Modern reactive power compensation for smart electrical grids

The Static Var Compensator (SVC) is a device of the Flexible AC Transmission Systems (FACTS) family using power electronics to control power flow on power grids. The SVC regulates voltage at its terminal by controlling the amount of reactive power injected into or absorbed from the power system. When system voltage is low, the SVC generates reactive power (SVC capacitive). When system voltage is high, it absorbs reactive power (SVC inductive). The variation of reactive power is performed by switching three-phase capacitor banks and inductor banks connected on the secondary side of a coupling transformer. Each capacitor bank is switched on and off by three thyristor switches (Thyristor Switched Capacitor or TSC). Reactors are either switched on-off (Thyristor Switched Reactor or TSR) or phase-controlled (Thyristor Controlled Reactor or TCR). The new challenges in the national romanian power system, namely the integration of very high electricity production from renewable sources and the concentration of wind power production in the South-East of the NPS (about 80% of the installed capacity in power plants) determines the change of power flows in short intervals time. Therefore, a fast voltage level adjustment is required and appropriate to the respective NPS mode of operation. In this paper, we present the influence of SVC, TCR model on the power quality improvement in smart electrical grids.