Digital computer solution of switching transients in transmission line models

Abstract

A transmission line may be subjected during switching to eletromagnetic stresses many times the normal levels. These excessive electromagnetic stresses damage power system equipment, transmission line hardware, transformers and generators. To protect power systems from excessive electromagnetic stresses, a prior knowledge of the maximum overvoltages that may develop is required.

Transient voltages and currents in a power system can be studied by either using miniature models called Transient Network Analysers (TNAs) or from digital solution of mathematical models. Existence of some very powerful transient analysis programs make the use of digital analysis approach relatively easier.

This thesis presents mathematical models of system components such as resistors, inductors, capacitors, transformers, generators, loads and lines. The theory of travelling waves and the trapezoidal rule of integration are used in the development of the models which are then tested for their validity. After verification of the validity of the models, switching transients in selected single phase systems are computed using a program developed by the author. Various system conditions are selected for these studies. The algorithm is then extended to compute transients in three phase transmission lines. The method of modal transformation is used in this algorithm. Various simplifying assumptions have been used in this work. The results are presented in the form of voltage/current waveforms as functions of time.