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.