【摘要】 准确判别出电流互感器(CT)饱和是区外故障还是区内故障引起的可提高母线保护的可靠性。区内外故障CT 饱和前存在线性传变性,在有效的数据窗内(通常取半个周波的数据作为差动保护判据的有效数据),饱和点前后差流与制动电流的大小和相位变化不同步,即饱和时刻超前于差动保护动作时刻,差流和制动电流变化量不一致,利用这种不同步关系文章提出了一种新的CT饱和判据,通过仿真和动模实验证明了该判据的可靠性,它可以有效避免因区外故障CT深度饱和而引起差动保护误动。更多还原

【Abstract】 The reliability of busbar protection will be improved if the reason causing serious saturation of CT in busbar protection, i.e., internal fault or external fault, could be correctly distinguished. When internal or external fault occurs, the CT signal can be linearly transmitted and transduced before CT saturation, and within effective data window (usually taking the data in half-period as the effective data for criterion of differential protection) the variations of magnitudes and phases of differential current and restraint current are not synchronous before and after the saturation of the CT, namely the moment when the CT is saturated is in advance of the moment when the differential protection acts, and the variation amount of differential current and that of restraint current are non-uniform. Using such asynchronous relation the authors propose a new saturation criterion of CT by which the maloperation of differential protection caused by serious saturation of CT can be effectively avoided. The reliability of this criterion is verified by digital and dynamic simulations.更多还原