应用解析法分析中性点接地系统中的工频铁磁谐振——非线性电感工频励磁特性的求取

STUDY OF FUNDAMENTAL FERRORESONANCE ON NEUTRAL-GROUNDED SYSTEMS BY USING ANALYTICAL METHOD-SOLUTION TO THE POWER FREQUENCY EXCITATION CHARACTERISTIC OF NONLINEAR INDUCTORS

分析工频铁磁谐振时,选择正确的非线性电感励磁特性类型至关重要。通常使用常规励磁特性,由于电压或电流含有高次谐波分量,结论不可靠。该文介绍两种方法来滤除常规励磁特性中高次谐波而求解工频励磁特性。方法一用EMTP进行模拟,得出工频励磁特性上的一些离散点;方法二利用级数法,推导出工频励磁特性的解析表达式。在工频励磁特性的饱和区域(谐振发生区)两种方法所得结果相吻合。

It is vital to choose the right excitation characteristic of the nonlinear inductor when analyzing ferroresonance. The traditional excitation characteristic (TEC) has been commonly employed. Due to the voltage or current harmonics in the TEC, the analysis does not necessarily lead to a correct conclusion. To filter out the harmonics and hence obtain the power frequency excitation characteristic (PEC), two methods are presented in this paper. One is fulfilled by EMTP simulation, which results in discrete points of the PEC. The other is based on series technique, and an analytical expression is achieved to approximate the PEC. The two methods match well in the saturated region (ferroresonant region) of the PEC.