转子过负荷保护中转化系数选取问题研究

针对目前转子过负荷保护中励磁变的交流侧电流与直流侧电流转化系统电流多取0.816系数的问题,应用整流器变流过程中交直流侧的基波电流转化关系,推导出转化系数与触发角、换相角的函数关系式,计算出不同工况下交直流侧电流转化系数。根据仿真和理论计算结果,得出交直流侧电流转化关系应为0.78左右,该研究成果为转子过负荷保护参数整定提供较好的参数依据,有利于维护保护动作的准确性和设备安全。

Research on the selection of conversion coefficients for rotor overload protection

In most cases, 0.816, a coefficient of the conversion between current on AC side and current on DC side of an excitation transformer, is adopted in rotor protection. The conversion of fundamental current on AC and DC sides by rectifier is applied to derive a function among conversion coefficient, trigger angle and commutation angle to calculate the current conversion coefficient under different operating conditions. According to the simulation and theoretical calculation results, it is concluded that the coefficient of current conversion between the AC and DC sides is about 0.78. The research results provide a favorable reference for parameter setting of rotor overload protection, which is conducive to maintaining the accuracy of the protection action and equipment safety.