Assumptions Made During Transient Stability Studies
1.Transmission line and synchronous machine resistances are neglected. Since resistance introduces a damping term in the swing equation, this gives pessimistic results.
2.Effect of damper windings is neglected which again gives pessimistic results.
3.Variations in rotor speed are neglected.
4.Mechanical input to the generator is assumed constant. The governor control loop is neglected. This also leads to pessimistic results.
5.The generator is modelled as a constant voltage source behind a transient reactance, neglecting the voltage regulator action.
6.Loads are modelled as constant admittances and absorbed into the bus admittance matrix.
The above assumptions, vastly simplify the equations.