International Research Publication House
During the past two decades, the increase in electrical energy demand has presented higher requirements from the power industry. More power plants, substations and transmission lines need to be constructed. However, the most commonly used devices in present power grid are the mechanically-controlled circuit breakers. The long switching periods and discrete operation make them difficult to handle the frequently changed loads smoothly and damp out the transient oscillations quickly. The demands of lower power losses, faster response to system parameter change and higher stability of system have stimulated the development of the Flexible AC Transmission Systems (FACTSs).