基于低频无功的柔性直流输电线路纵联保护方案

柔性直流输电技术发展迅速,但其线路保护还存在一些不足。传统的电流差动保护易受线路分布式电容影响的问题尚未完全解决。为解决柔性直流线路保护存在的问题,本文提出一种基于低频无功方向的柔性直流输电线路后备保护原理。该原理利用直流无功刻画线路分布参数的频率特性,并根据故障时直流低频无功方向识别区内、外故障。仿真结果表明所提保护原理不受分布电容电流的影响、不需要严格的通讯同步且具备较强的耐受故障电阻和噪声干扰的能力。

A Pilot Protection Scheme of flexible DC Transmission Line Based on Low-frequency Reactive Power

Flexible DC transmission technology has developed rapidly, but its line protection still has some shortcomings. The problem that traditional current differential protection is easily affected by line distributed capacitance has not been completely re-solved. In order to solve the problems of flexible DC line protection, this paper proposes a backup protection principle for flexible DC transmission lines based on low-frequency reactive power direction. The protection principle uses DC reactive power to express the frequency characteristics of line distribution parameters, and identifies internal and external faults according to the direction of DC low-frequency reactive power. The simulation results show that the pro-posed protection principle is not affected by distributed capacitance current, does not require strict communication synchronization, and has a strong ability to withstand fault resistance and noise interference.