弱电网下无功控制对并网变流器稳定性影响分析  

Analysis on Impact of Reactive Power Control on Stability of Grid-connected Converter in Weak Grid

作　　者：徐路遥 兰洲 陈飞 王晓菲 袁辉 辛焕海[1] XU Luyao;LAN Zhou;CHEN Fei;WANG Xiaofei;YUAN Hui;XIN Huanhai(College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China;Economic Research Institute of State Grid Zhejiang Electric Power Company, Hangzhou 310006, China)

机构地区：[1]浙江大学电气工程学院,浙江省杭州市310027 [2]国网浙江省电力公司经济技术研究院,浙江省杭州市310006

出　　处：《电力系统自动化》2019年第15期56-63,共8页Automation of Electric Power Systems

基　　金：国网浙江省电力有限公司科技项目“含高比例可再生能源的系统振荡风险分析方法及应用研究”~~

摘　　要：可再生能源经变流器接入弱电网时,变流器向电网输出无功功率有利于提高并网点的电压质量,但是无功控制的动态特性对变流器系统的稳定性有重要的影响。为分析此影响,文中建立了采用定无功功率控制策略下变流器的阻抗模型,通过分析无功控制外环动态改变所引起的各元素阻抗特性变化,判断无功控制外环动态对系统稳定性的影响,并采用广义奈奎斯特判据验证上述分析结论。其次,采用特征根轨迹法,分析了无功控制外环比例参数及电网强度的变化对系统稳定性的影响,结果表明弱电网下无功控制外环可能引发中高频振荡问题。最后,基于RT-LAB进行在环仿真验证理论分析结果。When the renewable energy is connected to the weak grid through the converter,the output reactive power from converter to grid is beneficial to improve the voltage quality of connection point.But the dynamic characteristics of reactive power control have huge impacts on the stability of the converter system.To explore the impacts,the impedance model of converters with the fixed reactive power control strategy is proposed.By analyzing the impedance characteristics of each element changed by the dynamic variation of outer reactive power control loop,the influence of the dynamic outer reactive power control loop on system stability is judged,and the generalized Nyquist criterion is used to verify the above analysis conclusion.Moreover,the eigenvalue analysis method is used to explore the influences of the proportional parameter of outer reactive power control loop and the strength of the grid on system stability.The results reveal that the outer reactive power control loop may cause medium/high frequency oscillations when the converters are connected to weak grids.Finally,the hardware-in-the-loop(HIL)simulation is conducted to validate the theoretical analysis results based on RT-LAB.

关 键 词：并网变流器 弱电网 阻抗模型 无功控制外环 小干扰稳定性 

分 类 号：TM46[电气工程—电器]