一种10kV电压等级非接触式电压互感器研究

Research on a 10 kV voltage level contactless voltage transformer

与电磁式电压互感器相比,电力系统中常用的电容式电压互感器存在诸如耐冲击电压强度高、造价较低以及维护成本及工作量小等优点,但仍存在一些常见问题,例如所占空间大,所需绝缘设计水平高(与高压直接接触),恶劣环境下绝缘失效等问题。针对这些问题,设计一种适用于10 kV及以下电压等级的非接触式耦合型电压互感器。首先基于电磁感应原理,利用电压互感器测量端与电缆内芯、输电线路、绝缘套管内部引出引入线等形成的耦合电容充当高压端电容,利用电压互感器测量端与大地间形成的电容充当低压端电容。然后理论分析电压互感器电容对频率特性的影响,通过有限元仿真计算并优化耦合式电压互感器测量端与高压输电线之间的电场和电容。最后在单相10 kV电压等级输电电缆上进行试验,结果表明所设计的互感器可以准确、实时的测量电压,能够为建立智能电力系统、电网实时在线监测、继电保护现场运行提供参考。

Compared with electromagnetic voltage transformer,capacitor voltage transformer commonly used in power system has many advantages,such as high impulse withstand strength,low production cost and low maintenance workload.However,some common problems that large space occupation,high insulation design level required(contact with high voltage directly),and insulation failure in severe environment are still exist in capacitor voltage transformer.In order to solve these problems,a non⁃contact capacitor⁃coupling voltage transformer suitable for 10 kV and below voltage level is designed in this paper.Based on electromagnetic induction principle,the coupling capacitors formed between the measuring end of voltage transformer and the inner core of cable,the transmission line or the wire inside the insulating bushing are designed as the high⁃voltage terminal capacitance.The capacitor formed between the voltage transformer measuring end and the earth is acted as the low⁃voltage terminal capacitance.Then the influence of voltage transformer capacitance on frequency characteristics is analyzed theoretically.The electric field and capacitance between the measurement end of coupling voltage transformer and high voltage transmission line is calculated and optimized by finite element simulation.Finally,experimental test is carried out on a single⁃phase 10 kV power transmission cable.The results show that the designed voltage transformer is capable of measuring the voltage accurately in real time,which can provide references for the establishment of intelligent power system,real⁃time online monitoring of power grid and field operation of relay protection.