并联型多端混合高压直流线路故障区域判别方法

对于并联型多端混合高压直流输电系统,直流线路故障区域的判别对于最小限度地隔离故障从而提高直流系统的可用度具有重要意义。为此,针对并联型多端混合高压直流输电系统中换流站并联接入这一特有结构,分析了其对故障暂态行波的影响。研究表明,并联接入的换流器对中低频段的故障行波有大幅削减。因此,利用小波变换对暂态电流进行分析,提出了基于T区两侧暂态电流能量差的故障方向判别原理,进而利用各换流站故障方向信息确定故障区域。最后,建立了四端混合高压直流输电系统的PSCAD/EMTDC仿真模型,验证了所提方法的正确性和有效性。

Fault Area Discrimination Method for Parallel Multi-terminal Hybrid HVDC Line

For the parallel multi-terminal hybrid HVDC transmission system, the discrimination of DC line fault area is of great significance to minimize the isolation of fault and improve the availability of DC system. In view of the unique structure of parallel connection of converter stations in the parallel multi-terminal HVDC transmission systems, the influence on transient traveling waves is analyzed. The research shows that the parallel connection converter has greatly reduced the fault traveling wave in the middle and low frequency band. Therefore, the wavelet transform is used to analyze the transient current, and the fault direction discrimination principle based on the energy difference of transient current on both sides of the T zone is proposed, and the fault area is determined by the fault direction information of each converter station. Finally, the PSCAD/EMTDC simulation model of four-terminal hybrid HVDC transmission system is established to verify the correctness and effectiveness of the proposed method.