磁势不均布的变压器绕组漏电抗计算

Calculation of Leakage Reactance for a Transformer Windings with Uneven Distribution of magnetic Force

研究了高压线圈饼式、低压线圈圆筒式且“HV- LV- HV”排列的变压器绕组的漏抗计算并给出了一种不均布磁势的等效变换方法。分析了线圈饼数和线饼间气隙对漏电抗影响的结果表明,线圈饼数较少时,横向漏磁使得电抗值随气隙的增大而迅速增加,但线饼数达到一定值以后趋势变缓。用有限元法计算漏磁场分布的基础上求得的电抗值验证了本方法。

The transformer windings which are made of pancake and helical coils for the primary and the secondary respectively have uneven distribution of magnetic-force, and produce the radial component of magnetic field which should be considered in the calculation of leakage reactance. In this paper, a leakage reactance calculation is done in the transformer windings with the above configurations and concentrically arranged HV-LV-HV on a core limb, and an equivalent transformation is proposed about the uneven distributed magnetic force, furthermore, the effect is analyzed on the leakage reactance by the coil pancake number and the gap lengths among coil pancakes. The investigation shows that the fewer the number of the coil pancakes, the faster the leakage reactance changes with the gap lengths among coil pancake number. When coil pancake number reaches some value, the leakage reactance changes little with the gap lengths. Finally the method is verified by the result based on the calculation of leakage magnetic field distribution by finite element method (FEM).