基于不平衡电流拟合的差动保护可靠性评估

电流差动保护广泛应用于电力系统,差动电流测量不准确将导致保护装置拒动或误动,严重影响大电网安全运行。为此,通过剖析差动保护不平衡电流产生机理,建立与其各支路二次电流和运行温度关联函数,并利用BP神经网络技术构建不平衡电流拟合模型,进而将不平衡电流实时拟合值与差动电流阈值对比,即可评估差动保护可靠性。算例验证所提方法的有效性,并提出整改措施。

Current differential protection is widely used in power system.Inaccurate measurement of differential current will lead to failure or misoperation of protection devices,which will seriously affect the safe operation of large power grid.For this reason,by analyzing the mechanism of the unbalanced current of the differential protection,establishing the correlation function with the secondary current and operating temperature of each branch of the differential protection,and using the BP neural network technology to construct the unbalanced current fitting model,and then by comparing the real-time fitting value of the unbalanced current with the differential current threshold,the reliability of differential protection can be evaluated.A numerical example is given to verify the effectiveness of the proposed method,and the rectification measures are put forward.