Comparison of signal processing methods for estimation of network impedance for remote protection

The improvement of selectivity and velocity of the protection systems in energy supply networks is investigated. The structure and the functioning of the electronic distance protection relay in an analog switching technique are described, and calculation possibilities for asymmetric defects are presented. A network short circuit model was developed to depict the influence of nonlinear and nonideal signal distortions. Comparative examinations of several impedance identification processes in the frequency and time areas are carried out. The linear differential equation for a condition model is solved by filtering and with linear estimation processes based on the least squares method and recursive processes. Autoregressive and moving average formulations for perturbation models are presented. The difference in convergence behavior of the studied processes is found to be neglectable.