中压电缆终端被广泛应用于柔性交流输电和作为逆变器和电机的连接中,这些电缆终端可能会遭受到高频谐波电压的冲击,从而导致其绝缘迅速失效.本文研制了模拟电网高频谐波电压和工频大电流的电热老化试验装置.首先,通过信号发生器和功率放大器产生低压大电流信号,再通过高频变压器升压获得高频高压;同时通过工频试验变压器产生工频高压,将工频高压和高频高压同时施加到样本上,形成叠加;并分别在两侧加以滤波器阻止高频和工频高压串入到低压系统;最后通过CT(电流互感器)施加150A左右的大电流模拟实际工况.通过实验和红外热成像结果分析,该装置有助于高频电压下的电缆终端绝缘老化研究.%Medium voltage cable terminations are widely used for flexible AC transmission (FACTS) and for conrnnecting terminations for electric motors driven by inverters. These cable terminations are possibly subjected to high rnelectrical stress because of high frequency voltage components. In this paper, an experimental setup was designed rnto test cable terminations insulation under high frequency sinusoidal voltage. A signal generator and a power amplirnfier were used to generate high frequency voltage and larger output power. The voltage was used for the input of rnhigh frequency transformer in order to generate high voltage. Also, work frequency high voltage was generated by rnwork frequency transformer. The two kinds of voltages were both applied to specimens at the same time. As a rernsult, a superposition waveform by high frequency and work frequency waveform was formed. Two filters composed rnof LC components were also needed. Furthermore, to simulate working condition, a current transformer is used to rnobtain 150A current. Through the analysis of experiment and thermal images, the experimental setup has positive rneffect on investigating insulation characteristics of cable termination.
展开▼
