Use of series and shunt FACTS devices to improve first swing stability limit

The series and shunt FACTS devices are usually used to control the bus voltage magnitude and line power flow, respectively. By placing these devices at appropriate locations, the electrical output power of the critical machine that initiates instability can dynamically be controlled. This feature of series and shunt FACTS devices is fully exploited in this study to improve the first swing stability limit of the critical machine and hence the overall power system. Following a large disturbance, the first swing stability limit of the critical machine is improved by increasing its electrical output power as much as possible by operating the FACTS devices at full capacitive ratings in early part of the post fault period. Afterwards, the control is switched to continuous type to improve damping in subsequent swings. The justification of using such a control strategy is described in a recent article. The above technique of improving the first swing stability limit is then tested for some faults in the 10-machine New England system and the results found are systematically described