基于系统等值阻抗的变压器抗短路能力核算

为评估在运的大型电力变压器抗短路能力水平,确保电网安全稳定运行,文章提出了一种基于系统等值阻抗的变压器短路电流核算方法。在对变压器高中侧的外部系统进行等值基础上,通过已知的母线短路电流和变压器参数反推系统的等值阻抗,然后根据系统阻抗和变压器参数求得各种短路情况下流过变压器的短路电流。仿真及实例验证说明了算法的准确性,应用算法可以实现对变电站各种方式下短路电流的快速批量计算。使用文章提出的方法对母线短路电流、变压器并联数量等因素对变压器短路电流的影响进行了分析,并结合制造厂提供的短路电流限值对变压器的抗短路能力进行评估,为生产管理部门的技术改造提供技术参考。

Short-Circuit Current Calculation of High-Voltage Transformers Based on System Equivalent Impedance

The paper proposes a new algorithm for the calculation of high-voltage transformer＇s short circuit current.This algorithm transforms the power system outside substation into equivalent networks,and the equivalent system impedance is computed from the bus short circuit current and the transformer parameters.The equivalent impedance and transformer parameters are used to calculate the short circuit current through transformer windings.The algorithm is valid by time domain simulation and real fault records.The influence of bus short circuit current and the parallel operation manner of transformers on winding short current are analyzed using the algorithm.The winding short circuit currents of transformers in use are calculated and the short circuit resistibility are analyzed by comparing the winding current with the limited value proposed by manufactures.The measures to improve the short circuit resistibility are also suggested.