基于阻抗模型的并网变流器低频振荡机理研究
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摘要
近年来世界范围内发生了多起新能源并网低频振荡现象。为揭示低频振荡机理,以弱电网条件下并网变流器为研究对象,根据阻抗理论,分别建立了dq坐标系下并网变流器常用的2种控制方式单电流环控制和电压电流双环控制的小信号阻抗模型,在此基础上给出了2种控制模式下的并网变流器低频导纳特性,分析了电流环与电压环PI参数对并网变流器低频振荡特性的影响,得到影响低频振荡的主要因素;对多台变流器分布式并联运行振荡特性进行分析,给出了弱电网与并网变流器以及并网变流器之间的交互特性。最后通过仿真和实验验证了所得结论的正确性,能够实现并网电流低频振荡现象可受控的复现与抑制。
Low frequency oscillations are presented in grid-connected renewable systems worldwide. In order to reveal the mechanism of low frequency oscillation, this paper takes the grid-connected converter under weak grid condition as an example. According to impedance theory, small signal impedance models with two control modes, i.e. single current loop control and voltage and current double loop control, commonly implemented in d-q coordinate system, are established respectively. On this basis, the low frequency characteristics of grid-connected converter under two control modes are given. The influence of PI parameters of current loop and voltage loop on low frequency oscillation characteristics of grid-connected converter is analyzed, and the main factors affecting low frequency oscillation are obtained. On this basis, the oscillation characteristics of multiple converters in distributed parallel operation are analyzed, and the interaction characteristics among weak grid and multiple converters are given. Finally, correctness of the conclusions is verified with simulation and experiment, where low frequency oscillations are controlled to appear and be suppressed.
Low frequency oscillations are presented in grid-connected renewable systems worldwide. In order to reveal the mechanism of low frequency oscillation, this paper takes the grid-connected converter under weak grid condition as an example. According to impedance theory, small signal impedance models with two control modes, i.e. single current loop control and voltage and current double loop control, commonly implemented in d-q coordinate system, are established respectively. On this basis, the low frequency characteristics of grid-connected converter under two control modes are given. The influence of PI parameters of current loop and voltage loop on low frequency oscillation characteristics of grid-connected converter is analyzed, and the main factors affecting low frequency oscillation are obtained. On this basis, the oscillation characteristics of multiple converters in distributed parallel operation are analyzed, and the interaction characteristics among weak grid and multiple converters are given. Finally, correctness of the conclusions is verified with simulation and experiment, where low frequency oscillations are controlled to appear and be suppressed.
引文
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[14]毕天姝,孔永乐,肖仕武,等.大规模风电外送中的次同步振荡问题[J].电力科学与技术学报,2012,27(1):10-15.Bi Tianshu,Kong Yongle,Xiao Shiwu,et al.Review of sub-synchronous oscillation with large-scale wind power transmission[J].Journal of Electric Power Science and Technology,2012,27(1):10-15(in Chinese).
[15]余希瑞,周林,郭珂,等.含新能源发电接入的电力系统低频振荡阻尼控制研究综述[J].中国电机工程学报,2017,37(21):6278-6290.Yu Xirui,Zhou Lin,Guo Ke,et al.A survey on low frequency oscillation damping control in power system integrated with new energy power generation[J].Proceedings of CSEE,2017,37(21):6278-6290(in Chinese).
[16]胡海涛,何正友,钱澄浩,等.基于模态分析的全并联AT网动态谐波谐振研究[J].电网技术,2012,36(1):163-169.Hu Haitao,He Zhengyou,Qian Chenghao,et al.Modal analysis based research on dynamic harmonic resonance of all-parallel autotransformer traction supply network[J].Power System Technology,2012,36(1):163-169(in Chinese).
[17]宋墩文,杨学涛,丁巧林,等.大规模互联电网低频振荡分析与控制方法综述[J].电网技术,2011,35(10):22-28.Song Dunwen,Yang Xuetao,Ding Qiaolin,et al.A survey analysis on low frequency oscillation in large-scale interconnected power grid and its control methods[J].Power System Technology,2011,35(10):22-28(in Chinese).
[18]辛焕海,李子恒,董炜,等.三相变流器并网系统的广义阻抗及稳定判据[J].中国电机工程学报,2017,37(5):1277-1292.Xin Huanhai,Li Ziheng,Dong Wei,et al.Generalized-impedance and stability criterion for grid-connected converters[J].Proceedings of the CSEE,2017,37(5):1277-1292(in Chinese).
[19]周毅,胡海涛,杨孝伟,等.电气化铁路车网耦合系统低频振荡分析[J].中国电机工程学报,2017,37(S1):72-80.Zhou Yi,Hu Haitao,Yang Xiaowei,et al.Analysis of low-frequency oscillation in train-traction network coupling system of electrified railway[J].Proceedings of the CSEE,2017,37(S1):72-80(in Chinese).
[20]陶海东,胡海涛,姜晓峰,等.牵引供电低频网压振荡影响规律研究[J].电网技术,2016,40(6):1830-1838.Tao Haidong,Hu Haitao,Jiang Xiaofeng,et al.Research on low frequency voltage oscillation in traction power supply system and its affecting factors[J].Power System Technology,2016,40(6):1830-1838(in Chinese).
[21]朱晓娟,胡海涛,陶海东,等.光伏并网系统的谐波不稳定产生机理及影响规律[J].电工技术学报,2017,32(10):33-41.Zhu Xiaojuan,Hu Haitao,Tao Haidong,et al.The mechanism and influence of harmonic instability for photovoltaic grid-connected system[J].Transactions of China Electrotechnical Society,2017,32(10):33-41(in Chinese).
[22]胡海涛,何正友,王江峰,等.基于车网耦合的高速铁路牵引网潮流计算[J].中国电机工程学报,2012,32(19):101-108.Hu Haitao,He Zhengyou,Wang Jiangfeng,et al.Power flow calculation of high-speed railway traction network based on train-network coupling systems[J].Proceedings of the CSEE,2012,32(19):101-108(in Chinese).
[23]王晖,吴命利.牵引网低频振荡及其抑制方法的仿真分析[J].电网技术,2015,39(4):1088-1095.Wang Hui,Wu Mingli.Simulation analysis on low-frequency oscillation in traction power supply system and its suppression method[J].Power System Technology,2015,39(4):1088-1095(in Chinese).
[24]IEEE Standard 1204-199.IEEE guide for planning DC links termination at AC locations having low short-circuit capacities[S].IEEE,1997.
[25]佟强,张东来,徐殿国,等.分布式电源系统中变换器的输出阻抗与稳定性分析[J].中国电机工程学报,2011,31(12):57-64.Tong Qiang,Zhang Donglai,Xu Dianguo,et al.Output impedance and stability analysis of converters in distributed power systems[J].Proceedings of the CSEE,2011,31(12):57-64(in Chinese).
[26]张兴,张崇巍.PWM整流器及其控制[M].北京:机械工业出版社,2012:255.
[2]Timbus,Liserre M,Teodorescu R,et al.Evaluation of current controllers for distributed power generation systems[J].IEEETransactions on Power Electronics,2009,24(3):654-664.
[3]李泽斌,罗安,田园,等.LCL型光伏并网逆变器电流内环控制方法[J].电网技术,2014,38(10):2772-2778.Li Zebin,Luo An,Tian Yuan,et al.Inner current loop control method for photovoltaic grid-connected inverter with LCL filter[J].Power System Technology,2014,38(10):2772-2778(in Chinese).
[4]曾正,赵荣祥,杨欢,等.多功能并网逆变器及其在微电网电能质量定制中的应用[J].电网技术,2013,36(5):58-67.Zeng Zheng,Zhao Rongxiang,Yang Huan,et al.A multi-functional grid-connected inverter and its application to customized power quality of microgrid[J].Power System Technology,2013,36(5):58-67(in Chinese).
[5]Huang Y H,Wang D,Shang L,et al.Modeling and stability analysis of dc-link voltage control in multi-VSCs with integrated to weak grid[J].IEEE Transaction on Energy Conversion,2017,32(3):1127-1138.
[6]聂程,雷万钧,王跃,等.多变流器并联时谐振特性及最优虚拟阻尼方法[J].中国电机工程学报,2017,37(5):1467-1477.Nie Cheng,Lei Wanjun,Wang Yue,et al.Resonance analysis of multi-paralleled converter systems and research on optimal virtual resistor damping methods[J].Proceedings of CSEE,2017,37(5):1467-1477(in Chinese).
[7]胡伟,孙建军,马谦,等.多个并网逆变器间的交互影响分析[J].电网技术,2014,38(9):2511-2518.Hu Wei,Sun Jianjun,Ma Qian,et al.Analysis on interactive influence among multi grid-connected inverters[J].Power System Technology,2014,38(9):2511-2518(in Chinese).
[8]高家元,赵晋斌,陈晓博,等.弱电网条件下基于阻抗的稳定性判据重塑[J].电网技术,2017,41(9):2762-2768.Gao Jiayuan,Zhao Jinbin,Chen Xiaobo,et al.Reconstruction of impedance-based stability criteria in weak grid[J].Power System Technology,2017,41(19):2762-2768(in Chinese).
[9]吴恒,阮新波,杨东升,等.弱电网条件下锁相环对LCL型并网逆变器稳定性的影响研究及锁相环参数设计[J].中国电机工程学报,2014,34(30):5259-5268.Wu Heng,Ruan Xinbo,Yang Dongsheng,et al.Research on the stability caused by phase-locked loop for LCL-type grid-connected inverter in weak grid condition[J].Proceedings of CSEE,2014,34(30):5259-5268(in Chinese).
[10]许德志,汪飞,毛华龙,等.多并网逆变器与电网的谐波交互建模与分析[J].中国电机工程学报,2013,33(12):64-71.Xu Dezhi,Wang Fei,Mao Hualong,et al.Modeling and analysis of harmonic interaction between multiple grid-connected inverters and utility grid[J].Proceedings of the CSEE,2013,33(12):64-71(in Chinese).
[11]李小强,伍小杰,耿乙文,等.感性电网阻抗下三相光伏逆变器稳定性分析[J].中国电机工程学报,2014,34(18):2906-2916.Li Xiaoqiang,Wu Xiaojie,Geng Yiwen,et al.Stability analysis of three-phase PV inverter under inductive grid impedance condition[J].Proceedings of CSEE,2014,34(18):2906-2916(in Chinese).
[12]薛禹胜.综合防御由偶然故障演化为电力灾难--北美“8.14”大停电的警示[J].电力系统自动化,2003,27(18):1-5.Xue Yusheng.Comprehensive defense evolved from accidental failure to power disaster-warning of“8/14”blackout in North America[J].Automation of Electric Power Systems,2003,27(18):1-5(in Chinese).
[13]梁志飞,肖鸣,张昆,等.南方电网低频振荡控制策略探讨[J].电力系统自动化,2011,35(16):54-58.Liang Zhifei,Xiao Ming,Zhang Kun,et al.Discussion on control strategy of low frequency oscillation in Southern Power Grid[J].Automation of Electric Power Systems,2011,35(16):54-58(in Chinese).
[14]毕天姝,孔永乐,肖仕武,等.大规模风电外送中的次同步振荡问题[J].电力科学与技术学报,2012,27(1):10-15.Bi Tianshu,Kong Yongle,Xiao Shiwu,et al.Review of sub-synchronous oscillation with large-scale wind power transmission[J].Journal of Electric Power Science and Technology,2012,27(1):10-15(in Chinese).
[15]余希瑞,周林,郭珂,等.含新能源发电接入的电力系统低频振荡阻尼控制研究综述[J].中国电机工程学报,2017,37(21):6278-6290.Yu Xirui,Zhou Lin,Guo Ke,et al.A survey on low frequency oscillation damping control in power system integrated with new energy power generation[J].Proceedings of CSEE,2017,37(21):6278-6290(in Chinese).
[16]胡海涛,何正友,钱澄浩,等.基于模态分析的全并联AT网动态谐波谐振研究[J].电网技术,2012,36(1):163-169.Hu Haitao,He Zhengyou,Qian Chenghao,et al.Modal analysis based research on dynamic harmonic resonance of all-parallel autotransformer traction supply network[J].Power System Technology,2012,36(1):163-169(in Chinese).
[17]宋墩文,杨学涛,丁巧林,等.大规模互联电网低频振荡分析与控制方法综述[J].电网技术,2011,35(10):22-28.Song Dunwen,Yang Xuetao,Ding Qiaolin,et al.A survey analysis on low frequency oscillation in large-scale interconnected power grid and its control methods[J].Power System Technology,2011,35(10):22-28(in Chinese).
[18]辛焕海,李子恒,董炜,等.三相变流器并网系统的广义阻抗及稳定判据[J].中国电机工程学报,2017,37(5):1277-1292.Xin Huanhai,Li Ziheng,Dong Wei,et al.Generalized-impedance and stability criterion for grid-connected converters[J].Proceedings of the CSEE,2017,37(5):1277-1292(in Chinese).
[19]周毅,胡海涛,杨孝伟,等.电气化铁路车网耦合系统低频振荡分析[J].中国电机工程学报,2017,37(S1):72-80.Zhou Yi,Hu Haitao,Yang Xiaowei,et al.Analysis of low-frequency oscillation in train-traction network coupling system of electrified railway[J].Proceedings of the CSEE,2017,37(S1):72-80(in Chinese).
[20]陶海东,胡海涛,姜晓峰,等.牵引供电低频网压振荡影响规律研究[J].电网技术,2016,40(6):1830-1838.Tao Haidong,Hu Haitao,Jiang Xiaofeng,et al.Research on low frequency voltage oscillation in traction power supply system and its affecting factors[J].Power System Technology,2016,40(6):1830-1838(in Chinese).
[21]朱晓娟,胡海涛,陶海东,等.光伏并网系统的谐波不稳定产生机理及影响规律[J].电工技术学报,2017,32(10):33-41.Zhu Xiaojuan,Hu Haitao,Tao Haidong,et al.The mechanism and influence of harmonic instability for photovoltaic grid-connected system[J].Transactions of China Electrotechnical Society,2017,32(10):33-41(in Chinese).
[22]胡海涛,何正友,王江峰,等.基于车网耦合的高速铁路牵引网潮流计算[J].中国电机工程学报,2012,32(19):101-108.Hu Haitao,He Zhengyou,Wang Jiangfeng,et al.Power flow calculation of high-speed railway traction network based on train-network coupling systems[J].Proceedings of the CSEE,2012,32(19):101-108(in Chinese).
[23]王晖,吴命利.牵引网低频振荡及其抑制方法的仿真分析[J].电网技术,2015,39(4):1088-1095.Wang Hui,Wu Mingli.Simulation analysis on low-frequency oscillation in traction power supply system and its suppression method[J].Power System Technology,2015,39(4):1088-1095(in Chinese).
[24]IEEE Standard 1204-199.IEEE guide for planning DC links termination at AC locations having low short-circuit capacities[S].IEEE,1997.
[25]佟强,张东来,徐殿国,等.分布式电源系统中变换器的输出阻抗与稳定性分析[J].中国电机工程学报,2011,31(12):57-64.Tong Qiang,Zhang Donglai,Xu Dianguo,et al.Output impedance and stability analysis of converters in distributed power systems[J].Proceedings of the CSEE,2011,31(12):57-64(in Chinese).
[26]张兴,张崇巍.PWM整流器及其控制[M].北京:机械工业出版社,2012:255.