Voltage stability assessment of the National Grid system using modern analytical tools

The paper presents a three-step analytical approach to identifying voltage stability concerns using modern network analysis tools. The first step in the analytical approach is to develop a load flow model for contingency analysis. This allows the identification of system steady-state low voltages or voltage collapses following contingencies. The second step is to apply an optimization algorithm/model to determine the reactive margin, or the amount and location of reactive compensation required to eliminate the low voltages or voltage collapses. P-V or Q-V curves are generated for comparison in this step. The final step is to verify the voltage stability response to the contingencies via time-domain simulation, including the impact of different load models.