并网变流器的频率耦合阻抗模型及其稳定性分析
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摘要
可再生能源并网系统中,如光伏、风电以及无功补偿等并网均采用电压源型变流器。变流器与交流电网之间的相互作用会引发新的振荡问题,阻抗模型分析成为研究此类问题的重要方法。多数阻抗模型往往忽略了变流器外环控制和频率耦合的影响,适用于变流器高频动态特性研究,但在分析变流器中低频动态(如次同步振荡)方面不够精确。为弥补这一缺陷,文中针对典型电压源型并网变流器提出了一种频率耦合阻抗模型,同时考虑了互补频率耦合效应和外环控制,采用详细电磁模型时域仿真与辨识验证了阻抗模型推导的正确性。进一步构建并网系统的整体阻抗模型,分析变流器并网系统的稳定性,时域仿真结果证实了所提模型在中低频率振荡分析中的有效性。
Voltage source converters are used for grid connection of photovoltaic energy,wind energy and reactive power compensation in the renewable energy generation system.An emerging kind of oscillation has been observed due to the interactions among converters and AC power grids.In this case,the impedance model analysis has become one of the most promising methods for solving this type of oscillation.However,most of the existing impedance models are focusing on the high-frequency dynamics of converter,while neglecting the impacts of converter outer-loop control and frequency coupling.Therefore,these models are inaccurate when analyzing the medium and low frequency dynamic characteristics(such as the subsynchronous oscillation)of converters.To overcome these defects,this paper proposes a frequency-coupled impedance model of voltage source converter.Both outer-loop control and complementary frequency coupling are considered in this model.And the correctness of the model derivation is verified by the time-domain simulation and identification of detailed electromagnetic model.Based on the proposed impedance model,the overall impedance model of the grid-connected system is further derived to evaluate the system stability.The time-domain simulation has also demonstrated the effectiveness of the frequency-coupled impedance model in the medium and low frequency oscillation analysis.
Voltage source converters are used for grid connection of photovoltaic energy,wind energy and reactive power compensation in the renewable energy generation system.An emerging kind of oscillation has been observed due to the interactions among converters and AC power grids.In this case,the impedance model analysis has become one of the most promising methods for solving this type of oscillation.However,most of the existing impedance models are focusing on the high-frequency dynamics of converter,while neglecting the impacts of converter outer-loop control and frequency coupling.Therefore,these models are inaccurate when analyzing the medium and low frequency dynamic characteristics(such as the subsynchronous oscillation)of converters.To overcome these defects,this paper proposes a frequency-coupled impedance model of voltage source converter.Both outer-loop control and complementary frequency coupling are considered in this model.And the correctness of the model derivation is verified by the time-domain simulation and identification of detailed electromagnetic model.Based on the proposed impedance model,the overall impedance model of the grid-connected system is further derived to evaluate the system stability.The time-domain simulation has also demonstrated the effectiveness of the frequency-coupled impedance model in the medium and low frequency oscillation analysis.
引文
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[10]严亚兵,苗淼,袁小明.新能源电站集电馈线对多变流器并网运行稳定性的影响[J].电力系统自动化,2016,40(15):86-92.DOI:10.7500/AEPS20150815006.YAN Yabing,MIAO Miao,YUAN Xiaoming.Impact of renewable power plant collector system on stability of gridconnected multi-converters[J].Automation of Electric Power Systems,2016,40(15):86-92.DOI:10.7500/AEPS20150815006.
[11]谢小荣,刘华坤,贺静波,等.直驱风机风电场与交流电网相互作用引发次同步振荡的机理与特性分析[J].中国电机工程学报,2016,36(9):2366-2372.XIE Xiaorong,LIU Huakun,HE Jingbo,et al.Mechanism and characteristics of subsynchronous oscillation caused by the interaction between full-converter wind turbines and ACsystems[J].Proceedings of the CSEE,2016,36(9):2366-2372.
[12]董晓亮,谢小荣,李江,等.大型风电场中不同位置的风机对次同步谐振特性影响程度的比较分析[J].中国电机工程学报,2015,35(20):5173-5180.DONG Xiaoliang,XIE Xiaorong,LI Jiang,et al.Comparative study of the impact on subsynchronous resonance characteristics from the different location of wind generators in a large wind farm[J].Proceedings of the CSEE,2015,35(20):5173-5180.
[13]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.
[14]EBRAHIMZADEH E,BLAABJERG F,WANG Xiongfei,et al.Harmonic stability and resonance analysis in large PMSG-based wind power plants[J].IEEE Transactions on Sustainable Energy,2018,9(1):12-23.
[15]WANG Xiongfei,HARNEFORS L,BLAABJERG F.Unified impedance model of grid-connected voltage-source converters[J].IEEE Transactions on Power Electronics,2018,33(2):1775-1787.
[16]CESPEDES M,SUN Jian.Impedance modeling and analysis of grid-connected voltage-source converters[J].IEEETransactions on Power Electronics,2014,29(3):1254-1261.
[17]WEN Bo,BOROYEVICH D,BURGOS R,et al.Analysis of D-Q small-signal impedance of grid-tied inverters[J].IEEETransactions on Power Electronics,2016,31(1):675-687.
[18]刘华坤,谢小荣,何国庆,等.新能源发电并网系统的同步参考坐标系阻抗模型及其稳定性判别方法[J].中国电机工程学报,2017,37(14):4002-4007.LIU Huakun,XIE Xiaorong,HE Guoqing,et al.Synchronous reference frame based impedance model and stability criterion for grid-connected renewable energy generation systems[J].Proceedings of the CSEE,2017,37(14):4002-4007.
[19]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):1277-1293.XIN Huanhai,LI Ziheng,DONG Wei,et al.Generalizedimpedance and stability criterion for grid connected converters[J].Proceedings of the CSEE,2017,37(5):1277-1293.
[20]年珩,杨洪雨.不平衡运行工况下并网逆变器的阻抗建模及稳定性分析[J].电力系统自动化,2016,40(10):76-83.DOI:10.7500/AEPS20150420006.NIAN Heng,YANG Hongyu.Impedance modeling and stability analysis of grid-connected inverters under unbalanced operation conditions[J].Automation of Electric Power Systems,2016,40(10):76-83.DOI:10.7500/AEPS20150420006.
[21]RYGG A,MOLINAS M,ZHANG Chen,et al.A modified Sequence-domain impedance definition and its equivalence to the dq-domain impedance definition for the stability analysis of AC power electronic systems[J].IEEE Journal of Emerging an Selected Topics in Power Electronics,2016,4(4):1383-1396.
[22]BAKHSHIZADEH M K,WANG Xiongfei,BLAABJERG F,et al.Couplings in phase domain impedance modeling of gridconnected converters[J].IEEE Transactions on Power Electronics,2016,31(10):6792-6796.
[23]SHAH S,PARSA L.Impedance modeling of three-phase voltage source converters in DQ,sequence,and phasor domains[J].IEEE Transactions on Energy Conversion,2017,32(3):1139-1150.
[24]VIETO I,DU Xiong,NIAN Heng,et al.Frequency-domain coupling in two-level VSC small-signal dynamics[C]//IEEE18th Workshop on Control and Modeling for Power Electronics(COMPEL),July 9-12,2017,Stanford,USA:8p.
[25]吕敬,蔡旭.基于谐波线性化的模块化多电平换流器阻抗建模[J].电力系统自动化,2017,41(4):136-142.DOI:10.7500/AEPS20160706009.LYU Jing,CAI Xu.Harmonic linearization based impedance modeling of modular multilevel converters[J].Automation of Electric Power Systems,2017,41(4):136-142.DOI:10.7500/AEPS20160706009.
[26]VIETO I,SUN J.Small-signal impedance modelling of type-IIIwind turbine[C]//IEEE Power&Energy Society General Meeting,July 26-30,2015,Denver,USA:5p.
[27]VIETO I,SUN J.Impedance modeling of doubly-fed induction generators[C]//17th European Conference on Power Electronics and Applications,September 8-10,2015,Geneva,Switzerland:10p.
[28]熊元新,陈允平.三相电路瞬时无功功率分析与计算[J].电力系统及其自动化学报,2001,13(1):15-17.XIONG Yuanxin,CHEN Yunping.Analysis and calculation on the instaneous reactive power of three-phase circuit[J].Proceedings of the CSU-EPSA,2001,13(1):15-17.
[29]XU Yunyang,NIAN Heng,WANG Tao,et al.Frequency coupling characteristic modeling and stability analysis of doubly fed induction generator[J].IEEE Transactions on Energy Conversion,2018,33(3):1475-1486.
[30]ZHANG Chen,CAI Xu,RYGG A,et al.Sequence domain SISO equivalent models of a grid-tied voltage source converter system for small-signal stability analysis[J].IEEETransactions on Energy Conversion,2018,33(2):741-749.
[2]袁小明,程时杰,胡家兵.电力电子化电力系统多尺度电压功角动态稳定问题[J].中国电机工程学报,2016,36(19):5145-5154.YUAN Xiaoming,CHENG Shijie,HU Jiabing.Multi-time scale voltage and power angle dynamics in power electronics dominated large power systems[J].Proceedings of the CSEE,2016,36(19):5145-5154.
[3]康重庆,姚良忠.高比例可再生能源电力系统的关键科学问题与理论研究框架[J].电力系统自动化,2017,41(9):1-11.DOI:10.7500/AEPS20170120004.KANG Chongqing,YAO Liangzhong.Key scientific issues and theoretical research framework for power systems with high proportion of renewable energy[J].Automation of Electric Power Systems,2017,41(9):1-11.DOI:10.7500/AEPS20170120004.
[4]鲁宗相,黄瀚,单葆国,等.高比例可再生能源电力系统结构形态演化及电力预测展望[J].电力系统自动化,2017,41(9):12-18.DOI:10.7500/AEPS20170109001.LU Zongxiang,HUANG Han,SHAN Baoguo,et al.Morphological evolution model and power forecasting prospect of future electric power systems with high proportion of renewable energy[J].Automation of Electric Power Systems,2017,41(9):12-18.DOI:10.7500/AEPS20170109001.
[5]李明节,于钊,许涛,等.新能源并网系统引发的复杂振荡问题及其对策研究[J].电网技术,2017,41(4):1035-1042.LI Mingjie,YU Zhao,XU Tao,et al.Study of complex oscillation caused by renewable energy integration and its solution[J].Power System Technology,2017,41(4):1035-1042.
[6]张琛,蔡旭,李征.电压源型并网变流器的机-网电气振荡机理及稳定判据研究[J].中国电机工程学报,2017,37(11):3174-3183.ZHANG Chen,CAI Xu,LI Zheng.Stability criterion and mechanisms analysis of electrical oscillations in the grid-tied VSC system[J].Proceedings of the CSEE,2017,37(11):3174-3183.
[7]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):1467-1478.NIE Cheng,LEI Wanjun,WANG Yue,et al.Resonance analysis of multiparalleled converter systems and research on optimal virtual resistor damping methods[J].Proceedings of the CSEE,2017,37(5):1467-1478.
[8]董炜,辛焕海,李子恒,等.变流器并网系统振荡与原-对偶复电路分析[J].中国电机工程学报,2017,37(22):6500-6515.DONG Wei,XIN Huanhai,LI Ziheng,et al.Primal-dual complex circuit of grid-connected converters for oscillation analysis[J].Proceedings of the CSEE,2017,37(22):6500-6515.
[9]谢小荣,刘华坤,贺静波,等.新能源发电并网系统的小信号阻抗/导纳网络建模方法[J].电力系统自动化,2017,41(12):26-32.DOI:10.7500/AEPS20170125005.XIE Xiaorong,LIU Huakun,HE Jingbo,et al.Small-signal impedance/admittance network modeling for grid connected renewable energy generation systems[J].Automation of Electric Power Systems,2017,41(12):26-32.DOI:10.7500/AEPS20170125005.
[10]严亚兵,苗淼,袁小明.新能源电站集电馈线对多变流器并网运行稳定性的影响[J].电力系统自动化,2016,40(15):86-92.DOI:10.7500/AEPS20150815006.YAN Yabing,MIAO Miao,YUAN Xiaoming.Impact of renewable power plant collector system on stability of gridconnected multi-converters[J].Automation of Electric Power Systems,2016,40(15):86-92.DOI:10.7500/AEPS20150815006.
[11]谢小荣,刘华坤,贺静波,等.直驱风机风电场与交流电网相互作用引发次同步振荡的机理与特性分析[J].中国电机工程学报,2016,36(9):2366-2372.XIE Xiaorong,LIU Huakun,HE Jingbo,et al.Mechanism and characteristics of subsynchronous oscillation caused by the interaction between full-converter wind turbines and ACsystems[J].Proceedings of the CSEE,2016,36(9):2366-2372.
[12]董晓亮,谢小荣,李江,等.大型风电场中不同位置的风机对次同步谐振特性影响程度的比较分析[J].中国电机工程学报,2015,35(20):5173-5180.DONG Xiaoliang,XIE Xiaorong,LI Jiang,et al.Comparative study of the impact on subsynchronous resonance characteristics from the different location of wind generators in a large wind farm[J].Proceedings of the CSEE,2015,35(20):5173-5180.
[13]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.
[14]EBRAHIMZADEH E,BLAABJERG F,WANG Xiongfei,et al.Harmonic stability and resonance analysis in large PMSG-based wind power plants[J].IEEE Transactions on Sustainable Energy,2018,9(1):12-23.
[15]WANG Xiongfei,HARNEFORS L,BLAABJERG F.Unified impedance model of grid-connected voltage-source converters[J].IEEE Transactions on Power Electronics,2018,33(2):1775-1787.
[16]CESPEDES M,SUN Jian.Impedance modeling and analysis of grid-connected voltage-source converters[J].IEEETransactions on Power Electronics,2014,29(3):1254-1261.
[17]WEN Bo,BOROYEVICH D,BURGOS R,et al.Analysis of D-Q small-signal impedance of grid-tied inverters[J].IEEETransactions on Power Electronics,2016,31(1):675-687.
[18]刘华坤,谢小荣,何国庆,等.新能源发电并网系统的同步参考坐标系阻抗模型及其稳定性判别方法[J].中国电机工程学报,2017,37(14):4002-4007.LIU Huakun,XIE Xiaorong,HE Guoqing,et al.Synchronous reference frame based impedance model and stability criterion for grid-connected renewable energy generation systems[J].Proceedings of the CSEE,2017,37(14):4002-4007.
[19]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):1277-1293.XIN Huanhai,LI Ziheng,DONG Wei,et al.Generalizedimpedance and stability criterion for grid connected converters[J].Proceedings of the CSEE,2017,37(5):1277-1293.
[20]年珩,杨洪雨.不平衡运行工况下并网逆变器的阻抗建模及稳定性分析[J].电力系统自动化,2016,40(10):76-83.DOI:10.7500/AEPS20150420006.NIAN Heng,YANG Hongyu.Impedance modeling and stability analysis of grid-connected inverters under unbalanced operation conditions[J].Automation of Electric Power Systems,2016,40(10):76-83.DOI:10.7500/AEPS20150420006.
[21]RYGG A,MOLINAS M,ZHANG Chen,et al.A modified Sequence-domain impedance definition and its equivalence to the dq-domain impedance definition for the stability analysis of AC power electronic systems[J].IEEE Journal of Emerging an Selected Topics in Power Electronics,2016,4(4):1383-1396.
[22]BAKHSHIZADEH M K,WANG Xiongfei,BLAABJERG F,et al.Couplings in phase domain impedance modeling of gridconnected converters[J].IEEE Transactions on Power Electronics,2016,31(10):6792-6796.
[23]SHAH S,PARSA L.Impedance modeling of three-phase voltage source converters in DQ,sequence,and phasor domains[J].IEEE Transactions on Energy Conversion,2017,32(3):1139-1150.
[24]VIETO I,DU Xiong,NIAN Heng,et al.Frequency-domain coupling in two-level VSC small-signal dynamics[C]//IEEE18th Workshop on Control and Modeling for Power Electronics(COMPEL),July 9-12,2017,Stanford,USA:8p.
[25]吕敬,蔡旭.基于谐波线性化的模块化多电平换流器阻抗建模[J].电力系统自动化,2017,41(4):136-142.DOI:10.7500/AEPS20160706009.LYU Jing,CAI Xu.Harmonic linearization based impedance modeling of modular multilevel converters[J].Automation of Electric Power Systems,2017,41(4):136-142.DOI:10.7500/AEPS20160706009.
[26]VIETO I,SUN J.Small-signal impedance modelling of type-IIIwind turbine[C]//IEEE Power&Energy Society General Meeting,July 26-30,2015,Denver,USA:5p.
[27]VIETO I,SUN J.Impedance modeling of doubly-fed induction generators[C]//17th European Conference on Power Electronics and Applications,September 8-10,2015,Geneva,Switzerland:10p.
[28]熊元新,陈允平.三相电路瞬时无功功率分析与计算[J].电力系统及其自动化学报,2001,13(1):15-17.XIONG Yuanxin,CHEN Yunping.Analysis and calculation on the instaneous reactive power of three-phase circuit[J].Proceedings of the CSU-EPSA,2001,13(1):15-17.
[29]XU Yunyang,NIAN Heng,WANG Tao,et al.Frequency coupling characteristic modeling and stability analysis of doubly fed induction generator[J].IEEE Transactions on Energy Conversion,2018,33(3):1475-1486.
[30]ZHANG Chen,CAI Xu,RYGG A,et al.Sequence domain SISO equivalent models of a grid-tied voltage source converter system for small-signal stability analysis[J].IEEETransactions on Energy Conversion,2018,33(2):741-749.