微网中载波移相并联变流器环流抑制
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摘要
PWM变流器载波移相并联可以增大系统容量,减小入网电流谐波,但存在环流问题。首先分析了三相PWM变流器环流的等效数学模型,讨论了零序环流(ZSCC)产生原因。对零序电压注入式SVPWM调制算法所产生的环流进行傅里叶分析,针对零序环流的直流分量和3、9、15次谐波分量,提出一种基于准比例谐振(QPR)和比例积分(PI)结合的零序环流抑制方法,对4个模块并联的变流器环流抑制方法仿真。搭建了实际微网系统并进行了并网和离网实验。仿真和实验结果表明该策略可以有效地减小入网电流谐波和环流。
Parallel PWM converters with carrier phase shifting can increase system capacity, reduce current harmonics into the grid, whereas lead to the problem of circulating current. Consequently, we established and analyzed the equivalent and average mathematic models of the zero-sequence circulating current(ZSCC). Based on space vector pulse width modulation(SVPWM) of zero sequence injecting to sinusoidal pulse width modulation(SPWM), the frequency characteristics and mathematic expression of ZSCC were researched. Aiming to reduce the dc and 3, 9 and 15 harmonic components of ZSCC, we proposed a suppression method for the ZSCC based on QPR and PI, and simulated ZSCC for a converter which consists of 4 parallel modules. A microgrid platform was built to perform experiments of grid-connected mode and island mode. Results indicate that the control strategy is effective in reducing harmonic current and ZSCC.
Parallel PWM converters with carrier phase shifting can increase system capacity, reduce current harmonics into the grid, whereas lead to the problem of circulating current. Consequently, we established and analyzed the equivalent and average mathematic models of the zero-sequence circulating current(ZSCC). Based on space vector pulse width modulation(SVPWM) of zero sequence injecting to sinusoidal pulse width modulation(SPWM), the frequency characteristics and mathematic expression of ZSCC were researched. Aiming to reduce the dc and 3, 9 and 15 harmonic components of ZSCC, we proposed a suppression method for the ZSCC based on QPR and PI, and simulated ZSCC for a converter which consists of 4 parallel modules. A microgrid platform was built to perform experiments of grid-connected mode and island mode. Results indicate that the control strategy is effective in reducing harmonic current and ZSCC.
引文
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[14]李凯,郑宏,马兰,等.基于有效零矢量脉宽调制和PR控制的并联零序环流抑制[J].电力系统自动化,2015,39(15):126-131.LI Kai, ZHENG Hong, MA Lan, et al. Zero-sequence circulating cur-rent inhibition of paralleled inverters based on active zero state PWMandPRcontrol[J].AutomationofElectricPowerSystems,2015,39(15):126-131.
[15]苑宾,许建中,赵成勇,等.模块化多电平换流器PR环流抑制器优化设计[J].中国电机工程学报,2015,35(10):2567-2575.YUAN Bin, XU Jianzhong, ZHAO Chengyong, et al. Optimal designofPRcirculatingcurrentsuppressingcontrollersformodularmulti-levelconverters[J].ProceedingsoftheCSEE,2015,35(10):2567-2575.
[16]MILLER S K T, BEECHNER T, SUN J. A comprehensive study ofharmoniccancellationeffectsininterleavedthree-phaseVSCs[C]∥Power Electronic Specialists Conference. Orlando, USA:[s.n.], 2007:29-35.
[17]CHEN T. Dual-modulator compensation technique for parallel invert-ers using space-vector modulator[J]. IEEE Transactions on IndustrialElectronics, 2009, 56(8):3004-3012.
[18]熊健,康勇.电压空间矢量调制与常规SPWM的比较研究[J].电力电子技术,1999,33(1):25-28.XIONG Jian, KANG Yong, Comparison study of voltage space vectorPWMandconventionalSPWM[J].PowerElectronics,1999,33(1):25-28.
[19]程启明,褚思远,程尹曼,等.Z源三电平并网逆变器的准PR控制系统[J].高电压技术,2016,42(10):3075-3082.CHENG Qiming, ZHU Siyuan, CHENG Yinman, et al. Quasi-PR con-trolsystemofgrid-connectedZ-sourcethree-levelinverter[J].HighVoltage Engineering, 2016, 42(10):3075-3082.
[20]YEPES A G, FREIJEDO F D, DOVAL-GANDOY J, et al. Effects ofdiscretization methods on the performance of resonant controllers[J].IEEE Transactions on Power Electronics, 2010, 25(7):1692-1712.
[21]张辉,宋琼,魏亚龙,等.离网运行的多微源微网调频调压控制策略[J].高电压技术,2017,43(1):149-156.ZHANG Hui, SONG Qiong, WEI Yalong, et al. Frequency and voltageregulation control strategy of micro-grid with multiple micro sourcesunderislandmode[J].HighVoltageEngineering,2017,43(1):149-156.
[2]韩坤,杨恩星,陈国柱.无零序环流三相PWM变流器线路级并联策略[J].电力电子技术,2009,43(3):65-67.HANKun,YANGEnxing,CHENGuozhu.Circuit-levelparallelstrategies of three phase PWM converters without zero sequence cir-culating current[J]. Power Electronics, 2009, 43(3):65-67.
[3]WEN C X, LI J L, ZHU X G, et al. Research on circulation of parallelthree-phaseconvertersinMWwindpowersystem[C]∥2008Work-shop on Power Electronic and Intelligent Transportation System. NewYork, USA:[s.n.], 2008:349-354.
[4]DIXONJW,OOIBT.Seriesandparalleloperationofhysteresiscurrent-controlled PWM rectifiers[J].IEEETransactionson IndustryApplication, 1989, 25(4):644-651.
[5]李瑞,徐殿国,徐壮,等.耦合电抗器在并联型三相并网逆变器中的应用[J].电机与控制学报,2012,16(12):7-12.LI Rui, XU Dianguo, XU Zhuang, et al. Application of interphase in-ductorforparallelthree-phasegrid-connectedinverters[J].ElectricMachines and Control, 2012, 16(12):7-12.
[6]李建林,高志刚,胡书举,等.并联背靠背PWM变流器在直驱型风力发电系统的应用[J].电力系统自动化,2008,32(5):59-62.LIJianlin,GAOZhigang,HUShuju,etal.Applicationofparallelback-to-backPWMconverteronthedirect-drivewindpowersys-tem[J]. Automation of Electric Power Systems, 2008, 32(5):59-62.
[7]YE Z H, BOROYEVICH D, CHOI J Y, et a1. Control of circulatingcurrent in two parallel three-phase boost rectifiers[J]. IEEE Transac-tions on Power Electronics, 2002, 17(5):609-615.
[8]胡维昊,王跃,姚为正,等.直驱型变速恒频风力发电系统中零序环流的研究[J].中国电机工程学报,2009,29(27):99-105.HU Weihao, WANG Yue, YAO Weizheng, et al. Zero-sequence currentindirectdrivevariable-speedconstantfrequencywindenergysys-tems[J]. Proceedings of the CSEE, 2009, 29(27):99-105.
[9]杨恩星,仇志凌,陈国柱,等.基于载波移相并联的直驱风力发电并网变流器控制策略[J].中国电机工程学报,2009,29(21):8-13.YANG Enxing, QIU Zhiling, CHEN Guozhu, et al. Control strategyfor direct-drive wind generation grid side converter based on carrierphaseshiftingparallel[J].ProceedingsoftheCSEE,2009,29(21):8-13.
[10]姜燕,王耀南,肖磊,等.直驱式永磁同步风力发电机交错并联网侧变流器环流控制策略[J].电工技术学报,2013,28(10):217-223.JIANG Yan,WANG Yaonan, XIAO Lei, et al. Control of circulatingcurrent in interleaved parallel topology of direct-drive PMSG grid-sideconverter[J]. Transactions of China Electronic Technical Society, 2013,28(10):217-223.
[11]马皓,林钊,张宁,等.逆变器并联系统开关环流的建模和分析[J].中国电机工程学报,2015,35(22):5823-5831.MA Hao, LIN Zhao, ZHANG Ning, et al. Modeling and analysis ofswitching frequency circulating currents in parallel inverter systems[J].Proceedings of the CSEE, 2015, 35(22):5823-5831.
[12]张学广,陈佳明,张文杰,等.并联三相PWM变换器零序环流带宽扩展[J].电工技术学报,2015,30(18):69-75.ZHANG Xueguang, CHEN Jiaming, ZHANG Wenjie, et al. Circulat-ing current loop bandwidth expansion for parallel three-phase PWMconverterconnectionsystem[J].TransactionsofChinaElectrotech-nical Society, 2015, 30(18):69-75.
[13]张明锐,宋柏慧,林显琦,等.直接并联模块化逆变器零序环流抑制[J].电工技术学报,2015,30(20):100-107.ZHANG Mingrui, SONG Baihui, LIN Xianqi, etal. Restraining ze-ro-sequence circulating current of directly parallel modular inverters[J].TransactionsofChinaElectronicTechnicalSociety,2015,30(20):100-107.
[14]李凯,郑宏,马兰,等.基于有效零矢量脉宽调制和PR控制的并联零序环流抑制[J].电力系统自动化,2015,39(15):126-131.LI Kai, ZHENG Hong, MA Lan, et al. Zero-sequence circulating cur-rent inhibition of paralleled inverters based on active zero state PWMandPRcontrol[J].AutomationofElectricPowerSystems,2015,39(15):126-131.
[15]苑宾,许建中,赵成勇,等.模块化多电平换流器PR环流抑制器优化设计[J].中国电机工程学报,2015,35(10):2567-2575.YUAN Bin, XU Jianzhong, ZHAO Chengyong, et al. Optimal designofPRcirculatingcurrentsuppressingcontrollersformodularmulti-levelconverters[J].ProceedingsoftheCSEE,2015,35(10):2567-2575.
[16]MILLER S K T, BEECHNER T, SUN J. A comprehensive study ofharmoniccancellationeffectsininterleavedthree-phaseVSCs[C]∥Power Electronic Specialists Conference. Orlando, USA:[s.n.], 2007:29-35.
[17]CHEN T. Dual-modulator compensation technique for parallel invert-ers using space-vector modulator[J]. IEEE Transactions on IndustrialElectronics, 2009, 56(8):3004-3012.
[18]熊健,康勇.电压空间矢量调制与常规SPWM的比较研究[J].电力电子技术,1999,33(1):25-28.XIONG Jian, KANG Yong, Comparison study of voltage space vectorPWMandconventionalSPWM[J].PowerElectronics,1999,33(1):25-28.
[19]程启明,褚思远,程尹曼,等.Z源三电平并网逆变器的准PR控制系统[J].高电压技术,2016,42(10):3075-3082.CHENG Qiming, ZHU Siyuan, CHENG Yinman, et al. Quasi-PR con-trolsystemofgrid-connectedZ-sourcethree-levelinverter[J].HighVoltage Engineering, 2016, 42(10):3075-3082.
[20]YEPES A G, FREIJEDO F D, DOVAL-GANDOY J, et al. Effects ofdiscretization methods on the performance of resonant controllers[J].IEEE Transactions on Power Electronics, 2010, 25(7):1692-1712.
[21]张辉,宋琼,魏亚龙,等.离网运行的多微源微网调频调压控制策略[J].高电压技术,2017,43(1):149-156.ZHANG Hui, SONG Qiong, WEI Yalong, et al. Frequency and voltageregulation control strategy of micro-grid with multiple micro sourcesunderislandmode[J].HighVoltageEngineering,2017,43(1):149-156.