基于电磁时间反演的VSC-HVDC系统架空线-电缆混合线路故障定位方法

针对传统故障定位方法无法应用于架空线-电缆混合直流线路的问题，提出了一种架空线-电缆混合直流线路的故障定位方法，该方法采用先确定故障点所在区段、后在区段中定位的原理。利用故障附加网络的直流分量定义了故障区段判别函数，通过该判别函数在不同区段发生故障时数值不同实现故障区段的判定。然后，分析了电磁时间反演理论在故障定位中的可行性，分析确定了故障特征谐波。利用线路两端特征谐波的电流行进波作为时间反演电路的电流源，设置与原线路拓扑结构镜像的线路，利用时间反演电流源与镜像线路构建时间反演电路。在此基础上，根据时间反演的能量聚焦特性列写故障区段内的故障定位方程并实现区段内故障定位。利用PSCAD/EMTDC搭建的电压源型换流器高压直流输电(VSC-HVDC)系统仿真证明了所提方法能实现线缆混合直流输电线路的故障定位。

Fault location for overhead and cable hybrid transmission line in VSC-HVDC systems based on EMTR

Aiming at the issue that the traditional fault location methods cannot be applied to overhead and cable hybrid direct current(DC) lines, a fault location method is proposed, which uses the principle of first determining the fault segment and then locating the fault point in the fault segment. The fault segment decision function is defined using the DC component of the fault additional network, and the fault segment is determined based on the different numerical values of fault segment decision function when fault occurs in different segments. Then, the feasibility of electromagnetic time reversal(EMTR) theory in fault location is analyzed, and the fault characteristic harmonics are determined. The current propagating wave of the characteristic harmonics at both ends of the line is taken as the current source of the time reversal circuit, the line mirrored with the original transmission line topology is set, and the time reversal circuit is constructed by using the time reversal current source and the mirrored line. On this basis, the fault location equation in the fault segment is established according to the energy focusing characteristics of time reversal circuit, and the fault location is realized. The simulation is carried out with a voltage source converter based high voltage direct current(VSC-HVDC) system simulation model built on the PSCAD/EMTDC platform, and simulative results show that the proposed fault location method is effective.