弱交流系统下STATCOM对LCC-HVDC小干扰稳定裕度的影响研究  

Impact of STATCOM on the Small-signal Stability Margin of LCC-HVDC Under Weak AC Grid Conditions

作　　者：郭春义[1] 蒋雯[1] 郑安然[1] 赵成勇[1] 刘炜[1] GUO Chunyi;JIANG Wen;ZHENG Anran;ZHAO Chengyong;LIU Wei(State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources（North China Electric Power University）,Changping District,Beijing 102206,China)

机构地区：[1]新能源电力系统国家重点实验室(华北电力大学)

出　　处：《中国电机工程学报》2018年第19期5679-5686,共8页Proceedings of the CSEE

基　　金：国家自然科学基金项目(51507060)~~

摘　　要：当电网换相换流器高压直流输电（linecommutated converter based high voltage direct current,LCC-HVDC）逆变侧交流母线处含有静止同步补偿器（static synchronous compensator,STATCOM）时,LCC-HVDC与STATCOM均需要各自的锁相环（phase-locked-loop,PLL）为其控制系统提供基准。该文考虑LCC与STATCOM锁相环各自动态建立含STATCOM的LCC-HVDC系统的小干扰模型,采用经典特征根分析方法,通过对比LCC-HVDC系统与含STATCOM的LCC-HVDC系统二者之间的锁相环与控制系统参数可行域的差异,研究STATCOM对LCC-HVDC小干扰稳定裕度的影响。最后,通过理论计算,对比有无STATCOM投入时LCC-HVDC系统在不同SCR与不同PLL参数下的最大传输有功功率（maximum available power,MAP）及临界短路比（critical short circuit ratio,CSCR）的变化规律。研究结果表明,当LCC-HVDC连接较弱系统时,控制系统之间的耦合作用对LCC锁相环的稳定可行域产生负面影响,可能引发由于LCC锁相环增益过大而导致的整个混合系统的小干扰失稳现象。When static synchronous compensator （STATCOM） is installed at the inverter bus of line commutated converter based high voltage direct current （LCC-HVDC） system, both LCC system and STATCOM need their respective phase-locked-loops （PLLs） to provide frequency reference for their own control system. This paper developed a small-signal model of LCC-HVDC system with STATCOM considering the dynamics of both the PLLs of LCC station and STATCOM. Then, by the classical root-locus method, the feasible region of the PLL gains and control parameters of LCC system with or without STATCOM were studied, and the impact of STATCOM on the small-signal stability margin of LCC-HVDC under weak AC grid conditions were investigated. Finally, this paper studied the maximum available power （MAP） and the critical short circuit ratio （CSCR） under different SCR values and different PLL gains for LCC-HVDC system with or without STATCOM. The results show that under weak AC grid conditions the controller coupling has negative impact on the whole system stability, and may cause oscillation/instability due to larger PLL gain of LCC system.

关 键 词：电网换相换流器高压直流输电 STATCOM 锁相环 小干扰稳定裕度 最大传输功率 临界短路比 

分 类 号：TM731[电气工程—电力系统及自动化]