限制单极接地故障过电压的关键因素分析

Analysis on the key factor that can impose restrictions on single-pole ground fault over voltage

直流输电系统十分适合远距离与大功率输电,作为直流线路中最常见的一种故障,接地故障会产生严重的过电压,需要对限制此类过电压的关键因素进行研究。在分析特高压直流输电线路单极接地故障过电压形成机理与现象的基础之上,明确了输电线路结构与参数、杆塔接地电阻、线路中点杆塔装设避雷器、输电线路长度与输送功率等影响该过电压的一般因素,并对其关键限制因素直流滤波器主电容进行了重点分析。结果显示,直流滤波器主电容值应控制在2μF的范围内,这样可基本保证单极接地故障过电压不超过额定电压的1.7倍。

Direct current transmission system is excellent for remote and high-power generating,as a most common fault in DC transmission line,earth fault can generate severe over voltage,it need to make a research on those key factors that can impose restrictions on this type of over voltage.On the basis of the formation mechanism and phenomenon analysis on uhv dc transmission line single-pole ground fault over voltage,the paper specifies the general factors that can influence the over voltage,they are transmission line structure,parameter,footing resistance and so on.And then,the paper makes an selective analysis on the key factor that can impose restrictions on single-pole ground fault over voltage about dc filter main capacitance.Result shows that,it should be controlled in 2μF,that can guarantee single-pole ground fault over voltage less than 1.7times rated voltage.