Dynamic voltage stability improvement using coordinated control of dynamic VAR-sources

Fast voltage collapse is a new phenomenon in today's stressed power system. To prevent fast voltage collapse sufficient amount of compensation from dynamic reactive sources such as generator, condenser, SVC and STATCOM are needed. This paper presents a new controller (called Power System Voltage Stabilizer or PSVS) for dynamic voltage stability enhancement of power systems and/or prevention of fast voltage collapse. The PSVS is implemented through coordinated control of dynamic reactive sources. For implementation of a PSVS, the given power system is first divided into several small Voltage Control Areas (VCAs) each of which include several loads and several dynamic reactive sources. Then for each VCA, a Dynamic Voltage Stability Index (DSVI) is defined that includes the voltage deviations of all load buses within the area. Finally, a coordinated control of all dynamic reactive sources of the area is used to improve the dynamic voltage index during voltage emergencies. The proposed method is applied for a modified IEEE 14-bus system and tested for severe voltage emergency. The simulation results obtained from PSS/E software package indicate significant improvement in dynamic voltage stability of the system.