EMTP Simulation Of An Active Filter Operating With Weak AC Distribution System Rachit Arora PDF
Preview EMTP Simulation Of An Active Filter Operating With Weak AC Distribution System Rachit Arora
EMTP Simulation Of An Active Filter Operating With Weak AC Distribution System Rachit Arora in The Department of Electrical and Cornputer Engineering Presented in Partiai FuifilIrnent of the Requirements for the Degree of Master of Applied Science at Concordi a Univeni ty Montreal, Canada January 1999 @ Rachit Arora, 1999 Be511 National Library Bibfiothèque nationale of Canada du Canada Acquisitions and Acquisitions et Bibliographie Services services bibliographiques 395 Wellington Street 395, rue Wellington Ottawa ON KI A ON4 Ottawa ON KtA ON4 Canada Canada The author has granted a non- L'auteur a accordé une licence non exclusive licence allowing the exclusive permettant à la National Librw of Canada to Bibliothèque nationale du Canada de reproduce, han, disûiiute or seil reproduire, prêter, distribuer ou copies of this thesis in rnicroform, vendre des copies de cette thése sous paper or electronic formats. la forme de rnicrofiche/film, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial emcts fiom it Ni la thèse ni des extraits substantiels may be printed or otherwise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation. Abstract EMTP Simulation Of An Active Filter Operating With A Weak AC Distribution System Rachit Arora An AC distribution system has a myriad of loads connected at the system bus. Many of the DC based loads cause disturbance on the ac bus due to high harmonic load currents. Traditionally passive filters are used for filtering these load harmonies. Recent technologicai advances have enabled the use of high frequency switching devices in the development of active filtenng techniques. In this thesis, an active filter topology was selected for the system, and a test sys- tem was modeled using EMTP. The objective of active filtering is to meet the harmonic and reactive load locally, and thus removing the harmonic content of source cunents. The AF controller based on the on-line power computation scheme was modeled. Tracking - control was demonstrated using two control methodologies hysteresis band control and sliding mode control. A performance cornparison was made between the two control schemes, and the impact of various circuit and control parameters on the filtering performance was studied. To assess the transient perfoxmance achieved with the control schemes presented, results frorn EMV based studies for this distribution system under various AC-DC fault condi- tions are analyzed. Acknowledgrnent 1 would like to thank my supervisor, Dr. V. K. Sood for his financial support dunng my Masters research work, and appreciate his valuable advice and patience with which he guided me during my delibentions. The other aspect of my stay here has been made possible in tne Company of many fnends who have been a constant support with their love, affection and presence. Thanks Meghana. Cthn~M. ahesh, Subha. ç! Pisini, Tanu & Vijq Miki. Uju. Dak- sha. Jqa. Jasjit and Sraddha for everything. 1 aiso thank al1 my colleagues at GM 905, for making the office a habitable place to stay late hours. The assistance of Department secretaries and Computing Services is appreciated. 1 also owe my ,ptitude to Dr. B. N. Singh and Dr. A. Chandra of the ETS for assisting me in technical clarifications. My parents and my sister, Ruchi were always a source of encouragement and mon1 support. 1 dedicate this work to them. Dedicated to my parents and my sister Ruchi CONTENTS Page List of Figures ................................................................................................. viii List of Tables ................................................................................................... X Cha~ter1 : Introduction ................................. ............................................. ,. Effect of Harmonics ...................................................................... Passive AC Filters ......................................................................... ProbIem Definition ....................................................................... Li terature Su rvey .......................................................................... ....................................................................... Proposed Approac h Thesis Outiine ....................................... ........ , .................................................................... Chapter 2: Sy stem Configuration 2.1 Introduction ................................................................................... 1.2 ActiveFilters ................................................................................. .................................................. 7.3 Active Filter Topology Selection ............................................................................... 7.4 System Mode1 7.5 Summafy ....................................................................................... Chapter 3: Control Circuits ........................................................................... 24 ................................................................................... 3.1 Introduction 34 3.3 Rectifier Control Unit ................................................................... 24 3.3 AF Control Unit ............................................................................ 25 3.3.1 On-line Power Computation Scheme (Feedforward Control) 17 3.3.2 Tracking Control (Feedback Control) ............................ 35 3.3 2.1 Hysteresis Control ........................ .. ............ 35 3.3 .3 .2 Sl iding-Mode Control ..................................... 49 ........................................................................................ 3.4 Surnmary Chapter 4: Transient Behavior of the Active Filter Mode1 .............................. ................................................................................... 4.1 Introduction 4.2 System Tests ............................................................................... 4.3 Initialization Tests ......................................................................... 4.3.1 Initialization of Rectifier Control Unit ........................... 4.3.2 Initidization of AF Control Unit .........................,,......... .... 4.3.3 Cornpaison of Hysteresis and Sliding-Mode Control ....................................................... 4.3.4 Harmonic Analysis 1.4 Dynamics Tests ................................................................*............. ........... 4.4.1 Step change of 30% in DC current reference, IRr 4.4.3 Fault Tests ....................................................................... 4.4.3.1 Single Phase Solid Line to Ground 3-cycle Fault at AC Bus (Commutation Failure Test) 1.1.2.2 Single Phase Line to Ground 3-cycle Fauit at AC bus (with fault impedance) 4.4.2.3 Line to Line 3-cycle Fault at AC bus (phases A. B) 3.4.2.4 Three Phase Solid Line to Ground Fault at AC bus (Phases AJ3.C) 4.1.2.5 DC 6-cycle Fault at Rectifier load end ............ ........................................................................................ 4.5 Summary ............................................................................... Chapter 5: Conclusions References ....................................................................................................... ..................................................................................................... Appendix A Appendix B .................................................................................................. ..................................................................................................... Appendix C vii List of Figures Page ..................... Harmonic Elimination by magnetic compensation Active Filter Topologies ............................................................. System Mode1 ............................................................................. High Pass Filter ........................................................................... Converter Unit .............................................. .............................. Voltage Source Inverter Unit ...................................................... Rectifier Control Unit ................................................................. System Modei ............................................................................ AF ControI Unit ............................... ........ ................................... AF Control Unit Schematic ........................................................ .................. Simulation of On-line Power Computation Scheme Hysteresis Controller implementation ..................................... Simulation of Hysteresis Controller ......................................... ............................................ Variation of Hysteresis Bandwidth ......................... Effect of variation of Hysteresis Bandwidth. hb Variation of L, ..................... . .................................................... Effect of variation of Lc ......................... ............. ...................... Effect of variation of Vdc ............................................................ Sl iding-Mode Controller implementation ................... ........ ..... ..................................... Simulation of Sliding-Mode convoller Vanation of decision frequency ................................ ..... .......... Effect of variation of decision frequency ................................. ... Variation with Lc ............................................... .................. Effect O. variation of Lc ............................ .. .......................... viii Effect of Vdc v"ation ................................................................ Initialization of Rectifier Unit ........................................ ............. Active Filter Initialization - Hysteresis control ........................... Active Filter Initialization - Sliding-Mode Control .................... Hysteresis Controller .t ransient response ................................... Sliding-Mode Controller .t ransient response ............................. Hysteresis Controller .S ingle phase fault at AC bus .................. Sliding-Mode Controllrr .S ingle phase fault at AC bus ............ Hysteresis Controller .S ingle phase fault (50%)a t .4 C bus ...... Sliding-Mode Controller .S ingle phase fault (50%) at AC bus Hysteresis Controller .L ine-Line fault at AC bus (ph . A-B) ..... Sliding-Mode Controller .L ine-Line fault at AC bus (ph .A -B) Hysteresis Controller .3 phase L-G fault at AC bus .................. Sliding-Mode Controller .3 phase L-Gf ault at AC bus ............ Hysteresis Controller .F ault at DC load .............*...................... Sliding-Mode Controller .F ault ût DC load ..........................*..** zndo rder high pass filter ............................................................ Single phase equivalent circuit ................................................... Wave-shaping of if, in hysteresis band ....................................... List of Tables Page ........................................ Variation of hysteresis bandwidth. hb 39 Vanation of Connection inductance. L, ...................................... 4 1-42 ................................................ Viuiation of DC bus voltage. Vdc 45 Variation of decision frequency. fd ............................................ 53 . Variation of Connection inductance Lc ...................................... 55-56 Variation of DC bus voltage. Vdc ................................................ 58 Harmonic Analyses (without AF compensation) ........................ 71 ............................. Harmonic Analyses (with AF compensation) 72
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