Abstract :
IN THE analysis of power systems it is customary to represent generators, transformers, and transmission lines by their equivalent circuits. The resulting circuit network is solved either by representation on a network calculator, from which the solution is read directly, or analytically by successive simplification of the network. When the network has been simplified as far as possible, it is usually relatively easy to solve the simplified network, by the application of Kirchhoff´s laws, for the currents in the remaining circuits and the voltages at the remaining terminals. When this solution has been obtained, the steps of simplification are reversed until the original network is restored, the currents and voltages being calculated at each step, until the desired quantities are finally obtained for the original network. When the system is unbalanced, as by an unbalanced fault condition, the method of symmetrical components is widely used. Equivalent networks are derived for the positive-, negative-, and zero-sequence components of current and voltage. Interconnections between the sequence networks are made, corresponding to the unbalanced condition, and the resulting network is solved by the methods just described.
