一种基于方向行波的多端VSC-HVDC系统保护策略

针对星型连接的多端柔性直流输电(VSC-HVDC)系统,提出一种基于方向行波小波能量比值的保护策略。首先分析了星型连接VSC-HVDC系统故障行波的传播特性,找出故障线路和非故障线路方向行波的不同传播规律;然后对电压和电流线模分量进行离散小波变换,计算相应线路方向行波的小波能量;最后通过各个线路正反向行波小波能量的比值确定故障线路。PSCAD/EMTDC仿真结果表明:提出的方法能够快速准确地判断星型拓扑VSC-HVDC系统的故障线路,并且不受故障线路、故障距离、故障类型和故障电阻的影响,具有很好的鲁棒性。

A Protection Scheme for Multiterminal VSC-HVDC System Based on Direction Traveling Waves

A protection scheme based on the ratio of energies of direction traveling waves is presented in this paper.Firstly,the propagation characteristic of fault traveling waves in a star-connected VSC-HVDC system is analyzed,and the different propagation law between fault and non-fault lines is studied.Then modal voltage and current are transformed in discrete wavelet transform (DWT),and wavelet energies of direction traveling waves are calculated.Finally,the fault line is determined by the ratio of positive and negative direction traveling waves.Simulation results of PSCAD/EMTDC show that the proposed method can identify the fault line quickly in the star-connected VSC-HVDC system.The proposed method is insensitive to different fault lines,fault distance,fault types and fault resistance,and has good robustness.