高压电力电缆护层感应电压的补偿研究

电力电缆敷设时常采用三段换位的方法以降低护层电压,但电力电缆线路改造时容易造成换位的电缆三段不等长,从而引起护层电压不平衡,产生护层环流。为解决此问题,通过对电缆护层电压的理论分析,推导了电缆单回路和双回路任意排列方式下的护层感应电压的计算模型;提出了在电缆终端加补偿装置(实际上为补偿电感器)的方法来平衡护层电压,抑制护层电流,其基本原理是将该补偿装置套装于电缆上,电缆中通过电流时,补偿装置产生感应电动势,利用该感应电势来抵消电缆护层电压。补偿电感的仿真计算表明,该法可有效减小电缆护层的感应电压,从而减小护层环流,大大减小电缆损耗。

Research on Compensation of Induced Voltage in the Metal Shield of the High-voltage Power Cable

In order to reduce the induced voltage of the metal shield in power cable,the method of three segments conversion is often adopted.But the unequal length of three segments will make the induced voltage of the metal shield unbalanced,and produce the circulating current in the metal shield when the power cable is renovated.According to analysis,the induced voltage models of the metal shield of power cable are deduced in this paper,these models include any arrangement way of the cable at single circuit and two-circuit.The method of adding compensating unit(in fact,compensating inductance device) at the end of the metal shield of power cable is presented,which can restrain circulating current.Its basic principle is that the compensating unit is set around the power cable,when current flows through the power cable,the induced voltage arises in compensating unit,the induced voltage is used to counteract the induced voltage of the metal shield.The calculation model of compensating inductance is derived,and emulation calculation are made.Research shows that the method proposed in this paper can reduce the induced voltage of the metal shield efficiently,reduce the circulating current in the metal shield,and decrease the loss of power cable greatly.