降低三端直流系统入地电流与功率损失的换流站电流调整策略  

Current Adjustment Strategy of Converter Station for Reducing Grounding Current and Power Loss of Three-terminal DC System

作　　者：黄曼茜 刘航 许建中 HUANG Manxi;LIU Hang;XU Jianzhong(State Key Laboratory of Altermate Electrical Power System with Renewable Energy Sources(North China Electric PowerUniversity),Beijing 102206,China;Maintenance and Test Center,Southern Power Grid EHV Power Transmission Company,Guangzhou 510663,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),北京市102206 [2]南方电网超高压输电公司检修试验中心,广东省广州市510663

出　　处：《电力系统自动化》2022年第13期130-138,共9页Automation of Electric Power Systems

基　　金：中央高校基本科研业务费专项资金资助项目(2020MS003)。

摘　　要：含接地极系统的多端双极直流系统不允许长时间带较大入地电流运行。在受端单极退出工况下,需要兼顾降低各换流站接地极电流与弥补停极换流站的功率损失。基于并联型双极三端直流系统,文中提出一种受端单极退出工况下的换流站电流调整策略。首先,通过调节各换流站两极电流降低入地电流,再利用空闲直流线路/备用线路作为金属支路,将停极受端的入地电流转移至相邻换流站的接地极上,最后降低相邻换流站的直流电流,从而转移相邻换流站部分功率以支援停极受端。基于PSCAD/EMTDC对所提策略进行仿真验证,由仿真结果可知,所提换流站电流调整策略能够将入地电流控制在安全水平,并减少停极受端直流功率损失。The multi-terminal bipolar DC system with the earth electrode system is not allowed to operate with the large grounding current for a long time. In the operation mode of unipolar exit at the receiving end, it is necessary to reduce the grounding pole current of each converter station and compensate the power loss of the converter station with the unipolar exit condition. Based on the parallel bipolar three-terminal DC system, this paper proposes a current adjustment strategy for the converter stations under the condition of unipolar exit at the receiving end. First, the grounding current is reduced by adjusting the current at both poles of each converter station. Then, the idle DC line or the standby line is used as a metallic branch to transfer the grounding current at the receiving end with the unipolar exit to the earth electrode of the adjacent converter station. Finally, the DC current of the adjacent converter station is reduced, so that part of the power of the adjacent converter station is transferred to support the receiving end with the unipolar exit. The proposed strategy is verified by the simulation based on PSCAD/EMTDC. The simulation results show that the proposed current adjustment strategy of the converter station can control the grounding current at a safe level and reduce the DC power loss at the receiving end with the unipolar exit.

关 键 词：多端直流输电 接地极系统 单极退出 入地电流 金属支路 备用线路 电流调整策略 

分 类 号：TM721.1[电气工程—电力系统及自动化]