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International Review on Modelling and Simulations  Vol. 5 N. 5---- Part A

International Review on Modelling and Simulations  Vol. 5 N. 5---- Part B



go to top    International Review on Modelling and Simulations (Vol. 5 N. 5)  - October 2012 - Papers (Part A)




go to top    International Review on Modelling and Simulations (Vol. 5 N. 5)  - October 2012 - Papers (Part B)









International Review on Modelling and Simulations - Papers (Part A)



go to top   Algorithms, Schemes and Techniques of Space-Vector Modulation for Dual-Inverter Systems with Symmetrical Multilevel Phase Voltage
         by Valentin Oleschuk, Gabriele Grandi

          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.
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Keywords: Cascaded Voltage Source Inverters, Modulation Strategy, Voltage Synchronization .



go to top   Modified Bacterial Foraging Algorithm Based OPF to Optimize Fuel Cost Function and Losses Using Shunt FACTS Device
         by K. Ravi, M. Rajaram

          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 accuracy.
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Keywords: FACTS Devices, Modified Bacterial Foraging Algorithm, Optimal Power Flow, Shunt Compensators.



go to top   Comparing Space Vector Pulse Width Modulation Switching Strategies in Three-Level NPC Inverter from Power Quality Point of View
         by M. R. Alizadeh Pahlavani, Y. Khadivi Vaneqi

          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.
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Keywords: SVPWM, Optimized SS, 3L NPC VSI, Power and Switching Losses, THD, DF.



go to top   Closed Loop Control of Soft Switched Interleaved Buck Converter
         by R. Shenbagalaksmi, T. Sree Renga Raja

          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.
Resonant components thus designed enable the application of zero current switching for both the converters connected in parallel thereby maintaining greater efficiency and minimizing voltage and current oscillations.
The system analysis, design and performance are verified through simulation using MATLAB/Simulink environment. The simulation approach reveals the high speed dynamic performance of the closed loop system designed using robust PID controller. The laboratory prototype of the Buck converter is developed to verify the controller platform using PIC16F877A microcontroller.

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Keywords: Buck Converter, Interleaved, Microcontroller, Resonant Component, Zero Current Switching.


go to top   FPGA Based Implementation of Selective Harmonic Elimination PWM for Cascaded Multilevel Inverter
         by Baharuddin Ismail, Muhd Hafiz Arshad, S. Thangaprakash

          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 results. 
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Keywords: Cascaded Multi Level Inverter, Pulse Width Modulation, Selective Harmonic Elimination, Total Harmonic Distortion, Field Programmable Gate Array.


go to top   Space Vector Modulated Z-Source H-Bridge Asymmetric Multilevel Inverter with Reduced Switches
         by M. Balachandran, P. Senthilkumar, N. P. Subramaniam

          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.
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Keywords: Z-Source Asymmetric MLI (ZAMLI), Space Vector Pulse Width Modulation (SVPWM), Reduced Switches, Low Cost, THD.



go to top   Harmonic Reduction of Three-Phase Multilevel Inverter for Grid Connected Photovoltaic System Using Closed Loop Switching Control
         by A. Ravi, P. S. Manoharan, M. Valan Rajkumar

          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.
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Keywords: PV Array MPPT, Diode Clamped Inverter, Fuzzy Logic Control, SPWM, SVPWM, THD.



go to top   An Intelligent Controlled Bidirectional DC to DC Converter
         by G. Themozhi, S. Rama Reddy

          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 presented.
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Keywords: DC to DC Converter, Mathematical Model, Neural Network, Online Training, VHDL.



go to top   HVDC Light Systems: An Overview
         by M. Ajay Kumar, K. U. Archana, N. V. Srikanth

          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 benign technology.
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Keywords: HVDC Light, HVDC Transmission, IGBT, Multilevel Converters, Voltage Source Converter Based HVDC, DC Circuit Breakers.



go to top   Common Mode Voltage Reduction of Three-Level Back to Back Converter in DFIG with Balanced Neutral Point Voltage
         by Davood Mazhary

          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:
1. Decreasing common mode voltage of DFIG.
2. Balancing the neutral point voltage of Dc link.
3. Controlling the active and reactive powers delivered by the wind generator to the electrical network.
Mathematical analyses besides simulation using Matlab/Simulink have been carried out to validate the proposed method
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Keywords: Space Vector Modulation (SVM), Neutral Point Clamped Voltage Source Inverter (NPC_VSI), Common Mode Voltage (CMV), Doubly Fed Induction Generator (DFIG).



go to top   A Solution Method to Optimize Power Converter Modeling for Real Time Digital Simulation Applications
         by Umashankar S., Vijayakumar D., Kothari D. P.

          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.
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Keywords: Real Time, Decoupled, Switching Function, Zero Crossing.



go to top   Impedance Source Converter Based Stabilization of a Stand Alone Wind Generator Using Inverted Sine PWM
         by K. Premalatha, S. Vasantharathna

          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.
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Keywords: Self Excited Induction Generator, Wind Energy Conservation System, Impedance Source Converter, Inverted Sine Carrier PWM.



go to top   Elimination of Speed Kink in Brushless DC Motor Operating in Open Loop
         by Binu K. Baby, Saly George

          Vol. 5. n. 5, pp. 1982-1986


Abstract - 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.
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Keywords: BLDC, Speed Kink, Insertion of Diode, Inductive Filtering.



go to top   A New Approach on Fault Discrimination for Diagnosis of Two-Winding Transformers Using Transfer Function Method
         by Danial Gorzin, Ebrahim Rahimpor, Alireza Gorzin

          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 were satisfactory.
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Keywords: Transformer, Diagnosis, Monitoring, Transfer Function.



go to top   Parameters Calculation of Transformer Winding Detailed Model Based on Finite Element Method to Study Partial Discharge
         by S. M. Hassan Hosseini, M. Vakilian, S. M. Enjavimadar

          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.
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Keywords: Partial Discharge, Power Transformers, Finite Element Analysis, Detailed Model.



go to top   Permanent Magnet Power Inductor Circuit and Physical Modeling
         by Zhigang Dang, Jaber A. Abu Qahouq, Shashank Wattal

          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.
Then, the PMPI physical model is developed by using ANSYS®/Maxwell® software package in order to evaluate the performance parameters including inductance, saturation current, flux density and current density distribution. The design and simulation results are presented based on a DC-DC buck power converter with 25A load current. The simulation results show that the presented PMPI is able to double the saturation current for the same size and inductance of conventional power inductor.

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Keywords: Power Inductor, Permanent Magnet, PMPI, Modeling, Simulation, DC-DC Converter.



go to top   Adaptive Neuro-Fuzzy Inference System (ANFIS) Based Simulation of Induction Motor Drives
         by P. M. Menghal, A. Jaya Laxmi

          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 reliable.
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Keywords: Adaptive Neuro-Fuzzy Inference System (ANFIS), Sugeno Fuzzy Controller, Hebbian Learning Genetic Algorithm, Expert System.



go to top   Control of Isolated Self-Excited Induction Generator with DTFC Strategy and DC Voltage Fuzzy Controller Used in Wind Turbin
         by A. Abbou, M. Akherraz, H. Mahmoudi, M. Barara

          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.
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Keywords: Self Excited Induction Generators (SEIG), DTFC, Fuzzy Logic Controller, DC Voltage Regulation, Wind Turbine.



go to top   Simulation and DSP Based Real Time Implementation of Closed Loop Variable Speed Operation of a PMBLDC Motor Drive System
         by Lekshmi A., Sankaran R., Ushakumari S.

          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 environment.
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Keywords: Closed Loop Operation, PMBLDC Motor, Predictive Current Control, Real Time DSP Controller, Space Vector PWM.



go to top   Position Sensorless Direct Torque Control of Brushless DC Motor Drive Using Four-Switch, Three Phase Inverter
         by S. M. Seyedi, A. Halvaei Niasar, H. Moghbelli

          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.
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Keywords: Brushless Dc Motor Drives, Direct Torque Control, Four-Switch Inverter, Sensorless Control, Cost Reduction.



go to top   Improved Dynamic Performance of IPMSM Over Wide Speed Range Based on Numerical Computation of id in the Field Weakening Region
         by S. Pervin, M. Nasir Uddin, Z. Siri

          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.
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Keywords: Interior Permanent Magnet Synchronous Motor, Field Weakening Operation, Newton-Raphson Method, High Precision Computation, Motor Drives.



go to top   Torque Profile Analysis of In-Wheel Switched Reluctance Motor with Pole Shape Modification
         by G. Nalina Shini, V. Kamaraj, M. Balaji

          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.
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Keywords: Finite Element Analysis, In- Wheel SRM, MagNet7. 1.1, Pole Shapes.


go to top   A Study of Various Drive Train Models of Fixed Speed Wind Generators and Their Simulation Using Simscape
         by Rajiv Singh, Asheesh Kumar Singh

          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.
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Keywords: Drive Train, Fixed-Speed Wind Generators, Simscape, Wind Gust, Wind Ramp, Wind Turbulence.



go to top   Self-Scheduling of a Plug-in Electric Vehicles Aggregator in Spinning Reserve Market
         by Mehdi Rahmani-Andebili

          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.
The aggregator maximizes its profit in SR market subject to some technical and contractual constraints. The said problem is a probabilistic and nonlinear problem which is solved using simulated annealing (SA) algorithm. 

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Keywords: Plug-In Electric Vehicles (PIEVS) Aggregator, Self-Scheduling (SS), Spinning Reserve (SR) Market.


go to top   Robust Neural Adaptive Control for a Class of Uncertain Nonlinear Complex Dynamical Multivariable Systems
         by Farouk Zouari, Kamel Ben Saad, Mohamed Benrejeb

          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 adaptive control.
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Keywords: Neural Adaptive Control, Robust Neural Adaptive Control, Neural Indirect Adaptive Control, Lyapunov Theory, Uncertain Nonlinear Multivariable Systems.



go to top   Investigate Balancing in Rotating Structures Using Modal Testing and Analysis Results for Structural Health Monitoring Purpose and Design
         by H. Al-Khazali, M. Askari

          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 problems.
The experimental technique used is called Modal Testing, however the full implementation of Modal Testing in active structures and the implications are not fully understood and are therefore in need of much further and more in depth investigations.
The modal parameters of a rotor system with load in the effective length (two discs) was investigated in different applications (before and after added mass), the reaction force in the bearings with different speed of rotation has been studied.
The purpose of the study is to develop a multi-methods modal technique, using modal testing in vibration analysis and (FE), it is envisaged that the approach isn’t limited to the condition monitoring, has evolved into a standard tool for structural dynamics problem analysis and design optimization. The main objective of the research work presented here is to use the dynamic characteristics help to better understand how the structure will behave and how to adjust or improve the component or system design subsequently a health monitoring approach is investigated for rotor machines applications.

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Keywords: Balancing, Modal Analysis, Rotor Dynamics, Health Monitoring, System Identification.



go to top   Investigation by Simulation of Closed-Loop Optimal Control Law Implementation Using Artificial Neural Network
         by Xavier Matieni, Stephen J. Dodds, Sin Wee Lee

          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.
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Keywords: Closed-Loop, Optimal Control, ANN, Training, Maximum Principle.



go to top   Based Feature Comparison between two Topologies of an Axial-Flux Permanent-Magnet Synchronous Motor Intended for Traction Application
         by Helmi Aloui, Nadia Chaker, Rafik Neji

          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.
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Keywords: Axial-flux permanent-magnet motor, mono-disc, torus-NN, power-train, circulation mission.



go to top   Advanced Simulation Model of Five Phase PMBLDC Motor Drive for Low Power High Torque Applications
         by Inayathullaah M. A., Anita R.

          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.
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Keywords: Brushless DC Motor, Drive Modelling, Five Phase Motor, High Torque, Simulation.



International Review on Modelling and Simulations - Papers (Part B)



go to top   Application of Multi Objective Optimization to Optimal Power Dispatch Problem with Facts Devices Using Refined BFA
         by S. Jaganthan, S. Palaniswami

          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 previous work.
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Keywords: Optimal Real and Reactive Power Dispatch, Refined Bacterial Foraging Algorithm, Multi-Objective Optimization, Load Flow, FACTS Devices, Voltage Stability Margin



go to top   Application of Reinforcement Learning for Load Scheduling
         by T. P. Imthias Ahamed, S. Danish Maqbool, Nazar H. Malik

          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.
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Keywords: Demand Response, Reinforcement Learning, Load Scheduling, Q-Learning, Learning Automata.



go to top   Damping Local and Inter-Area Power System Oscillation Improvement by Using Fuzzy Logic Power System Stabilizer
         by M. Mehrzadi, A. Panahi, M. Bayatmokhtari

          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.
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Keywords: Power System Stabilizer, Multi Machine, Fuzzy Logic Controller, Conventional Controller, Inter-Area.



go to top   Comprehensive Analysis of the Impacts of Different Parameters on Transmission Line Switching Overvoltages
         by Heresh Seyedi, Zaher Abam, Smko Golabi

          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 capital saving.
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Keywords: Insulation Coordination, Switching Overvoltage, Power System Transients.



go to top   Power System State Estimation Based on PMU Measurements vs SCADA Measurements
         by V. Kirincic, S. Skok, I. Pavic

          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.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: State Estimation, Synchronized Phasor Measurements, Renewable Energy Sources, Power System Control, Smart Transmission Grid.



go to top   Design a Power System Stabilizer Based on Fuzzy Sliding Mode Control Theory
         by Ghazanfar Shahgholian, Hamed Karimi, Hamid Mahmoodian

          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.
The advantage of this method is making the system insensitive and robust against changes in the system operation conditions. By applying fuzzy mechanism the problem of the common mode sliding controllers (SMC), which is the lack of a regular way to select controlling gain, is solved and met. Finally, computerized simulation results are shown on a single machine power system connected to infinitive bus, and then the provided results are compared with a classic power system stabilizer (CPSS) in different operation conditions.

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Keywords: Power System Stabilizer (PSS), Sliding Mode Control, Fuzzy Logic Controller.



go to top   High Impedance Fault Detection on Power Distribution Feeder
         by Marizan Sulaiman, Adnan H. Tawafan, Zulkifilie Ibrahim

          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.
Fast Fourier Transformation (FFT) is used to extract the feature of the fault signal and other power system events. The effect of capacitor banks switching, non-linear load current, no-load line switching and other normal event on distribution feeder harmonics is discussed. HIF and other operation event data were obtained by simulation of a 13.8 kV distribution feeder using PSCAD. The results show that the proposed algorithm can distinguish successfully HIFs from other events in distribution power system.

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Keywords: High Impedance Faults, FFT, TSK Fuzzy Modeling, Power Distribution Feeder.



go to top   Distance Protection Algorithm for Three Terminal Transmission Lines Using Local Measurements
         by A. Esmaeilian, P. Jambor Salamati, M. Salay Naderi

          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.
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Keywords: Distance Relay, Three Terminal Transmission line, Current Distribution Factor, Multi-Tapped Line, Infeed/Outfeed Current.



go to top   Effect of Dynamic and Static Load in the Voltage Stability
         by Chokri Bouchoucha, Saďdi Abdelaziz, M. N. Mansouri, F. Mimouni

          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 system.
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Keywords: Voltage Collapse, Voltage Stability Index, Slow Collapse, Fast Collapse, Stability, Static Load, Dynamic Load.



go to top   Development of Variable Structure Fuzzy Gain Scheduling Controller for an Interconnected Power System
         by K. R. M. Vijaya Chandrakala, S. Balamurugan, K. Sankaranarayanan

          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 Error techniques. 
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Keywords: Load Frequency Control, Proportional Integral Controller, Variable Structure System Controller, Hydrothermal Power Plant, Fuzzy Gain Scheduling, Variable Structure Fuzzy Gain Scheduling.


go to top   Machine Learning for Steady State Security Assessment in Power System
         by I. S. Saeh, M. W. Mustafa

          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.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Steady State Security Assessment, Artificial Intelligence Classifiers, Power System .



go to top   Design and Development of Embedded Controller for High Efficient Grid Connected Solar Power System
         by J. R. Maglin, R. Ramesh

          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 system.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Solar Energy, Embedded, Power Quality, Inverter, Converter, MPPT.



go to top   Small Signal Stability Analysis of Power System with VSC Based HVDC Link Employing Phase Angle Control
         by S. V. Anbuselvi, R. P. Kumudini Devi, P. Somasundaram, T. S. Nargunadevi

          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 analysed.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Small Signal Stability, VSC Based HVDC Link, Phase Angle Control.



go to top   Dynamic Embedded Optimization Based Security Assessment of an Interconnected Power System with D- FACTS Devices
           by T. A. Ramesh Kumaar, I. A. Chidambaram

          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.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved


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).



go to top   Forecasting of Wind Speed Using Artificial Neural Networks
         by Ramesh Babu N., Arulmozhivarman P.

          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 forecasting.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Wind Speed Forecast, BPN, GRNN, RBFN, ARMA.



go to top   Analysis and Simulations of Three-Phase Uniform Charge Power Sources with Current Harmonic Decrease
         by Gabriel N. Popa, Sorin I. Deaconu,Corina M. Diniş, Angela Iagăr

          Vol. 5. n. 5, pp. 2281-2290


Abstract - 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.
The main objective of this work is to measure, simulate, and analyze, currents, voltages, total harmonic distortion, and powers from the sources that are used (thyristor- controlled reactor type) taking into account a news electric model, more close to reality, of the sections. It’s analyzed the modification of the current waves shape and total harmonic distortion in case of using shunt active filter.

Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved


Keywords:  Plate-Type Electrostatic Precipitators, Power Supplies, Simulation, Total Harmonic Distortion, Active Filter.



go to top   Optimal Allocating and Rating Selection of STATCOM for Power System Voltage Stability Enhancement by Normal Forms of Diffeomorphism
         by M. Pishvaei, Z. Mokhtarnezhad, M. R. Banaei

          Vol. 5. n. 5, pp. 2291-2298


Abstract - 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.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Optimal Allocation, STATCOM, Voltage Stability, Normal Forms of Diffeomorphism.



go to top   Integration/Analysis of Green Energy and Conventional Electricity Generation with Interconnected Distribution Networks
         by Pushpendra Singh, D. P. Kothari, Mool Singh

          Vol. 5. n. 5, pp. 2299-2306


Abstract - 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.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Distributed Generators, Distribution Networks, Smart Grid, Power Quality.



go to top   Load Frequency Control of Hydrothermal System Under Open Market Considering Capacitive Energy Storage
         by P. Marimuthu, C. Govindaraju

          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 areas.
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Keywords: Load Frequency Control, Capacitive Energy Storage, Open Market System, Hydrothermal System.



go to top   A Hybrid Algorithm Using Modified LR –PSO for Solving Unit Commitment Problem with Various Constraints
         by B. Saravanan, K. S. Swarup, D. P. Kothari, J. Belwin Edward, S. Prabhakar Karthikeyan

          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.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Unit Commitment, Optimization, Two Stage Programming, Modified Lagrange Relaxation, Priority List, Particle Swarm Optimization.



go to top   The Simulated Annealing Q-Learning Application to the Dynamic Power Markets
         by Thanhquy Bach, Jiangang Yao

          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.
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Keywords: The SA-Q Learning Algorithm, Optimal Bidding Strategy, Dynamic Power Market, Double-Sided Auction.



go to top   Modeling, Simulation and Hardware Implementation of Wind-Solar Hybrid System
         by Pranati Katyal, B. L. Mathur

          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 suggested.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Hybrid System, Inverter, Off-Grid, Permanent Magnetic Synchronous Generator (PMSG), Small Wind Turbine (SWT) / Aerogenerator, Solar Photovoltaic System (SPV).



go to top   Degradation of Surrounding Dielectrics of a Micro-Channel Due to Partial Discharges, Part 1: The Model
         by Alireza A. Ganjovi, Azam Mirzaei, Soghra Sadr, Amir Mojtahedzadeh

          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.
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Keywords: Partial Discharges, Dielectric Degradation, PIC-MCC Simulation.



go to top   An Extension to the Theory of the Transmission Lines
         by Nakka Lakshmi Srinivasa Rao, G. Govinda Rao, S. Sivanagaraju

          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.
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Keywords: Compensation, Flatness Index, Transmission Line, Voltage Profile, Hyperbolic Sag.



go to top   Bees Colony Intelligence in Optimization: an Application to PSS design
         by R. Sheeba, M. Jayaraju, K. Sundhareswaran

          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.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Optimization, Bees, Power System Stabilizer.



go to top   Performance Analysis and Protection of Air Distribution Cables from Lightning Faults
         by M. A. Omidiora, M. Lehtonen, P. Hyvönen

          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.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Air distribution cable, Grounding resistance, Induced flashovers, Insulators, Lightning, Shield wire, Tree, Wooden pole.




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