利用低频故障分量F检验的直流输电线路后备保护新原理

A Novel Backup Protection Principle for DC Transmission Lines Based on F-Test of Low-Frequency Fault Components

直流输电技术发展迅速,但其线路保护还存在一些不足,电流差动保护作为后备保护易受线路分布式电容影响而延时较长。为解决直流线路后备保护的长延时问题,本文提出一种基于低频故障电流F检验的纵联保护新原理。该原理根据故障时线路两端故障电流变化趋势的差异,采用S变换提取低频故障电流,并利用F检验对其进行趋势检验,从而识别区内、外故障。利用双端直流输电系统模型实验证明了本文保护原理的正确性,并验证了该原理具有较强的抗过渡电阻、分布电容电流和噪声干扰的能力。

DC transmission technology is developing rapidly,but its line protection still has some shortcomings.As a backup protection,current differential protection is susceptible to the influence of line distributed capacitance and has a long delay.In order to solve the long delay problem of DC line backup protection,this paper proposes a new principle of pilot protection based on low-frequency fault current F-test.The principle is based on the difference in the change trend of the fault current at both ends of the line at the time of the fault.The S-transform is used to extract the low-frequency fault current,and the F-test is used to perform the trend test to identify the internal and external faults.Finally,the double-terminal DC transmission system model experiment proves the correctness of the protection principle and verifies that the principle has strong resistance to transition resistance,distributed capacitance and noise interference.