换相电压负序分量对LCC-HVDC输电系统换相的影响分析及其抑制策略  

Influence analysis of negative sequence components of commutation voltage on commutation of LCC-HVDC transmission system and its suppression strategy

作　　者：刘对 李晓华[1] 蔡泽祥[1] 殷珊珊 LIU Dui;LI Xiaohua;CAI Zexiang;YIN Shanshan(School of Electric Power Engineering,South China University of Technology,Guangzhou 510640,China)

机构地区：[1]华南理工大学电力学院,广东广州510640

出　　处：《电力自动化设备》2022年第3期45-52,共8页Electric Power Automation Equipment

基　　金：国家自然科学基金委员会-国家电网公司智能电网联合基金资助项目(U1766213);国家自然科学基金资助项目(51677073)。

摘　　要：针对逆变侧交流系统故障下传统的基于电网换相换流器的高压直流(LCC-HVDC)输电系统容易发生换相失败这一问题,推导了换相电压负序分量与锁相环的定量关系,并定性分析了换相电压负序分量对LCC-HVDC输电系统换相的影响。在此基础上提出了一种改进双二阶广义积分器锁相环以抑制多次换相失败。该锁相环首先采用具有分离特性的相序解耦谐振控制器来解耦换相电压的正、负序分量;接着利用双二阶广义积分-正交信号发生器再次分离换相电压的正、负序分量以及消除谐波分量;最后采用正交谐波消除模块滤除低次谐波,提升锁相环的抗干扰能力,完成同步信号的准确提取。仿真结果表明,改进的锁相环具有较好的动态性能与较强的换相电压负序分量与谐波抑制效果;在电网电压不对称、谐波含量较高时仍能够高效地追踪电网电压的频率与相位;并能够减少换相失败的发生概率。Aiming at the problem that LCC-HVDC(Line Commutated Converter based High Voltage Direct Current)transmission system may have commutation failure when the AC system fault occurs on the inverter side,the quantitative relationship between the negative sequence components of the commutation voltage and PLL(Phase Locked Loop)is deduced,and the influence of the negative sequence component of the commutation voltage on the commutation of LCC-HVDC transmission system is qualitatively analyzed.On this basis,an improved double second-order generalized integrator PLL is proposed to suppress multiple commutation failures.Firstly,the phase sequence decoupled resonant controller with separation characteristics is used to decouple the positive and negative components of commutation voltage.Then,using the double second-order generalized integrator-quadrature signal generator,the positive and negative sequence components are separated,and harmonic components are eliminated again.Finally,the quadrature harmonic cancellation module is used to filter the low-order harmonics,improve the anti-interference ability of PLL,and complete the accurate extraction of the synchronization signal.Simulative results show that the improved PLL has better dynamic performance and a strong suppression capability of negative sequence components of commutation voltage and harmonic.The frequency and phase of the grid voltage can be captured efficiently when the grid voltage is asymmetric and the harmonic content is high.And the improved PLL can reduce the probability of commutation failure.

关 键 词：LCC-HVDC输电系统 换相电压负序分量 换相失败 锁相环 相序解耦谐振控制器 

分 类 号：TM721.1[电气工程—电力系统及自动化]