Application of Different Least Square Methods for Transmission Line Parameter Estimation

Estimation of line parameters is a mathematically demanding process that depends on constructional characteristics and surrounding environment. Modern transmission systems and smart grids require the most efficient methodology for line parameters estimation where dynamic system behaviour and time-dependent parameters have to be taken into account. The least squares method is one of the most important family of methods which are widely used for processing experimentally obtained data. Different variants of least squares methods for transmission line parameters are proposed in literature. Most of the methods proposed are tested on simulated data, adding noise and/or systematic bias to measured quantities. In this paper, three different least squares methods, ordinary least squares, improved ordinary least squares and total least squares, are analysed and applied to real measurement data from two 220 kV lines. Results of parameter estimation are compared to classical measurement solutions. Only the ordinary least squares method produces satisfactory results for analysed cases.