电力系统接地电阻精确测量仿真研究

摘要

An accurate measurement method of ground resistance in power system based on green function is proposed.The current in ground resistance is calculated via operating principle for ground resistance with series circuit breaker,and constrain condition required by average absolute value of current is worked out.Then excitation control mode with voltage drooping is used to obtain increment of branch current,and the maximum constraint value of incremeut of generator output current is acquired.The calculating equation of ground resistance with industrial frequency is obtained,and green function is used to calculate electric potential vector of electric charge density of each microsegment at any point.Finally,the coefficient of resistance is acquired via boundary condition.Simulation results show that the method has high measurement precision.It provide feasible gist for ensuring normal operation of electrical equipment.%对电力系统中接地电阻的精确测量,能够保证电力设备正常运行.接地电阻的精确测量,需要获取发电机输出电流增量的最大约束值,得到工频接地电阻计算方程,完成对接地电阻的精确测量.传统方法先组建一个电阻网络来等效实际接地网,将该问题进行转换,但忽略了工频接地电阻计算方程的求取.提出基于格林函数的电力系统接地电阻精确测量方法.上述方法通过附加接地电阻串联断路器的操作原理计算出接地电阻上的电流,计算出电流的平均绝对值需要满足的约束条件,采用电压下垂的励磁控制方式得到支路电流的增加量,获取发电机输出电流增量的最大约束值,得到工频接地电阻计算方程,利用格林函数方法计算各微段的电荷密度在任一点所产生的电位向量,利用边界条件求得电阻系数.实验结果表明,所提方法测量精度较高,为保障电力设备正常运行提供了可行的依据.