考虑SVG补偿装置的大型光伏并网系统振荡分析与抑制
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摘要
大型光伏电站由于远离负荷中心,长距离输电线路所产生的电网阻抗不可忽略,电网阻抗对于多逆变器相并联的大型光伏电站中某一个光伏发电单元而言将会等效放大数倍,从而造成并网点电压降低导致系统不稳定。光伏电站中的静止无功发生器(static var generator,SVG)等无功补偿装置可以用来降低电网阻抗对于并网点电压的影响。然而,研究发现,在补偿容量逐渐增大的情况下,无功补偿装置与逆变器系统之间的相互影响将会使系统出现振荡现象,而在逆变器控制回路内采用串联校正方式可以有效消除这种现象,从而保证系统的稳定运行。仿真结果与实验验证了理论分析的正确性。
In general, the large-scale PV station locates in rural areas far from the loads center, so, the grid impedance caused by long transmission line should not be ignored. It will be equivalently amplified several times for one certain generation unit, which usually causes the voltage decline and further unstable phenomenon. This influence of gird impedance on the connecting voltage can be eliminated by the static var generator(SVG) compensator in PV station. However, after further study, the system will become unstable due to the interaction between the PV inverter and the reactive compensation equipment with the increase of reactive power demanded by the grid impedance. In order to maintain the system stable and with better performance, the cascade lead correction was adopted to refine the system character. Finally,the correctness was verified by simulation and experiment.
In general, the large-scale PV station locates in rural areas far from the loads center, so, the grid impedance caused by long transmission line should not be ignored. It will be equivalently amplified several times for one certain generation unit, which usually causes the voltage decline and further unstable phenomenon. This influence of gird impedance on the connecting voltage can be eliminated by the static var generator(SVG) compensator in PV station. However, after further study, the system will become unstable due to the interaction between the PV inverter and the reactive compensation equipment with the increase of reactive power demanded by the grid impedance. In order to maintain the system stable and with better performance, the cascade lead correction was adopted to refine the system character. Finally,the correctness was verified by simulation and experiment.
引文
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[14]杨硕,王伟胜,刘纯,等.改善风电汇集系统静态电压稳定性的无功电压协调控制策略[J].电网技术,2014,38(5):1250-1256.Yang Shuo,Wang Weisheng,Liu Chun,et al.Coordinative strategy of reactive power and voltage control for improving static voltage stability of wind power centralized system[J].Power System Technology,2014,38(5):1250-1256(in Chinese).
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[16]Althobaiti A,Armstrong M,Elgendy M A.Current control of three-phase grid-connected PV inverters using adaptive PR controller[C]//2016 7th International Renewable Energy Congress(IREC),2016:1-6.
[17]郭小强,贾晓瑜,王怀宝,等.三相并网逆变器静止坐标系零稳态误差电流控制分析及在线切换控制研究[J].电工技术学报,2015,30(4):8-14.Guo Xiaoqiang,Jia Xiaoyu,Wang Huaibao,et al.Analysis of zero steady-state error current control and on line switching control for static synchronous system of three-phase grid connected inverter[J].Transactions of China Electrotechnical Society,2015,30(4):8-14(in Chinese).
[18]鲍陈磊,阮新波,王学华,等.基于PI调节器和电容电流反馈有源阻尼的LCL型并网逆变器闭环参数设计[J].中国电机工程学报,2012,32(25):133-140.Bao Chen Lei,Ruan Xinbo,Wang Xuehua,et al.Design of grid-connected inverters with LCL filter based on PIregulator and capacitor current feedback active damping[J].Proceedings of the CSEE,2012,32(25):133-140(in Chinese).
[19]肖华锋,许津铭,谢少军.LCL型进网滤波器的有源阻尼技术分析与比较[J].电力自动化设备,2013,33(5):55-59.Xiao Huafeng,Xu Jinming,Xie Shaojun.Analysis and comparison of active damping technologies of LCLfilter[J].Electric Power Automation Equipment,2013,33(5):55-59(in Chinese).
[20]Zheng C,Zhou L,Yu X,et al.Online phase margin compensation strategy for a grid-tied inverter to improve its robustness to grid impedance variation[J].IET Power Electronics,2016,9(4):611-620.
[21]董云龙.静止同步补偿器(STATCOM)的仿真与实现[D].南京:东南大学,2004.Dong Yunlong.Simulation and realization of static var compensation(STATCOM)[D].Nanjing:Southeast University,2004(in Chinese).
[2]张密.大型光伏并网系统谐振现象分析[D].重庆:重庆大学,2014.Zhang Mi.Analysis of resonance phenomenon of large photovoltaic grid connected system[D].Chongqing:Chongqing University,2014(in Chinese).
[3]Liserre M,Teodorescu R,Blaabjerg F.Stability of photovoltaic and wind turbine grid-connected inverters for a large set of grid impedance values[J].IEEE Transactions on Power Electronics,2006,21(1):363-372.
[4]杨明.大型光伏电站逆变器并网控制策略及稳定性分析[D].重庆:重庆大学,2014.Yang Ming.Control strategy and stability analysis for grid-connected inverters in large-scale photovoltaic power plants[D].Chongqing:Chongqing University,2014(in Chinese).
[5]Agorreta J L,Borrega M,Marroyo L,et al.Modeling and control of N-paralleled grid-connected inverters with LCLfilter coupled due to grid impedance in PV plants[J].IEEETransactions on Power Electronics,2011,26(3):770-785.
[6]周林,任伟,廖波,等.并网型光伏电站无功电压控制[J].电工技术学报,2015,30(20):168-175.Zhou Lin,Ren Wei,Liao Bo,et al.Reactive power and voltage control for grid-connected PV power plants[J].Transactions of China Electrotechnical Society,2015,30(20):168-175(in Chinese).
[7]谢宁,罗安,陈燕东,等.大型光伏电站动态建模及谐波特性分析[J].中国电机工程学报,2013,33(36):10-17.Xie Ning,Luo An,Chen Yandong,et al.Dynamic modeling and characteristic analysis on harmonics of photovoltaic power stations[J].Proceedings of the CSEE,2013,33(36):10-17(in Chinese).
[8]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 gridconnected inverters and the utility grid[J].Proceedings of the CSEE,2013,33(12):64-71(in Chinese).
[9]Ye Qing,Mo Ran,Shi YanJun,et al.A unified impedance-based stability criterion(UIBSC)for paralleled grid-tied inverters using global minor loop gain(GMLG)[C]//Energy Conversion Congress and Exposition(ECCE).Montreal,QC:IEEE,2015:5816-5821.
[10]Sun J.Impedance-based stability criterion for gridconnected inverters[J].IEEE Transactions on Power Electronics,2011,26(11):3075-3078.
[11]葛虎,毕锐,徐志成,等.大型光伏电站无功电压控制研究[J].电力系统保护与控制,2014,42(14):45-51.Ge Hu,Bi Rui,Xu Zhicheng,et al.Research on reactive power and voltage control of large-scale photovoltaic power station[J].Power System Protection and Control,2014,42(14):45-51(in Chinese).
[12]Zhou Lin,Chao Yang.The research of reactive power control strategy for grid-connected photovoltaic plants[C]//2013 World Congress on Sustainable Technologies(WCST),IEEE,2013:12-17.
[13]邵念斌.大型光伏电站站内无功电压优化控制策略研究[D].重庆:重庆大学,2014.Shao Nianbin.Research of the reactive power voltage optimization in large-scale PV plant[D].Chongqing:Chongqing University,2014(in Chinese).
[14]杨硕,王伟胜,刘纯,等.改善风电汇集系统静态电压稳定性的无功电压协调控制策略[J].电网技术,2014,38(5):1250-1256.Yang Shuo,Wang Weisheng,Liu Chun,et al.Coordinative strategy of reactive power and voltage control for improving static voltage stability of wind power centralized system[J].Power System Technology,2014,38(5):1250-1256(in Chinese).
[15]Roy N K,Pota H R,Mahmud M.A.,et al.D-STATCOMcontrol in distribution networks with composite loads to ensure grid code compatible performance of photovoltaic generators[C]//2013 IEEE 8th Conference on Industrial Electronics and Applications(ICIEA),IEEE,2013:55-60.
[16]Althobaiti A,Armstrong M,Elgendy M A.Current control of three-phase grid-connected PV inverters using adaptive PR controller[C]//2016 7th International Renewable Energy Congress(IREC),2016:1-6.
[17]郭小强,贾晓瑜,王怀宝,等.三相并网逆变器静止坐标系零稳态误差电流控制分析及在线切换控制研究[J].电工技术学报,2015,30(4):8-14.Guo Xiaoqiang,Jia Xiaoyu,Wang Huaibao,et al.Analysis of zero steady-state error current control and on line switching control for static synchronous system of three-phase grid connected inverter[J].Transactions of China Electrotechnical Society,2015,30(4):8-14(in Chinese).
[18]鲍陈磊,阮新波,王学华,等.基于PI调节器和电容电流反馈有源阻尼的LCL型并网逆变器闭环参数设计[J].中国电机工程学报,2012,32(25):133-140.Bao Chen Lei,Ruan Xinbo,Wang Xuehua,et al.Design of grid-connected inverters with LCL filter based on PIregulator and capacitor current feedback active damping[J].Proceedings of the CSEE,2012,32(25):133-140(in Chinese).
[19]肖华锋,许津铭,谢少军.LCL型进网滤波器的有源阻尼技术分析与比较[J].电力自动化设备,2013,33(5):55-59.Xiao Huafeng,Xu Jinming,Xie Shaojun.Analysis and comparison of active damping technologies of LCLfilter[J].Electric Power Automation Equipment,2013,33(5):55-59(in Chinese).
[20]Zheng C,Zhou L,Yu X,et al.Online phase margin compensation strategy for a grid-tied inverter to improve its robustness to grid impedance variation[J].IET Power Electronics,2016,9(4):611-620.
[21]董云龙.静止同步补偿器(STATCOM)的仿真与实现[D].南京:东南大学,2004.Dong Yunlong.Simulation and realization of static var compensation(STATCOM)[D].Nanjing:Southeast University,2004(in Chinese).