电缆接头局部放电电磁仿真与多传感器联合检测

目前对于已敷设的电力电缆的局部放电检测,单一的采用高频电流法或超高频法都易受到现场干扰信号的影响。因此,为提高检测的有效性和准确度,文中采用高频电流法和超高频法联合检测的方法,通过对比两种检测结果中是否同时存在脉冲信号来相互鉴别去除干扰信号。对于其中的超高频检测,为了克服内置式传感器在已投运电缆中无法应用的局限性,采用了外置式传感器。其使用时面临着信号辐射出来及在空气传播过程中强度会有较大衰减的情况,针对这一情况结合用于三相交叉互联的电缆中间接头的屏蔽层是断开的这一特征,进行了建模仿真,验证了采用外置式传感器的可行性,得到了信号最强的传感器最佳安装位置。最后利用研制的传感器进行了现场实测,验证了仿真结论,并证明了联合检测的方法能够很好的甄别干扰信号与真正的局部放电信号。

Electromagnetic Simulation of Partial Discharge in XLPE Cable Joint and Multi Sensor Joint Detection

At present, taking a monolithic approach of high frequency current transformer (HFCT) method or ultra high frequency (UHF) method is susceptible for partial discharge detection in the power cable. Joint detection of HFCT method and UHF method is used to improve the effectiveness and accuracy of cable partial discharge detection. In the joint method, the impulse interference is removed by analyzing the simultaneity of two detection results of the pulse signal. The built-in sensor in UHF method cannot be applied to measure partial discharge of the cable in operation, so the external sensor is presented in this paper. In the process of using external sensor, the signal intensity has great attenuation after radiation out of cable joint and propagation in the air. For 110kV three-phase cross-bonded cable, the shield of cable joint is disconnected. Considering that, electromagnetic simulation is conducted to verify the feasibility of using external sensor and find the optimal placement. Finally, the sensors are used in on-site detection. The simulation results are proved to be valid and the joint detection is able to identify the interference signal and real partial discharge signal.