一种非对称输电线路参数的在线测量方法

An Online Measuring Method of the Parameters for Asymmetric Transmission Lines

针对输电线路参数在线测量方法存在不能对线路导纳参数及非对称输电线路参数进行测量的问题,提出了一种基于输电线路∏型模型的非对称输电线路参数在线测量新方法。该方法首先根据三相非对称输电线路的∏型模型,建立起线路参数计算的电路方程,然后针对该线路参数计算方程的欠定性,提出了一种独特的欠定方程求解方法。该方法通过对输电线路两端电压和电流进行多次测量,建立求解线路导纳参数的超定方程,应用复数域内的最小二乘法,推导出导纳参数的计算公式,并利用导纳参数,推导出线路阻抗参数计算公式。仿真结果表明,线路零序阻抗及导纳模误差分别为-0.011%、-0.119%,正序阻抗及导纳模误差分别为-0.005 1%、0.064%,远小于实际工程误差要求。该方法不仅可以求得输电线路的阻抗与导纳参数,以及线路的正序、负序、零序以及各序间的耦合参数,解决了线路参数在线测量法不能求解导纳及非对称线路参数的问题,还具有很高的计算精度,可为三相非对称输电线路参数的在线测量提供理论依据。

In view of the difficulty for measuring transmission line admittance parameters and asymmetric transmission line parameters in the existing online measuring methods,a novel online measuring method based on the ∏ model of three-phase asymmetric transmission lines is proposed.And the transmission line equations for parameter calculation are established,the underdetermined equations are solved with a new algorithm.The overdetermined equations for admittance parameters are established with multiple synchronous measurement signals of voltage and current on both sides of the transmission lines,and the calculation formula of admittance parameters for asymmetric transmission lines is derived by least square method,then the calculation formula of impedance parameters is derived according to the admittance parameters.The simulation shows that the errors of transmission lines zero sequence impedance and admittance reach-0.011% and-0.119%,respectively,the positive sequence impedance and admittance errors reach-0.005 1% and 0.064%,respectively,which are greatly less than the engineering requirement. This method enables to evaluate the impedance and admittanceparameters of transmission lines,positive sequence,negative sequence and zero sequence parameters of lines and coupling parameters among each sequence with higher calculation accuracy.