工频–雷电冲击叠加电压检测GIS金属尖刺缺陷有效性研究

气体绝缘封闭式组合开关设备(gas insulated switchgear,GIS)在电力系统具有广泛应用,GIS运行过程中金属尖刺缺陷严重威胁其绝缘可靠性。然而,高电压等级下金属尖刺缺陷难以被传统现场试验检出。该文提出工频-雷电冲击叠加电压检测法。首先构建工频-雷电冲击叠加电压实验研究平台,针对工频-雷电冲击叠加电压下金属尖刺缺陷放电特性进行研究,继而研究工频-雷电冲击叠加电压检测金属尖刺缺陷方法有效性。结果表明:当交流电压(UAC)大于起晕电压时,同极性叠加导致击穿电压(Us)增大,反极性叠加导致Us减小。叠加相位对Us的影响稍滞后于工频波形。随不均匀度增加,曲线平台期缩短直至消失。在交流电压135°叠加负极性雷电冲击电压,GIS金属尖刺缺陷放电电压最低,外施电压较雷电冲击试验下降24.9%,可以有效检出缺陷。

Research on the Effectiveness of Detecting Metal Spike Defects in GIS Under Lightning Impulse Superimposed Power Frequency Voltage

Gas insulated switchgears(GIS)are widely used in electrical power system.In practical operation,its insulation reliability is inevitably threatened by the metal spike defects.However,it's difficult to detect metal spikes at high voltage levels by traditionnal on-site tests.This paper presents a test method using combined voltage of AC and lightning impulse(LI)voltage.Firstly,an experimental platform was constructed to facilitate the controllable superposition of power frequency and LI voltage at any phase,and the discharge characteristics of metal spike defect under power frequency superimposed with LI voltage was studied.Then,the effectiveness of this method was studied.The results show that,when the AC voltage(UAC)is higher than corona inception voltage,the breakdown voltage(Us)increases with homo-polar superposition,and decreases with reversed-polar superposition.The influence of the superimposed phase on Us lags behind the AC voltage waveform.With the increase of unevenness,the platform period gradually shortens until it disappears.Superimposing the negative lightning impulse voltage at the 135°phase of AC voltage makes the lowest discharge voltage of GIS metal spike defect,which decreases applied voltage by 24.9%compared with lightning impulse withstand voltage test and can effectively detect insulation defects.