基于模域回路理论的配网电缆-架空线混合线路重合闸过电压特性分析

Analysis of Reclosing Overvoltage in Cable-Overhead Line Hybrid Line Based on Return Circuit Theory in Modal Domain

该文基于模域回路中波的传播特性与频率特性研究混合线路中电缆与架空线不同比例下重合闸过电压幅值和主导频率的变化规律。通过电报方程得到相模转换的变换矩阵,计算了模域中各回路的电压传播常数。并采用电磁暂态仿真软件(EMTP)建立10kV配网非对称结构的混合线路模型,研究了不同比例的混合线路统计过电压变化规律。结果表明,随着电缆占比的增加,暂态电压的变化并非单调下降,而是出现极小值。基于模域回路的分析结果与EMTP计算结果相符。由于传播常数不受线路长度影响,当线路总长度变化时,可采用同样的方法分析不同比例混合线路的重合闸过电压变化。

The amplitude and dominant frequency characteristics of reclosing overvoltage with different cable proportions in cable-overhead hybrid line were studied based on the wave propagation in modal domain.The propagation constants of 10 kV cable and overhead line(OHL)in modal domain circuit were obtained through modal transformation.Using electro-magnetic transients program(EMTP),an asymmetrical line model was established,and the variation tendency of statistical overvoltage under different cable proportions was investigated.The results show that statistical values vary non-monotonically and a minimum value appears when the cable proportion increases.The results based on voltage propagation in modal domain are consistent with those calculated by EMTP.This method can also be applied in hybrid lines with different proportions since the propagation constants are not influenced.