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EPE-PEMC 2006 - Topic 11: POWER ELECTRONICS IN ELECTRICAL ENERGY GENERATION, TRANSMISSION AND DISTRIBUTION
You are here: EPE Documents > 04 - EPE-PEMC Conference Proceedings > EPE-PEMC 2006 - Conference > EPE-PEMC 2006 - Topic 11: POWER ELECTRONICS IN ELECTRICAL ENERGY GENERATION, TRANSMISSION AND DISTRIBUTION
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	A New Approach to DVR Control with Minimised Energy Injection   By Krzysztof Piatek	[View]   [Download]
Abstract: A new controller for a dynamic voltage restorer (DVR) is proposed in this paper. The controller allows minimisation of DVR injected active power, and stabilisation of DC side voltage. It allows also recharging a DC side using no extra recharging circuit. The controller works according to the progressive phase advance strategy, and since it does not require complicated numerical computations, the controller unit is very simple. Simulation results of a singlephase numerical model are presented in the paper. It has been shown that a DVR controlled according to the presented solution works satisfactorily.
	A Study of Synchronous Motor Drive using Static Frequency Converter   By Ho-Seon Ryu, Bong-Suck Kim, Joo-Hyun Lee, Ik-Hun Lim	[View]   [Download]
Abstract: SFC (Static Frequency Converter) system has been used as drive of large synchronous machine in many industry applications. But many papers have been presented on the control algorithm of SFC system, not the acceleration and start-up but the rated speed operation with line connection and the braking operation with regeneration which is used in the industry. This paper presents all control algorithms for the large synchronous machine connected with SFC system. The experimental results show that the proposed several algorithms are proper and effective.
	Active Power Control for Capacitive Divider Tapping Method   By Dan V. Nicolae, Adisa A. Jimoh, Anton C, Britten	[View]   [Download]
Abstract: Capacitive divider systems for tapping electric power from high voltage transmission lines are known to exhibit certain detrimental problems of stability, sub-resonance harmonic oscillations, and ferroresonance when coupled with non-linear loads. On the other hand, they can improve reactive power flow, power factor and contribute to improved harmonic filtration of the larger power system. This paper, therefore, proposes a controlled power flow conditioner as an essential integral component of a capacitive divider system to control power transfer between the high voltage transmission line, capacitive divider system, and the load. The ultimate objective of this conditioner is to mitigate or minimize the attendant problems associated with coupling the system to the load, and optimize the derivable benefits to the larger network.
	An Active Compensation Strategy for the Low-Voltage Network in Case of Harmonic Current-Producing Loads   By Ossama M. Elgendy, Abedel-Monem A. Abass, Ahmed M. A. Mahmoud, A. D. Alkoshery	[View]   [Download]
Abstract: In this paper, a strategy for compensating reactive and harmonic currents produced by non-linear loads, when being connected to the low- voltage side of the power system, is investigated. The loads in the low-voltage network can be classified, from the harmonics point of view, into a harmonic current producing type, a harmonic voltage producing type and a harmonic sensitive type. In spite of its associated problems, the compensation in the low- voltage network seems more reliable, economical, effective and straightforward. In general, these problems arise due to the interaction between the load and the power network parameters. The idea here stems from the fact that when applying a pollution treatment for a river, it is not the optimum solution (for all cases) to establish a treatment station across the river. The reliable alternative is to purify those outlets discharging into the river in an individual manner. The proposed strategy will be presented and demonstrated through analysis, design and practical simulation. The flexibility of the technique makes it suitable even to be applied to a small scale loads e.g. a productionline in a factory. It is amazing to deal with the instantaneous reactive power (q) as a time-signal to extract the reference reactive current, without introducing low-pass or high-pass filters into the forward control path. On the other hand, the characterization of loads according to the classification mentioned above is strongly recommended. It will be seen that this task can be done using a shunt active power filter.
	Appropriate Control Methods for PWM AC-to-DC Converters Applied in Active Line-Conditioning   By Robert Paku, Cristian Popa, Mircea Bojan, Richard Marschalko	[View]   [Download]
Abstract: The paper investigates the performances of a PWM ac-to-dc converter operating with the help of new control strategies, implemented so that the conditioning of the utilities may become possible. It is discussed the idea to use the PWM dc converters as power conditioner equipments too. The new concept of the ac line-conditioning with the help of the dc converters the dc converters is introduced and systematically classified. Appropriate control strategies are studied with the purpose to apply the active line conditioning. Corresponding Matlab/Simulink structures are developed. The result of the simulations, depicted in the paper proves the line-conditioning capabilities of the investigated converter.
	Asynchronous Generator Excited by Current Controlled Voltage Source Inverter using Rotor Field Oriented Control   By Jose Faria, Elmano Margato, Maria J. Resende	[View]   [Download]
Abstract: This paper presents a strategy used to appropriately excite and control the desired output active power of an asynchronous generator fed by a current controlled three-phase voltage source inverter. A dc voltage control loop, with a classical PI controller, is used to maintain at a reference value the dc bus voltage of the source inverter under a large rotor speed variation. The proposed asynchronous generator control strategy is developed using rotor field orientation technique and carried out by a digital signal processor (dsp). The proposed control strategy and adopted system models are validated by numerical simulation and experimental results obtained from a laboratory prototype.
	Comparison Between Line and Capacitor Commutated Converters for HVDC Controlled by Fuzzy Controllers   By Ahmed Abbas, Ahmed Hossam-Eldin, Mohamed Abdulla	[View]   [Download]
Abstract: A HVDC transmission system has two main parts, the power electronic part and the control part. There are two ways to connect the power electronic to the AC system, the line commutated converter topology (LCC) and the capacitor commutated converter topology (CCC). The control part might be implemented as a proportional plus integral (PI) or as a fuzzy controller. This paper presents a comparison between the performance of a HVDC system using LCC and a HVDC system using CCC both controlled by fuzzy logic controller. The study shows that the system using CCC has a better performance and characteristics than the system using LCC when fuzzy controller is used.
	Conditioning of Dynamic Power Gradients of Windparks   By Constaninos Sourkounis, Jan Wenske, Florian Richter	[View]   [Download]
Abstract: The stochastically fluctuating offer of wind energy limits the supply capacity in electrical grids by means of technical and economical reasons. To increase the supply, a concept of dynamic conditioning with the objective to increase the quality of supply was developed. The concept envisages supporting and managing of the electrical grid respectively by compensating active and reactive power with static converters ("Electronic Synchronous Machine") and short term storage. Short term fluctuation of the energy sources and changes of the load can be absorbed or smoothed directly on location using the four-quadrant operation of the converters. Stochastically offered primary energy is intermediately stored by using dynamic storage systems. This low order energy can thereby be converted into high order recallable energy, which can even be used to satisfy peak demands. The local compensation of the fluctuating energy supply on the one hand and of the changes of the demand on the other hand, permits a more steady energy demand from the nation-wide electrical grid.
	Digital Control Method for Single Phase Utility Interactive Inverter using Deadbeat Control with FPGA based Hardware Controller   By Sayaka Takamatsu, Eigo Shimada, Tomoki Yokoyama	[View]   [Download]
Abstract: A new current control method for the utility interactive inverter based on deadbeat control with FPGA based hardware controller is proposed. In the utility interactive system, the utility line voltage should be included in the system model, so the procedure to derive the discrete time system model is the key point to achieve the accurate control characteristics. In the proposed method, different approaches were applied to derive the discrete model to the utility voltage and the inverter voltage. As a result, superior characteristics were derived with very small LC filter component. Also to utilize the capability of FPGA based hardware controller, all the control circuit for the proposed current control method using voltage deadbeat control and PLL control with quasi-dq transformation are implemented in FPGA based hardware controller. The design concept of the controller is also described, and the advantages and the disadvantage are discussed through simulations and experiments.
	Discrete-Time Dead-Beat Control of a VSC Transmission Scheme Including Voltage and Current Limitations for Wind Farm Connection   By Joaquin Eloy-Garcia, Serge Poullain, Benchaib Abdelkrim	[View]   [Download]
Abstract: This paper presents a discrete-time nonlinear control of a Voltage Source Converter (VSC) transmission system for wind farm connection to electrical network. After introducing discrete-time modeling of a VSC transmission scheme, discrete-time currents (i.e. P and Q) and DC bus voltage controllers synthesis is presented. Both voltage and current limitations are then taken into account through the introduction of voltage and current limitation circles. Control performances are then illustrated by simulation results. More particularly, transient behavior in case of voltage and current limitations is discussed. Finally, some conclusions and perspectives are given.
	Discrete-Time Sliding Mode Control of Load Frequency in Power Systems with Input Delay   By Kresimir Vrdoljak, Ivan Petrovic, Nedjeljko Peric	[View]   [Download]
Abstract: This paper presents a new approach for loadfrequency control in large scale power systems. The method uses only samples of area control error signals from which it estimates all states and disturbances in the system. Predictor is used to compensate for the time delay in control signal. A novel approach for designing a sliding surface is presented. Simulation results of three-area power system using designed controller are shown.
	Discrete-Time Sliding-Mode Control of a STATCOM Including Voltage and Current Limitations for Wind Farm Applications   By Joaquin Eloy-Garcia, Serge Poullain, Abdelkrim Benchaib	[View]   [Download]
Abstract: This paper presents a discrete-time slidingmode control of a VSC based STATCOM, intended for its application to wind farm connection to the grid. A sliding-mode controller has been used for currents while pole placement with a slower dynamic response has been used for DC bus voltage control, as DC voltage has been assumed to have slower dynamics than currents. Besides, the voltage and current limitations of the system has been studied and their influence analyzed by means of limitation circles.
	Dynamic Behaviour Identification of Electrical Gen-Set   By Jan Leuchter, Pavol Bauer, Vladimir Rerucha, Zdenek Krupka	[View]   [Download]
Abstract: This paper brings some practical results of research devoted to the new generation of mobile electrical power sources, based on the VSCF technology (Variable Speed – Constant Frequency). In this generation of mobile electrical power sources the driving motor and generator speed is optimally controlled in accordance with the load power thus decreasing the fuel consumption. The output voltage and frequency are stabilized by means of power electronics converter. The measurements show that the real drawback of this concept of EGS with variable speed of engine is the engine-generator dynamics at sudden transient from low load to high load. Dynamic behaviour of the driving engine in the case of sudden power output increase requires the time of few seconds to change the speed of engine from low to higher speed. During this time, the power required by the load is not available and diesel engine can by high load at the low speed stop undesirably. Electronic converter can improve the dynamic behaviour of whole EGS system by means of inserting accumulated energy to the DC link of AC/DC/AC converter.
	Feasibility of HVDC for Very Weak AC Systems with SCR below 1. 5   By Jorge Wilson Gonzalez, Christian Weindl, Gerhard Herold, Dietmar Retzman, Hugo A. Cardona, Idi A. Isaac, Gabriel J. Lopez	[View]   [Download]
Abstract: This paper exposes the feasibility to connect high voltage dc transmission (HVDC) systems to very weak ac networks leading to short circuit ratios (SCR) lower than 1.5. The existing literature does not provide solutions for such a low SCR systems and often the HVDC expansions cannot grow enough as expected. The studies developed are for the short-term voltage stability phenomena, where a solution using the PSCAD/EMTDC program for a very weak ac network with SCR = 1.0 is presented. The reactive power characteristics are shown since they are important to judge the behavior of solutions for ac/dc interactions.
	Frequency Spectrum based Coordinate Control Scheme for Several Types of Distributed Power Generation Systems in a Micro Grid   By Shinichi Kusagawa, Daisuke Sekine, Jumpei Baba, Shigeo Numata, Atsushi Denda, Tanzo Nitta, Eisuke Masada	[View]   [Download]
Abstract: A power control method to compensate power fluctuation of the load in the micro grid systems is proposed and discussed. Active power responses of several kinds of distributed power generation systems (DGs) such as gas engine, micro gas turbine etc., energy storage system, and load fluctuation of a site have been measured. Based on the measurements, coordinate control system for several kinds of DGs has been constructed. Simulation and experiments have been carried out with small-scale micro grid model system. It is shown that the load fluctuation has been compensated by the proposed method.
	Fuzzy Logic Control of Synchronous Generator under the Condition of Transient Three Phase Short Circuit   By Damir Sumina, Tomislav Idzotic, Igor Erceg	[View]   [Download]
Abstract: This article is focused on the implementation of fuzzy logic excitation control of a synchronous generator. A simple fuzzy logic control scheme for voltage control and generator stabilization is tested on the real laboratory model that includes digital system for excitation control (based on four DSPs) and synchronous generator connected to an AC system through transformer and two parallel transmission lines. The experiments were performed for transient three phase short circuit on the one transmission line. The behaviour of the excitation system with fuzzy logic stabilizing controller is compared with excitation system based on the PI voltage controller and conventional power system stabilizer.
	Harmonic Voltage Mitigation in Industrial Power Systems by using Multiple Active Power Filter Configuration   By Josef Tlusty, Viktor Valouch	[View]   [Download]
Abstract: The procedure for calculating optimum controller parameters of the APFs, which are implemented into a multibus industrial power system for harmonic voltage mitigation, is presented. The node voltage detection control strategy is applied and the optimum controller parameters are found by solving the multiple APF – multiple harmonic problem. Thus, the best places for several APFs may be proposed, taking into account also a real control strategy as well as APF controller parameters.
	Improvement of Synchronous Generator Characteristics using Bi-Directional Current Phase Control Switch   By Jan Arild Wiik, Taku Takaku, Fransisco Danang Wijaya, Tadayuki Kitahara, Ryuichi Shimada	[View]   [Download]
Abstract: This paper has suggested a new configuration for reducing the excitation need of synchronous generators. The configuration consists of a synchronous generator connected in series with a bi-directional current switch. The switch injects a series voltage which cancels the synchronous reactance of the generator. The series voltage is automatically generated by absorbing the magnetic energy stored in the synchronous reactance. The excitation level reduction has been verified with experimental results for an island grid. The low change in excitation for various loads also indicates that this concept can be used with constant excited generators, also permanent magnet generators.
	Inverter Control for Distributed Generation   By Erik Stjernholm Hoff, Lars Einar Norum	[View]   [Download]
Abstract: Grid connection of many small-scale renewable energy resources, such as photovoltaics, requires an inverter. The way in which this inverter is controlled, is important in respect to safety and voltage quality. Control of such an inverter for Distributed Generation is designed and tested. This is performed on a 3 kW three-phase transformerless lab setup. In addition the inverter is also used as an Uninterruptible Power Supply in case of power outages.
	LV and MV Distribution Networks Reconfiguration for Minimum Losses   By Willi M. Siti, Dan V. Nicolae, Adisa A. Jimoh	[View]   [Download]
Abstract: The reconfiguration of the distribution network feeders can be defined as the restructuring of the feeders through the changing of the open/close states of the sectionalizing and tie switches. This creation of a new distribution network topology is normally required to improve the performance of the network, and thus sometimes the efficiency of the electricity supply. For optimum loss reduction, feeder reconfiguration is often considered as an option. This, however, requires the implementation of an appropriate switching control strategy. It would be desirable for the switching to be automatic, that is to follow the connected load situation of the feeder. The proposed optimal reconfiguration of the phase balancing using the heuristic method proves to be robust compared to neural network method, to turn ON and OFF the different switches, allowing the three phases supply of the transformer to the end-users to be balanced. This paper presents the application examples of the proposed method using the real data.
	Modeling and Real Time Estimation of Lumped Equivalent Circuit Model of a Lithium Ion Battery   By Jae Moon Lee, Sonu Jun, Jae Ho Lee, On Yong Nam, Jong Hun Kim, Bo Hyung Cho, Han-Seok Yun, Soon-Seok Choi, Kiho Kim, J. H. Kim	[View]   [Download]
Abstract: In this paper, a real time estimate of a battery model is proposed. The existing impedance model is accurate in predicting the behavior of a battery. However, it is complex and not applicable for real time applications. Also, it requires much time and cost to obtain the parameters of the model. A simple lumped circuit model is presented. The parameters and states (overvoltages) of the battery are estimated with a filtering technique and system identification theory. It is verified through simulations and experiments that the proposed method is in good agreement with the dynamic characteristics of the battery, regardless of the conditions of the battery, and the estimated overvoltages are given physical meanings through a comparison with an impedance model with complex RC ladder circuits.
	Modeling of DC/DC Converter for DC Load Flow Calculation   By Menghua Zhao, Zhe Chen, Frede Blaabjerg	[View]   [Download]
Abstract: With the development of power electronic techniques, more and more attention has been paid to DC power systems. This paper analyzes the load flow issues containing DC/DC converters in a DC power system. The load flow model of DC/DC converters, which considers the power losses and control strategy of the converter, has been presented and integrated into the traditional load flow algorithm by modifying the Jacobian matrix. Two typical DC/DC converter examples have been presented: the boost converter and full bridge converter.
	Parallel Operation of Distributed Generation in Weak Distribution Systems   By Fainan Magueed, Jaap Daalder	[View]   [Download]
Abstract: The main aim of connecting distributed generation (DG) to the distribution network is to increase the power capacity to meet an increased demand. In case of implementing DGs with a power electronics interface, more functions can be added simply by modifying the control targets. DGs can enhance the voltage reliability by regulating the voltage level at critical load connection points in weak grids. To this end, parallel operation of DGs in weak grids is discussed with respect to the input power limitation of a DG, the power angle at the connection bus, and the voltage profile of the feeder.
	Passive and Active Anti-Resonance Capacitor Systems for Power Factor Correction   By Dulce Fernao Pires, Vitor Fernao Pires, Carlos Henggeler Antunes, Antonio Gomes Martins	[View]   [Download]
Abstract: This paper presents passive and active antiresonance capacitor systems for power factor correction. Normally, shunt capacitors should be designed carefully before installation in order to avoid series and/or parallel harmonic resonance between the capacitors and line/load inductances. To avoid these problems passive systems, such as shunt capacitors, connected in series with reactors can be used. However, the system parameters are dynamically changing, according to the power system configurations and loads. In the last years, new active systems together with capacitors banks have been used to avoid harmonic resonance. In this paper passive and active anti-resonant systems for power factor correction are presented. A new active system will also be presented. Several results are presented showing the effectiveness of the proposed system.
	Positive and Negative Sequence based Sensorless Control for Stand-Alone Slip-Ring Generator   By Grzegorz Iwanski, Wlodzimierz Koczara	[View]   [Download]
Abstract: A stand alone power generation system with doubly fed induction generator and its control method is presented in the paper. A slip-ring induction generator is equipped with the stator connected capacitances for filtering the switching frequency harmonics produced by the rotor connected power electronics converter. The proposed Direct Voltage Control method, based on the stator voltage vector reference, provides fixed frequency and amplitude of the generated stator voltage operation. Different types of load (linear nonlinear) can be supplied keeping high quality voltage. A star connected stator provides the four wires system, supplying a single phase or unbalanced load. However the high load asymmetry produces the unbalanced stator voltage and in this case the additional part of the voltage control method is necessary for voltage asymmetry correction. As the main part of the control method bases of the positive sequence component of the stator voltage vector, the asymmetry correction algorithm bases on the negative sequence components. To extract both positive and negative sequence components of the stator voltage vector, two independent rotating frames are used. The coordinates systems rotates in opposite directions with synchronous and counter to synchronous angular speed. A PSIM software is used for control method design and prototyping. A proposed stand alone power generation system was build and tested. The developed stator voltage control with voltage asymmetry algorithm is proved by simulations and by oscillograms from laboratory tests.
	Power Factor Correction and Active Filtering Technology Application for Industrial Power Systems with Non-Linear Loads   By Michail Smirnov, Roman Grinberg, Maxim Riabchitsky, Yuriy Rozanov	[View]   [Download]
Abstract: Power factor and harmonics problem in industrial power systems with non-linear loads is presented. Traditional and modern advanced technologies for power factor improvement and harmonic mitigation are reviewed. Advantages of power electronics based static reactive power compensation (STATCOM) and active harmonic filtering are shown. Design issues for power electronics converter operating as STATCOM&active filter are discussed. Modeling and experiment results are presented for both advanced technologies.
	Power Factor Correction and Compensation of Unbalanced Loads by PWM DC/AC Converters   By Rafael Jardan, Istvan Nagy, Tamas Ruzsanyi, Hiroyuki Ohsaki	[View]   [Download]
Abstract: A solution developed for Power Quality Conditioning (PQC) applied in Distributed Generation System is presented. The method is exploiting the capabilities of the DC/AC converter of a system that has been developed to generate electric power by utilizing alternative, renewable and waste energies. The Power Quality Conditioning is based on the application of space vector theory, using an algorithm easy to implement. The paper describes a control structure that is capable of both power factor correction and elimination of negative sequence components in the mains current. The theoretical analysis is confirmed by computer simulation results.
	Simulation of a Power Electronic based Fault Current Limiter (FCL) in Case of Different Faults   By Hubert Rubenbauer, Gerhard Herold	[View]   [Download]
Abstract: The effects of a Fault Current Limiter (FCL) on different types of faults in a three-phase network are presented in this paper. The FCL is based on a six-pulse thyristor rectifier with a freewheeling diode. Parallel to the three branches of the rectifier a further thyristor branch is added to handle faults with connection to earth. The FCL is directly connected to a transformer’s neutral terminal. For the simulations in Matlab/Simulink a simple network is used.
	STATCOM Control for Operation with Unbalanced Voltages   By Bostjan Blazic, Igor Papic	[View]   [Download]
Abstract: In view of STATCOM operation analysis, special attention must be paid to the operation with unbalanced network voltages. In this paper a control algorithm that enables STATCOM operation with unbalanced voltages is presented. The algorithm is based on the compensator mathematical model in the d-q coordinate system. In case of an unbalanced voltage sag the compensator unbalances the generated voltages to limit the negative sequence currents. The problem of low-order harmonics generation is solved with the use of appropriate switching function modulation that enables the use of a relatively small capacitor on the dc side. The proposed algorithm was tested by means of simulation of STATCOM operation in the PSCAD program. The algorithm shows a good transient response also in the case of relatively deep voltage sags.
	The Flywheel Energy Storage with Brushless DC Motor – the Practical Results   By Tomasz Siostrzonek, Stanislaw Pirog	[View]   [Download]
Abstract: This paper presents the results of research of the rotating energy accumulator. In the study the brushless DC motor with permanent magnet (PN=2,98kW) was used as the motor-generator. The rotating mass made up the steel pipe. This accumulator stored about 4MJ kinetic energy. The rotation speed was 6000 rpm. The inverter was constructed from Intelligent Power Modules. The control of this one is based on module with FPGA and DSP.
	Using Super Capacitor based Energy Storage to Improve Power Quality in Distributed Power Generation   By Yonghua Cheng, Joeri Van Mierlo, Peter Van den Bossche, Philippe Lataire	[View]   [Download]
Abstract: Distributed power generation will be formed in many weak distribution networks, after renewable energy sources are connected to them. It is very important to increase the reliability and efficiency of using these renewable energy sources. By using DVR (Dynamic Voltage Restorer), the power quality problem in distributed power generation (e.g. voltage fluctuation) can effectively be solved. In this paper, super capacitor based energy storage will be used as the peak power unit, to ensure the power quality on the both sides of the DVR during short time and on the one side of the DVR during long time duration. The proposed control methods of each inverter and converter have been verified in Matlab simulation and tested in our laboratory. High power quality can be achieved in distributed power generation with the presented systems.
	Voltage and Frequency Control for a Self-Excited Induction Generator using a Three-Phase Four-Wire Electronic Converter   By Jose Antonio Barrado, Robert Grino	[View]   [Download]
Abstract: This work proposes a system, based on a selfexcited induction generator (SEIG) with a shunt electronic converter, to feed isolated three-phase and single-phase linear or nonlinear loads. The electronic converter is composed by a three-phase four-wire shunt active filter and a dc chopper attached to its dc bus. The converter compensates the current harmonics, the reactive power and the load unbalances at its ac side and dissipates the active power excess through the chopper at its dc side. The designed control architecture assures that, in steady state, the rms values of the voltages and the frequency remain at the their reference values. The simulated results show a good performance of the system under different loading conditions.