计及不确定变量的过电流保护配合优化

Optimal coordination of overcurrent protection relays considering uncertainties

目前,过电流保护的整定优化配合主要是在参数确定状态下研究的,然而,故障电流可能导致电流互感器(CT)变比改变,线路参数也不是完全恒定。因此,需要研究在参数不确定时的过电流保护配合问题。提出利用区间变量表征CT变比和线路参数的不确定性,从而进行过电流保护配合优化。分析了优化过程中需要考虑的区间变量,给出了过电流保护配合优化模型,从而确定了区间线性规划模型。针对保护动作时间上下限的求解,提出利用蒙特卡洛模拟法求解,并与线性规划算法共同求解继电保护优化变量。最后在8节点系统中进行了仿真分析,对比不考虑不确定性的情景,说明了计及不确定性的意义以及蒙特卡洛方法的准确性。

At present,the optimal coordination of the overcurrent protection is mainly studied under the deterministic parameter.However,the fault current may cause the current transformer(CT)ratio to change,and the line parameters are not completely constant.Therefore,it is necessary to optimize the coordination of overcurrent relays when the parameters are uncertain.In this paper,interval variables are used to characterize the uncertainty of CT and the uncertainty of line parameters,so as to optimize the overcurrent protection coordination.Firstly,the interval variables that need to be considered in the optimization process are analyzed,and then the overcurrent protection coordination optimization model is built,solving by the interval linear programming model.For the solution of the upper and lower limits of the protection operation time,Monte Carlo simulation method is used.Finally,the simulation analysis is carried out in an 8-node system.The comparison of the case without considering the uncertainty illustrates the significance of considering the uncertainty and the accuracy of the method.