交直流系统连锁故障引发功率倒向方向保护策略

针对目前交直流混联系统连锁故障引发的功率倒向导致纵联方向保护存在适应性的问题,以交流线路发生率较高的单相接地故障为例,在分析了过渡电阻对功率倒向和工频故障电流频率偏移影响的基础上,根据故障后母线电压突变量、故障点电压突变量、补偿电压突变量幅值之间的关系提出一种基于补偿电压突变量的本地信息判据方法。该方法不需要通信设备的参与,仅靠本地的故障信息进行区内外故障判别,不受交直流混联系统功率倒向的影响,并利用频率修正算法对故障电流进行修正。利用PSCAD软件建模仿真验证了该方法的有效性。

Directional protection strategy of power inversion caused by chain fault of AC/DC hybrid system

Aiming at the adaptability problem of directional pilot protection under power inversion caused by the chain faults in AC/DC hybrid system, taking the single-phase grounding fault with high incidence of AC lines as an example, based on the analysis of the influence of the transition resistance on power inversion and frequency offset of the fault current, a local information criterion method based on compensating voltage mutation is proposed according to the relationship among the bus voltage mutation, fault point voltage mutation and compensation voltage mutation. The proposed method can distinguish internal and external faults only by the local fault information without the participation of communication equipment. It is not affected by the power inversion of the AC/DC hybrid system and can modify the fault current by frequency correction algorithm. The validity of the proposed method is verified by the modeling simulation in PSCAD software.