Development of static and simulation programs for voltage stability studies of bulk power system

In the analysis and evaluation of power system voltage stability, it is necessary to accurately identify the stability margin at each load point under specific system configuration or power balance condition. The voltage stability margin can be basically identified by the multi-solution load flow calculation method. When predicted by this static analysis that voltage instability may occur, time domain simulation will be required which includes the models of various control equipment related with power system voltage profile. To deal with this, the following two analytical computer codes were developed: (1) a voltage stability static analysis computer code employing a new load flow calculation method; and (2) a time-domain long-term simulation computer code for voltage stability. These computer codes can also calculate the voltage stability index at each load point which is based on the margin to the stability power limit at each load point. The practicality of these codes developed were verified by applying to the IEEE-118 test system