±500 kV鹅城换流站换流阀避雷器直流试验方法

DC Test Method of Converter Valve Arrester in±500 kV Echeng Converter Station

换流阀避雷器直流试验是检测其非线性伏安特性的主要方法,但换流阀空气间隙短、空间泄漏电流干扰导致直流升压有风险。提出了一种阀避雷器不拆引线直流试验方法,将整体加压改为中部并联加压,并设计屏蔽装置降低换流阀受冲击风险。通过等效电路计算放电条件下的电流电压分布,证明了屏蔽保护的换流阀不会受损;研究不同间距下加压点与屏蔽布间的空间泄漏电流,实测间距500 mm时放电几率较小,空间泄漏电流约15μA。鹅城站年度检修应用此方法后,成功诊断出鹅城站1支4 mA直流参考电压不合格的阀避雷器,并节省了试验时间34人·天,证明了该方法能有效应用于阀避雷器直流试验。

DC test of converter valve arrester is the main method to detect its nonlinear volt ampere characteristics,but the short air gap of converter valve and the interference of space leakage current lead to the risk of DC boost.A DC test method of valve arrester without removing the lead is proposed.The overall voltage application is changed to the middle parallel voltage application,and the shielding device is designed to reduce the impact risk of converter valve.The current and voltage distribution under discharge condition is calculated by equivalent circuit,which proves that the shielded converter valve will not be damaged;The space leakage current between the pressurization point and the shielding cloth under different spacing is studied.When the measured spacing is 500mm,the discharge probability is small,and the space leakage current is about 15μA。After the application of this method in the annual maintenance of Echeng station,a valve arrester with unqualified 4 mA DC reference voltage in Echeng station is successfully diagnosed,and the test time is saved by 34 people·day.It is proved that this method can be effectively applied to the DC test of valve arrester.