特高压GIS开关设备电磁波衰减特性及在线监测传感器布点方案研究

Research on the Attenuation Characteristics of UHF Electromagnetic Waves Inside UHV GIS Switchgear

特高压气体绝缘金属封闭开关设备(gas insulated switchgear,GIS)在壳体内部布置在线监测传感器,用于实时监测局部放电产生的特高频电磁波信号,然而特高频电磁波信号在GIS内部传播时会产生不同程度的衰减,若在线监测传感器布置不合理,则可能无法发现衰减后的特高频电磁波信号,尤其是如断路器与隔离开关气室等内部组部件繁多的开关设备,特高频电磁波的衰减过程更为复杂,无法通过简单的经验公式进行计算。因此有必要对特高压开关设备内部电磁波的衰减特性及在线监测传感器布点方案开展研究。根据国内主流型号的特高压开关设备的实际结构尺寸,建立三维等比例的电磁场仿真模型,对300~1500 MHz频率范围内的特高频电磁波信号在其内部的衰减特性进行分析,结果显示,由于众多组部件对电磁波信号的衰减作用,特高压断路器气室的平均传输系数比隔离开关气室低10 dB左右。之后在满足相邻两个传感器之间平均正向传输系数不小于-70 dB的基础上,进一步研究特高压开关间隔在线监测传感器的布点方案,结果显示,一个开关间隔内需要在两个电流互感器(current transformer,CT)气室及靠近出线分支的过渡气室共布置3处传感器。研究结果可为特高压GIS在线监测传感器的布点选择提供借鉴。

Online monitoring sensors are installed inside the enclosure of the UHV gas insulated switchgear(GIS)for real-time monitoring of ultra-high frequency(UHF)electromagnetic wave signals generated by partial discharge.However,the UHF electromagnetic wave signals will attenuate to varying degrees,while propagating inside the GIS.If the online monitoring sensor arrangement is not reasonable,it may not be sufficient to detect the attenuated electromagnetic wave signals,especially for switchgear with numerous internal components,such as circuit breakers and disconnector chamber.The attenuation process of electromagnetic waves is more complex and cannot be calculated through simple empirical formulas,therefore,it is necessary to conduct research on the attenuation characteristics of electromagnetic waves inside UHV switchgear and the layout scheme of online monitoring sensors.This article established a three-dimensional scale simulation model based on the actual structure and size of domestic mainstream UHV switchgear,and analyzed the attenuation characteristics of electromagnetic wave signals within the frequency range of 300~1500 MHz.The results showed that due to the attenuation effect of many components,the average propagation coefficient of the UHV circuit breaker chamber was about 10 dB lower than that of the disconnector chamber.Therefore,it is necessary to meet the requirement that the average forward propagation coefficient between two adjacent sensors is not less than-70 dB,which provides a basis for further research on the layout scheme of online monitoring sensors for UHV switchgear intervals.The results showed that three sensors need to be arranged in two CT chambers and the transition chamber near the branch within a switch interval,which could provide references for the online monitoring sensor placement for UHV GIS.