基于直流电流瞬时微分的特高压直流分层接入系统非故障层换相失败预防控制策略  

Control strategy for commutation failure prevention at non-fault layer of UHVDC hierarchical connection system based on DC current instantaneous differential

作　　者：王渝红[1] 李元琦 廖建权 陈立维 赏成波 WANG Yuhong;LI Yuanqi;LIAO Jianquan;CHEN Liwei;SHANG Chengbo(College of Electrical Engineering,Sichuan University,Chengdu 610065,China)

机构地区：[1]四川大学电气工程学院,四川成都610065

出　　处：《电力自动化设备》2024年第2期126-132,146,共8页Electric Power Automation Equipment

基　　金：国家重点研发计划项目(2021YFB2400800)。

摘　　要：在特高压直流分层接入系统中,由于层间耦合作用,某一层交流系统发生故障可能导致非故障层换流器发生换相失败。为此,考虑到故障过程直流电流的变化,提出一种基于直流电流瞬时微分的换相失败预防控制策略。该策略基于故障后直流电流的变化特性,得到换相电流时间面积控制中触发角修正量,代替原有换相失败预防控制,提高非故障层换相失败预防控制的启动精度;同时基于电流预测量和等效直流输入电阻动态调整低压限流控制器的指令值,提高其响应速度。在PSCAD/EMTDC中搭建仿真模型对不同工况下所提控制策略进行验证。结果表明,该策略可降低高低端换流器同时发生换相失败的风险,改善故障后系统的运行性能。In the ultra high voltage direct current(UHVDC)hierarchical connection system,due to the coupling between layers,when a layer of AC system fails,commutation failure of non-fault layer converter may occur.Therefore,considering the change of DC current during the fault process,a commutation failure prevention control strategy based on the instantaneous differential of DC current is proposed.Based on the change characteristics of DC current after fault,the trigger angle correction in commutation current-time area control is obtained,which replaces the original commutation failure prevention control and improves the starting accuracy of commutation failure prevention control in the non-fault layer.At the same time,the command value of voltage dependent current order limiter is dynamically adjusted based on current prediction and equal DC input resistance to improve its response speed.The simulation model is built in PSCAD/EMTDC to verify the proposed control strategy under different working conditions.The results show that this strategy can reduce the risk of commutation failure of both high and low voltage end converters,and improve the operation performance of the system after failure.

关 键 词：特高压直流输电 分层接入系统 换相失败 电流预测 换相电流时间面积 低压限流控制器 

分 类 号：TM721.1[电气工程—电力系统及自动化]