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00648 Adaptive decentralized load frequency control of multi-area power systems
06 Electrical power supply and utilization (scientific, technical) shed have been accounted. For the purpose of optimization, Hopfield m o d e l in its modified form has been employed. This gives easy c o m p u t a t i o n a l sequence. The developed algorithm has been tested rigorously on 91 bus Indian practical power system.
06•00647 rectifiers
A unified and simple model for uncontrolled
Herraiz, S. et al. Electric Power Systems Research, 2005, 74, (3), 331 340. A simple m o d e l for uncontrolled rectifiers with capacitive filter working in discontinuous current m o d e is developed in this paper. The p r e s e n t e d model allows the rectifier ac line current harmonics to be obtained in an easy way. Previously, both the width and the peak value of the ac current pulse are calculated by means of analytical equations. This model is obtained w h e n the rectifier working point is defined by dc current consumption or dc power consumption. In the first case, the expressions of the width and p e a k value are analytical, whereas in the second case they are non-linear; thus, an iterative algorithm is proposed to solve them. The rectifier behaviour is also graphically characterized in both cases from the previous equations normalization. Several examples of the proposed m o d e l application are presented. Lastly, it is exposed that the m o d e l allows harmonic current emission to be studied in an easy, friendly way, according to the present regulations for both rectifiers.
06•00648 Adaptive decentralized load frequency control of multi-area power systems Zribi, M. et al. International Journal o f Electrical Power & Energy Systems, 2005, 27, (8), 575 583. This paper addresses the load frequency control problem of multi-area power systems. A decentralized adaptive control scheme is designed; the control scheme g u a r a n t e e s that the fluctuations of the load frequency converge to a range, which can be m a d e very small. Simulation results for a t h r e e - a r e a power system are given to illustrate the developed theoretical results. The simulation results indicate that the proposed control scheme works well and it is robust to changes in the p a r a m e t e r s of the power systems and to b o u n d e d disturbances acting on the systems.
06•00649 An optimization technique of robust load frequency stabilizer for superconducting magnetic energy storage Ngamroo, I. Energy Conversion and Management, 2005, 46, (18 19), 3060 3090. As an interconnected power system is subjected to rapid load disturbances with changing frequencies in the vicinity of the inter-area oscillation mode, a system frequency may be heavily disturbed and oscillate. U n d e r the circumstances, the stabilizing effect of the conventional load frequency control (LFC), i.e. a governor, cannot be expected. To c o m p e n s a t e for such load disturbances and stabilize frequency oscillations, the active power controlled by superconducting magnetic energy storage (SMES) can be applied. In this paper, a new optimization technique of a robust load frequency stabilizer equipped with SMES is presented. To enhance the robustness of the load frequency stabilizer against system uncertainties such as various load changes, system p a r a m e t e r s variations etc., the multiplicative uncertainty is included in the system modelling. As a result, the robust stability of the stabilized system can be easily g u a r a n t e e d in terms of the multiplicative stability margin (MSM). The configuration of the load frequency stabilizer is practically based on a second order lead/lag c o m p e n s a t o r with a single feedback input. The control p a r a m e t e r s are automatically optimized by a tabu search algorithm, so that the desired d a m p i n g ratio of the target inter-area mode and the best MSM are achieved. The simulation study exhibits the high robustness of the load frequency stabilizer against uncertainties. Moreover, a SMES unit requires small power capacity for frequency stabilization.
06•00650 Analysis of the dynamic response improvement of a turbocharged diesel engine driven alternating current generating set Katra~nik, T. et al. Energy Conversion and Management, 2005, 46, (18 19), 2838 2855. Reliability of electric supply systems is a m o n g the most required necessities of m o d e r n society. T u r b o c h a r g e d diesel engine driven alternating current generating sets are often used to prevent electric black outs and/or as prime electric energy suppliers. It is well known that turbocharged diesel engines suffer from an i n a d e q u a t e response to a sudden load increase, this being a consequence of the nature of the energy exchange between the engine and the turbocharger. The dynamic response of t u r b o c h a r g e d diesel engines could be improved by electric assisting systems, either by direct energy supply with an i n t e g r a t e d starter g e n e r a t o r ~ o o s t e r (ISG) m o u n t e d on the engine flywheel, or by an indirect energy supply with an electrically assisted turbocharger. A n experimentally verified zero d i m e n s i o n a l computer simulation m e t h o d was used for the analysis of both types of electrical
assistance. The p a p e r offers an analysis of the interaction between a turbocharged diesel engine and different electric assisting systems, as well as the r e q u i r e m e n t s for the supporting electric motors that could improve the dynamic response of a diesel engine while driving an A C generating set. W h e n performance class compliance is a concern, it is evident that an i n t e g r a t e d starter g e n e r a t o r ~ o o s t e r outperforms an electrically assisted turbocharger for the investigated g e n e r a t i n g set. However, the electric energy c o n s u m p t i o n and frequency recovery times are smaller w h e n an electrically assisted turbocharger is applied.
06/00651 Application of the normal forms to analyse the interactions among the multi-control channels of UPFC Zou, Z. Y. et al. International Journal o f Electrical Power & Energy Systems, 2005, 27, (8), 584 593. One of the most i m p o r t a n t features of the unified power flow controller ( U P F C ) is its multiple control functions, which are i m p l e m e n t e d by multiple controllers. However, recent simulation studies have d e m o n s t r a t e d the existence of the dynamic interactions a m o n g different controller channels of UPFC, i.e. power flow controller, A C voltage controller and DC voltage controller. This paper is concerned with the application of the n o r m a l forms to analyse the interactions a m o n g the multi-controller channels of U P F C in power systems. Moreover, a non-linear interaction index is developed to investigate the interactions a m o n g these U P F C controllers. The employed approach has been applied to two test systems: a single machine infinite bus power system (SMIB) and the New E n g l a n d test power system (NETPS). The simulation results validate the proposed approach.
06•00652 Determination of PSS location based on singular value decomposition Karimpour, A. et al. hTternational Journal o f Electrical Power & Energy Systems, 2005, 27, (8), 535 541. In a multi-machine power system, it is i m p o r t a n t to d e t e r m i n e the best location for the application of power system stabilizers. A technique based on singular value decomposition to identify generators that contribute in each oscillation m o d e is introduced. M e a s u r e s based on singular value decomposition for controllability and observability for every mode are described and the selection of the best location for the installation of the PSSs is done according to these measures. The proposed m e t h o d o l o g y is designed to use the system transfer function. Studies illustrate the effectiveness of the proposed technique.
06/00653 Discrete control of unified power flow controller for stability improvement Krishna, S. and Padiyar, K. R. Electric Power Systems Research, 2005, 75, (2 3), 178 189. The e m e r g i n g flexible ac transmission system (FACTS) controllers are considered to be suitable for transient stability control due to their speed and flexibility. In this paper, a control strategy is developed to achieve maximal i m p r o v e m e n t in transient stability and d a m p the rotor oscillations using unified power flow controller (UPFC). The control strategy involves maximization and minimization of power flow in a line. In general, this involves the solution of a constrained optimization problem at each step to d e t e r m i n e the voltage and current injected by the UPFC. For the special case of a loss-less symmetrical line, when the U P F C is located at the m i d p o i n t of the line, analytical solution can be derived. The control strategy can be extended to multi-machine system and maximizing and minimizing power flow on a critical line can improve transient stability. The control strategy is evaluated by simulation studies.
06/00654 Evaluation study for the integration of electromagnetic transients simulator and transient stability simulator Su, H. T. et al. Electric Power Systems Research, 2005, 75, (1), 67 78. This p a p e r is devoted to the d e v e l o p m e n t of a hybrid simulator, which integrates the electromagnetic transients ( E M T ) simulator and transient stability (TS) simulator. It discusses how two very different simulators can be coordinated to work together and produce accurate solution. A new selection approach is p r e s e n t e d to identify the interaction location for interfacing the E M T and TS simulators. P s e u d o - t r a n s i e n t caused by frequency m i s m a t c h d u r i n g the interaction is discussed with r e m e d y presented. Based on the interaction protocol proposed in the paper, case studies were performed on two test systems, 9-bus systems and 39-bus systems, to assess the performance of the integration on both E M T and TS aspects.
06/00655 Fault diagnosis of power transformer based on multi-layer SVM classifier Lv, G. et al. Electric Power Systems Research, 2005, 75, (1), 9 15. Support vector machine ( s v M ) is a novel machine learning m e t h o d based on statistical learning theory (SLT). SVM is powerful for the problem with small sampling, nonlinear and high dimension. A multilayer SVM classifier is applied to fault diagnosis of power transformer
Fuel and Energy Abstracts
March 2006
99
06•00647 rectifiers
A unified and simple model for uncontrolled
Herraiz, S. et al. Electric Power Systems Research, 2005, 74, (3), 331 340. A simple m o d e l for uncontrolled rectifiers with capacitive filter working in discontinuous current m o d e is developed in this paper. The p r e s e n t e d model allows the rectifier ac line current harmonics to be obtained in an easy way. Previously, both the width and the peak value of the ac current pulse are calculated by means of analytical equations. This model is obtained w h e n the rectifier working point is defined by dc current consumption or dc power consumption. In the first case, the expressions of the width and p e a k value are analytical, whereas in the second case they are non-linear; thus, an iterative algorithm is proposed to solve them. The rectifier behaviour is also graphically characterized in both cases from the previous equations normalization. Several examples of the proposed m o d e l application are presented. Lastly, it is exposed that the m o d e l allows harmonic current emission to be studied in an easy, friendly way, according to the present regulations for both rectifiers.
06•00648 Adaptive decentralized load frequency control of multi-area power systems Zribi, M. et al. International Journal o f Electrical Power & Energy Systems, 2005, 27, (8), 575 583. This paper addresses the load frequency control problem of multi-area power systems. A decentralized adaptive control scheme is designed; the control scheme g u a r a n t e e s that the fluctuations of the load frequency converge to a range, which can be m a d e very small. Simulation results for a t h r e e - a r e a power system are given to illustrate the developed theoretical results. The simulation results indicate that the proposed control scheme works well and it is robust to changes in the p a r a m e t e r s of the power systems and to b o u n d e d disturbances acting on the systems.
06•00649 An optimization technique of robust load frequency stabilizer for superconducting magnetic energy storage Ngamroo, I. Energy Conversion and Management, 2005, 46, (18 19), 3060 3090. As an interconnected power system is subjected to rapid load disturbances with changing frequencies in the vicinity of the inter-area oscillation mode, a system frequency may be heavily disturbed and oscillate. U n d e r the circumstances, the stabilizing effect of the conventional load frequency control (LFC), i.e. a governor, cannot be expected. To c o m p e n s a t e for such load disturbances and stabilize frequency oscillations, the active power controlled by superconducting magnetic energy storage (SMES) can be applied. In this paper, a new optimization technique of a robust load frequency stabilizer equipped with SMES is presented. To enhance the robustness of the load frequency stabilizer against system uncertainties such as various load changes, system p a r a m e t e r s variations etc., the multiplicative uncertainty is included in the system modelling. As a result, the robust stability of the stabilized system can be easily g u a r a n t e e d in terms of the multiplicative stability margin (MSM). The configuration of the load frequency stabilizer is practically based on a second order lead/lag c o m p e n s a t o r with a single feedback input. The control p a r a m e t e r s are automatically optimized by a tabu search algorithm, so that the desired d a m p i n g ratio of the target inter-area mode and the best MSM are achieved. The simulation study exhibits the high robustness of the load frequency stabilizer against uncertainties. Moreover, a SMES unit requires small power capacity for frequency stabilization.
06•00650 Analysis of the dynamic response improvement of a turbocharged diesel engine driven alternating current generating set Katra~nik, T. et al. Energy Conversion and Management, 2005, 46, (18 19), 2838 2855. Reliability of electric supply systems is a m o n g the most required necessities of m o d e r n society. T u r b o c h a r g e d diesel engine driven alternating current generating sets are often used to prevent electric black outs and/or as prime electric energy suppliers. It is well known that turbocharged diesel engines suffer from an i n a d e q u a t e response to a sudden load increase, this being a consequence of the nature of the energy exchange between the engine and the turbocharger. The dynamic response of t u r b o c h a r g e d diesel engines could be improved by electric assisting systems, either by direct energy supply with an i n t e g r a t e d starter g e n e r a t o r ~ o o s t e r (ISG) m o u n t e d on the engine flywheel, or by an indirect energy supply with an electrically assisted turbocharger. A n experimentally verified zero d i m e n s i o n a l computer simulation m e t h o d was used for the analysis of both types of electrical
assistance. The p a p e r offers an analysis of the interaction between a turbocharged diesel engine and different electric assisting systems, as well as the r e q u i r e m e n t s for the supporting electric motors that could improve the dynamic response of a diesel engine while driving an A C generating set. W h e n performance class compliance is a concern, it is evident that an i n t e g r a t e d starter g e n e r a t o r ~ o o s t e r outperforms an electrically assisted turbocharger for the investigated g e n e r a t i n g set. However, the electric energy c o n s u m p t i o n and frequency recovery times are smaller w h e n an electrically assisted turbocharger is applied.
06/00651 Application of the normal forms to analyse the interactions among the multi-control channels of UPFC Zou, Z. Y. et al. International Journal o f Electrical Power & Energy Systems, 2005, 27, (8), 584 593. One of the most i m p o r t a n t features of the unified power flow controller ( U P F C ) is its multiple control functions, which are i m p l e m e n t e d by multiple controllers. However, recent simulation studies have d e m o n s t r a t e d the existence of the dynamic interactions a m o n g different controller channels of UPFC, i.e. power flow controller, A C voltage controller and DC voltage controller. This paper is concerned with the application of the n o r m a l forms to analyse the interactions a m o n g the multi-controller channels of U P F C in power systems. Moreover, a non-linear interaction index is developed to investigate the interactions a m o n g these U P F C controllers. The employed approach has been applied to two test systems: a single machine infinite bus power system (SMIB) and the New E n g l a n d test power system (NETPS). The simulation results validate the proposed approach.
06•00652 Determination of PSS location based on singular value decomposition Karimpour, A. et al. hTternational Journal o f Electrical Power & Energy Systems, 2005, 27, (8), 535 541. In a multi-machine power system, it is i m p o r t a n t to d e t e r m i n e the best location for the application of power system stabilizers. A technique based on singular value decomposition to identify generators that contribute in each oscillation m o d e is introduced. M e a s u r e s based on singular value decomposition for controllability and observability for every mode are described and the selection of the best location for the installation of the PSSs is done according to these measures. The proposed m e t h o d o l o g y is designed to use the system transfer function. Studies illustrate the effectiveness of the proposed technique.
06/00653 Discrete control of unified power flow controller for stability improvement Krishna, S. and Padiyar, K. R. Electric Power Systems Research, 2005, 75, (2 3), 178 189. The e m e r g i n g flexible ac transmission system (FACTS) controllers are considered to be suitable for transient stability control due to their speed and flexibility. In this paper, a control strategy is developed to achieve maximal i m p r o v e m e n t in transient stability and d a m p the rotor oscillations using unified power flow controller (UPFC). The control strategy involves maximization and minimization of power flow in a line. In general, this involves the solution of a constrained optimization problem at each step to d e t e r m i n e the voltage and current injected by the UPFC. For the special case of a loss-less symmetrical line, when the U P F C is located at the m i d p o i n t of the line, analytical solution can be derived. The control strategy can be extended to multi-machine system and maximizing and minimizing power flow on a critical line can improve transient stability. The control strategy is evaluated by simulation studies.
06/00654 Evaluation study for the integration of electromagnetic transients simulator and transient stability simulator Su, H. T. et al. Electric Power Systems Research, 2005, 75, (1), 67 78. This p a p e r is devoted to the d e v e l o p m e n t of a hybrid simulator, which integrates the electromagnetic transients ( E M T ) simulator and transient stability (TS) simulator. It discusses how two very different simulators can be coordinated to work together and produce accurate solution. A new selection approach is p r e s e n t e d to identify the interaction location for interfacing the E M T and TS simulators. P s e u d o - t r a n s i e n t caused by frequency m i s m a t c h d u r i n g the interaction is discussed with r e m e d y presented. Based on the interaction protocol proposed in the paper, case studies were performed on two test systems, 9-bus systems and 39-bus systems, to assess the performance of the integration on both E M T and TS aspects.
06/00655 Fault diagnosis of power transformer based on multi-layer SVM classifier Lv, G. et al. Electric Power Systems Research, 2005, 75, (1), 9 15. Support vector machine ( s v M ) is a novel machine learning m e t h o d based on statistical learning theory (SLT). SVM is powerful for the problem with small sampling, nonlinear and high dimension. A multilayer SVM classifier is applied to fault diagnosis of power transformer
Fuel and Energy Abstracts
March 2006
99