变压器油道内冲流电流的一种计算方法

A Computation Method for Streaming Currents in the Oil Ducts of Power Transformer

对紊流态下变压器油道内冲流电流的计算进行了研究。描述油内电荷分布的输运方程是一个非线性方程,不存在精确的解析解。应用文中所给定的绝缘油/纸板界面的边界条件并经过合理的简化,推出了该方程的近似解析解和冲流电流的计算公式。公式能描述油流速度、电导率、油温和外加交流电场对变压器油流带电的影响,所引入的修正量可通过实验数据确定。实验证明,计算公式可以用于预测冲流电流的大小,从而避免了繁重的数值计算,为变压器油流带电的计算提供了一种方便的手段。

The calculation of streaming currents induced by turbulent duct flow in a power transformer is studied. The equation describing charge distribution in oil is a nonlinear equation with no accurate analytical solution. By introducing the new proposed boundary condition at the oil/paper interface and based on some reasonable simplifications, an approximate analytical solution to the equation and a formula for streaming current are derived. The formula can describe influences of the flow velocity, conductivity, temperature and external electric field on streaming electrification and the correction variables in it can be determined with experimental data. It is proved with experiment that the formula can be applied to predict streaming currents, thus providing a convenient method to compute streaming electrification in power transformer that gets rid of the hard task of numerical calculation.