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Home>Products>Journal and Reviews>I.R.E.E.>Latest issue
International Review of Electrical Engineering Vol. 6 N. 7-- Part A International Review of Electrical Engineering Vol. 6 N. 7-- Part B
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International Review of Electrical Engineering - Papers- Part A
Analysis and Implementation of Zero Voltage Switching Integrated Buck-Flyback
Converter
by Bor-Ren Lin,
Chien-Lan Huang
Abstract - This paper presents the system analysis and circuit implementation of a soft switching converter based on buck-flyback topology to have a large voltage step-down between the output and input sides. Compared with the conventional buck converter, the proposed converter has wide turn-on period so that the lower output voltage can be achieved. An active snubber circuit is connected in parallel with the main switch to achieve zero voltage switching (ZVS). The resonance is based on the output capacitance of power switch and resonant inductance at the transition interval between the main and auxiliary switches. Therefore, the turn-on switching losses of power switch are reduced. The circuit configuration, system analysis, and design consideration of the proposed converter are presented in detail. Finally, experimental results based on a laboratory prototype with 240W rated power are provided to verify the effectiveness of the proposed converter.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Zero Voltage Switching, Integrated Buck-Flyback Converter.
Small Power, Three to One Phase Matrix Converter for Wind Generators
by P.J. Ehlers,
C.G. Richards, D.V. Nicolae
Abstract - This paper investigates the concept of an isolated small wind power system based on a three-phase generator and a direct ac-to-ac conversion. The ac-to-ac conversion is performed by a matrix converter and thus removing the need of a large smoothing capacitor in the typical rectifier-inverter solution. The paper is briefly presenting the operation for a particular topology of a three-phase to single-phase matrix converter. The control of this conversion ensures system’s frequency and voltage stability. Simulation results and practical results are presented to validate the frequency and voltage regulation of the isolated power system.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Wind Power System, Power Conditioner, Voltage Regulation, Sinusoidal Pulse Width Modulation.
A
Novel 3-D Space Vector Modulation Algorithm for Cascaded Multilevel Inverter
by R.Karthikeyan,
Dr.S.Chenthur Pandian
Abstract - Multilevel inverters have been widely used in high-power applications, because of its low switching losses and good harmonic rejection capabilities. Various multilevel pulse width modulation (PWM) strategies have been developed. Among them, space-vector pulse width modulation (SVPWM) technique offers significant flexibility to optimize switching waveforms and is well suited for digital implementation. This paper presents a novel space vector pulse width modulation (SVPWM) algorithm for n-level three-phase inverters. The 3-D SVPWM presented in this paper can be applied practically in hybrid multilevel inverters with unequal or varying voltage steps; it can be applied to most multilevel topologies. The algorithm offers an intuitive method for minimizing the total harmonic distortion (THD) of the output voltage of the inverter and the proposed techniques lead to a significant reduction in THD. The algorithm developed improves factor such as the computational cost and voltage distortion. Finally, the algorithm was implemented on a Field programmable gate array (FPGA) and the scheme is explained for a five level inverter, and experimental results are presented for single phase five-level cascaded inverter to validate the proposed modulation technique.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Multilevel Inverter, Power Conversion, 3-D Space Vector Modulation (3-D SVPWM), Total Harmonic Distortion.
Analysis
of an Interleaved Zero Voltage Switching Boost Converter
by Bor-Ren Lin
Abstract - An interleaved boost converter is presented in this paper to achieve zero voltage switching (ZVS), DC bus voltage regulation and reduce ripple current and input and output sides. Active snubber is adopted between the main switch and output side to limit the voltage stress on switch. When main switch is turned off, the positive resonant inductor current flows through the anti-parallel diode of auxiliary switch so that the auxiliary switch can be turned on at ZVS. When auxiliary switch is turned off, the negative resonant inductor current will discharge the output capacitor of main switch so that the ZVS turn-on of main switch can be achieved. The interleaved pulse-width modulation (PWM) can further reduce the input and output ripple currents such that the sizes of input inductor and output capacitor are reduced. The circuit configuration, principle operation, system analysis, and design consideration of the proposed converter are presented. Finally, experiments conducted on a laboratory prototype rated at 160W were presented to demonstrate the performance of the proposed converter.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Zero Voltage Switching, Boost Converter, Interleaved PWM Scheme.
Quantitative Analysis and Experimental Verification of Feasible Output Filters
for DG Inverters
by Tsao-Tsung Ma
Abstract - When distributed generation (DG) units attempt to connect to the utility distribution system (DS) a wide range of system issues arise, i.e., protection, power quality and system operation. With the growing use of inverters in DG systems, the problem of injected harmonics becomes critical. Eliminating these harmonics requires the use of proper low pass filters installed between the inverter output terminals and the network. This paper presents a quantitative design method for the output LC filter of the DG inverters in grid-tie applications. The design criteria are made according to the harmonics standards that determine the level of current harmonics injected into the DS. Mathematical derivations of the maximum inductor ripple current with a given set of parameters are carried out. The value of filter capacitor is designed on the allowable level of switching components injected into the DS. To improve the performance of conventional LC filters a number of damping techniques for suppressing resonance effects are investigated and evaluated via comprehensive numerical simulation studies. Finally, a set of measured results from a DSP based experimental setup is presented with brief discussions to conclude this study.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Distributed Generation, Power Quality, Harmonics, LC Filter, DG Inverters.
A Three-Level Soft-switching Active Power Filter with DC Self-Balancing
Capability
by Io-Keong Lok,
Ning-Yi Dai, Man-Chung Wong
Abstract - The three-level neutral-point-clamped (NPC) inverter was applied in active power filters (APFs). The three-level NPC inverter has the structure of split dc capacitors. So the existing dc neutral point can be directly utilized as the ground return in a three-phase four-wire system. DC bus voltage unbalance has been one of the major problems of three-level NPC inverters. In addition, high voltage and current stresses during switching cause higher system losses and lower efficiency. In this paper, a generalized three-level quasi-resonant dc-link (QRDCL) inverter is proposed, which has both the soft-switching and dc voltage self-balancing capabilities. The switching sequence for all the power switches in the proposed three-level QRDCL inverter is designed. The inverter is controlled by the 3-dimensional direct pulse width modulation with embedded auxiliary switches triggering. The proposed generalized three-level QRDCL inverter is applied in a three-phase four-wire APF. Simulation results and experimental results verified that the proposed system can achieve dc-link balance and switching losses reduction simultaneously. The efficiency of the proposed active power filter is improved and the high voltage stress during switching is released.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Active Filters, DC Unbalance, Quasi-resonant DC-link, Soft-switching Template.
Isolated
Zero-voltage-switching SEPIC Converter
by Hyung Chul Park
Abstract - An isolated zero-voltage-switching (ZVS) single-ended primary inductor converter (SEPIC) is presented in this paper. An active clamp circuit is added to the conventional isolated SEPIC converter to provide ZVS operation. A coupled inductor and an auxiliary capacitor are utilized to obtain the ripple-free input current. Moreover, the reverse-recovery problem of the output diode is alleviated due to the leakage inductance of the transformer. The major advantages of this converter besides step up/down capability and an electrical isolation are the ripple-free input current and soft-switching commutations of the power semiconductor devices. The operation principle and steady-state analysis of the proposed converter are provided in detail. A prototype of the proposed converter is developed, and its experimental results are presented for validation.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
SEPIC Converter, Coupled Inductor, Zero-voltage-switching,
Ripple-Free Input Current.
Implementation
of an Interleaved AC/DC Converter with High Power Factor and High Voltage
Conversion Ratio
by Bor-Ren Lin,
Chih-Cheng Chien
Abstract - This paper presents an interleaved AC/DC converter to achieve power factor correction (PFC) and line current harmonic reduction. Double boost topology is used to overcome the limit of a narrow turn-off period in a conventional boost converter and to achieve a high voltage conversion ratio. The continuous conduction mode (CCM) with fixed switching frequency is used to control active switch such that the line current is a sinusoidal waveform in phase with line voltage. Compared to the boundary conduction mode (BCM) approach, the proposed converter with CCM scheme has less conduction losses on power semiconductors and inductors. In order to increase the load power and reduce the size of magnetic components, the interleaved pulse-width modulation (PWM) is adopted to control two circuit modules. Thus the ripple currents at input and output sides are decreased and the size of inductors and capacitors are also reduced. The circuit configuration, principle operation, system analysis, and design consideration of the proposed AC/DC converter are presented in detail. Finally, experiments conducted on a laboratory prototype rated at 800W were presented to demonstrate the performance of the proposed converter.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: PFC, Interleaved PWM, CCM, Double Boost, High Voltage Step-up.
Design & Implementation of Transformer-Less Multi Output DC Power Supply
by Rakesh Maurya,
S.P. Srivastava, Pramod Agarwal
Abstract - Electronic circuits often require power supply which can furnish more than one regulated output with different voltage and current specifications. Traditionally, these power supplies are accomplished by Multi-winding High frequency Power transformer with each output regulated through individual control and hence, uneconomical. Transformer-less DC-DC power converter based on buck topology is described in this paper which provides three independently controlled output voltages of different voltage and current rating, from a two power handling power switches and a single dc source voltage. The converter can operate with high efficiency and circuit complexity, cost, size and weight are significantly reduced as compared to conventional solutions. The proposed DC power supply is an attractive choice in applications which require low conversion ratio, non-isolation, good regulation against load and line disturbances, and fast dynamic response. A prototype model of dc-dc converter which provides three regulated dc outputs- 5V/10A, 15V/5A and 12V/20A DC is developed in laboratory for experimentation. Simulation results are validated through it.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Buck Converter, Multi-Output Power Supply, PWM Control.
Stability
Analysis of AC Distribution System with Six-Pulse Diode Rectifier and
Multi-Converter Power Electronic Loads
by T. Sopapirm,
K-N. Areerak, K-L. Areerak
Abstract - This paper deals with the stability assessment of the AC distribution system including a three-phase diode rectifier feeding paralleled controlled buck converters. These regulated converters behave as a constant power load that can significantly degrades the system stability. The averaging methods called DQ modeling and generalized state-space averaging methods are used to derive the dynamic model suitable for the stability analysis. The time-domain simulation via the full topology model is used to support the theoretical results. Moreover, the experimental results are also used to validate the unstable point that can be predicted from the theory. The results show that a good agreement between theoretical, simulation, and experimental results can be achieved.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: DQ Modeling Method, Generalized State-Space Averaging Method, Diode Rectifier, Buck Converter, Constant Power Load, Stability Analysis, Modeling, Simulation.
Thrust Optimization of Linear Oscillatory Actuator Using Permeance Analysis
Method
by F. Azhar, M.
Norhisam, N.F Mailah, M. R. Zare, H.Wakiwaka, M.Nirei
Abstract - This paper describes thrust optimization of linear oscillatory actuator (LOA). The objective of the optimization is to obtain the highest as possible thrust at restricted weight of LOA in order to ensure it equipped with adequate thrust and mobility features. In this research, the LOA is aim to have a starter thrust higher than 200 N while having total of weight lower than 2.0 kg. The thrust of LOA was optimized by using permeance analysis method (PAM). The thickness of the permanent magnets and the height of coils have been varied at different fixed total of radius of LOA in order to obtain the optimized structure. The optimized structure of LOA was decided by using two different methods. The first method is by evaluating the each point of the calculation output. The second method is by using generic algorithm. Both output of these method giving a different result in term of LOA PM’s thickness however having similar thrust characteristics. The FEM and measurement results were used to verify the PAM output. Consequently, the LOA has been designed with optimum parameters which having value of starter thrust of 245 N and the total weight is 2.0 kg.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Linear Oscillatory Actuator, Thrust Optimization, Permeance
Analysis Method, Generic Algorithm.
Comparison of Two Novel Sensorless Methods for Indirect Rotor Position
Estimation in a Field Assisted Switched Reluctance Motor
by H.Torkaman,
H.Amiri, N.Ghadimi
Abstract - This
paper presents two novel methods to estimate the rotor position of a new
field assisted switched reluctance motor at standstill and also low
speeds.In the first method, a high frequency signal is injected to the
field assisted winding on the stator and then the phase of induced
signals on each phase winding is monitored. This method evaluates
current phase variation with respect to input voltage at a resonant
frequency which is obtained at aligned rotor position. The second method
for indirect sensing of rotor position is founded on Phase Modulation
technique in standstill mode. It then continues to sense the rotor
position while the motor is running at low speed by utilizing the same
sine wave signal to the field winding. In the running mode, the phase of
induced voltage on each un-energized stator winding is measured and
compared to other phases.in this regard, a prototype of the field
assisted switched reluctance motor is built and two methods are
implemented in a proper test bed. Finally,the paper presents the results
obtained which demonstrates the feasibility and practicability of the
methods and outlines the advantages of these techniques.
Copyright © 2011 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Rotor Position Estimation, Sensorless Methods, Field Assisted Switched Reluctance Motor.
ANN Speed Controller for Induction Motor Drive with Vector Control
by P.
Brandstetter, M. Skotnica
Abstract - The paper describes application of artificial neural networks in the speed control of the induction motor drive with vector control. The predictive speed controller consists of one feedforward and one recurrent neural network. The weights and thresholds of both artificial neural networks are constructed rather than trained and require no adaption during the control process. Such strategy allows for very efficient implementation of the controller using the digital signal processor. The speed control with the ANN controller was experimental proved on the experimental stand with frequency converter and induction motor.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Artificial Neural Network, Speed Control, Vector Control, Induction Motor, AC Drive.
Starting and Ultra Low-Speed Control Strategy for Gearless Traction Permanent
Magnet Synchronous Machine
by Gaolin Wang,
Fang Wu, Rongfeng Yang, Qiang Gao, Dianguo Xu
Abstract - This paper proposes an improved control strategy of gearless traction permanent magnet synchronous machine installed with an incremental encoder for the direct-drive elevator applications. To achieve the accurate current vector decoupling control for the traction machine at starting operation, the initial rotor position estimation at standstill based on a hybrid signal injection method is present. Firstly, a high-frequency oscillating sinusoidal voltage signal is injected to obtain the magnetic pole position. Then, two pulse voltage vectors are injected in the positive and the negative direction to identify the magnet polarity. On the basis of the traction machine state equations, a continuous speed observer is proposed adopting a full-order state observer. Therefore the continuous speed feedback information can be obtained according to the output signal from an ordinary incremental encoder. This way can make the traction machine drive achieve high-performance extra low-speed operation. The experimental results demonstrate the feasibility of the control strategy by an 11.7kW gearless elevator traction machine.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Elevator, Direct Drive, Traction Permanent Magnet Synchronous
Machine, Incremental Encoder, Initial Rotor Position Estimation, Hybrid
Signal Injection, Ultra Low-speed Operation, Speed Observer.
Design and Implementation of a Capacity Estimator Using Simple Neural Networks
for Lead-Acid Batteries
by K. H. Chao, J.
W. Chen
Abstract - A portable capacity estimator based on a modified neural network (MNN) is designed and implemented for lead-acid batteries in this paper. The internal resistance, open-circuit voltage and short-circuit current are chosen as the characteristics for estimating the capacity of lead-acid batteries. First, many cycles of charging-discharging experiments for lead-acid batteries are made to measure the distributed range of characteristic values. Then, the battery capacity is classified into 21 states and the measured characteristic values are adopted to construct an extension matter-element model according to the proposed modified neural network for differentiating the capacity of lead-acid batteries. Finally, a programmable system-on-chip (PSoC) microcontroller is employed to implement the proposed intelligent portable capacity estimator with high precision, fast speed and small size of hardware circuits for lead-acid batteries. Some experimental results are made to verify the validness of the proposed intelligent capacity estimator for lead-acid batteries.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Modified Neural Networks, Extension Matter-Element Model, Battery Capacity Estimator, Programmable System-on-Chip.
A
Review of Passive and Active Battery Balancing based on MATLAB/Simulink
by Mohamed Daowd,
Noshin Omar, Peter Van Den Bossche, Joeri Van Mierlo
Abstract - Battery systems are affected by many factors, a key one being the cells unbalancing. Without the balancing system, the individual cell voltages will differ over time, battery pack capacity will decrease quickly. That will result in the failure of the total battery system. Thus cell balancing acts an important role on the battery life preserving. Different cell balancing methodologies have been proposed for battery pack. This paper presents a review and comparisons between the different proposed balancing topologies for battery string based on MATLAB/Simulink® simulation. The comparison has been carried out according to circuit design, balancing simulation, voltage/current stress, practical implementations, application, balancing speed, complexity, balancing system efficiency, size, cost … etc.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Battery Balancing Review, Cell Equalization, MATLAB/Simulink Simulation, Battery Management System.
Using
Harmony Search Algorithm for Optimization the Component Sizing of Plug-in Hybrid
Electric Vehicle
by M. Mohammadi,
A. Houshyar, A. Pahlavanhoseini, N. Ghadimi
Abstract - In recent years, Harmony Search Algorithm have gained a lot of attention from the optimization research community. In this paper, harmony search algorithm is presented to optimize the component sizing of a parallel plug-in hybrid electric vehicle. In this study, the objective function is defined so as to minimize the drivetrain cost. In addition, the driving performance requirements are considered as constraints. Finally, the optimization process is performed over two types of batteries and three different All Electric Range (AER). The results show that the proposed optimization approach can be considered a viable alternative to solve design and manufacturing optimization problems.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Hybrid Electric Vehicle (HEV), Cost, Component Sizing, Harmony Search Algorithm.
Research
on Power Quality Conditioner Based on Three Level Hysteresis Current Control for
Electric Railway System
by
Zhibing Wang, Kunshan Yu, Xiaoxin Zhou
Abstract - Aiming to solve power quality problems caused by Electric Railway such as reactive power, unbalanced voltage and current harmonics, a complex power conditioner based on differentiation cascade H-bridge topology and balanced traction transformer is described herein. The paper has been proposed a special control strategy based on shift phase three-level hysteresis current control and priority compensating negative sequence strategy, and which includes kinds of advantages, such as fast dynamic responsibility, and composite power quality management. Simulation and prototype experimental results illustrated the feasible.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Differentiation Cascade H-bridge Topology, Electrified Railway, Power Quality, Railway Power Quality Conditioner, Three-Level Hysteresis Current Control.
Power Electronic Transformer for Advanced Grid Management in Presence of
Distributed Generation
by G. Brando, A.
Dannier, A. Del Pizzo, R. Rizzo
Abstract - Innovative architectures for electric energy distribution grids (e.g., microgrid, LoCal grid) have recently been proposed that virtualize a local generator as a constant load, source, or zero load to the grid, making it possible to connect distributed generation into the grid without reducing its reliability. Using these architectures, distributed generation may enhance the stability of the power grid. A new strategy is here proposed to improve the efficiency, flexibility, and stability of smart grids. This paper deals with a high performance solution based on a Power Electronic Transformer (PET), which includes dc-links, multilevel converters, and a medium-frequency (MF) transformer. Together with the reduced size of the whole conversion apparatus, the proposed topology ensures the compatibility of the distribution system and grid by appropriate strategy management. Good levels for the power quality indexes of the grid are obtained with a multilevel NPC front-end: mainly low values of harmonic distortion, and voltage and current dissymmetry. This occurs even if the commutation frequency of the switching devices of this converter is not high (1÷2 kHz). This paper mainly focuses on the control technique for the multilevel converters connected to the primary and secondary windings of the MF transformer, imposing multistep- or square-wave voltages. Control algorithms are presented that successfully meet the demands of the grid, and cases-studies are compared under ordinary and heavy conditions.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Smart Grid, Power Electronic Transformer, Multilevel Converter,
Distributed Generation.
Implementation of Solar Photovoltaic Source Fed Current Source Inverter
by R.Ramaprabha,
K.Santhosh, B.L.Mathur
Abstract - This paper presents a complete modeling, simulation and implementation of Solar Photovoltaic (SPV) source fed Current source inverter (CSI) system. Individual subsystems are simulated using MATLAB/SIMULINK for proper design and then implemented practically using FPGA controller. Perturb and Observe (P&O) algorithm is used to realize Maximum Power Point Tracking (MPPT) and Sinusoidal Pulse Width Modulation (SPWM) technique is applied for producing control pulses for CSI with current loop to maintain constant current at the output of the inverter.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Solar PV Source, MPPT, Current Source Inverter, MATLAB, FPGA.
Automated
Procedure for Calculating the Controller Parameters in Photovoltaic dc/dc
Converters
by D. Gonzalez,
C.A. Ramos-Paja,G.Petrone
Abstract - In the photovoltaic (PV) systems, the main objective of the control strategies is to extract the maximum power from the source, which is usually obtained by combining the action of the MPPT algorithm with a voltage regulator used to attenuate the disturbances at the source terminals. This work proposes an automatic procedure for designing the parameters of the voltage compensation network in which, the system stability margins and dynamic constraints are previously defined. Such a method permits the controller calculation by means of sequential operations without dealing with formal concepts of linearization and control design. Moreover, the method is based on the modeling of the complete PV system (source, converter and load) and takes into account the main parasitic components also. The method has been implemented in Matlab code, and validated by means of dynamic simulations and the power electronics simulator PSIM. The designed voltage control loop has been tested also together with a P&O MPPT algorithm in order to regulate the PV voltage in a double stage grid-connected system in presence of a wide voltage oscillation at the DC-bulk and with fast irradiance variation. Experimental results were also carried out to verify the goodness the proposed approach.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Photovoltaic Systems, Grid Connected, State Space Model, Control Systems, Automatic Controller Calculation.
International Review of Electrical Engineering - Papers- Part B
Decentralized
VSC-Based Microgrid’s General Power Flow
by P. Hasanpor
Divshali, S.H Hosseinian, M. Abedi
Abstract - In VSC-based microgrids which employ the frequency/voltage droop control method, the power sharing controllers alter the frequency and magnitude of each VSC output voltage based on the output active and reactive power, respectively. This method employs the variable voltage and frequency instead of physical communication link in order to active and reactive power sharing. Since there is no communication link, and the voltage and frequency are not constant in different load conditions, and no DG is large enough to provide all the demand variations, the PV bus model and slack bus model cannot be employed in these networks. Hence the conventional power flow method is not appropriate to calculate the steady state solution in such microgrids. As a result, previous works in this area in order to obtain the steady state solution perform a time domain simulation, which is very time-consuming process for this purpose. Therefore, developing new methods that calculate the steady state solution in a suitable time is a necessity. This paper presents a new approach to construct power flow equations in these networks without PV and slack bus model. The steady state solution of these equations is calculated, and the operating point is obtained much easier and faster than time domain simulation algorithm. In order to validate the proposed method, the time response of the proposed equations is compared with the time domain simulation results of PSCAD/EMTDC, which is an electromagnetic transient simulation program. The comparison indicates that the results of the proposed method, is very accurate. Moreover, the calculation time of this method outperforms other time domain simulation based method.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Autonomous Microgrid, Distributed Generation, Frequency/Voltage Droop, Power Flow Algorithm, Load Sharing, Small Signal Stability, Voltage Source Converter.
Security Constrained Optimal Power Flow Solved by Mixed Integer Non Linear
Programming
by S. M. Ezzati,
H. Vahedi, G. R. Yousefi, M. M. Pedram
Abstract - This paper proposes a Mixed Integer Non Linear Programming (MINLP) for solving Security Constrained Optimal Power Flow (SCOPF) that has been simulated in Generalized Algebraic Modeling System (GAMS). The objective function of SCOPF is minimize total generation cost considering transmission security, reduces transmission loss and improves the bus voltage profile under two cases that are normal and contingent states. In this paper we have used 26-bus and the IEEE 30-bus test systems, and have compared results with the Particle Swarm Optimization Algorithm with Reconstruction Operators (PSO-RO) and Mixed-Integer Bacterial Foraging Algorithm (MIBFA) in terms of solution quality and evolutionary computing efficiency.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Security Constraint Optimal Power Flow, Mixed Integer Non Linear
Programming, Dependent Variables, Control Variables.
Sequential Islanding of Power Systems as a Security Strategy
by Ricardo Moreno,
Álvaro Torres, George Anders, Mario A. Ríos
Abstract - Sequential islanding is a strategy that consists of tripping off properly selected lines to separate the network into one or more islands as a way to improve the security of the power system. This paper proposes an application of some concepts of the spectral graph theory to identify the minimum cutset of transmission lines that allows the partitioning of a power system into several regions based on the minimum net flow between them. The approach provides an effective tool for the identification islands scenarios. The concepts are illustrated by splitting two large-scale systems.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Fiedler, Islanding, Minimal Cutset, Network Configuration, Spectral Graph Theory, Security Of Power Systems.
Optimal Ga/Pso-Based Allocation of Facts Devices Considering Voltage Stability
through Optimal Power Flow
by A. Abbaszadeh,
J. Soltani, B. Mozafari, F. Partovi
Abstract - This paper utilizes a novel method that uses the application of GA/PSO techniques to find the optimal location of FACTS devices in order to enhance voltage stability through Optimal Power Flow (OPF). Three different types of FACTS devices, Thyristor Controlled Series Compensator (TCSC), Unified Power Flow Controller (UPFC) and Thyristor Controlled Phase Shifter (TCPS) are considered. While finding the optimal location of these three types of FACTS devices all of the operational and security constraints are satisfied. Simulations are performed on IEEE 30 bus test system and results are presented.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: FACTS devices, GA, OPF, PSO, Voltage Stability.
Augmentation of Electrolyzer Control Effect by PSS for Microgrid Stabilization
using PID-based Mixed H2/H∞ Control
by Issarachai
Ngamroo
Abstract - In an isolated microgrid with hybrid wind, fuel cell (FC) with electrolyzer (EZ) and diesel generations, the intermittent wind power may cause the serious power fluctuation. In addition to the hydrogen production for FC, the EZ can be used to alleviate power fluctuation by control of the absorbed power. Nevertheless, the EZ may fail to suppress the power fluctuation due to the severe faults. To augment the EZ control performance, a power system stabilizer (PSS) which is assumed to be equipped with a diesel generator can be applied. This paper proposes the robust stabilization of isolated microgrid by EZ and PSS. The structure of power controller of EZ and PSS is a proportional-integral-derivative (PID) controller. To improve the damping performance and robustness of EZ controller and PSS, the PID parameters of both EZ and PSS are simultaneously tuned based on the mixed H2/H∞ control by bee colony optimization. Simulation studies show that the stabilizing performance and robustness of the proposed EZ and PSS are superior to those of the individual device under system uncertainties such as various wind patterns, loading conditions and severe faults.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Electrolyzer, Power System Stabilizer, Mixed H2/H∞ Control, System Uncertainties, Bee Colony Optimization.
Multi-Tasking
Optimal Placement and Sizing of Distributed Generations
by Mohsen Rezaie
Estabragh, Mohsen Mohammadian
Abstract - This
paper proposes a novel approach for optimal allocation and sizing
problem of Distributed Generations (DGs) as a non-linear and
multi-objective optimization problem. The proposed method establishes a
tradeoff between security index, power losses, voltage deviations and
cost investment as important indexes in DG allocation and size
selection. The analysis is performed using a steady state voltage
stability index for assessment of system security. The proposed
optimization problem has been performed as a hierarchical optimization
problem. In the first stage, Hybrid Genetic Algorithm Particle Swarm
Optimization (HGAPSO) method has been used to reach the coordinated
pattern of sizing and placement of DG. Also, a toolbox has been
developed to evaluate the voltage stability margin respectively each
coordinated pattern during HGAPSO search. Proposed toolbox is based on a
nonlinear optimization problem which it tries to evaluate loadability
limit as voltage stability index by using Lagrangian method. The
proposed method has been implemented on IEEE 14 bus and IEEE 30 bus test
systems and results show the proper performance and acceptable
operation. For demonstrating the validity and the convenience of
proposed approach, obtained results have been compared with PSO method.
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All rights reserved
Keywords: DG Planning, Loadability Limit, Static Voltage Stability, Hierarchical Optimization, HGAPSO.
Optimal
Power Flow using Artificial Bee Colony with Incorporation of FACTS Devices: a
Case Study
by Linda Slimani,
Tarek Bouktir
Abstract - This paper presents solution of optimal power flow (OPF) problem of practical power system via an Artificial Bee Colony (ABC) algorithm. The objective is to minimize the total fuel cost of generation and environmental pollution caused by fossil based thermal generating units and also maintaining an acceptable system performance in terms of limits on generator reactive power outputs, bus voltages, Static VAR Compensator (SVC) parameters and overload in transmission lines. CPU times can be reduced by decomposing the problem in two subproblems, the first subproblem minimize the fuel cost of generation and environmental pollution and the second one is a reactive power dispatch so optimum bus voltages can be determined and reduce the losses by controlling tap changes of the transformers and the static Var Compensators (SVC). To verify the proposed approach and for comparison purposes, we perform simulations on IEEE 30-bus system with six generating units and on the Algerian network with 114 buses, 175 branches (lines and transformers) and 15 generators. The obtained results indicate that ABC is an easy to use, fast, robust and powerful optimization technique compared to the other global optimization method (PSO).
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Economic Power Dispatch, Optimal Power Flow, Artificial Bee Colony, FACTS Device, Optimization, Algerian Network, Pollution Control, Nox Emission.
Particle Swarm Optimization Method to Assess a Voltage Stability Region by
Multi-Parameter Bifurcation Analysis
by Juan J. Flores,
Claudio R. Fuerte-Esquivel, Julio Barrera, H. R. Carvajal
Abstract - An electrical power system’s feasibility region of a power system is defined by all operating points that can be reached by the continuous variation of its parameters without causing leading the system to system’s instability. The information about the size of this region and its boundary is important for utilities to guarantee the secure operation of power systems. In this paper a new approach is proposed to calculate determine the feasibility region without applying the principle of continuation. For this purpose, a particle swarm optimization is developed to transform the problem of finding one equilibrium point for a given system’s conditions into a problem of computing several (all in most cases) equilibrium points for the same operating conditions. Determining several equilibrium points for all possible operating conditions, then joining all results, allow us to assemble a complete bifurcation diagram of the system under analysis. A benchmark power system is used to numerically illustrate the effectiveness of the proposed approach, whose results are compared with those obtained by the application of a continuation method.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Particle Swarm Optimization, Bifurcation Analysis, Power System
Security, Stability Regions, Voltage Stability.
Voltage
Stability Index and Line Loadability Index for Radial Power Distribution
Networks
by Kultar Deep
Singh, Smarajit Ghosh
Abstract - This paper reports a voltage stability index and line loadability index for radial distribution networks. The change in resistance with the change in operating temperature of the branch conductors is incorporated in the computation of voltage stability index and line loadability index. The voltage stability index computes the voltage stability limit of the radial distribution network in the fault conditions or at the time of load contingency, it identifies the most sensitive node of the distribution network and gives information about time within which the voltage collapse will occur for above said conditions. The line loadability index is based on the maximum permissible steady state operating temperature of the line conductors. The loadability limit of the distribution network is supposed to be within the maximum permissible operating temperature of the conductor. Line loadability index gives the loadability limit of the network in normal steady state conditions and identifies the most sensitive branch of the network. The values of voltage stability limit and line loadability limit are not unique for a distribution networks, the values might be different for the same network in different ambient conditions. So a very practical aspect is incorporated in the proposed work. The importance of the proposed voltage stability index is discussed in context of over current protection. The proposed voltage stability index and line loadability index can be used for voltage stability study and the loadability margin, optimal conductor size selection, capacitor placement studies, reconfiguration of distribution networks, over current protection system design etc at planning stage as well as in operation of the electrical power distribution system.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Radial, Distribution Networks, Voltage-stability, Loadability and Current Carrying Capacity.
Multiple
PSS Design Using an Improved Honey Bee Mating Optimization Algorithm to
Enhance Low Frequency Oscillations
by H. Shayeghi, A.
Ghasemi
Abstract - Optimal tuning of the PSS parameters is importance and a challenging undertaking to accommodate variations in the power system dynamics, especially when several PSSs are employed. Because, it has a complex computational optimization process. Thus, an Improved version of Honey Bee Mating Optimization (IHBMO) algorithm is developed and applied for optimal tuning of multiple PSSs, simultaneously in order to decrease the PSS design effort and find the optimal solution in this paper. IHBMO technique is a hybrid evolutionary algorithm which combines the power of genetic algorithms and simulated annealing with a fast problem specific local search heuristic to obtain the best possible solution. To find out the optimal parameters of PSSs a nonlinear time domain-based objective function under various operating conditions is used. The IHBMO uses a new adaptive mechanism to change speed reduction factor for calculating queen's speed with iterations for considerable increasing the probability of finding the global optimum solution within a reasonable computation effort. The effectiveness of the proposed IHBMO based PSSs is demonstrated on a three-machine power system through the nonlinear time domain simulation and some performance indices under different operating conditions. The results are compared with those of Genetic Algorithm (GA), original version of HBMO and classical methods based tuned PSSs to illustrate robust performance of the proposed stabilizer.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: IHBMO, Multiple PSS Design, Multi-machine Power Systems, Honey Bee Mating Optimization, Power System Dynamics.
Multi-agent
Based Frequency Control of Islanded Microgrid
by Wei Gu, Chen
Shen, Zhi Wu
Abstract - Islanded microgrid is an independent micro power system with small equivalent inertial and different characteristics of kinds of distributed generations, which makes its frequency control more difficult than conventional grids.This paper presents a multi-agent based frequency control approach forislanded microgrid. The characteristics of agents are discussed and then hierarchical multi-agent control framework is proposed. In order to make the frequency control approach more adaptive, a new underfrequency load shedding method is used in the multi-agent control system. Simulation results show that the proposedmulti-agent based frequency control approachcan maintain the frequency stability of islanded microgrid even in emergency conditions.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Islanded Microgrid, Frequency Control, Multi-Agent System, Equivalent Inertial.
Active and Reactive Power Control in a Single-Phase Grid-Connected PV System
with Optimization of the Ferrite Core Volume
by K.C. A. de
Souza, W.M. dos Santos, D.C. Martins
Abstract - This paper presents a method to minimize the losses and the magnetic cores volume in a single-phase active power filter based in a two stages grid-connected PV system. The proposed circuit injects PV generated power into the utility, and always acts as an active power filter to compensate load harmonics and reactive power such that the input power factor is very high independently of the solar radiation and the type of the load connected. In sunny days, the system processes all the reactive and active load power and the excessive power from the PV module can be fed to the utility. On the other hand, on cloudy days for instance, if the PV power is not enough, the system processes all the reactive load power and the shortage of active load power is supplemented by the utility. Besides, just using one current sensor, the control strategy is simple and of suitable for practical implementation.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Single-Phase Circuits, Grid-Connected PV Systems And Active Power Filter.
Power Quality Disturbances Recognition Based on Hyperbolic S-transform and
Rule-based Decision Tree
by Nantian Huang,
Xiaosheng Liu, Dianguo Xu, Lin Lin
Abstract - Power quality disturbances recognition is the foundation of power quality analysis and control. A novel high performance recognition method based on a generalized S-transform with Hyperbolic window (Hyperbolic S-transform) and rule-based decision tree is proposed in this paper. The original power signals are analyzed by the HS-transform. 4 features are extracted to formulate decision rules. Finally, a rule-based decision tree is constructed to classify power quality disturbances. 8 types of power quality disturbances including 2 types of complex power disturbance are recognized precisely by the decision tree. The new approach has simple classification process and high classification effectiveness. It is very satisfied for the real-time requirement of smart grid in real work. The simulation result shows the robustness and effectiveness of proposed method.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Power Quality, Power Quality Disturbance, HS-transform, Decision Tree.
A
New Control Technique for Improving the Oscillations and Decreasing the Harmonic
Components of Voltage in STATCOM
by Ghazanfar
Shahgholian, Behzad Bayat
Abstract - Static Synchronous Compensator (STATCOM) is one of the most important and advanced shunt compensators whose main function is controlling the reactive power and compensating the voltage drop in transmission line. In this paper designing two new controllers for a 24 pulse two-level Static Synchronous Compensator is dealt with and its performance in controlling the reactive power and compensating the voltage drop in the cases of load oscillations and occurrence of fault in transmission grid is compared with a conventional controller. In other words, in this paper the structure of three controllers are studied: a) the conventional controller based on decoupled control of the current applied in the recent papers; b) the completely reformed conventional controller based on the strategy of decoupled control of the current and voltage of the terminal and control of the voltage of the DC capacitor; c) the new controller based on Pulse Width Modulation (PWM). Designing the last two ones was done in this paper and their function is studied in maintaining the stability of the system during the occurrence of a three-phase fault and also under the effect of the changes of different loads in both inductive and capacitive modes. Finally, the effect of these three controllers on the decrease of the harmonic components of the voltage of STATCOM is evaluated and the results are compared. All simulations were executed in SPS (Sim Power System) of Matlab/Simulink software. The results of simulations demonstrate the higher efficiency of the controllers b and c in comparison to the conventional controller a.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: STATCOM, 24 Pulse Convertor, Decoupled Control, PWM , THD.
Combined Voltage Stability Index for Charging Station Effect on Distribution
Network
by J.J. Jamian, H.
Musa, M.W. Mustafa, H. Mokhlis, S.S. Adamu
Abstract - This paper presents the effect of Distributed Generation (DG) as well as Charging Station (CS) to the voltage stability index (VSI) on distribution network. Various locations for CS within the network are used in order to evaluate the effect of increment of the CS. The DG that is used is operated in PV mode.There are three types of VSI formulae applied to indicated the condition of the network as either collapsed or not which are P-VSI, Q-VSI (known as FVSI) and C-VSI. The study clearly shows that the increment of CS and location of DG has greater impact on Q-VSI and P-VSI towards attaining voltage collapse point. Further study conducted has reviled that voltage collapse indication in radial distribution network is better monitored by use of the Combined VSI ( C-VSI). The analysis was tested on a 33 bus distribution system.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Charging Station, Distributed Generation, Distribution System,
Electric Vehicle, Voltage Stability Index.
On the Application of Heuristic Method and Saddle-Node Bifurcation for Optimal
Placement of FACTS Devices in Power System
by M. Karami, N.
Mariun, M. Z. A.AbKadir
Abstract - This study focuses on an optimal placement of five major types of FACTS devices, namely, Static Var Compensator (SVC), Thyristor Controlled Series Compensator (TCSC), Static Synchronous Compensator (STATCOM), Static Synchronous Series Compensator (SSSC) and Unified Power Flow Controller (UPFC) in power system network using a well-known and applicable heuristic method known as genetic algorithm to seek the optimum location and setting of these controllers in the system. The locations of controllers are determined based on Saddle-Node Bifurcation theory on voltage collapse. In this paper, all the possible control parameters of each device including its location are optimized simultaneously to increase the distance to collapse point of the system. The IEEE 118-bus test system is utilized to verify the recommended method. The achievedresultsclearly proved that the proposed method is an effective approach for the placement of FACTS in power system.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: FACTS, Voltage Stability Analysis, Continuation Power Flow Analysis Geneticalgorithm, Bifurcation.
An Improved Selective Harmonics Elimination Method to Reduce Voltage THD in
Parallel Multilevel Inverters
by A. Shojaei,
S.H. Fathi
Abstract - Selective Harmonics Elimination (SHE) modulation is being widely used in multilevel inverters with base frequency switching. However, due to the limited number of levels in the waveform, the Total Harmonics Distortion (THD) of the output voltage would be high compared to admissible values in the codes. In this paper, an improvement to this modulation has been proposed in order to reduce the voltage THD at point of common coupling. This method can be used in wind or solar farms, where multiple inverters are often employed to interface the generating units with the network.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Multilevel Inverter, Parallel Inverters, Renewable Energy Source (RES), Selective Harmonic Elimination, Total Harmonics Distortion (THD).
Intelligent Reliability Constrained Unit Commitment with Wind Power Penetration:
A Cost-Reliability-Emission Optimization
by E.Alishahi,
M.Siahi
Abstract - Wind power generation as a green and cost-effective electric power resource is the best candidate for solution of energy and environmental crisis. Because of inherent intermittency of wind power generation, there are many concerns with the impacts on reliability indices. Hence, the basic aim of this work is the implementation of an intelligent procedure to solve reliability constrained unit commitment (RCUC) problem with wind penetration. Both economical and environmental purposes are considered in objective function formulation besides a constraint on reliability included to common formulation of UC problem. Numerical results show a considerable reduction in operation cost and emission, the risks of high levels of dependency on wind power generation should be also investigated deeply to prevent contingencies and reliability challenges in power system.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Ant Colony Optimization, Cost, Emission, Hybrid Particle Swarm
Optimization, Reliability, UC, Wind Power Generation.
A
Hybrid Particle Swarm Optimization Employing Genetic Algorithm for Unit
Commitment Problem
by R. Lal Raja
Singh, C. Christober Asir Rajan
Abstract - This paper presents an efficient approach for solving the unit commitment problemusing an hybrid approach based on Particle Swarm Optimization (PSO) and Genetic Algorithm (GA). Unit Commitment Problem (UCP) used for achieving minimum operating cost in the scheduling operation of power system generating units subjected to needed demand and reserve constraints is a nonlinear mixed integer optimization problem. The on/off state of the generating units at each hour interval of the planning period that optimally transmits load and reserve among the committed units is determined by the UC problem. The significance of the need for a more competent optimal solution to the UCP problem is increasing with the routinely changing demand. To accomplish this, hereby, we propose a hybrid approach that yields optimal commitment of the units by solving the unit commitment problem subjected to essential constraints. To verify the effectiveness of the proposed method numerical studies have been performed for the NTPS 7 unit system for a period of 24 hours. The results show that the proposed method outperforms the other state-of-the-art algorithms and the conventional methods in solving the unit commitment problems.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Generation Schedule, Genetic Algorithm (GA), Particle Swarm
Optimization (PSO), Power Flow Constraints (PFC), Unit Commitment
Problem (UCP).
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