Binary controlled static VAr compensator, based on electronically switched capacitors

A binary control strategy for reactive power compensation, based on a chain of branches using unidirectional power switches is presented. This strategy allows, with an adequate number of compensating branches, a fine and precise control of reactive power in electric systems. The amount of reactive power is evaluated by storing the value of instantaneous line current during the “zero-crossing” of the mains voltage. Other characteristics of this control strategy are: (1) it does not generate harmonics; (2) it can compensate reactive power in an almost continuous form; and (3) inrush problems during connection and/or disconnection are avoided. The paper explains the control strategy proposed, the way it works and some results obtained under operation