防止特高压直流工程单双极闭锁的关键措施

特高压直流输电工程因其输送容量大、送电距离远得到越来越广泛的应用，然而，直流系统单双极的强迫停运严重影响着其安全运行。针对直流系统潜在的风险，从主回路接线方式和控制保护策略等方面开展了特高压直流输电工程主接线方案优化、直流线路重启动策略、金属回线自动转换方案、双极中性母线差动保护动作时序和直流滤波器保护配置等研究，提出了防止特高压直流工程单双极闭锁的关键措施。通过实时数字仿真系统对提出的措施进行了仿真分析，仿真结果及工程应用验证了措施的有效性。研究结果对提高直流系统运行可靠性、提升直流工程成套设计水平具有实际指导意义。

Key Measure for Monopol/Bipole Blocking in UHVDC Project

UHVDC project has been widely applied in power system because of its high-capacity and long transmission distance. However, the forced outage of monopole/bipole in DC system seriously affects its safe operation. According to the potential risk of the DC system, this paper studied the optimization of main wiring scheme, the restart logic of DC line, the automatic transformation scheme of metallic return, the differential protection action sequence of bipolar neutral bus and the protection configuration of DC filter in UHVDC transmission projects, from aspects of main circuit wiring mode, control & protection strategy, etc. Then, the key measure was proposed to prevent monopole/bipole blocking in UHVDC transmission projects. Finally, the effectiveness of the proposed measure was verified by real-time digital simulation analysis and engineering application. The research results have the practical guidance significance to improve the reliability of DC system and the design level of DC project.