大规模光伏发电经串补并网系统次同步振荡机制  

SSO Mechanism of Large-scale PV Generation Connected to Series-compensated Power System

作　　者：陈武晖[1] 杨彦霁 谢永胜 常喜强 林勇 余浩 张军[1] CHEN Wuhui;YANG Yanji;XIE Yongsheng;CHANG Xiqiang;LIN Yong;YU Hao;ZHANG Jun(School of Electrical and Information Engineering,Jiangsu University,Zhenjiang 212013,Jiangsu Province,China;State Grid Xinjiang Electric Power Co.,Ltd.,Urumqi 830000,Xinjiang Uygur Autonomous Region,China;Grid Planning&Research Center,Guangdong Power Grid Co.,Ltd.,Guangzhou 510080,Guangdong Province,China)

机构地区：[1]江苏大学电气信息工程学院,江苏省镇江市212013 [2]国网新疆电力有限公司,新疆维吾尔自治区乌鲁木齐市830000 [3]广东电网有限责任公司电网规划研究中心,广东省广州市510080

出　　处：《电网技术》2021年第12期4711-4720,共10页Power System Technology

基　　金：国家自然科学基金项目(51977098);南方电网公司科技项目(037700KK52190012(GDKJXM20198282))。

摘　　要：根据以往研究经验,由于串补输电系统存在串联谐振点,大规模光伏发电经串补并网系统被怀疑存在次同步振荡风险。研究发现光伏并网逆变器采用恒电流控制,其特性近似电流源,只能激励并联谐振点,而大规模光伏发电经串补并网系统与变压器励磁支路在交流侧产生并联谐振点,可能会成为影响系统振荡稳定性的主导因素。因此,分别建立了考虑和忽略变压器励磁支路的大规模光伏经串补并网系统的小信号模型,利用特征值法分析振荡机理。特征值研究证实,当逆变器采取电流源控制模式时,交流侧并联谐振点存在对应的特征值,而由于电流源钳制光伏发电系统的电流量,并不存在与串联谐振点对应的特征值,因而变压器励磁支路与串补电容构成的并联谐振点主导系统的次同步振荡特性。Based on previous researches,the risk of sub-synchronous oscillation(SSO)is suspected in the large-scale photovoltaic(PV)generation connected to a series-compensated power system because of the series resonance points in the series compensation transmission system.This paper finds that the PV grid-connected inverter adopts constant current control,which is only able to excite the parallel resonance points,the similar characteristics as a current source.On the other hand,the AC side parallel resonance points between the large-scale PV series compensation grid-connected system and the transformer excitation branch may be the dominant factor affecting the oscillation stability of the system.Therefore,the small signal models of the large-scale PV series compensation grid-connected system considering or ignoring the transformer excitation branch are established respectively,and the oscillation mechanisms are analyzed in the eigenvalue method.The eigenvalue research confirms that when the inverter adopts the current source control mode,the parallel resonance point of the AC side has corresponding eigenvalues.while because the current source clamps the current of the PV generation system,there is no eigenvalue corresponding to the series resonance point.Therefore,the parallel resonance point formed by the transformer excitation branch and the series compensation capacitor dominates the SSO characteristics of the system.

关 键 词：光伏经串补并网系统 变压器励磁支路 特征值分析 谐振点 次同步振荡 

分 类 号：TM721[电气工程—电力系统及自动化]