多种电流互感器暂态饱和特性及其复杂工况下动模试验研究

Study on multiple types of CTs transient saturation and its dynamic simulation tests in complex operating conditions

电流互感器暂态饱和易引发差动保护误动。现场大量投用的P级、PR级和TPY级电流互感器因结构和材料等差异表现出不同的暂态特性。针对这3种类型,选用工业实用电流互感器,通过实验测试和数学拟合的方法获取相关参数,得到铁芯磁通解析表达式,与实测饱和磁通对比判断饱和状态,获取进入饱和的时间。针对这3种实用电流互感器进行动模试验,考虑了系统单次短路、重合闸于永久故障、转换型故障以及励磁涌流等复杂暂态工况,分析了各自暂态饱和特性和特点。在理论分析和动模试验的基础上,简要讨论了电流互感器暂态饱和的应对方法及互感器选型问题。

The current transformer （CT） transient saturation easily leads to the misoperation of differential protection. The P-class, PR-class and TPY-class CTs which are widely used on site show different transient characteristics. For these three types, industrial practical CTs are selected, experimental test and mathematical fitting are carried out to get the relevant parameters and then obtain the mathematical expression of core flux. Whether the CT is saturated or not and when the CT get into saturation can acquired by comparing the expression with the measured saturation flux. Three types of industrial practical CTs are used to carry out dynamic simulation tests for single short circuit, reclosing in the permanent fault, conversion fault and magnetizing current. Their transient saturation characteristics are analyzed. On the basis of theoretical analysis and dynamic tests, the methods for CT transient saturation and the CT selection scheme are discussed.