TABLE OF CONTENTS Knowledge of the initial conditions is critical to the solution of most power system transients. The electromagnetic transient packages usually include some type of frequency domain initialisation program [1] [5] to try and simplify the user's task. These programs, however, are not part of the electromagnetic transient simulation discussed in this book. The starting point in the simulation of a system disturbance is the steady-state operating condition of the system prior to the disturbance.
The steady-state condition is often derived from a symmetrical (positive sequence) fundamental frequency power-flow program. If this information is read in to initialise the transient solution, the user must ensure that the model components used in the power-flow program represent adequately those of the electromagnetic transient program. In practice, component asymmetries and non-linearities will add imbalance and distortion to the steady-state waveforms.
Alternatively the steady-state solution can be achieved by the so-called ' brute force' approach; the simulation is started without performing an initial calculation and is carried out long enough for the transient to settle down to a steady-state condition. Hence the electromagnetic transient programs themselves can be used to derive steady-state waveforms. It is, thus, an interesting matter to speculate whether the correct approach is to provide an 'exact' steady state initialisation for the EMTP method or to use the latter to derive the final steady-state waveforms. The latter alternative is discussed in this chapter with reference to power quality application.
A good introduction to the variety of topics considered under 'power...
