特高压直流分层接入方式下抑制连续换相失败的直流电流控制策略  

Continuous Commutation Failure Suppression Strategy Considering DC Current for UHVDC Transmission System Under Hierarchical Connection

作　　者：何思行 郝亮亮[1] 和敬涵[1] 陈争光 HE Sihang;HAO Liangliang;HE Jinghan;CHEN Zhengguang(School of Electrical Engineering,Beijing Jiaotong University,Haidian District,Beijing 100044,China;State Grid Corporation of China,Xicheng District,Beijing 100031,China)

机构地区：[1]北京交通大学电气工程学院,北京市海淀区100044 [2]国家电网有限公司,北京市西城区100031

出　　处：《电网技术》2024年第7期3013-3022,共10页Power System Technology

基　　金：国家自然科学基金项目(U2066210)。

摘　　要：特高压直流分层接入系统逆变侧交直流间均存在耦合,单一换流站发生连续换相失败容易导致电网发生连锁故障。针对这一问题,从层间交互作用机理出发,深入分析了高低端换流器控制响应差异以及其动态无功特性。分析表明:故障恢复阶段的无功交互量增加会导致非故障层换流母线电压的跌落,并直接引起该层换流器关断角的减小,从而引发连续换相失败。在此基础上,提出一种抑制连续换相失败的直流电流控制策略。该策略综合考虑无功交换量与换流母线电压的波动特征,通过系统实际运行状态实时计算直流电流指令来实现对高低端换流器的连续换相失败抑制。最后,建立了分层接入系统电磁暂态模型,通过多工况对比验证了策略的有效性。所提策略能够降低分层接入系统发生连续换相失败的概率,同时改善两层交流系统电压恢复特性,有利于系统安全稳定运行。Due to the coupling of the ultra-high voltage direct current(UHVDC)hierarchical connection system,continuous commutation failure at an inverter can easily lead to cascading faults in the power grid.This article analyzes the difference in control response of high-end and low-end inverters and their dynamic reactive power characteristics based on the inter-layer interaction mechanism.Analysis shows that an increase in reactive power exchange during the fault recovery will lead to a voltage drop of the non-fault layer,and directly causes a decrease in the extinction angle,leading to continuous commutation failure of the non-fault layer.Based on this,a current control strategy is proposed to suppress continuous commutation failure.The strategy suppresses continuous commutation failure by calculating the current command in real-time through reactive power exchange and voltage fluctuation characteristics.An electromagnetic transient model is established,and the strategy's effectiveness is verified by comparing multiple operating conditions.The proposed strategy can reduce the probability of continuous commutation failure while improving the voltage recovery characteristics of the hierarchical connection system,which is conducive to the safe and stable operation of the system.

关 键 词：特高压直流输电 分层接入 连续换相失败 抑制策略 

分 类 号：TM721[电气工程—电力系统及自动化]