Dynamic static VAr compensation and stability of HVAC-An outlook and trend

Static VAr compensators are reviewed for their application in transmission line compensation and load compensation. Emphasis is given to the application of thyristor controlled reactors and thyristor switched capacitors. After a quick review of the application of static VAr compensators, a detailed theoretical analysis of the reactive power requirement is made. A mathematical model of the compensator is established for the possible controllable parameters. In the theoretical analysis, both symmetrical line and radial line systems are considered. Stability of a transmission line is analyzed for reactive power compensation. Present trends are discussed for finer continuous reactive power control. Solid state reactive power compensation without the need for large capacitors and reactors is seen to be the most probable candidate. Solid state devices for high power capability and transient response along with other reactive power requirements are also discussed