10 kV交直流配网弧光过电压特性分析

小电阻接地是提高交直流配电网保护灵敏性、降低过电压水平的有效手段。弧光接地过电压威胁设备绝缘,因而分析该问题对交直流配网安全运行具有重要价值。通过搭建交直流混合配网,在10 kV交流侧模拟发生配电网弧光过电压场景,研究了交直流电网过电压水平和故障穿越特性。首先基于PSCAD/EMTDC仿真软件搭建了柔性直流配网仿真模型,构建了弧光接地过电压数学模型;然后,仿真交直流混合配网系统发生故障后非故障相过电压故障响应曲线,分析了交流侧发生单相接地故障时,零序、负序分量造成的弧光过电压穿越特性;最后,通过对比分析不同接地电阻条件下交直流电网过电压数据获得了其变化规律,结果表明接地电阻为6Ω时对过电压的抑制效果最佳。

Analysis of Arc Overvoltage Characteristics of 10 kV AC/DC Distribution Network

Small resistance grounding is an effective means to improve the protection sensitivity of AC and DC distribution network and reduce the overvoltage level.Arcing grounding overvoltage threatens equipment insulation,so it is of great value to analyze this problem for the safe operation of AC and DC distribution network.In this paper,an AC/DC hybrid distribution network is built to simulate the arc overvoltage scenario of the distribution network on the 10 kV AC side,and the AC/DC power grid overvoltage levels and fault ride-through characteristics are studied.Firstly,based on PSCAD/EMTDC simulation software,a flexible DC distribution network simulation model and arc grounding overvoltage mathematical model are built.Then,the overvoltage fault response curves of the non-fault phase after the AC/DC hybrid distribution network system fails are simulated,and the arc overvoltage ride-through characteristics caused by zero-sequence and negative-sequence components when a single-phase ground fault occurs on the AC side are analyzed.By comparing and analyzing the overvoltage data of AC and DC power grids under different ground resistance conditions,the change rule is obtained.The results show that the effect of suppressing overvoltage is the best when the ground resistance is 6Ω.