新型变压器三角形侧绕组环流计算方法

A New Method of Calculating Circulating Current in Delta Windings of Transformers

Y,d接线变压器三角形侧绕组电流对励磁涌流识别方法的性能有很大影响,利用绕组电流实现的算法能大幅提高变压器保护的性能。指出了目前三角形侧绕组环流计算方法的不足。首先给出了一种新的电流互感器配置方案,然后在变压器回路方程的基础上推导了星形侧零序电流和三角形侧环流的关系式,利用星形侧相电流和零序电流的组合得到各相的拟合励磁电流,并用相关技术来描述拟合励磁电流的特征,根据相关系数的大小确定星形侧零序电流和三角形侧环流的比例系数,进一步即可通过零序电流计算环流。该方法无需知道变压器各侧绕组的参数,不受断路器合闸时刻的影响,易于实现。ATP仿真实验结果验证了该方法的正确性和有效性。

The performances of the inrush current identification methods are influenced by the winding currents on the delta side of transformer windings.Algorithms based on winding currents can be used to improve the performance of transformer protection.The drawbacks of the present method of calculating the circulating current are discussed.Firstly,a new current transformer configuration is presented,and the relationship between zero sequence current on the star side and the circulating current on the delta side is derived based on the transformer voltage loop equations.The per phase inrush current is fitted with the combination of phase current and zero sequence current.The correlation formula is used to describe the characteristics of the fitted magnetizing currents,and the ratio between zero sequence current and circulating current is determined according to the value of the correlation coefficient.The circulating current can then be obtained.This method does not need the parameters of the windings and is not affected by the different switching phase angles.It can be easily realised in practice.The usefulness and correctness of the presented method are verified by the ATP simulations.