利用虚拟阻抗及无功电流控制提高光伏故障电压支撑能力研究  

Research on Improving Photovoltaic Fault Voltage Support Capability by Virtual Impedance and Reactive Current Control

作　　者：何昭辉 曹锐 刘海鹏 周成 HE Zhaohui;CAO Rui;LIU Haipeng;ZHOU Cheng(State Key Laboratory of Smart Grid Protection and Control,Nari Group Co.,Ltd.,Nanjing 211106,China)

机构地区：[1]南瑞集团(国网电力科学研究院)有限公司智能电网保护和运行控制国家重点实验室,南京211106

出　　处：《电力电容器与无功补偿》2022年第5期42-49,共8页Power Capacitor & Reactive Power Compensation

摘　　要：光伏发电并网系统通过公共耦合点与电网相连,当网侧发生短路时,并网系统会因为电压突变造成设备脱网等严重事故。当故障切除后又会因为电网电压骤升,增加逆变器直流侧过压、过流风险。本文引入虚拟阻抗来改变电压控制环节的参考信号,起到故障期间电压支撑作用,通过分析发生对称和不对称短路故障后的正、负序电压、电流,得出虚拟阻抗幅值及阻感比。针对故障切除后电压骤升带来的暂态冲击问题,分析有功、无功功率变化情况,提出一种无功电流控制策略来稳定并网点母线电压。将上述控制策略通过Matlab/Simulink仿真和试验,验证本文方案可以使光伏发电并网系统平稳穿越网侧故障,故障切除后无电压震荡现象。The grid-connected system of photovoltaic power generation is connected to the grid through the common coupling point.In case of short circuit on the grid side,the grid-connected system will cause such serious accidents as equipment off grid due to voltage leap.After the fault is removed,the risk of overvoltage and over-current on DC side of inverter is increased due to the voltage swell of grid.The virtual impedance is introduced in this paper to change the reference signal of voltage control linkso as to play a role of voltage support during the fault period.The virtual impedance amplitude and impedance ratio are obtained through analyzing the positive and negative sequence voltage and current after symmetrical and asymmetrical short-circuit fault.In view of the transient impact due to voltage swell after the removal of the fault as well as the analysis of variation of the active and reactive power,a kind of reactive current control strategy is proposed to stabilize bus voltage of the grid-connected point.It is verified by Mattab/Simulink simulation and test of above control strategy that the scheme in this paper can make the photovoltaic grid connected system pass through the grid side fault smoothlyand no voltage oscillation phenomena is appeared after removal of the fault.

关 键 词：光伏发电并网系统 电压突变 电压骤升 虚拟阻抗 无功电流控制 

分 类 号：TM615[电气工程—电力系统及自动化]