Calculation of the extreme loading condition of a power system for the assessment of voltage stability

The extreme loading condition (XLC) of a power system is defined by assuming a load increase (according to a predefined pattern for both active and reactive powers) until a maximum is reached for one of the loads. The XLC is significant for the assessment of voltage stability. Its calculation, as presented, is based on increasing the load admittances while first keeping the generator voltage phasors constant and then adjusting these phasors for satisfying operational requirements with respect to the generation powers. The secant method is used for the efficient and reliable determination of the maximal value of the loading parameter μ, while for the voltage adjustment a fast convergent Newton module is employed. The XLC can be calculated for both normal operation and contingencies