【摘要】 对特征阻抗和传播系数的有理函数拟合是考虑参数频变的输电线路建模中的关键步骤。传统的模域输电线路模型采用的Bode渐近线拟合法会产生大量零极点,其中一部分对提高模型精度没有作用并会导致电磁暂态仿真中产生不必要的计算。为避免冗余零极点的产生,提出了一种应用于频变输电线路模型中的低阶有理函数拟合方法。首先对线路特征阻抗和传播系数进行低阶零极点定位,然后用非线性最小二乘法提高拟合精度,从而实现对特征阻抗和传播系数的低阶有理函数拟合。对比Bode渐近线法的拟合结果,低阶拟合方法能够在保证拟合精度的同时降低拟合函数的阶数,从而提高电磁暂态计算效率。更多还原

【Abstract】 Rational function approximations of characteristic impedance and propagation coefficient are crucial in modeling of frequency-dependent transmission line. Traditional Bode asymptotic method produces lots of pole-zeros. Some of them have no contribution to fitting accuracy and cause unnecessary calculation in electromagnetic transient simulation. To avoid appearance of redundant pole-zeros, a low-order approximation method of frequency-dependent transmission line model is proposed. Firstly, low-order pole-zeros are located for characteristic impedance and propagation coefficient. Then approximation accuracy is improved with nonlinear least square method. Thus low-order rational function approximations of characteristic impedance and propagation coefficient are achieved consequently. Case studies show that compared to Bode asymptotic method, fitting with low-order approximation method is more accurate and rational function order is reduced, therefore electromagnetic transient simulation is accelerated.更多还原