ABSTRACT

Analysis of power systems is based on mathematical representations for the electrical components used to generate power, distribute it, and consume it. In general, linear representations are used to study the behavior of the circuits due to small disturbances, then when appropriate, nonlinear models are employed to investigate response due to large disturbances. The circuit breakers, switchgear, and protective relays are not shown on this diagram because emphasis is on the elements that affect the steady-state transmission of power. All physical elements represented in the diagram are assumed to be three-phase and balanced, in the sense that impedances are equal in all phases, even though it is possible to carry out the subsequent analysis for the more detailed unbalanced case. There are transforms used in power systems, but the symmetrical component transformation is the most common. It is subsequently used for the unbalanced fault-current calculations on networks with balanced supply voltages.