特高压直流换流站中性母线开关失灵逻辑分析与优化

Logic analysis and optimization of neutral bus switch failure in ultra-high voltage direct current grid project converter station

中性母线开关失灵(NBSF)逻辑是特高压直流输电工程控制保护系统的典型设计,主要是考虑直流输电工程在双极运行过程中,若其中一个极故障,保护动作执行极隔离时,故障极中性母线开关拉不开且动作于重合,无法隔离故障点,通过借助站内接地开关(NBGS)转移电流,然后拉开故障极中性母线开关、中性线隔离开关,对故障点进行隔离。本文详细介绍NBSF的具体逻辑,结合仿真对该逻辑在逆变侧单极故障时可能引起双极闭锁的重大隐患进行深入分析,提出优化改进方案,并对优化后的方案进行仿真分析,以期对在运工程中该逻辑的改进及今后的工程设计提供参考。

Neutral bus switch failure(NBSF)logic is a typical design of the control and protection system of ultra-high voltage(UHV)DC transmission project.When the DC transmission project is in bipolar operation,if one pole fails,the neutral bus switch of the fault pole cannot be opened and acts on reclosing when the protection action performs pole isolation,so it is unable to isolate the fault point.By NBSF logic,the current can be transferred through the neutral bus grounding switch(NBGS)in the station,thus the neutral bus switch of fault pole and neutral line disconnector are opened to isolate the fault point.In this paper,the specific logic of NBSF is introduced in detail.Combined with simulation,the major hidden danger of bipolar locking caused by unipolar fault on the inverter side is deeply analyzed,the optimization and improvement scheme is put forward,and the optimized scheme is simulated and verified.It is expected to provide reference for the improvement of the logic in operation engineering and future engineering design.