WSEAS Transactions on Power Systems

Print ISSN: 1790-5060
E-ISSN: 2224-350X

Volume 9, 2014

Notice: As of 2014 and for the forthcoming years, the publication frequency/periodicity of WSEAS Journals is adapted to the 'continuously updated' model. What this means is that instead of being separated into issues, new papers will be added on a continuous basis, allowing a more regular flow and shorter publication times. The papers will appear in reverse order, therefore the most recent one will be on top.

Volume 9, 2014

Title of the Paper: Addressing the Sustainable Energy Conversion in Electric Railway Vehicles with Traction Synchronous Motors

Authors: Cornelia A. Bulucea, Doru A. Nicola, Daniel C. Cismaru, Nikos E. Mastorakis, Carmen A. Bulucea, Constantin Brindusa

Abstract: This paper addresses some aspects illustrating sustainable energy conversion processes during the operation of electric railway vehicles with traction synchronous motors. Increasing efforts are being expended to enhance the sustainability of transportation technologies and systems, and supporting transport systems’ sustainability is a key way of thinking towards cleaner production. In line with this idea, this paper addresses the operation sustainability of electric railway vehicles with traction synchronous motors, highlighting the chain of interactions among the main electric equipment on an electrically driven railway system. The paper supports the findings that electric traction drive systems using traction synchronous motors powered by network-side converters and machine-side converters enhance the sustainable operation of railway trains.

Keywords: Electromagnetic torque, high speed electric train, railway vehicle, sustainability dynamics, synchronous motor

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #51, pp. 495-506

Title of the Paper: Effect of CaO, Al2O3 and Fe2O3 in Coal Ash on the Retention of Acid-Forming Elements During Coal Combustion

Authors: Lucie Bartoňová

Abstract: Industrial coal combustion ashes as well as laboratory-scale experiments were used for the evaluation whether CaO, Al2O3 and Fe2O3 can help with the retention of volatile and acid-forming elements (S, Cl, Br, As and Se). Both industrial ashes evaluation and laboratory combustion experiments lead to the conclusion that CaO can efficiently help with the capture of not only S, but also of Cl, Br, As and Se.

Keywords: Coal combustion, desulphurization, limestone, trace elements, emissions, sulphur, chlorine, bromine, arsenic, selenium

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #50, pp. 486-494

Title of the Paper: Prediction of Egyptian 500 kV Overhead Transmission Lines Radio-Interference by Using the Excitation Function

Authors: Adel Z. El Dein

Abstract: This paper presents applications of the excitation function on the prediction of the Radio-Interference (RI) of overhead transmission line, due to corona effect. These applications are done under different weather conditions such as: heavy rain, wet conductor and fair weather. Also, this paper investigates the factors influencing the RI level namely; the height of conductors, phase spacing, number of subconductors in the bundle, diameter of subconductor and subconductor spacing in the bundle. In this paper, it is shown that the RI level is dependent on the weather conditions. Where, the RI level under heavy rain has the maximum level, hence, it should be considered as a basic level of any overhead transmission line (OHTL).

Keywords: Corona, Excitation function, Radio interference, Overhead transmission line

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #49, pp. 479-485

Title of the Paper: Implementation of a MPPT Neural Controller for Photovoltaic Systems on FPGA Circuit

Authors: Naoufel Khaldi, Hassan Mahmoudi, Malika Zazi, Youssef Barradi

Abstract: The maximum power point tracking (MPPT) system controls the voltage and the current output of the photovoltaic (PV) system to deliver maximum power to the load. Parameters values were extracted using Newton Raphson method from characteristics of Shell SP75 module. This paper presents a comparative analysis of incremental conductance (IC), and neural network based MPPT techniques. The Artificial Neural Network (ANN) method is used to deliver the appropriate duty cycle signal used to drive boost converter to track the MPP even with variations of the input values using Matlab/Simulink for the simulation and Hardware Description Language (VHDL) for the implementation on kit Field Programming Gate Array (FPGA) Spartan-3E of Xilinx.

Keywords: Artificial neural network, Photovoltaic systems, Incremental conductance, MPPT, VHDL, FPGA

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #48, pp. 471-478

Title of the Paper: Optimal Location of Thyristor Controlled Series Capacitor for reduction of Transmission Line losses using BAT Search Algorithm

Authors: B. Venkateswara Rao, G. V. Nagesh Kumar

Abstract: This paper presents a new metaheuristic algorithm called BAT search Algorithm (BAT). The BAT search algorithm is used to solve Optimal Power Flow (OPF) problem with the Thyristor Controlled Series Capacitor (TCSC). The TCSC is used to reduce the transmission line losses and improve the voltage profile of the power system. The effectiveness of the BAT Algorithm has been tested for various bus systems like 5 bus test system, the IEEE 14 bus system and the modified IEEE 30 bus system. The obtained results were compared with Genetic Algorithm (GA) and Differential Evolution (DE) with and without TCSC. Results clearly indicate the effectiveness of the BAT Algorithm over the Genetic algorithm and the Differential Evolution algorithms in solving OPF problem with the TCSC.

Keywords: BAT Algorithm, Differential Evolution, FACTS device, Genetic Algorithm, Optimal Power Flow, TCSC

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #47, pp. 459-470

Title of the Paper: Observer-Based Stabilizer of A Single Machine Power System with Lossy Transmission Line

Authors: A. A. Abouelsoud, Abdullah Al-Odienat, Hany Abdelfattah

Abstract: This paper proposes a stabilizing controller for single machine power system with nonzero conductance of transmission line. The proposed controller uses a reduced order observer to estimate the power angle of the system. The stability of the reduced order observer and that of the closed loop system incorporating the observer based stabilizer are given based on Lyapunov direct method. Simulation results included in the paper demonstrate the efficacy of the proposed stabilizer. The comparison with a classical type confirms the advantage of the proposed controller.

Keywords: Single machine power system, lossy transmission, line-reduced order observer, Lyapunov direct method

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #46, pp. 452-458

Title of the Paper: Hybrid PSO-ANN Application for Improved Accuracy of Short Term Load Forecasting

Authors: A. G. Abdullah, G. M. Suranegara, D. L. Hakim

Abstract: Short Term Load Forecasting (STLF) is a power system operating procedures that have an important role in terms of realizing the economic electric production. This research focuses on the application of hybrid PSO-ANN algorithm in STLF. Load data grouped by the type of weekdays and holidays. Consumption of electricity load in West Java Indonesia, used as input to the learning algorithm PSO-ANN. Data are grouped according to three clusters, namely the weekdays that starts on Monday to Friday. Weekends are Saturdays and Sundays and national holidays. The forecasting results from the PSO-ANN algorithm compared against the load planning system (LPS) from Indonesia Power Company. The results from the load forecasting PSO-ANN algorithm has a better accuracy than the forecasting of the LPS. Load forecasting accuracy will reduce the level of energy losses and cost of generation.

Keywords: Particle Swarm Optimization, Artificial Neural Network, Short Term Load Forecasting

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #45, pp. 446-451

Title of the Paper: Power Quality Expansion for Grid Connected Wind Power System using Permanent Magnet Synchronous Generator and Trans-Z Source Inverter

Authors: E. Rajendran, C. Kumar

Abstract: This paper presents the expansion of power quality for variable speed Wind Power System (WPS) using Permanent Magnet Synchronous Generator (PMSG) and Trans Z-Source Inverter. The PMSG is having compact collection and dimensions, compare to Induction Generator. Induction Generator needs the grid power, then only start the power production. But without take up the grid power PMSG should produce the power. The impedance-source (Z-source) inverters idea to the Transformer-based Z-Source Inverter (Trans-ZSI) is implemented. The unique Z-Source Inverter (ZSI) employs an impedance network of two inductors and two capacitors coupled in an exceptional preparation to accessing the dc source. In the proposed Fuzzy Logic Controller (FLC) based trans-Z-Source Inverters, the entire impedance networks structure consists of a two transformers and capacitor. While maintaining the major quality of the earlier accessible Z-source network, the new networks demonstrate some unique compensation, such as the enlarged voltage gain, compact voltage stress, privileged inversion capability and very less harmonics content.

Keywords: Wind Power System (WPS), Permanent Magnet Synchronous Generator (PMSG), Transformer-based Z-Source Inverter (Trans-ZSI) and Fuzzy Logic Controller (FLC)

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #44, pp. 439-445

Title of the Paper: Power System Stability Enhancement via New Coordinated Design of PSSs and SVC

Authors: Ali E. S., Abd-Elazim S. M.

Abstract: In this paper, the assessment of new coordinated design of Power System Stabilizers (PSSs) and Static Var Compensator (SVC) in a multimachine power system via statistical method is proposed. The coordinated design problem of PSSs and SVC over a wide range of loading conditions is handled as an optimization problem. The Bacterial Swarming Optimization (BSO), which synergistically couples the Bacterial Foraging (BF) with the Particle Swarm Optimization (PSO), is employed to seek for optimal controllers parameters. By minimizing the proposed objective function, in which the speed deviations between generators are involved; stability performance of the system is enhanced. To compare the capability of PSS and SVC, both are designed independently, and then in a coordinated manner. Simultaneous tuning of the BSO based coordinated controller gives robust damping performance over wide range of operating conditions and large disturbance in compare to optimized PSS controller based on BSO (BSOPSS) and optimized SVC controller based on BSO (BSOSVC). Moreover, a statistical T test is executed to validate the robustness of coordinated controller versus uncoordinated one.

Keywords: SVC, PSSs, Multimachine Power System, Coordinated design, Bacteria Swarm Optimization, Statistical Assessment

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #43, pp. 428-438

Title of the Paper: Control of Series HVDC Bridges with Different Firing Angles

Authors: Hussein. D. Al-Majali, Sulaiman. M. Al-Dhalaan

Abstract: Three-phase controlled rectifiers have a wide range of applications, from small rectifier to large high voltage direct current (HVDC) transmission systems which are increasingly used throughout the world for long distance transmission and asynchronous interconnection. The transient performance of an HVDC power system is highly dependent on the parameters of the current/voltage regulators of the converter controls. This paper describes an alternative application of conventional bridge circuits using series connected bridges, of dissimilar rating, with different firing angles. Both steady-state and transient operations are presented. The experimental and analytical results are compared.

Keywords: Series bridges, dissimilar rating, transient response, control

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #42, pp. 418-427

Title of the Paper: A Novel Analytical Study on Voltage Instability Mitigation Using Multiple Severity Functions by Optimal Placement of SVC in N-2 Contingency Analysis Using Gravitational Search Algorithm

Authors: S. P. Mangaiyarkarasi, T. Sree Renga Raja

Abstract: Voltage stability analysis based on the number of limit violating buses apart from considering the voltage magnitude violations using several severity functions is performed in this work. Deviating from existing works in literature, the double line contingency is considered based on the three types of severity functions: discrete, continuous and percentage of violation severity functions. The severity functions are analyzed and their merits and drawbacks are discussed. The N-2 line outage comprising of all the 820 possible combinations of contingency states in the IEEE 30 bus system is effectively analyzed and contingency ranking is done based on the severity. FACTS devices are utilized to improve the voltage profile of the system during line outages. The Static VAr Compensator (SVC) is considered here, as the compensating device. A multi-objective optimization, with the objective of minimizing the voltage deviation and also the number of limit violating buses with optimal reactive power support is achieved through the Gravitational search algorithm (GSA). The effectiveness of the proposed work is tested on IEEE 30 bus system under double line contingencies. The results of the work are compared with several optimization methods and the results substantiate the effectiveness of the proposed methodology.

Keywords: Voltage Stability, Severity Functions, N-2 line contingency, FACTS, Static VAr Compensator, Gravitational Search Algorithm

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #41, pp. 408-417

Title of the Paper: Towards an Accurate Modeling of Frequency-Dependent Wind Farm Components under Transient Conditions

Authors: M. A. Abd-Allah, Mahmoud N. Ali, A. Said

Abstract: Frequency dependence complete model is set up for describing the lightning transient behaviour of the wind turbines (WTs).To get an appropriate wind turbine model, a high frequency models of surge arrester protecting the boost transformer, transformer and ground electrode soil ionization are implemented. The transient responses and Ground Potential Rise (GPR) can be obtained at different locations in the WTs and connected grid in the time domain as well as in the frequency domain using Fast Fourier Transform (FFT). To check the validity of the model, surge arresters protection levels at different locations, i.e. LV, MV and HV, are compared with ABB manufacture data, also a comparison has been made between simple and frequency dependence model of overall wind farm components using ATP/EMTP. This paper provides an accurate simulation of wind farm components under transient condition.

Keywords: WTs, Surge arrester model, Transient response, GPR, FFT, ATP/EMTP

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #40, pp. 395-407

Title of the Paper: Symmetrical Components Definition and Analyze for Power Electronic Converters in Non-Sinusoidal Conditions

Authors: Majid Nayeripour, M. Mahdi Mansouri

Abstract: As symmetrical components are very useful tools for power system analyzing in unbalance condition and defining phasor is hard for power electronics because of their switching behaviors, Time variable phasor is defined for power electronic wave forms at the first. Then some methods are proposed and evaluated for defining symmetrical components for power electronic converters. These methods are developed for zero, positive and negative circuits of a three phase half wave rectifier. The final proposed method satisfies ABC to ZPN transform and vice versa and is tested with harmonics in voltage source. This study is started and has many steps to complete in future.

Keywords: Symmetrical components, non-sinusoidal condition, power electronic converters

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #39, pp. 388-394

Title of the Paper: Speed Control of Switched Reluctance Motor Fed by PV System Using Ant Colony Optimization Algorithm

Authors: A. S. Oshaba, E. S. Ali, S. M. Abd Elazim

Abstract: This paper proposes a speed control of Switched Reluctance Motor (SRM) supplied by Photovoltaic (PV) system. The proposed design of speed controller is formulated as an optimization problem. Ant Colony Optimization (ACO) algorithm is employed to search for optimal Proportional Integral (PI) parameter of speed controller by minimizing the time domain objective function. The behaviour of the proposed ACO has been estimated with the behaviour of Genetic Algorithm (GA) in order to prove the superior efficiency of the proposed ACO in tuning PI controller over GA. Also, the behaviour of the proposed controller has been estimated with respect to the change of load torque, variable reference speed, ambient temperature, and radiation. Simulation results confirm the better behaviour of the optimized PI controller based on ACO compared with optimized PI controller based on GA over a wide range of operating conditions. Simulation results have shown the validity of the proposed technique in controlling the speed of SRM.

Keywords: Ant Colony Optimization; Genetic Algorithm; High Speed SRM; Speed Control; PI Controller; Photovoltaic System

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #38, pp. 376-387

Title of the Paper: Modelling of Fixed Speed Squirrel Cage Induction Generators for Small Signal Stability Assessment

Authors: Bhinal Mehta, Praghnesh Bhatt, Vivek Pandya

Abstract: Fixed speed squirrel cage induction generators (FSIG) for the wind power generations have been widely used worldwide due to its salient features like cost effectiveness, simplicity and robustness. It takes utmost importance to analyse their impact on power system stability as their penetration levels are continuously increasing. The state space approach is presented to analyse both small signal and transient stability by developing a mathematical model of full order squirrel cage induction generator. The small signal behaviour of FSIG has been studied for both one-mass and two-mass model representation of drive train. The eigenvalue and participation factor analysis for developed state space model of FSIG connected to infinite bus are carried out to identify the nature of modes of oscillations under different operating conditions such as varying wind speed and grid strength. The transient analyses are also presented to investigate the capability of FSIG to satisfy the Grid Code requirements.

Keywords: Fixed Speed Induction Generator, Drive Train, Eigenvalue Analysis, Small Signal Stability, Fault Ride Through

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #37, pp. 360-375

Title of the Paper: Comparison of Parallel Metaheuristics for Flux Optimization for Induction Motor

Authors: Vincent Roberge, Mohammed Tarbouchi

Abstract: An essential aspect of efficiency control of a three-phase induction motor is the ability to generate the optimal magnetic flux required for different operating modes. In this paper, we use the genetic algorithm (GA), the particle swarm optimization algorithm (PSO) and the simulated annealing (SA) to cope with the complexity of the problem and compute feasible and quasi-optimal magnetic flux needed for three-phase induction motors with time varying load and parameters. The characteristics of the optimal magnetic flux are represented in the form of a multi-objective cost function that we developed. We reduce the execution time of our solutions by using the “single-program, multiple-data” parallel programming paradigm and achieve real-time performance on a multi-core CPU.

Keywords: Magnetic flux optimization, genetic algorithm, particle swarm optimization, simulated annealing, parallel computation

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #36, pp. 352-359

Title of the Paper: Thermal Analysis and Cost Estimation of Stirling Cycle Engine

Authors: Ana C. Ferreira, Manuel L. Nunes, Luís B. Martins, Senhorinha F. Teixeira

Abstract: Stirling engine technologies have been applied to cogeneration systems mainly for residential applications. The performance of Stirling engines has been evaluated considering different operational conditions, which include the electrical and thermal production. Thermodynamic analysis of the Stirling engine’s performance has been conducted, using specially designed computing codes along with the thermal balance study of the technology. The performance of the unit has been evaluated considering different operational conditions, which include the electrical and thermal production, working fluid mean pressure or mass, components geometrical sizing. The thermal-economic evaluation represents an effective tool to optimize a power plant with this type of technology. This study presents a mathematical model that includes a set of equations able to describe and simulate the physical system, as well as a set of equations that define the cost of each plant component. The physical model attempts to simulate the real conditions of a micro-CHP unit based on an alpha type Stirling Engine, by taking into account the imperfect regeneration and the pumping losses. The cost expression for each component integrates thermodynamic and cost coefficients adjusted for this kind of technology and also taking into account real market data. The simulations were performed through a MatLab® code that assesses the thermodynamic efficiency, including heat transfer limitations and pumping losses throughout the system, and the purchase costs of the equipment. Results showed the Stirling engine performance depends on geometrical and physical parameters which optimization is required in order to obtain the best performance. Regenerator is one of the most important components of the Stirling engine. The maximum heat transferred to and from the regenerator matrix is higher than the energy transferred to the other two heat exchangers. Results demonstrated that the engine efficiency achieves a higher value when hydrogen is the working fluid. It is verified that cost estimation based on sizing and quality parameters has a good correlation with the capital investment costs of commercial models. The total capital costs are close to real commercial models for similar applications. Plus, the engine bulk and the heater are the most expensive components.

Keywords: CHP Applications, High-efficiency, Energy Conversion, Stirling Engines, Cost Estimation

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #35, pp. 341-351

Title of the Paper: Bottom-up Reliability Analysis of a Base Load Diesel Engine Driven Electric Power Unit

Authors: E. C. Nasioulas, G. J. Tsekouras, F. D. Kanellos

Abstract: Power systems are usually based on thermal-electric power units as they have several advantages, such as predetermined installation and operation cost, easy active and reactive power control and high reliability. The reliability of a thermal power unit is usually quantified by the Unavailability or Forced Outage Rate (F.O.R.) indicator expressing the unexpected and unforeseen failure rate. It can be calculated from fault data records obtained during diesel engine lifetime. However, a thermal electric power unit is a sophisticated system with several subsystems. In case of a diesel engine driven electric power unit the respective subsystems constituting the unit are diesel engine, electric generator, frequency controller, automatic voltage regulator, and the circuits of compressed air, oil, fuel, water cooling, air cooling etc. In this paper, the reliability analysis of a ship diesel engine power unit is carried out based on a bottom-up approach and the assumption of having constant expected failure rate and constant repair rates for each sub-system’s component. In this way, unavailability of diesel engine can be accurately determined and the most frequently malfunctioning parts of the unit can be identified so as proactive measures for increasing overall reliability of the engine could be decided.

Keywords: Forced outage rate, reliability, thermal electric power unit

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #34, pp. 327-340

Title of the Paper: Electric Vehicle Charger – Analysis and Measuring

Authors: Peter Janiga, Martin Liška, Dominik Viglaš, Boris Cintula

Abstract: Electric vehicle has received more and more extensive attention, which is one of the major development directions of motor vehicles using new energy sources. Electric vehicles are development promising green transports, and important means to solve energy and environmental problems. The construction of charging infrastructure is an important prerequisite for the advancement of electric vehicles. Electric vehicle charging station provides power supply for electric vehicles running. They are necessary important supporting infrastructure for the development of electric vehicles. [6] The aim of this paper is describe behavior of electric vehicle charging at different operating conditions. In paper are analyzed values, which were measured in power system with connected domestic charger and fast charger which belong to the charging infrastructure. The paper analyzes the main parameters which may have effect on the power system, like currents, voltages, distortion of measured values and power factor. These values and parameters may have the effect on charging infrastructure too.[10]

Keywords: Fast charger, electric vehicle, charging infrastructure, electric vehicle charging, measuring, current, voltage, power factor

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #33, pp. 319-326

Title of the Paper: Calculation of Magnetic Field Produced by OHTL under Normal and Abnormal Conditions

Authors: Nagat M. K. Abdel-Gawad, Adel Z. El Dein, Mohamed Magdy

Abstract: Ground level magnetic field from overhead transmission lines (OHTLs) is of increasingly important considerations in several research areas due to their harmful effect on human health and environment. This paper computes the ground level magnetic field, under normal and abnormal conditions of Egyptian 500-kV single circuit transmission line, in three dimension (3-D) coordinates by using 3-D integration technique. Abnormal conditions include symmetric fault, un-symmetric faults, direct stroke, and indirect stroke on the OHTL. Where, ATP software is used to simulate the OHTL under all faulty and lightning conditions. Varying time magnetic fields under normal and abnormal conditions, at certain points that located at mid-span, tower height and right-of-way (ROW), are also computed that to indicate the worst case.

Keywords: Magnetic field, Overhead transmission line, Normal and abnormal conditions, Right-of-way

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #32, pp. 311-318

Title of the Paper: Power Source Unit of a Small Airship

Authors: Martin Pospisilik

Abstract: This paper describes a proposal on a construction of a power supply module that is intended to be implemented in a small airship. Because the bearing capacity of the airship is limited, simple and efficient voltage converters must be employed. The paper provides a description of a proposal on mutual timing of these converters that leads to eliminating of the interferences caused by the currents that are drawn by the converters. The hereby described method allows the designers to use smaller capacitors and inductors which will result in smaller weight and dimensions of the power supply unit. Furthermore, an example of a voltage converter design is provided in the framework of the paper.

Keywords: Timing, Synchronization, Switched Voltage Converter, Airship, Interferences

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #31, pp. 300-310

Title of the Paper: Short-Circuit - Analysis and Calculation

Authors: Peter Janiga, Žaneta Eleschová, Dominik Viglaš

Abstract: This paper discusses about analysis and calculation of short – circuit by the program created to solve a short – circuit ratios in the power system according to Standard IEC 60909. One of the main subject is describing short-circuit current in system with currents without attenuation alternating component and short-circuit current in system with currents with attenuation alternating component. A short circuit is a part of the circuit that for some reasons has become “shorter” than it should be.[4] The current in an electrical circuit flows the easiest way and if two points in a circuit with different potentials are connected with low electrical impedance the current is taking a shortcut between the two points. The consequences of short circuit can be everything from just a minor malfunction to a disaster. The consequences are dependent of the system´s capacity for driving current in short circuit situation and how long time the short circuit current is allowed to flow. In almost every electric circuit there has to be some kind of protection against short circuit currents.[5]

Keywords: Short-circuit impedance matrix, power system, short-circuit current, three-phase short-circuit power, positive sequence short-circuit impedance matrix, negative sequence short-circuit impedance matrix, zero sequence short-circuit impedance matrix

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #30, pp. 291-299

Title of the Paper: Adaptive Fuzzy Sliding Mode Control of Variable Speed Wind Turbine for Maximum Power Extraction

Authors: R. Saravanakumar, Debashisha Jena

Abstract: This paper deals with nonlinear control of variable speed wind turbine (VSWT), where the dynamics of the wind turbine (WT) is obtained from single mass model. The main objective of this work is to maximize the energy capture form the wind with reduced oscillation on the drive train. The generator torque is considered as the control input to the WT. In general the conventional control techniques such as Aerodynamic torque feed forward (ATF) and Indirect speed control (ISC) are unable to track the dynamic aspect of the WT. The nonlinear controllers such as nonlinear dynamic state feedback linearization with estimator (NDSFE) and nonlinear static state feedback linearization with estimator (NSSFE) are not robust with respect to model uncertainty and disturbances. To overcome the above drawbacks a Fuzzy Sliding mode controller (FSMC) with the estimation of effective wind speed is proposed. The Modified Newton Raphson (MNR) is used to estimate the effective wind speed from aero dynamic torque and rotor speed. The proposed controller is tested with different wind profiles with the presence of disturbances and model uncertainty. From the results the proposed controller was found to be suitable in maintaining a trade-off between the maximum energy capture and reduced transient on the drive train.

Keywords: Variable speed Wind turbine, Fuzzy Sliding mode controller, Modified Newton Raphson, ATF and ISC

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #29, pp. 281-290

Title of the Paper: Comparative Advantages Using Solar and Wind Energy in Hybrid Systems at the Same Site

Authors: Ajla Merzic, Mustafa Music, Elma Redzic, Damir Aganovic

Abstract: Main objectives of the paper were to examine the complementary nature of solar and wind energy in primary and in “useful” form. Analyses are performed on real, measured solar and wind potential data at the same site. Solar irradiation and wind power density have been assessed as primary forms. In order to examine effects of their complementarity in real applications, i.e. in power systems, a hybrid system, consisting of a photovoltaic power plant (PVPP) and a wind power plant (WPP), was modelled and simulated. Those effects were verified through output power variations of these facilities individually, compared to output power variations of two different hybrid system configurations. Analyses were also made with respect to hourly load demand profile of the consumption centre located in proximity of the potential hybrid power plant.

Keywords: Complementary nature, demand, hybrid system, power output variability,solar energy, wind energy

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #28, pp. 273-280

Title of the Paper: Improving the Quality of Energy Using Phase Shifting Transformer PST

Authors: Khelfi Abderrezak

Abstract: The power flow is importing in transport of energy the transient stability. Power flow control of energy in system transmission have many problem ;a novel technologies are introduced. Flexible AC transmission systems (FACTS); like Phase shifting transformer (PST). PST aims at introducing voltage phase shift between sending and receiving of transmission line; the voltage phase shift is controlled by adding to the voltage of one end of transmission line a quadrature voltage component. In this paper we improving the quality and power flux by controlling the phase shifting between sending and receiving voltage bus; using PST controlling with thyristors (TCPST).we evaluate the control to obtain the max power flow in different status in network. For get optimal control we put our TCPST in a single-machine infinite-bus (SMIB) system. The results of different simulations realized under the MATLAB / Simulink.

Keywords: Phase Shifting Transformer, FACTS, Power Flow and Energy Quality, PWM-control, SMIB

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #27, pp. 267-272

Title of the Paper: Congestion Management in Deregulated Power System by Fuzzy Based Optimal Location and Sizing of UPFC

Authors: Uma. V, P.Lakshmi, J. D. Anunciya

Abstract: This paper presents a congestion management methodology in deregulated power systems by optimal location and sizing of Unified Power Flow Controller (UPFC) in a transmission network. A multi-objective optimization problem has been developed by considering total congestion cost, power loss and system severity. A Fuzzy based approach has been proposed to identify the optimal location and sizing of UPFC for relieving congestion in a deregulated power system. The reliability of the proposed work has been analyzed under severe contingencies and line overloading. Simulation results obtained from the Fuzzy method are compared with the solutions obtained by the conventional Sequential Quadratic Programming (SQP) approach. This comparison confirms the effectiveness of the proposed fuzzy method for relieving congestion. The validation of the proposed work is analyzed using IEEE 30-bus system.

Keywords: FACTS, UPFC, Congestion Management, LMP, Fuzzy Logic Technique, RPPI

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #26, pp. 258-266

Title of the Paper: Economic/Environmental Power Dispatch for Power Systems Including Wind Farms

Authors: Imen Ben Jaoued, Tawfik Guesmi, Yosra Welhazi, Hsan Hadj Abdallah

Abstract: This paper presents the problem of the Economic/Environmental Dispatching (EED) of hybrid power system including wind energies. The power flow model for a stall regulated fixed speed wind generator (SR-FSWG) system is discussed to assess the steady-state condition of power systems with wind farms. Modified Newton-Raphson algorithm including SR-FSWG is used to solve the load flow equations. In which the state variables of the wind generators are combined with the nodal voltage magnitudes and angles of the entire network. The EED problem is a nonlinear constrained multi-objective optimization problem, two competing fuel cost and pollutant emission objectives should be minimized simultaneously while satisfying certain system constraints. In this paper, the resolution is done by Algorithm multi-objective particle swarm optimization (MOPSO). The effectiveness of the proposed method has been verified on IEEE 6-generator 30-bus test system and using MATLAB software package.

Keywords: EED, Wind farm, SR-FSWG, Power flow, Newton–Raphson algorithm, MOPSO

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #25, pp. 249-257

Title of the Paper: FUZZY Logic Based Space Vector PWM Controlled Hybrid Active Power Filter for Power Conditioning

Authors: Jarupula Somlal, Mannam Venu Gopala Rao

Abstract: This paper investigates the comparative analysis of a Hybrid Active Power Filter with PI based SVPWM controller and fuzzy based space vector PWM controller for mitigating the harmonics, improving the power factor and increasing the distribution power of the three phase distribution system. This paper concluded that the power conditioning by fuzzy based SVPWM hybrid active power filter is superior than PI controller based SVPWM technique. In the proposed control filters three control circuits are used such as PI control unit, fuzzy unit and SVPWM control unit. Fuzzy arithmetic‟s are used for adjusting proportional–integral coefficients timely. The desired output voltage is generated based on generated reference voltage by fuzzy based SVPWM. A MATLAB code is developed to generate the SVPWM switching pulses fed to the two-level inverter topology. Simulations are carried out using MATLAB. It is found that the %THD has been improved from 2.67 to 1.57and power factor is improved to 0.9718. The simulation results shows that the effectiveness and feasibility of the proposed filter.

Keywords: Hybrid Active Power Filter, Fuzzy Logic Controller, IGBT Inverter, Space Vector PWM, Total Harmonic Distortion (THD), Distribution system

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #24, pp. 242-248

Title of the Paper: Real World Maximum Power Point Tracking Based on Fuzzy Logic Control

Authors: Ahmed M. Othman, Mahdi M. El-Arini, Ahmed Fathy

Abstract: In the recent years, the solar energy becomes one of the most important alternative sources of electric energy, so it is important to improve the efficiency and reliability of the photovoltaic (PV) systems. Maximum Power Point Tracking (MPPT) plays an imp

Keywords: Solar Energy, Photovoltaic system, Fuzzy Logic Control, Maximum Power Point Tracking (MPPT)

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #23, pp.232-241

Title of the Paper: Synoptic Approach of Synchronous Generator on Disconnection Processes in Electric Power Systems Comprising Generator Circuit Breakers

Authors: Cornelia A. Bulucea, Marc A. Rosen, Doru A. Nicola, Nikos E. Mastorakis, Carmen A. Bulucea

Abstract: This paper is a sequel to a study by the authors of electric power systems comprising the generator circuit-breakers (GCBs) at power plant generator terminals. A sustainable assessment of the current interruption requirements of a GCB addresses the main s

Keywords: Electric arc, generator circuit-breaker, sustainability, synchronous generator, transient recovery voltage

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #22, pp.219-231

Title of the Paper: Power Disturbance Analysis via Discrete Wavelet Transform

Authors: Chau-Shing Wang

Abstract: Electric power quality is an aspect of power engineering that has been with us since the inception of power systems. To investigate this issue, engineers have proposed various schemes to deal with the power disturbance waveforms. Among these approaches, w

Keywords: DSP, wavelet transform, power quality

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #21, pp.208-218

Title of the Paper: Influx of Random Variables in the Unit Commitment Problem

Authors: P. C. Thomas, P. A. Balakrishnan

Abstract: With rapid strides in the realm of power restructuring, the Unit commitment problem (UCP) has transformed itself into a dysfunctional amalgam of several variables relating to power system operation; commercial ones of the system operators and stochastic p

Keywords: Unit Commitment, Reliability constraints, State space, State transition, State merger, Generator scheduling, Markov chains, Ergodic theorem

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #20, pp.196-207

Title of the Paper: Bacteria Foraging: A New Technique for Speed Control of DC Series Motor Supplied by Photovoltaic System

Authors: A. S. Oshaba, E. S. Ali

Abstract: This paper presents the speed control of a DC series motor supplied by Photovoltaic (PV) system. The proposed design problem of speed controller is formulated as an optimization problem. Bacteria Foraging Optimization Algorithm (BFOA) is employed to searc

Keywords: DC Series Motor, Photovoltaic System, Speed Control, PI Controller, Bacteria Foraging Optimization Algorithm

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #19, pp.185-195

Title of the Paper: Transient Stability Assessment of Power Systems Based on KPCA and Gaussian Process

Authors: Yang Li, Xueping Gu

Abstract: This paper presents a new method for transient stability assessment of power systems using kernel principal component analysis (KPCA) and Gaussian process (GP). Considering the possible real-time information provided by PMU, a group of system-level classi

Keywords: Transient stability assessment, KPCA, Gaussian process, composite kernel function, machine learning, phasor measurement unit

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #18, pp.178-184

Title of the Paper: Hybrid Shunt Active Filter: Impact of the Network’s Impedance on the Filtering Characteristic

Authors: C. Benoudjafer, C. Benachaiba, A. Saidi

Abstract: The filtering system is an indispensible way to cancel all harmonics which are generated by the nonlinear load. In this paper, we will study the impact of the network’s impedance on the filtering characteristic in two cases: In the first one, we will trea

Keywords: Compensation, Harmonics, Power Quality, Hybrid Shunt Active Filter, Shunt Active Filter, Passive Filter, THD

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #17, pp.171-177

Title of the Paper: An Efficient BFO Algorithm for Self Tuning Pi-Controller Parameters for Shunt Active Power Filter

Authors: P. Saravanan, P. A. Balakrishnan

Abstract: In recent decades, the utilization of highly automatic electric equipments has resulted in enormous economic loss. Thus, the power suppliers as well as the power consumers are very much concerned about the power quality issues and compensation approaches.

Keywords: Bacterial Forge Optimization, Shunt Active Power Filter, Space Vector Pulse Width Modulation

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #16, pp.155-170

Title of the Paper: Stability of Multi-Machine Power System by used LQG Controller

Authors: Ahmed Said Oshaba

Abstract: This paper has been designed optimize feed-back controller for dynamic response of the power systems. The power system consists of the infinite bus through a transmission line supplied by a synchronous machine and also multi machine power system. The effe

Keywords: LQR controller , LQG controller, power system stabilizer and multi-machine power system

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #15, pp.143-154

Title of the Paper: Improved FOC of Induction Motor with Online Neural Network

Authors: Azuwien Aida Bohari, Wahyu Mulyo Utomo, Zainal Alam Haron, Nooradzianie Muhammad Zin, Sy Yi Sim, Roslina Mat Ariff

Abstract: This paper proposed improvement performance from offline towards online neural network scheme for speed control of induction motor field oriented control based on load disturbance and parameter variation. The neural network is design as 1-3-1 network stru

Keywords: Neural Network, Induction Motor, Field Oriented Control

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #14, pp.136-142

Title of the Paper: Computation of Ancillary Service Requirement Assessment Indices for Load Frequency Control in a Restructured Power System using SMES Unit

Authors: N. D. Sridhar, I. A. Chidambaram

Abstract: This paper proposes various design procedures for computing Power System Ancillary Service Requirement Assessment Indices (PSASRAI) for a Two-Area Thermal Reheat Interconnected Power System (TATRIPS) in a restructured environment. In an interconnected pow

Keywords: Bacterial Foraging Optimization, Load- Frequency Control, Superconducting Magnetic Energy Storage, Proportional plus Integral Controller, Restructured Power System, Ancillary Service, Power System Ancillary Service Requirement Assessment Indices.

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #13, pp.119-135

Title of the Paper: A Modified Perturb and Observe Maximum Power Point Tracking Technique for Single-Stage Grid-Connected Photovoltaic Inverter

Authors: M. Quamruzzaman, K. M. Rahman

Abstract: There is an inherent tracking-oscillations trade-off problem in Perturb and Observe (P&O) maximum power point tracking (MPPT) technique for photovoltaic (PV) system. Higher perturbation step-size increases the tracking speed at the cost of greater oscilla

Keywords: Photovoltaic (PV), Perturb and Observe (P&O), Maximum Power Point Tracking (MPPT), Grid-connected PV, Inverter, Modulation Index, Phase Angle

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #12, pp.111-118

Title of the Paper: New Algorithms for Removal of DC Offset and Subsynchronous Resonance terms in the Current and Voltage Signals under Fault Conditions

Authors: Kamalesh Kumar Sharma

Abstract: Two filtering algorithms for removal of DC offset and subsynchronous resonance terms in the current/voltage signals in a transmission line under fault condition are presented. One of the algorithms utilizes the samples of the signal over a time interval slightly greater than one cycle time of the fundamental component and is computationally less demanding than the existing Fourier filters. The second algorithm is based on sampling the signal at arbitrary locations and hence, the signal samples can be acquired during a time interval much less than the full-cycle period of the fundamental component. This results in the calculation of the fundamental component in a time less than the full-cycle time of the signal, and hence is more attractive. It is shown that the Fourier filters used for the removal of DC offset etc. can also be interpreted as the weighted moving-average filters. Moreover, the Fourier filters, although having similarity with the discrete Fourier transform (DFT) computation of a signal, do not precisely involve the computation of the DFT coefficients of the sliding windowed sampled signal. Lastly, simulation results are presented to validate the approach of both the proposed algorithms under noiseless as well as noisy conditions.

Keywords: Discrete Fourier transform, Power system protection, Power system transients, Power transmission lines

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #11, pp.103-110

Title of the Paper: PI and Sliding Mode Control of a Multi-Input-Multi-Output Boost-Boost Converter

Authors: Zengshi Chen, Weiwei Yong, Wenzhong Gao

Abstract: A proportional-integral (PI) controller and a sliding mode controller (SMC) are used to control a fourth-order Boost-Boost (BB) converter in continuous conduction mode with two input switches and two output voltages. Based on the equivalent control method, a closed-loop system is developed. The resultant PI gains have a nonlinear relationship with each other. The appropriate PI gains are obtained through the least squares method. The converter under the controller is stable and robust. The converter has voltage tracking accuracies within ±0.1 V for the first load and ±0.02 V for the second load. The maximum switching frequency is not greater than 100 KHz.

Keywords: PI, SMC, closed-loop, Boost-Boost, equivalent control method

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #10, pp.87-102

Title of the Paper: A Sensorless Control Strategy for IPMSM based Electric Power Steering Systems

Authors: Giacomo Scelba, Salvatore De Caro, Antonio Testa, Giuseppe Scarcella, Mario Cacciato

Abstract: Electric power steering systems are a quite common equipment of modern vehicles. They are based on torque controlled electromechanical actuators assisting the driver in moving the steering wheel. These systems must generate low torque fluctuations and mechanical vibrations, while featuring a low cost and a simple and rugged control system. In order to comply with these requirements an electromechanical actuator based on a sensorless controlled synchronous motor is proposed in this paper. It exploits a sensorless torque control technique based on the injection of high frequency voltage signals and the manipulation of induced high frequency stator current components. A key feature of this technique is a very simple implementation using a low cost mixed (analog/digital) circuitry, requiring a minimal computational power. Implementation issues and experimental results obtained on a laboratory prototype, based on a standard electric power steering system, are presented to confirm the consistence of the proposed approach.

Keywords: Sensorless Control; Electric Power Steering systems (EPS); Automotive; Interior Permanent Magnet Synchronous Machine (IPMSM)

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #9, pp.77-86

Title of the Paper: Computation of Time Delay Margins for Stability of a Single-Area Load Frequency Control System with Communication Delays

Authors: Şahin Sönmez, Saffet Ayasun, Ulaş Eminoğlu

Abstract: Time delays have become unavoidable in power systems since communication links are extensively used for sending and receiving control signals. This paper investigates the effect of time delays on the stability of a single-area load Frequency Control (LFC) system. A direct and exact method to compute delay margins is presented. The delay margin is the maximum amount of the time delay that the system can tolerate before it becomes unstable for a given operating point.The proposed method starts with the determination of all possible purely imaginary characteristic roots for any positive time delay. To achieve this, Rekasius substitution is first used to convert the transcendental characteristic equation of the LFC system into a polynomial. Then, Routh stability criterion is applied to determine the critical root, the corresponding oscillation frequency and the delay margin for stability. For a wide range of controller gains, delay margins of LFC system are determined to find out the qualitative effect of controller gains on the delay margin. Finally, theoretical delay margin results are verified by using the time-domain simulation capabilities of Matlab/Simulink.

Keywords: Load Frequency Control System, Time Delay, Stability, Delay Margin

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #8, pp.67-76

Title of the Paper: Hybrid BFOA-PSO Approach for Optimal Design of SSSC Based Controller

Authors: E. S. Ali, S. M. Abd-Elazim

Abstract: A novel hybrid approach involving Particle Swarm Optimization (PSO) and Bacterial Foraging Optimization Algorithm (BFOA) called Bacterial Swarm Optimization (BSO) is illustrated for designing Static Synchronous Series Compensator (SSSC) for single and multimachine power systems. In BSO, the search directions of tumble behavior for each bacterium are oriented by the individual’s best location and the global best location of PSO. The proposed hybrid algorithm has been extensively compared with the original BFOA algorithm and the PSO algorithm. Simulation results have shown the validity of the proposed BSO in tuning PSSs compared with BFOA and PSO. Moreover, the results are presented to demonstrate the effectiveness of the proposed controller to improve the power systems stability over a wide range of loading conditions.

Keywords: SSSC; Particle Swarm Optimization; Bacterial Foraging; Hybrid Algorithm; Damping Oscillations; Different Power Systems

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #7, pp.54-66

Title of the Paper: An Approach for Transmission Usage & Loss Allocation by Graph Theory

Authors: Baseem Khan, Ganga Agnihotri

Abstract: Restructuring of Electricity supply industry introduced many issues such as transmission pricing, transmission loss allocation and congestion management. Many methodologies and algorithms were proposed for addressing these issues. In this paper a power flow tracing based method is proposed which involves Matrices methodology for the transmission usage and loss allocation for generators and demands. This method provides loss allocation in a direct way because all the computation is previously done for usage allocation. The proposed method is simple and easy to implement in a large power system. Further it is less computational because it requires matrix inversion only a single time. Results are shown for the sample 6 bus system and IEEE 14 bus system.

Keywords: Modified Kirchhoff Matrix, Power flow tracing, Transmission Pricing, Transmission Loss Allocation

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #6, pp.44-53

Title of the Paper: Maintenance Scheduling of Thermal Power Units in Electricity Market

Authors: Adnan Muharemovic, Smajo Bisanovic, Mensur Hajro

Abstract: The objective of this paper is to present a decision-based function to determine the optimal maintenance scheduling strategy of thermal power units taking into account the particular obligations of Generation Company, such as bilateral contracts. Opportunities for energy selling at the electricity market as well as a detailed modeling of the power plants are considered in the optimization problem. The deterministic constrained combinatorial optimization problem that considers maximization of profit is solved using the interior point cutting plane method. This method possesses the advantages of both, the interior point method and the cutting plane method, and becomes very promising approach for the large-scale discrete optimization problem. Furthermore, in order to improve the robustness and efficiency of this method, a new general optimal base identification method is developed and introduced to deal with various types of optimal solutions. The implementation and performances of proposed solution technique are presented. The effectiveness of the approach is tested on the realistic size case study, and numerical results are demonstrated and discussed.

Keywords: Maintenance scheduling; electricity market; bilateral contracts; market prices, interior point cutting plane method, optimal base identification method

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #5, pp.31-43

Title of the Paper: Load Flow Solution for Unbalanced Radial Power Distribution using Monte-Carlo Simulation

Authors: Mini Thomas, Rakeshranjan, Roma Raina

Abstract: In modern power system, voltage stability is a major concern. To maintain voltage stability, it is desirable to assess effect of any unforeseen events and identify the nodes which are more sensitive. The most important task for distribution engineer is to efficiently simulate the system so that effective corrective actions can be taken. Load flow analysis is one of the techniques to simulate the system. This paper presents a probabilistic modeled load flow solution for three phase Radial Power Distribution System (RDS). Probabilistic model uses Monte Carlo Simulation (MCS) and considers input parameters as random variables. Input uncertainties are addressed using a specific shape of probability distribution function and simulation is run for 500 trails. Simulation calculates system losses, nodal voltages and voltage stability index (SI) for all the nodes. The simulation results obtained incorporates the uncertainty and provides distribution of output which can be used as input for corrective action and planning purposes

Keywords: Branch Voltage, Three phase load flow, Voltage Stability Index, Radial power distribution, Monte Carlo, Probability distributions

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #4, pp.24-30

Title of the Paper: Feasible Positioning of Super Conducting Fault Current Limiters for Wind Farm intermittency and Fault currentReduction in a Smart Power System

Authors: Sujil A., Rajesh Kumar

Abstract: The promotion of recent power system fault current reduction research has been directed towards the super conducting fault current limiters. Many conventional protective devices installed for protection of excessive fault current in electric power systems especially at power stations are circuit breaker tripped by over current relay protection. They have a responds time delay that can pass initial two to three fault current cycles through it before getting activated. Super conducting fault current limiter (SFCL) is innovative electric equipment which has the capability to limit fault current within first cycle. The first cycle suppression of fault current by SFCL results in an increased transient stability of power system carrying higher power with greater stability. This paper presents a wind farm based smart power system with super conducting fault current limiter for wind farm fault current reduction. In this work, a resistive type SFCL model is implemented by integrating Simulink and Sim power system block in Matlab. In addition, typical smart grid model including generation, transmission and distribution network with dispersed energy resource (wind farm) is modeled to determine the performance of SFCL. Three phase fault have been simulated at different locations in smart grid and the fault current analysis is done with and without SFCL.

Keywords: Fault current, Super Conducting Fault Current Limiter, Smart grid, wind farm, Super Conductor.

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #3, pp.16-23

Title of the Paper: Monitoring of Photovoltaic Wind-Turbine Battery Hybrid System

Authors: Mohamed Zahran, Ali Yousef

Abstract: The purpose of the work is to investigate a monitoring of autonomous photovoltaic battery wind turbine hybrid system (PVBWHS). The PV array, wind turbine and the storage batteries sizes are estimated based the site of application; Jazan province, KSA. The sizing result of the proposed PVBWHS is generator with 2.16kW, wind turbine generator with 2kW, Battery Bank with ~400Ah, and 5kW ratings of inverter and hybrid system controller. In this paper an intelligent graphical user interface (GUI) is built in sub-menus for system characterization. The PVBWHS modeling, simulation, and performance monitoring are also introduced. Models are made to simulate the different power sources; PV system, Wind turbine, a storage battery, the electrical loads, and required meteorological conditions. A LabVIEW model is designed whereby the hybrid system components are simulated as virtual instruments [VI] interacted with functional blocks. The developed monitoring system measures continuously the available power generated from the solar array and wind turbine, and the functional VI compare this with the actual load demand on real time estimates the storage battery operation mode.

Keywords: PV array, wind turbine, sizing, modeling, monitoring system, hybrid system, sensors and actuators, LabVIEW, Virtual Instrumentation

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #2, pp.7-15

Title of the Paper: Evolutionary Programming for Reactive Power Planning Using FACTS Devices

Authors: Biplab Bhattacharyya, Vikash Kumar Gupta, S. Das

Abstract: This paper discusses the use of Genetic Algorithm (GA), Differential Evolution (DE) and Particle Swarm Optimization (PSO) based approach for the allocation & coordinated operation of multiple Flexible AC Transmission System (FACTS) devices for the economic operation as well as to increase power transfer capacity of an interconnected power system under different loading conditions. These Evolutionary programming based approaches for reactive power planning is applied on IEEE 30-bus system under different cases of loading. FACTS devices are installed in the different locations of the power system and system performance is noticed without and with FACTS devices. First, the locations, where the FACTS devices are to be placed are determined by calculating active and reactive power flows in the lines. GA, DE and PSO algorithms those under the category of Evolutionary Programming are used to find the magnitudes of the FACTS devices. Finally comparison between all these techniques for the placement of FACTS devices is presented.

Keywords: FACTS Devices, Line Power Flow, FACTS devices optimal locations, Active power loss, Operating cost, Evolutionary programming

WSEAS Transactions on Power Systems, ISSN / E-ISSN: 1790-5060 / 2224-350X, Volume 9, 2014, Art. #1, pp.1-6

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