Dynamic and static analysis of the shunt capacitors control effect on the long-term voltage instability

This paper concerns the dynamic and static analysis of the effect of shunt capacitor control strategies on the long-term voltage instability. For this purpose a simplified test system called N3area, reflecting the key voltage instability characteristics of NORDIC32 is considered. Two different control strategies for shunt capacitors including the local and neighboring schemes are applied to improve the voltage control in the system. First the dynamic simulation results for a specified long-term voltage instability scenario are explained and discussed then the static investigation is conducted based on the PV curves and it is shown that the neighboring scheme injects more reactive power to the system. Afterward, based on the modal analysis technique and V-Q sensitivity analysis, it is demonstrated that the possibility of involving the most critical buses from voltage stability perspective in the capacitors connection decisions are much higher in the neighboring scheme compared to the local one. The two strategies are explained and compared in both dynamic and static analysis and it is shown that control using the voltage at neighboring buses gives better performance.