带间隙线路避雷器雷电冲击绝缘配合特性极性效应研究

Study on Polar Effect of the Lightning Impulse Insulation Coordinating Characteristic of Transmission Line MOA with External Series Gap

部分现行线路避雷器标准仅规定了正极性雷电冲击50%放电电压的上限值,但是在线路避雷器试验及检测过程中,发现负极性雷电冲击电压下线路避雷器与绝缘子串的绝缘配合裕度明显低于正极性,按正极性雷电冲击放电电压进行配置的线路避雷器,在遭遇负极性雷电时,可能出现保护裕度不足的问题。为验证这一现象,基于110kV线路避雷器和绝缘子串开展了大量的研究性试验,并在此基础上建立了放电过程仿真模型,得出线路避雷器的负极性雷电冲击50%放电电压和伏秒特性曲线均明显高于正极性,这种极性效应主要由线路避雷器串联间隙引起。

Some current standards of the transmission line MOA only specify the upper limit of the 50% positive lightning impulse discharge voltage, but during the test and detection, the margin of insula- tion coordination between MOA and insulator under the negative lightning impulse is lower than under the positive lightning impulse. It may not adequate if configuring the MOA only using the positive light- ning impulse. To verify this phenomenon, based on 110 kV line lightning arrester and insulator string, a large amount of research tests are carried out, and the simulation model of the discharge process is estab- lished~ The results show that the 50% negative lightning impulse discharge voltage and volt second char- acteristic curve are obviously higher than the positive polarity. This polarity effect is mainly caused by the series gap of the lightning arrester.