同步关合空载变压器抑制励磁涌流和过电压的研究

Research on Elimination of Inrush Currents and Over-voltages for Unloaded Transformer by Synchronous Closing

高压断路器在随机关合空载变压器时会产生幅值、频率很高的涌流和过电压,从而可能导致继保装置误动、变压器绕组机械应力增加和用户电能质量下降。采用同步开关技术选相关合空载变压器能有效减少励磁涌流和操作过电压。分析了空载变压器同步关合的原理和最佳目标关合相位确定,提出空载变压器铁芯剩磁计算方法,并采用最小二乘算法实现剩磁计算。最后,采用ATP-EMTP建立空载变压器同步关合仿真模型,验证了提出的空载变压器同步关合和铁芯剩磁计算算法有效性,为空载变压器的同步关合减少励磁涌流和过电压提供了理论基础。

The inrush currents and over-voltages generated by the random energization of unloaded transformer have undesirable effects,including protective relay misoperation,imposed sever mechanical stresses on the transformer windings and reduced power quality of the system.Synchronous switching technology of unloaded transformer can potentially eliminate these inrush currents and over-voltages.This paper analyses the theory of synchronous closing unloaded power transformer and the method of determination of the optimum instant is presented.A new method of estimating the residual flux is proposed and achieved by using the least square algorithm.Finally,the simulation model is established by ATP-EMTP software to verify the effectiveness of the synchronous closing technology for unloaded transformer and the algorithm of estimating the residual flux,and this provides a theoretical basis for the elimination of inrush currents and over-voltages of unloaded transformer by synchronous closing.