis on industrial structures, are confronted on a daily
basis. New trends in modal testing and analysis that specifically
address these problems are reviewed and illustrated with case studies.
This includes the issues of instrumentation, test definition,
measurement principles, and parameter estimation. We present here a
generalise procedure for solving many of related rotating machine
Keywords: Balancing, Modal Analysis, Rotor Dynamics, Health Monitoring, System Identification.
Investigation by Simulation of Closed-Loop Optimal Control Law Implementation
Using Artificial Neural Network
Vol. 5. n. 5, pp. 2119-2127
Abstract - The main
contribution of the paper is the investigation of the possibility of
implementing a nonlinear optimal state feedback control law using an
Artificial Neural Network (ANN). Time optimal control (TOC) of a double
integrator plant is selected as its state trajectories are easily
computed with negligible errors to form a benchmark with which the
corresponding ANN implemented closed loop control law performance can be
compared. This is intended as a for-runner of further work on
applications for which closed loop optimal control laws are unknown or
unattainable. In these cases, the authors propose Pontryagin’s method to
generate state trajectories to train an ANN to implement the closed loop
optimal control. Pontryagin’s method is also used in this paper to aid
the derivation of the double integrator closed loop TOC. Also a
modification of the time optimal control law is made based on the
boundary layer method of sliding mode control that eliminates control
chatter about the desired state. This increases the final state
acquisition time beyond the minimum value but by a relatively small
amount. A further contribution avoids inaccurate training of the ANN due
to excessive derivatives of the control with respect to the state
variables in the region of the boundary layer. This is achieved by
training the ANN using only the output of the continuous switching
function, the saturation function that directly generates the control
being implemented outside the ANN. The simulations predict that the ANN
based controller will be sufficiently accurate.
Keywords: Closed-Loop, Optimal Control, ANN, Training, Maximum Principle.
Based Feature Comparison between two Topologies of an Axial-Flux Permanent-Magnet Synchronous Motor Intended for Traction Application
Vol. 5. n. 5, pp. 2128-2135
Abstract - This paper is aimed at the comparison between “Mono-Disc Topology” (MDT) and “Torus-NN Topology” (TNNT) of an axial-flux surface mounted permanent-magnet synchronous motor used for traction in a leisure vehicle. This work focuses, for same radial topology and same loading level, an axial sizing followed by a performance comparison between both cited motor configurations. It has been found that the TNNT satisfies required specifications with an important improvement of the cost-effectiveness ratio with respect to the MDT.
Keywords: Axial-flux permanent-magnet motor, mono-disc, torus-NN, power-train, circulation mission.
Advanced Simulation Model of Five Phase PMBLDC Motor Drive for Low Power High Torque Applications
Vol. 5. n. 5, pp. 2136-2145
Abstract - This paper presents an advanced modelling, simulation and analysis of a low-power high-torque five phase permanent magnet brushless direct current (PMBLDC) motor drive. For achieving high torque density in the air gap, a 144° mode of excitation is used. The proposed model helps to determine and analyze the dynamic characteristics of the PMBLDC motor such as speed, torque and pulse width modulation (PWM) inverter components such as phase currents and voltages effectively. This model is suggested to be used as an effective tool for the development of five phase PMBLDC motor drive applications including control algorithms and topological variations with reduced computation time and memory size. The entire work is validated using MATLAB simulation software.
Keywords: Brushless DC Motor, Drive Modelling, Five Phase Motor, High Torque, Simulation.
International Review on Modelling and Simulations - Papers (Part B)
Application of Multi Objective Optimization to Optimal Power Dispatch Problem
with Facts Devices Using Refined BFA
Vol. 5. n. 5, pp. 2146-2159
Abstract - This
paper describes a simple effective and reliable Refined Bacterial
Foraging Algorithm (RBFA) presented and its applied to solve
multi-objective optimal real and reactive power dispatch problem for
provide, economic and stable operation of power systems. The optimal
location and control of FACTS devices along with real and reactive power
output, bus voltages, reactive power compensation, and transformer taps
are tuned with a view to simultaneously optimize the optimal (real and
reactive) power dispatch, power losses, reactive power planning via
switchable reactive power support, voltage stability margin, investment
cost and operating cost of a complex power system. The new foraging
algorithm known as RBFA algorithm is applied for solving the multi
objective multivariable problems, with the real and reactive power
outputs, generator bus voltages, shunt power capacitors or reactors,
transformer tap settings and FACTS devices location as the control
variables. The new RBFA is an evolutionary optimization technique and
it’s modified from basic bacterial foraging algorithm. The RBFA is
motivated by the foraging behavior of the E. coli bacteria and the
biological aspects of the bacterial foraging strategies and is well in
multiple objective optimization problems, high dimensional problems and
dynamic environment. The solutions of this problem deliberate via RBFA
algorithm and the feasibility of the algorithm is demonstrated using the
IEEE-30 and IEEE-57 bus system, the test results are compared with
Keywords: Optimal Real and Reactive Power Dispatch, Refined Bacterial Foraging Algorithm, Multi-Objective Optimization, Load Flow, FACTS Devices, Voltage Stability Margin
Application of Reinforcement Learning for Load Scheduling
Vol. 5. n. 5, pp. 2160-2168
Abstract - This
paper formulates load scheduling problem under various price based
demand response regimes and a Reinforcement Learning (RL) based approach
is presented to solve this new formulation. This approach could be used
to learn the optimum commitment schedule for a class of loads when
methods such as time of use (TOU), critical peak pricing (CPP) or real
time pricing are employed. The proposed approach also takes into
consideration the discomfort caused by delay in scheduling the loads.
The efficacy of the algorithm is investigated when the price of
electricity is available in advance as well as for the case when it is
random. The scalability of the approach is also investigated. Guidelines
for finding a tradeoff between consumer comfort and total price of
electricity used are also discussed.
Keywords: Demand Response, Reinforcement Learning, Load Scheduling, Q-Learning, Learning Automata.
Damping Local and Inter-Area Power System Oscillation Improvement by Using Fuzzy
Logic Power System Stabilizer
Vol. 5. n. 5, pp. 2169-2173
Abstract - This
paper introduces a fuzzy controller as a power system stabilizer used to
damp local and inter-area modes of oscillation following disturbances in
power systems. Power Systems are subjected to wide ranges of transient
instability and the dynamic instability. The dynamic instability is
damped by using the Power System Stabilizers (PSS). The Power System
Stabilizer is developed by using the conventional and non conventional
controller. Simulation of Multi-Machine Power Systems with conventional
and non conventional controller Power System Stabilizers subjected to
three-phase fault disturbances and operating conditions are presented.
On comparing simulation results is observed that the fuzzy set theory
based Power System Stabilizer for Multi-Machine power system has better
performance than conventional Power System Stabilizer.
Keywords: Power System Stabilizer, Multi Machine, Fuzzy Logic Controller, Conventional Controller, Inter-Area.
Comprehensive Analysis of the Impacts of Different Parameters on Transmission
Line Switching Overvoltages
Vol. 5. n. 5, pp. 2174-2182
Abstract - In this
paper a comprehensive study of transmission lines closing overvoltages
is performed. This analysis concentrates on the phenomena related to the
three phase high-speed auto-reclosing of transmission lines. Effects of
several important parameters on the switching overvoltages are
investigated using the Electro-Magnetic Transients Program. In each case
an accurate statistical study is performed to evaluate the severity of
switching overvoltages. Eventually, the key parameters, affecting
switching overvoltages, are identified. The results of this analysis
might be applied by electric utilities, as a helpful guide to restrict
the magnitude of transmission line switching overvoltages. Limitation of
transmission line switching overvoltages will result in significant
Keywords: Insulation Coordination, Switching Overvoltage, Power System Transients.
Power System State Estimation Based on PMU Measurements vs SCADA Measurements
Vol. 5. n. 5, pp. 2183-2190
Abstract - Several
power system blackouts in the last decade indicate that the power system
is being operated close to its stability limits and with lower security
margins. Therefore, power system operators have to adopt power system
control solutions to support the electric energy consumption increase,
the electric energy market development, the renewable energy sources
integration (RES) and the aim of greenhouse gases (GHG) reduction.
Possible answer are Wide Area Monitoring, Protection and Control systems
(WAMPAC), which are based on Synchronized Measurement Technology (SMT).
A power system state estimator is one of the basic applications in power
system control centres. It is expected that the increase of number of
Phasor Measurement Units (PMUs) deployed in the power system would
significantly contribute to the power system state estimation. This
paper overviews the traditional state estimation theory and gives the
application of the SMT in the state estimation. The enhancement of the
state estimator’s performances will help the power system operator to
make crucial decisions while operating the power system with large
amount of the RES.
Keywords: State Estimation, Synchronized Phasor Measurements, Renewable Energy Sources, Power System Control, Smart Transmission Grid.
Design a Power System Stabilizer Based on Fuzzy Sliding Mode Control Theory
Vol. 5. n. 5, pp. 2191-2196
Abstract - In a
power system, because of different operation conditions such as active and
reactive power changes, transmission line parameters changes,…, it is needed to
protect the given power system against low-frequency oscillations due to the
mentioned changes by applying a controlling system and finally attain a suitable
dynamic stability. In this paper, the fuzzy sliding mode control theory is used
to design a power system stabilizer.
Keywords: Power System Stabilizer (PSS), Sliding Mode Control, Fuzzy Logic Controller.
High Impedance Fault Detection on Power Distribution Feeder
Vol. 5. n. 5, pp. 2197-2204
Abstract - This
paper presents an intelligent algorithm using a Takagi Sugeno-Kang (TSK)
fuzzy modeling approach based on subtractive clustering to detect high
impedance fault. High impedance fault (HIF) is abnormal event on
electric power distribution feeder which does not draw enough fault
current to be detected by conventional protective devices. The algorithm
for HIF detection based on the amplitude ratio of second and (3rd,
5th, 7th, 9th, 11th)
harmonics to fundamental is presented.
Keywords: High Impedance Faults, FFT, TSK Fuzzy Modeling, Power Distribution Feeder.
Distance Protection Algorithm for Three Terminal Transmission Lines Using Local
Vol. 5. n. 5, pp. 2205-2213
Abstract - Distance
protection is commonly a preferred way to protect transmission lines.
However, tapped transmission lines are usually used to supply small
communities or facilities in sparsely populated and isolated rural
areas. Also, tapped lines are difficult to be protected by distance
relays due to the effect of infeed/outfeed current from third terminal
as well as reactance effect. To deal with mentioned problems a novel
distance algorithm is introduced, which applies generalized models of
fault loop voltage and current to formulate the distance relay
algorithm. The derived algorithm has a very simple first-order formula
and does not require knowledge of data from other two terminals. By
calculating the current distribution factor and estimating the current
from two other ends, the algorithm measures the exact impedance from
distance relay to fault point. EMTDC/PSCAD simulator is used to evaluate
the performance of the proposed distance relay algorithm. The result of
simulation verifies the high accuracy of the method with regard to
various equivalent source impedances, fault resistances and locations as
well as fault types. Finally, the algorithm is expanded to multi-tapped
lines and accuracy and robustness of the proposed distance protection
algorithm is evaluated.
Keywords: Distance Relay, Three Terminal Transmission line, Current Distribution Factor, Multi-Tapped Line, Infeed/Outfeed Current.
Effect of Dynamic and Static Load in the Voltage Stability
Vol. 5. n. 5, pp. 2214-2227
Abstract - The
voltage collapse is a dynamic process that may take a few minutes which
is called the slow voltage collapse, or that may take a few seconds
which is called the fast voltage collapse. These collapses can be
avoided through preventives and curatives measures. The load shedding
activated by voltage criterion is a defensive mode that allows limiting
the degradation of the voltage at unusable values. This load shedding by
undervoltage must consider the dynamics of the voltage drop and
irreversible degradation. In other cases, the voltage collapses may
occur following the failure of the transmission network, related to the
maximum power transmissible, to ensure the transfer of energy. Thus a
phenomenon of static stability loss is generally initiated. The study of
voltage stability of the Tunisian network showed that the sensitive
lines studied at collapse of each area are not necessarily those which
are responsible for the reduction of the total transfer capacity.
However, the modal analysis of the Tunisian network shows that the
fragile areas in terms of stability always contribute to the instability
of tension in Normal and N-1 situation. Therefore, these areas should be
treated with caution during the planning phases of the electrical
Keywords: Voltage Collapse, Voltage Stability Index, Slow Collapse, Fast Collapse, Stability, Static Load, Dynamic Load.
Development of Variable Structure Fuzzy Gain Scheduling Controller for an
Interconnected Power System
Vol. 5. n. 5, pp. 2228-2234
Abstract - This
paper investigates on enhanced Load Frequency Control of two-area
hydrothermal power plant when subjected to unit step load disturbance.
The frequency and tie-line power deviations are controlled using
conventional Proportional and Integral controller tuned using Zeigler
Nichols’ method. By switching the controller action during transient and
steady state period using Variable Structure System, the performance is
improved. Fuzzy Gain Scheduling further improves the system performance
by changing the proportional and integral gain according to the
variations in the power plant. Finally, Variable Structure Fuzzy Gain
Scheduling Controller is developed by integrating Fuzzy in Variable
Structure System Controller resulting better controller action during
transient and steady state period. The performance of these controllers
is judged using Integral Time Absolute Error and Integral Time Squared
Load Frequency Control, Proportional Integral Controller, Variable
Structure System Controller, Hydrothermal Power Plant, Fuzzy Gain
Scheduling, Variable Structure Fuzzy Gain Scheduling.
Machine Learning for Steady State Security Assessment in Power System
Vol. 5. n. 5, pp. 2235-2242
Abstract - The
objective of this paper is to investigate the reliability of the SSA in
determining the security level of power system from serious interference
during operation. Artificial Neural Network (ANN), Adaptive Network
Based Fuzzy Inference System (ANFIS) and Decision Trees (DT) are
implemented to classify the security status in the test power system,
comparison are made in terms of computation time and accuracy of the
networks. Impact of Attribute Selections on train and test set is
proposed. The impact of attributes number and cross validation on
performance of the train and test data set is proposed as well. Data
obtained from Newton Raphson Load Flow (NRLF) analysis method are used
for the training and testing purposes of the proposed AI techniques. The
data are used also as a benchmark to validate the results from AI
techniques to achieve high speed of execution and good classification
accuracy. A new methodology of feature selection technique based on
extracting variables has also been applied. The proposed techniques have
been extended and tested on various IEEE test systems. Generally, the
proposed AI techniques have successfully been applied to evaluate SSA
for various IEEE test system.
Keywords: Steady State Security Assessment, Artificial Intelligence Classifiers, Power System .
Design and Development of Embedded Controller for High Efficient Grid Connected
Solar Power System
Vol. 5. n. 5, pp. 2243-2250
Abstract - The
research enhancement and the investigation of power quality issues in
solar power system are becoming necessary due to the involvement in more
number of power electronics components. Harmonics are created by the
switching system of the power electronic circuit and can cause damage to
power equipment on the utility side and sensitive loads on the customer
side. The main objective of this work is to study of the behaviors of
the solar PV systems and model the Reliable and High efficient Grid
connected solar Power system. The embedded controller has been designed
to monitor the various parameters of solar power system and analyses the
parameters. The embedded controller also produces the control signal to
reduce the harmonics and increase the overall performance of solar power
Keywords: Solar Energy, Embedded, Power Quality, Inverter, Converter, MPPT.
Small Signal Stability Analysis of Power System with VSC Based HVDC Link
Employing Phase Angle Control
Vol. 5. n. 5, pp. 2251-2260
Abstract - In
this paper small signal stability of the power system with VSC based
HVDC link employing phase angle control is analyzed. The ac network on
both sides of the converters (HVDC link) is modelled as thevenin’s
voltage sources behind the thevenin’s impedances viewed from the
converter transformer terminal. Dynamic equations of the ac side, the dc
side and the controllers are developed. The standard nine-bus system is
considered for analysis with a VSC based HVDC link between buses 8 and
9.The network parameters such as short circuit ratios (SCR) at PCC, dc
capacitor in the dc link and the venin’s equivalent resistances (system
damping) are varied and their effect on the eigenvalues and damping are
Keywords: Small Signal Stability, VSC Based HVDC Link, Phase Angle Control.
Dynamic Embedded Optimization Based Security Assessment of an Interconnected
Power System with D- FACTS Devices
Vol. 5. n. 5, pp. 2261-2275
Abstract - Power
system dynamic security assessment is studied and enhanced by
incorporating few Flexible AC Transmission System (FACTS) devices.
Generally Hybrid systems can be modeled in a systematic way by a set of
differential-algebraic equations with the sensitivities that can be used
to form approximate trajectories for parameter sets that are
perturbations from the nominal parameter values. The influence of
parameter uncertainty can then be expressed as a bound that is mapped
along with the nominal trajectory. Power system dynamic performance
enhancement can often be formulated as a dynamic embedded optimization
problem and the evolving state variables are used with the dynamic model
which is embedded within the constraints. In this approach, IEEE 14-bus
system with ZIP load models are considered for the study and for quick
restoration few FACTS devices are incorporated with different boundary
values. The dynamic security assessment results are provided to
highlight the overall security and suitability of the approach.
Keywords: Dynamic Embedded Optimization (DEO), Load Shedding, Flexible AC Transmission System (FACTS), SVC (Static Var Compensator), UPFC (Unified Power Flow Controller), Interline Power Flow Controller (IPFC), ZIP Load, Dynamic Security Assessment (DSA).
Forecasting of Wind Speed Using Artificial Neural Networks
Vol. 5. n. 5, pp. 2276-2280
Abstract - Wind
speed forecast is essential in wind energy conversion system and may
fail to operate power plant at non optimal region if not properly
forecasted. This paper focuses the short term wind speed forecasting
using conventional statistical method and artificial neural networks
such as back propagation network (BPN), generalized regression neural
network (GRNN) and radial basis function networks (RBFN). The developed
algorithms and networks are trained and tested for wind speed data which
are measured at an interval of 15 minutes. In this paper we compared the
performance of RBFN and other networks for effective wind speed
Keywords: Wind Speed Forecast, BPN, GRNN, RBFN, ARMA.
Analysis and Simulations of Three-Phase Uniform Charge Power Sources with
Current Harmonic Decrease
Vol. 5. n. 5, pp. 2281-2290
Plate-type electrostatic precipitators are the main installations of
separating particles from industries (especially for large gas flow) and
must operate in its electromagnetic environment without interfering with
the operation of other equipments. The power supplies have non-linear
elements that cause distortions of the sources currents.
Keywords: Plate-Type Electrostatic Precipitators, Power Supplies, Simulation, Total Harmonic Distortion, Active Filter.
Optimal Allocating and Rating Selection of STATCOM for Power System Voltage
Stability Enhancement by Normal Forms of Diffeomorphism
Vol. 5. n. 5, pp. 2291-2298
Instability of voltage mostly occurs due to reactive power inequality
Voltage instability and collapse can be prevented by careful and rapid
injection and absorption of reactive power in different moments and this
is done by STATCOM. The important point in using STATCOM to achieve this
goal is finding the optimum allocation to install and proper rating
selection for STATCOM with regard to the other conditions in the
network. The method used to optimum allocation of STATCOM in this
article is diffeomorphism normal method. With the increase of loading,
the network acts close to crisis point, the purpose of this method is to
find a proper place for STATCOM in this condition. This method has been
tested on two networks of 30buses of IEEE and 39 buses of New England.
The simulation results obtained through using the DIgSILENT and MATLAB
soft wares have well shown the desired performance of this method in
improving the voltage stability.
Keywords: Optimal Allocation, STATCOM, Voltage Stability, Normal Forms of Diffeomorphism.
Integration/Analysis of Green Energy and Conventional Electricity Generation with Interconnected Distribution Networks
Vol. 5. n. 5, pp. 2299-2306
Presently, electricity is being generated at remotely located centralized generating stations. The generated power is transmitted to the dispersed consumers through the transmission and distribution networks at specified voltage and frequency. The transmission networks are designed smartly and operate in intelligent manner. However, the distribution networks are designed only for unidirectional flow of power. There is an urgent need to generate power from the available renewable energy sources at or near to the consumers end. The main issue arises when distributed generators are incorporated with the nearby available distribution networks.
This paper proposes the advanced power system configuration which allows the integration of conventional energy generation and renewable energy sources efficiently. The proposed power system configuration has been simulated using MATLAB/ simulink.
Keywords: Distributed Generators, Distribution Networks, Smart Grid, Power Quality.
Load Frequency Control of Hydrothermal System Under Open Market Considering
Capacitive Energy Storage
Vol. 5. n. 5, pp. 2307-2313
Abstract - This
paper presents the analysis of Load Frequency Control (LFC) of an
interconnected hydrothermal system under open market scenario. The
improvement of dynamic performance of LFC with the addition of a small
capacity Capacitive Energy Storage (CES) unit has been carried out. Time
domain simulations are used to study the performance of the power system
and control logic. A Suitable method for controlling the CES unit is
also described. Analysis reveals that due to the presence of CES, the
system improves in terms of Peak time, settling time and overshoot than
the system without CES following a load disturbance in either of the
Keywords: Load Frequency Control, Capacitive Energy Storage, Open Market System, Hydrothermal System.
A Hybrid Algorithm Using Modified LR –PSO for Solving Unit Commitment Problem
with Various Constraints
Vol. 5. n. 5, pp. 2314-2320
Abstract - Unit
commitment (UC) problem is one of the medium term decision problems in
power system and it is used to determine the mix/ combination of
generators to be operated or to be idle. By solving the UC problem, once
the binary data is obtained the next level is to find the optimum level
of dispatch of each generators in the mix. For a large generating system
UC program is a large scale, non linear mixed integer programming (MIP).
This paper proposes a hybrid algorithm to solve UC problem by
considering equality and inequality constraints. The objective of the
algorithm is to minimize the fuel cost after meeting all the possible
constraints. The proposed algorithm initially solved the UC problem by
modified LR method. LR method most often gives sub optimal solution, so
once the problem is solved by LR and if some of the output is infeasible
then by solving it by heuristic technique such as priority list method,
we can modify LR. The generation output level is determined by particle
swarm optimization method. The algorithm was tested in four unit eight
hour systems and ten unit twenty four hour system. The simulation output
shows that the developed algorithm performed well and also applicable
for large systems.
Keywords: Unit Commitment, Optimization, Two Stage Programming, Modified Lagrange Relaxation, Priority List, Particle Swarm Optimization.
The Simulated Annealing Q-Learning Application to the Dynamic Power Markets
Vol. 5. n. 5, pp. 2321-2327
Abstract - The
dynamic power market model based on double-sided auction market is
proposed in this paper. In this market model, the generation companies (Gencos)
and the load service entities (LSEs) may change their offers and bids,
respectively. The independent system operation (ISO) used DC-optimal
power flow (DC-OPF) solution to clear the real power units and the
electricity prices at each node. Some information such as the
electricity prices, the real power at each node, and so forth are
published after each transaction. The participants’ goal in proposed
model is maximum profits so that they used the SA-Q learning algorithm
such as the tool for optimal bidding strategy. The IEEE 30-bus test
system with six Gencos is used for simulations. The simulation results
demonstrated the feasible of proposed model.
Keywords: The SA-Q Learning Algorithm, Optimal Bidding Strategy, Dynamic Power Market, Double-Sided Auction.
Modeling, Simulation and Hardware Implementation of Wind-Solar Hybrid System
Vol. 5. n. 5, pp. 2328-2337
Abstract - The
combined utilization of two weather driven renewable viz., wind and solar are
becoming increasingly attractive particularly in remote rural / village
locations and islands. The aim of this paper is to enhance the current
state-of-art, operation and control requirements of a typical 5kW wind-solar
hybrid system with a continuous power backup from grid source suitable for
remote telecommunication applications. The proposed system is modeled using
MATLAB SIMULINK tool and is verified through the hardware implementation. The
strategies for efficient utilization by connecting simultaneously the tri-system
to feed the battery and load for economic requirement and availability are
Keywords: Hybrid System, Inverter, Off-Grid, Permanent Magnetic Synchronous Generator (PMSG), Small Wind Turbine (SWT) / Aerogenerator, Solar Photovoltaic System (SPV).
Degradation of Surrounding Dielectrics of a Micro-Channel Due to Partial
Discharges, Part 1: The Model
Vol. 5. n. 5, pp. 2338-2347
Abstract - A two
dimensional Particle in Cell - Monte Carlo Collision (PIC-MCC) model is
developed in order to simulate partial discharges inside a narrow
micro-channel encapsulated within the volume of a dielectric material.
Under the application of an electric field, a pulse-type discharge
ensues by repeated ionization of the gaseous medium. Electrons gain
energy from the electric field, and cause degradation of neighboring
dielectric surfaces on impact. In this paper, the damage to the
dielectric and the increase in surface conductivity are estimated based
on the number of C-H bond-scissions produced by the impacting electrons
in a single partial discharge (PD) pulse. The changes in surface
conductivity of the surrounding dielectrics of the micro-channels is
considered via formation of acid molecules due to interaction of PD
pulse with polymer surface in presence of air and humidity is
considered. The consequent degradation of the dielectric and the time
required to increase surface conductivity is computed based on the
number of C-H bond-scissions produced by the impacting electrons in a
single PD pulse. The scatter plots in phase space for velocities of
charged particles are obtained. The net charge density and electric
field within the micro-channel at different instants of time are shown.
Keywords: Partial Discharges, Dielectric Degradation, PIC-MCC Simulation.
Extension to the Theory of the Transmission Lines
Vol. 5. n. 5, pp. 2348-2354
Abstract - This
paper deals with a humble presentation of an extension to the
transmission line theory and also relevant case studies with results and
analysis. It is well known that a transmission line with mechanical
constraints on either side exhibits parabolic sag. It had already been
shown by the authors that, under certain assumptions, with electrical
constraints on either side of the line, the voltage profile over the
line exhibit a voltage sag which are hyperbolic in nature. A Flatness
Index (FI) had been defined which is 1.0 if the line exhibits the same
voltage from sending end to the receiving end with full shunt
compensation. It is zero when the line is uncompensated. This paper
briefly reviews this theory already developed and extends the
theoretical formalism involved with respect to long transmission lines.
Equations are derived for the sag in terms of the phase constant of a
lossless long line. Furthermore, equations for the line with losses are
also derived. These equations are implemented on a practical loaded
transmission line obtaining the voltage profiles under varying
conditions. The results are presented and analyzed.
Keywords: Compensation, Flatness Index, Transmission Line, Voltage Profile, Hyperbolic Sag.
Bees Colony Intelligence in Optimization: an Application to PSS design
Vol. 5. n. 5, pp. 2355-2362
Abstract - This paper reports the development of a new optimization technique based on the biological behaviour of a colony of honey bees. The proposed optimization method is prepared by closely imitating the foraging pattern of bees. The development of the algorithm and their validation through the design of Power System Stabilizer for a standard three machine nine bus test system is well documented in this work. Simulation results are carried out to validate the proposed algorithm.
Keywords: Optimization, Bees, Power System Stabilizer.
Performance Analysis and Protection of Air Distribution Cables from Lightning Faults
Vol. 5. n. 5, pp. 2363-2372
Abstract - This paper presents the lightning performance of air distribution cables and possible protection methods against lightning faults by means of analysis and laboratory experiment. The analysis is made with reference to international standards for evaluating the lightning performance of power distribution lines. The work deals with the theoretical estimation of lightning faults on distribution cables and the protection improvement options against the faults. The performance and protection of the lightning phenomena are analyzed using typical Finnish air distribution cable designs. With series of laboratory tests, practical examination of lightning hazard to air cables is conducted, and the need for shield wire protection is established. This study will strive to provide possible methods and solutions for the protection of air distribution cables against lightning and other weather-related phenomena, which may potentially reduce electricity rates to end-use customers.
Keywords: Air distribution cable, Grounding resistance, Induced flashovers, Insulators, Lightning, Shield wire, Tree, Wooden pole.
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