【摘要】 换流变压器绝缘材料电导率受电场强度、温度和压力等因素影响,即呈现非线性特性。为了考查非线性对换流变压器极性反转电场分布的影响,针对电导率对电场强度的非线性,对绝缘纸板和油的电导率非线性特性进行了数值拟合,并用于分析1台±500kV换流变压器的非线性极性反转电场。线性和非线性媒质条件下的计算结果表明,考虑1min极性反转的过程时,线性媒质中反转完成时刻的油中最大电场强度值同瞬间完成极性反转的数值结果几乎相同,而非线性条件下反转完成时刻的油中最大电场强度值要比瞬间完成极性反转的数值结果小50%。针对这一现象,进一步对非线性条件下空间电荷加速重新分布的过程进行了分析。更多还原

【Abstract】 The conductivity of insulation oil and paper of the converter transformer is influenced by electric field strength,temperature and pressure etc.In order to study the influence of electric dependent conductivity on electric field distributions,the nonlinear characteristics between electric field strength and conductivity of the oil is fitted by an exponential curve.Using the new nonlinear curve,the transient nonlinear electric field of a ±500 kV converter transformer under PR(polarity reversal) voltage is calculated by the C-N(Crank-Nicolson) method.The numerical results under linear and nonlinear conditions show that,when we consider the 1 minutes duration of the PR process,the linear maximum electric field strengths at the end of the ramp voltage of the PR are almost equal to the results under the step voltage,while the nonlinear maximum electric field strengths at the end of the ramp voltage of the PR are about 50 percent less than the results under the step voltage.The phenomena of the less value under the nonlinear condition are explained by the acceleration of the space charges under the electric dependent conductivity.更多还原