选相关合技术抑制空载变压器励磁涌流的实验研究

Experimental research on inrush current suppression of unloaded transformers based on the controlled switching

针对随机关合空载变压器产生励磁涌流的问题,采用选相关合技术来抑制励磁涌流。在分析选相关合空载变压器原理的基础上,研究了同时合闸策略、快速合闸策略和延时合闸策略下铁芯磁通的变化规律,并对比分析三种合闸策略的适用条件。最后搭建选相投切10 kV空载变压器实验平台,对有无剩磁时不同关合相位下的励磁涌流进行分析。实验结果表明:变压器铁芯无剩磁时,在电压峰值处合闸可以有效抑制励磁涌流;铁芯存在剩磁时,在电压峰值处合闸仍会产生励磁涌流。因此,有必要预测铁芯剩磁以确定最佳合闸相位,实现空投变压器的无冲击平滑过渡。

Random energiziation of unloaded transformers may generate inrush current, In order to solve this problem, controlled switching technology is used for suppressing the inrush current. Based on the analysis of the principle of controlled switching of unloaded transformers, the changing laws of magnetic flux under circumstances of simultaneously, rapidly and delayed closing strategies are studied, and the applicable conditions of the three closing strategies are compared and analyzed. Finally, the test platform for controlled switching of 10 kV unloaded transformer is built and the inrush currents under different closing phases are analyzed when residual flux is zero or not. Tests results show that closing at the voltage peak can effectively reduce the inrush currents when the core has no residual flux; but inrush current still can be generated when the core has residual flux. Therefore, it is necessary to estimate the residual flux in order to obtain the optimal closing phase and realize the no impact transition of energizing unload transformer.