Voltage profile improvement in power systems - A review

Voltage Stability is a severe problem in power systems, which steadily reach operating limits imposed by economic and environmental conditions. Whenever there is a change in load the system voltage level changes. With the drop in voltage level, the reactive power demand increases. If the reactive power demand is not met, then it leads to further decline in bus voltage resulting in the cascading effect on neighbouring regions. Hence to maintain the voltage profile within permissible limits becomes essential. This paper reviews various methods and techniques with their advantages and limitations adopted to retain the voltage level. The review presents sensitivity based control strategies, Control based on structural characteristics of power system, secondary voltage control strategies, design and optimal placement of FACTS devices using various optimization algorithms for VAR compensation.