为保证电压源换流器型高压直流输电(voltage sourced converter-HVDC,VSC.HVDC)系统的可靠运行,提出一种基于分布参数模型的VSC-HVDC输电线路单端行波自动化故障定位方法。在1模故障分量网络中,电压行波具有以下2个特点:行波反射会改变极性,折射不改变极性;行波在两端直流母线处会发生全反射,在故障点处则折射大于反射。据此可以得出,测点接收到的所有电压反行波中,来自对端母线第1次反射的反行波是最强的正极性反行波。进而可以根据电压行波首次到达本端测点和对端直流母线处第1次反射的反行波到达测点的时间差实现故障定位。PSCAD下的仿真结果表明,本算法原理正确,具有较高的定位精度,最大误差不超过600m,且理论上不受过渡电阻的影响,更重要的是无需人工识别行波波头,易于实现故障定位的自动化。
To ensure the reliable operation of voltage sourced converter-HVDC (VSC-HVDC) transmission system, based on distributed parameter model and using one-terminal traveling wave an automatic fault location method for VSC-HVDC transmission line is proposed. In one mode fault component network, high frequency component of voltage traveling wave possesses two properties as the following: the polarity of voltage traveling wave will be changed due to the reflection and does not depend on the refraction; total reflection of voltage traveling wave occurs at both DC busbars of two-terminal HVDC transmission system and at the fault point the refraction of traveling wave is stronger than the reflection. Accordingly, among all backward voltage traveling waves arrived at the measuring point, the backward voltage traveling wave due to the first reflection at the opposite busbar is the strongest backward traveling wave, and then the fault location can be implemented according to the time difference between two moments: one is the moment when the voltage traveling wave arrives at local measuring point for the first time, and the another is the moment when the backward traveling wave due to the first reflection at opposite DC busbar arrives local measuring point. The PSCAD-based simulation results show that the principle of the proposed algorithm is correct and using this algorithm the fault location accuracy is higher, that is, the maximum fault location error is not more than 600 m, and the proposed algorithm is not affected by transition resistancetheoretically. Besides, the most important feature of the proposed algorithm is that it is no need to artificially recognize the wavefront of the traveling wave and the automation of fault location is easy to implement by use of the proposed algorithm.