Dynamic voltage stability reserve studies for deregulated environment

This paper first analyzes why voltage instability occurs in mature yet competitive power systems, and then investigates diverse voltage stability issues in deregulated power markets using the EUROSTAG commercial transient simulation program. Dynamic behaviors of major power system components, i.e., speed governor, excitation element, inductive motor, ULTC and mechanically switched shunt capacitor etc., are thoroughly examined by a small yet typical equivalent system. The presented simulation results help better understand the mechanism of the voltage collapse phenomena, and highlight the importance of dynamic reactive reserves, like generators, in dynamic voltage stability enhancement.