用于内部故障分析的变压器电感参数计算模型

针对电力变压器内部故障分析和保护的需要，详细分析了现有模型中确定电抗参数或电感参数存在的问题，指出问题的关键是没有考虑到发生内部短路故障之后，变压器内部的漏磁场分布发生了变化，因而用变压器没有故障时的漏电抗或漏电感推算发生故障后的模型参数是不正确的。在此基础上，提出了一种满足磁势平衡关系并且适用于具有任意截面形状和大小的线圈的漏电感计算模型。

AN INDUCTANCE CALCULATION MODEL OF POWER TRANSFORMER FOR INTERNAL FAULT ANALYSIS

For the purpose of precious internal faultanalysis and relay protection of the power transform er,some problem s in the existing m odels are pointed out.The key problem is that the difference of the leakage m agnetic field distribution between normal operation and fault condition has not been taken into account.Therefore,the original short circuit reactance or leakage inductance of the transformer can't be used to develop the model param eters of the faulty transformer.This paper presents a new method to determ ine the leakage inductance of a power transformer. Based on the principle of linear superposition of the leakage magnetic field,the leakage inductance of the faulty transform er is firstly calculated on the basis of the geom etric dim ensions of the windings by subdividing windings into several sections according to the fault location.Then, the obtained inductance m atrix will be m odified according to the conceptthat the sum of the am pere- turns of all harmonics in the transformer windings is equal to zero.The application of the proposed m ethod has shown that the method has the flexibility and sufficient precision in the internal fault analysis.