电力变压器操作冲击试验时等效电容的计算

Equivalent Capacitance Calculation of Power Transformer in Switching Impulse Test

用感应法对电力变压器进行操作冲击试验时,为了预测操作冲击电压的波形是否满足要求,以及为了估计电压效率,需要先求出变压器受压时的等效电容值。文中推荐使用电压比平方折合法来计算等效电容,根据变压器理论中阻抗在原、副边间的折合原理,先将绕组对地(或其他绕组)电容换算到其顶端对地的等效电容,再将变压器高压侧的电容折合到低压侧。对单相和三相变压器的一些接线方式,文中给出了等效电容的计算方法和结果,相比其他方法文中方法更为简单和方便。

When the power transformer is subjected to the switching impulse test using inductive method, it is neces- sary to find the equivalent capacitance value of the transformer with voltage, for the purpose of predict whether the waveform of switching impulse voltage meets the requirements and estimating the voltage efficiency. This paper recommended the use of the converting method by square value of voltage-ratio to calculate the equivalent capacitance. According to the principle of equivalent impedance between the primary and secondary side of the transformer theory, the capacitance of the winding to ground（or to other winding） is first converted to its top to ground, then the capacitance of high voltage side will be equivalent to the low voltage side. For various connection modes of single phase and three phase transformers, the calculation methods of equivalent capacitance and calculation results are given. Compared with other methods, the method introduced in this paper is simpler and more convenient