EPE Association: EPE 2001 - Topic 10c: FACTS

EPE 2001 - Topic 10c: FACTS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2001 - Conference > EPE 2001 - Topic 10: POWER ELECTRONICS IN GENERATION, TRANSMISSION AND DISTRIBUTION OF ELECTRICAL ENERGY > EPE 2001 - Topic 10c: FACTS

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   A New Series Voltage Compensator scheme
By S-J. Lee; S-K. Sul [View]
[Download]

Abstract: This paper describes a new scheme of series voltage compensator, which compensates the voltage sag or swell in utility grid. Conventionally, the configuration consists of three single-phase full bridge inverters and three single-phase transformers has been used. The proposed system consists of a threephase inverter, a three-phase transformer, and a transformer with a half bridge inverter to compensate the zero sequence voltage. The new scheme of series voltage compensator can effectively compensate the distorted voltage in the utility grids less expensively than the conventional scheme can.

   A Transformerless STATCOM Based on Cascaded Multilevel Inverters with
By S. Chen; G. Joós [View]
[Download]

Abstract: This paper aims at fully digital control of cascaded multilevel converters for custom power application in a 13.8 kV distribution system. The three-phase STATCOM consists of three chains of cascaded 5 identical single-phase converters. The individual converters are switched at very low frequency, and are fed from self-powering dc capacitor voltages. A new space vector modulation algorithm is systematically developed, which decomposes multilevel space vector diagram into simple ones for each of the seriesconnected cells. Advantages include computationally effective, low injected voltage harmonics, wide linear modulation range, and fast response to changes in the compensation level. Performance assessment is presented by simulation and experimental results.

   A.C. Railway System with Active Return Conductor
By C. Tuttas [View]
[Download]

Abstract: Today the transmitted power in a.c. railway networks increases due to the higher density and speed of the trains. Therefore higher currents are flowing via the tracks and the earth causing problems with the electromagnetic compatibility (EMC) and problems with the personnel safety. Both phenomena can be significantly reduced by means of a new transmission scheme working with an active return conductor. A conventional return conductor is installed near the catenary and connected with the track at equidistant points. In every return conductor-track-loop an Unified Power Flow Controller (UPFC) suppresses the track current. Simultaneously the earth current is drastically reduced. Besides improving the EMC behaviour and the personnel safety the UPFC-stations can also be used for stabilising the catenary-track-voltage in an a.c. railway system.

   Application of linear voltage and current sources in UPFC system
By R. Porada; M. Gwózdz; L. Frackowiak [View]
[Download]

Abstract: The article presents application of power electronics linear sources of voltage and current in UPFC system. It shows structure of these sources as a feedback system as well as some selected measured results of the prototype model operation. In this work we discuss rules of series- parallel active compensation and proposal of UPFC system with a use of independent power electronics voltage and current sources of wide bandwidth. We talk over a method of control system, taking into account necessity of fast and precise identification of parameters of basic harmonics voltage of power network and synchronization of reference signals of voltages and currents. We present also simulation results of UPFC system with application of the above mentioned sources. The obtained results show that the deformations of voltage and current were effectively reduced even for strong distorted voltage and current of a nonlinear load.

   Circuit and Control Scheme of VSI for Balanced Supply of Railway Loads
By D. Hasenkopf; J. Xie [View]
[Download]

Abstract: Railway traction power supply systems can be fed directly from the public three phase grid, if they operate at the same frequency. The railway substations are high power single phase loads causing high unbalanced line currents and, due to voltage drops at line impedances, negative sequence voltage components. In this paper a shunt inverter arrangement is described to compensate these negative sequence line currents. The inverter consists of three full-bridge modules with neutral point clamped three-level topology. Two different modulation strategies are discussed, which use off-line computed pulse patterns for harmonic elimination. A phasor oriented control scheme is presented for the use with these modulation techniques. To show the dynamic control performance, simulation results are presented.

   Compensation by UPFC the electrical lines
By S. Saadate; K. Belacheheb [View]
[Download]

Abstract: Many papers over FACTS generally or UPFC device particularly are available nowadays. Most of them use these new devices as phase controllers in the transmission lines, in order to control the power flow in the mains. But, UPFC is capable to control the power flow by acting over three basic electrical parameters which are line voltage, impedance and electrical angle. So, the main objective of this paper is to compare these three power flow control approaches. Three comparison points are aimed which are the limitation of each approach in term of line active power correction, the UPFC device power rating and finally the impact over the reactive power circulation in the controlled line. With respect to these comparisons, one can choose the best control parameter among voltage, impedance or electrical angle, according to the envisaged application. After a basic theoretical study on power flow control by UPFC, the numerical simulations using SABER are realized in order to validate, through a simple case, the obtained results. Moreover, as these compensations are mainly realized by the series part of UPFC, the contribution of the shunt part in reactive compensation is also considered in these simulations.

   Control System Design Of Unified Power Flow Controller
By D.A. Pastos; G.B. Giannakopoulos; N.A. Vovos [View]
[Download]

Abstract: In this paper a control strategy is proposed for a Unified Power Flow Controller (UPFC), which achieves active power flow control through a transmission line and voltage magnitude control at both ends of the line. The controller is designed to use only local measurements. A linearized model of the system, based on vector analysis, is derived for control system design purposes. Detailed three-phase simulations for a case study, using PSCAD/EMTDC program, are presented to evaluate the performance of the proposed scheme.

   Elimination of Low Order Harmonics in a 3-Level Inverter Used for Stat
By L. Ran; L. Holdsworth; G. Putrus [View]
[Download]

Abstract: This paper is concerned with the harmonic absorption of DC side capacitors in a 3-level inverter operated as an ASVC. The effects of the load level and the switching pattern are analysed. It is shown that the DC voltage ripple will affect the AC side harmonic spectrum. Requirements to eliminate the dominant 3rd harmonic absorption are identified. A switching strategy to control the DC side harmonics and an expanded system configuration are investigated. A new dynamic selective harmonic elimination modulation method (SHEM) is described to improve the inverter output voltage; the switching angles to track the operating point are derived. The analysis is illustrated using simulation and experiment.

   Fast acting solid-state circuit breaker using power-electronic devices
By L. Klingbeil; W. Kalkner; C. Heinrich [View]
[Download]

Abstract: Recent advancement in power semiconductors has been remarkable and the use of power semiconductor devices in applications for distribution of electrical energy has become an important field of research. The paper describes investigations on modern power-semiconductors for use in fast-acting circuit breakers. Aim of the investigations is a comparison of different types of solid-state switching devices as well as the proof of their eligibility for use in medium-voltage distribution systems. Laboratory tests were made to show the switching behaviour at high currents. Simulations were done to compare the experimental results with the simulation models and to predict the operation behaviour in networks.

   Flicker mitigation, Application to a STATCOM
By G. De Préville [View]
[Download]

Abstract: Flicker, caused by large fluctuating loads as arc furnace, is one of the power quality problems that include interruptions, voltage sags and dips, harmonics. The state of the art technology to reduce flicker is shunt compensation using Static Var Compensator with thyristors. However, this kind of technology has an intrinsic limited flicker mitigation capability. Traditionally, flicker is mainly due to reactive power fluctuation. However, Flicker generation is more complicated and in the paper, drop voltage and shunt compensation methods are described step by step to explain flicker. Simulations of arc furnace installation with shunt compensation device using Voltage Source Converter or STATCOM with its control are presented. Multilevel structure simulation is shown. Reduction of PST versus shunt compensation methods is shown.

   Investigation Of The 3-Level Unified Power Flow Controller (UPFC)
By A. Sapin; J.-J. Simond; P. Allenbach [View]
[Download]

Abstract: Flexible AC Transmission Systems (FACTS) are systems based on power electronics using GTO or IGCT semiconductors [1] that allow a better use of the transfer capacities of the transmission lines and permit to satisfy the requirements due to the liberalization of the electrical energy market. The Unified Power Flow Controller (UPFC) is one of the most versatile topologies of the FACTS family. The UPFC can be decomposed in two different power circuits: the parallel one maintaining the network bus voltage by consuming or producing reactive power, and the series one controlling the active and reactive power flow with the insertion of a series voltage in the transmission line. The aim of the present paper is to investigate in details the power quality and the dynamic performance of the 3-level UPFC.

   Operation of the 15 MVA System-Tie Frequency Converter at Nuernberg after relocation
By A. Effenberger; H. Weiss [View]
[Download]

Abstract: In 1994 the first static system tie frequency converter of the German Railways went into operation at Muldenstein but was relocated to Nuernberg in 1996/1997. It is a 3-level GTO converter capable of transfering 15MVA rated apparent power from the 50 Hz mains to the 16.7 Hz railway supply line or into the other direction. Since 1997 this GTO converter is again feeding the local railway supply in a very demanding operation. Special attention was given to the transient operation e.g. at line short circuits. Improvements in the control system have been accomplished, a diagnosis system was added.

   State-Space Calculation of Systems w. Controlled Compensation Devices
By C. Weindl; G. Herold [View]
[Download]

Abstract: In this paper a new calculation method for current converters and SVC is further generalized to systems including thyristor controlled compensation devices. The entire system is represented in complex space-phasor networks for two exemplarily switching states. The resulting state-space description considers the eigenvalues and switching sequence of the complete network structure. The respective linear independent circuits are coupled into a linear inhomogeneous boundary value problem which is analytically solved as a whole. The presented analytic solution holds for all thyristor controlled compensation devices in all operating modes. Additionally the calculation method is independent to the size of the investigated network.

   UPFC modelisation and optimal location in applications in networks
By S. Dupuis; M. Crappe; J. Trécat [View]
[Download]

Abstract: This paper studies UPFC with Eurostag software simulations. Eurostag UPFC modelling is presented and compared with UPFC modellings found in literature. Influence of UPFC location is investigated in the IEEE 14 bus test system further than in paper [1] and is analysed in network with power flow regulation.

   UPFC with matrix converters
By R. Strzelecki; A. Noculak; H. Tunia; K. P. Sozañski; Z. Fedyczak [View]
[Download]

Abstract: This paper describes unified power flow controllers (UPFC) with matrix converter. The basic problems of UPFC are discussed. The main aim of this paper is to present selected results of the analyses of the new UPFC based on matrix converter. This paper describes models of matrix converters and control rules for UPFC. Some results of simulation research are also presented in the paper.

   Using SVC for voltage regulation in railways network. HVB EC project
By S. Bacha; I. Etxeberria; M. Crappe; S. Fahe; Z. A. Styczynski; C. Courtois; A. Talibart; M. Fracchia; M. Stuart; T. Consani; E. Merli; P. Borgignon [View]
[Download]

Abstract: This paper deals with a high voltage (25kV) booster for railways based on SVC topology. The aim is to obtain a fast response for voltage drop compensation (substation transformer and catenary) against deep variation of power consumption taking into account the railway specifications. Results of studies are made in the scope of a joint project funded by the European Commission (DG XII) under the Fifth PCRD program.

   Voltage Sags Compensation with Minimum Energy Injection by Use of
By S. Polmai; T. Ise; S. Kumagai [View]
[Download]

Abstract: This paper presents a method to compensate voltage sag with minimum energy injection for a series connected voltage compensator by use of a micro-SMES. A simple method for detecting the fundamental positive sequence components from sag voltage and a minimum energy injection algorithm are described. Simulations of voltage sag compensation were carried out using PSCAD/EMTDC. The simulation results confirm the validity of the proposed method and show the possibility to reduce the size of energy storage device.

EPE 2001 - Topic 10c: FACTS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2001 - Conference > EPE 2001 - Topic 10: POWER ELECTRONICS IN GENERATION, TRANSMISSION AND DISTRIBUTION OF ELECTRICAL ENERGY > EPE 2001 - Topic 10c: FACTS
	[return to parent folder]

	A New Series Voltage Compensator scheme By S-J. Lee; S-K. Sul	[View] [Download]
Abstract: This paper describes a new scheme of series voltage compensator, which compensates the voltage sag or swell in utility grid. Conventionally, the configuration consists of three single-phase full bridge inverters and three single-phase transformers has been used. The proposed system consists of a threephase inverter, a three-phase transformer, and a transformer with a half bridge inverter to compensate the zero sequence voltage. The new scheme of series voltage compensator can effectively compensate the distorted voltage in the utility grids less expensively than the conventional scheme can.

	A Transformerless STATCOM Based on Cascaded Multilevel Inverters with By S. Chen; G. Joós	[View] [Download]
Abstract: This paper aims at fully digital control of cascaded multilevel converters for custom power application in a 13.8 kV distribution system. The three-phase STATCOM consists of three chains of cascaded 5 identical single-phase converters. The individual converters are switched at very low frequency, and are fed from self-powering dc capacitor voltages. A new space vector modulation algorithm is systematically developed, which decomposes multilevel space vector diagram into simple ones for each of the seriesconnected cells. Advantages include computationally effective, low injected voltage harmonics, wide linear modulation range, and fast response to changes in the compensation level. Performance assessment is presented by simulation and experimental results.

	A.C. Railway System with Active Return Conductor By C. Tuttas	[View] [Download]
Abstract: Today the transmitted power in a.c. railway networks increases due to the higher density and speed of the trains. Therefore higher currents are flowing via the tracks and the earth causing problems with the electromagnetic compatibility (EMC) and problems with the personnel safety. Both phenomena can be significantly reduced by means of a new transmission scheme working with an active return conductor. A conventional return conductor is installed near the catenary and connected with the track at equidistant points. In every return conductor-track-loop an Unified Power Flow Controller (UPFC) suppresses the track current. Simultaneously the earth current is drastically reduced. Besides improving the EMC behaviour and the personnel safety the UPFC-stations can also be used for stabilising the catenary-track-voltage in an a.c. railway system.

	Application of linear voltage and current sources in UPFC system By R. Porada; M. Gwózdz; L. Frackowiak	[View] [Download]
Abstract: The article presents application of power electronics linear sources of voltage and current in UPFC system. It shows structure of these sources as a feedback system as well as some selected measured results of the prototype model operation. In this work we discuss rules of series- parallel active compensation and proposal of UPFC system with a use of independent power electronics voltage and current sources of wide bandwidth. We talk over a method of control system, taking into account necessity of fast and precise identification of parameters of basic harmonics voltage of power network and synchronization of reference signals of voltages and currents. We present also simulation results of UPFC system with application of the above mentioned sources. The obtained results show that the deformations of voltage and current were effectively reduced even for strong distorted voltage and current of a nonlinear load.

	Circuit and Control Scheme of VSI for Balanced Supply of Railway Loads By D. Hasenkopf; J. Xie	[View] [Download]
Abstract: Railway traction power supply systems can be fed directly from the public three phase grid, if they operate at the same frequency. The railway substations are high power single phase loads causing high unbalanced line currents and, due to voltage drops at line impedances, negative sequence voltage components. In this paper a shunt inverter arrangement is described to compensate these negative sequence line currents. The inverter consists of three full-bridge modules with neutral point clamped three-level topology. Two different modulation strategies are discussed, which use off-line computed pulse patterns for harmonic elimination. A phasor oriented control scheme is presented for the use with these modulation techniques. To show the dynamic control performance, simulation results are presented.

	Compensation by UPFC the electrical lines By S. Saadate; K. Belacheheb	[View] [Download]
Abstract: Many papers over FACTS generally or UPFC device particularly are available nowadays. Most of them use these new devices as phase controllers in the transmission lines, in order to control the power flow in the mains. But, UPFC is capable to control the power flow by acting over three basic electrical parameters which are line voltage, impedance and electrical angle. So, the main objective of this paper is to compare these three power flow control approaches. Three comparison points are aimed which are the limitation of each approach in term of line active power correction, the UPFC device power rating and finally the impact over the reactive power circulation in the controlled line. With respect to these comparisons, one can choose the best control parameter among voltage, impedance or electrical angle, according to the envisaged application. After a basic theoretical study on power flow control by UPFC, the numerical simulations using SABER are realized in order to validate, through a simple case, the obtained results. Moreover, as these compensations are mainly realized by the series part of UPFC, the contribution of the shunt part in reactive compensation is also considered in these simulations.

	Control System Design Of Unified Power Flow Controller By D.A. Pastos; G.B. Giannakopoulos; N.A. Vovos	[View] [Download]
Abstract: In this paper a control strategy is proposed for a Unified Power Flow Controller (UPFC), which achieves active power flow control through a transmission line and voltage magnitude control at both ends of the line. The controller is designed to use only local measurements. A linearized model of the system, based on vector analysis, is derived for control system design purposes. Detailed three-phase simulations for a case study, using PSCAD/EMTDC program, are presented to evaluate the performance of the proposed scheme.

	Elimination of Low Order Harmonics in a 3-Level Inverter Used for Stat By L. Ran; L. Holdsworth; G. Putrus	[View] [Download]
Abstract: This paper is concerned with the harmonic absorption of DC side capacitors in a 3-level inverter operated as an ASVC. The effects of the load level and the switching pattern are analysed. It is shown that the DC voltage ripple will affect the AC side harmonic spectrum. Requirements to eliminate the dominant 3rd harmonic absorption are identified. A switching strategy to control the DC side harmonics and an expanded system configuration are investigated. A new dynamic selective harmonic elimination modulation method (SHEM) is described to improve the inverter output voltage; the switching angles to track the operating point are derived. The analysis is illustrated using simulation and experiment.

	Fast acting solid-state circuit breaker using power-electronic devices By L. Klingbeil; W. Kalkner; C. Heinrich	[View] [Download]
Abstract: Recent advancement in power semiconductors has been remarkable and the use of power semiconductor devices in applications for distribution of electrical energy has become an important field of research. The paper describes investigations on modern power-semiconductors for use in fast-acting circuit breakers. Aim of the investigations is a comparison of different types of solid-state switching devices as well as the proof of their eligibility for use in medium-voltage distribution systems. Laboratory tests were made to show the switching behaviour at high currents. Simulations were done to compare the experimental results with the simulation models and to predict the operation behaviour in networks.

	Flicker mitigation, Application to a STATCOM By G. De Préville	[View] [Download]
Abstract: Flicker, caused by large fluctuating loads as arc furnace, is one of the power quality problems that include interruptions, voltage sags and dips, harmonics. The state of the art technology to reduce flicker is shunt compensation using Static Var Compensator with thyristors. However, this kind of technology has an intrinsic limited flicker mitigation capability. Traditionally, flicker is mainly due to reactive power fluctuation. However, Flicker generation is more complicated and in the paper, drop voltage and shunt compensation methods are described step by step to explain flicker. Simulations of arc furnace installation with shunt compensation device using Voltage Source Converter or STATCOM with its control are presented. Multilevel structure simulation is shown. Reduction of PST versus shunt compensation methods is shown.

	Investigation Of The 3-Level Unified Power Flow Controller (UPFC) By A. Sapin; J.-J. Simond; P. Allenbach	[View] [Download]
Abstract: Flexible AC Transmission Systems (FACTS) are systems based on power electronics using GTO or IGCT semiconductors [1] that allow a better use of the transfer capacities of the transmission lines and permit to satisfy the requirements due to the liberalization of the electrical energy market. The Unified Power Flow Controller (UPFC) is one of the most versatile topologies of the FACTS family. The UPFC can be decomposed in two different power circuits: the parallel one maintaining the network bus voltage by consuming or producing reactive power, and the series one controlling the active and reactive power flow with the insertion of a series voltage in the transmission line. The aim of the present paper is to investigate in details the power quality and the dynamic performance of the 3-level UPFC.

	Operation of the 15 MVA System-Tie Frequency Converter at Nuernberg after relocation By A. Effenberger; H. Weiss	[View] [Download]
Abstract: In 1994 the first static system tie frequency converter of the German Railways went into operation at Muldenstein but was relocated to Nuernberg in 1996/1997. It is a 3-level GTO converter capable of transfering 15MVA rated apparent power from the 50 Hz mains to the 16.7 Hz railway supply line or into the other direction. Since 1997 this GTO converter is again feeding the local railway supply in a very demanding operation. Special attention was given to the transient operation e.g. at line short circuits. Improvements in the control system have been accomplished, a diagnosis system was added.

	State-Space Calculation of Systems w. Controlled Compensation Devices By C. Weindl; G. Herold	[View] [Download]
Abstract: In this paper a new calculation method for current converters and SVC is further generalized to systems including thyristor controlled compensation devices. The entire system is represented in complex space-phasor networks for two exemplarily switching states. The resulting state-space description considers the eigenvalues and switching sequence of the complete network structure. The respective linear independent circuits are coupled into a linear inhomogeneous boundary value problem which is analytically solved as a whole. The presented analytic solution holds for all thyristor controlled compensation devices in all operating modes. Additionally the calculation method is independent to the size of the investigated network.

	UPFC modelisation and optimal location in applications in networks By S. Dupuis; M. Crappe; J. Trécat	[View] [Download]
Abstract: This paper studies UPFC with Eurostag software simulations. Eurostag UPFC modelling is presented and compared with UPFC modellings found in literature. Influence of UPFC location is investigated in the IEEE 14 bus test system further than in paper [1] and is analysed in network with power flow regulation.

	UPFC with matrix converters By R. Strzelecki; A. Noculak; H. Tunia; K. P. Sozañski; Z. Fedyczak	[View] [Download]
Abstract: This paper describes unified power flow controllers (UPFC) with matrix converter. The basic problems of UPFC are discussed. The main aim of this paper is to present selected results of the analyses of the new UPFC based on matrix converter. This paper describes models of matrix converters and control rules for UPFC. Some results of simulation research are also presented in the paper.

	Using SVC for voltage regulation in railways network. HVB EC project By S. Bacha; I. Etxeberria; M. Crappe; S. Fahe; Z. A. Styczynski; C. Courtois; A. Talibart; M. Fracchia; M. Stuart; T. Consani; E. Merli; P. Borgignon	[View] [Download]
Abstract: This paper deals with a high voltage (25kV) booster for railways based on SVC topology. The aim is to obtain a fast response for voltage drop compensation (substation transformer and catenary) against deep variation of power consumption taking into account the railway specifications. Results of studies are made in the scope of a joint project funded by the European Commission (DG XII) under the Fifth PCRD program.

	Voltage Sags Compensation with Minimum Energy Injection by Use of By S. Polmai; T. Ise; S. Kumagai	[View] [Download]
Abstract: This paper presents a method to compensate voltage sag with minimum energy injection for a series connected voltage compensator by use of a micro-SMES. A simple method for detecting the fundamental positive sequence components from sag voltage and a minimum energy injection algorithm are described. Simulations of voltage sag compensation were carried out using PSCAD/EMTDC. The simulation results confirm the validity of the proposed method and show the possibility to reduce the size of energy storage device.