某电厂220kV线路高阻接地故障分析及其改进研究

Analysis and Improvement Research of the 220 kV Line High-resistance Grounding Fault of a Hydropower Project

线路经高阻接地是电力系统中较难发现的一类故障,通常发生在导线与树木、草地、沙石等高阻抗物体接触的时候,此时故障电流幅值较小,并且电压变化幅值不大,导致以纵联距离和纵联零序为主体的主保护在发生故障时无法迅速动作,判别难度大大提高,增加设备的损坏程度[1]。本文通过对某电厂两起220 kV线路经高阻接地的保护动作逻辑进行分析,针对保护配置、系统运行方式、保护动作结果进行理论分析,并结合保护动作波形图和故障时系统等效图进行论证,提出提高继电保护运行可靠性的改进方法,提升电力设备的安全运行水平。

The high-resistance grounding of the line is a type of fault that is difficult to find in the power system.It usually occurs when the conductor is in contact with high-resistance objects such as trees,grass,and sand.At this time,the fault current amplitude is small,and the voltage change amplitude is not large,so that the main protection with longitudinal distance and longitudinal zero sequence as the main body cannot act quickly when a fault occurs,the difficulty of discrimination is greatly improved,and the degree of damage to the equipment is increased.This paper analyzes the protection action logic of two 220 kV lines in a power plant through high-resistance grounding,theoretically analyzes the protection configuration,system operation mode,and protection action results,and combines the protection action waveform diagram and fault system equivalent diagram to demonstrate,puts forward an improvement method to improve the reliability of relay protection operation,to provide a reference for the operation analysis of other similar power plants,and improve the safe operation level of power equipment.