合闸750kV空载变压器引起的系统电压暂降现场实测与计算分析

Analysis on Field Measured System Voltage Sag Caused by Energizing 750kV No-Load Transformer and Its Simulation Comparison

结合新疆与西北750 kV联网工程乌北变电站合闸750 kV空载变压器现场实施情况,分析了合闸空载变压器引起系统工频电压暂降现象的机制,提出励磁涌流及系统短路容量是影响合空变电压暂降的主要因素。并利用EMTP工具对合空变引起的电压暂降进行仿真建模分析,得出的合空变励磁涌流及系统电压暂降特性与现场实测基本一致,验证了仿真方法的有效性。提出了采取断路器装设合闸电阻的措施可以有效抑制合空变操作引起的系统电压暂降,另外采取系统调压、调整系统运行方式、消除剩磁等措施也有助于缓解合空变电压暂降对系统运行造成的不利影响。

Based on the field implementation of energizing 750 kV no-load transformer located in Wubei substation within the 750 kV interconnection project of Xinjiang power grid and Northwest power grid,the mechanism of system power frequency voltage sag caused by energizing no-load transformer was analyzed and it was proposed that the inrush current and the short-circuit capacity of the interconnected power grid were the main factors influencing the voltage sag due to energizing no-load transformer.Using EMTP tools,the modeling and simulation analysis of the voltage sag caused by energizing no-load transformer were performed,and the obtained simulation results,namely the characteristics of system voltage sag and inrush current due to energizing no-load transformer,were basically conform to the results from field measurement,thus the effectiveness of the simulation was verified.It was proposed to install closing resistor in parallel with the circuit breaker to restrain system voltage sag effectively,besides,adopting such measures as regulating system voltage,adjusting operating modes of power grid and eliminating residual magnetism of the transformer would contribute to mitigate the adverse effect of system voltage sag on power grid operation.