Inductively Loaded Current Controlled Solid-State Lead-Lag Var Compensator: Special Feature and Performance

An electronic current-controlled lead-lag var compensator, which can be used as a low cost excitation controller for a brushless Self-Excited Induction Generator (SEIG), has been critically evaluated. The compensator uses a dc inductor, which has inherent resistive element. This resistance plays a special role in the operation of the compensator. Depending upon the critical value of the resistance, the compensator may change its modes of operation from lag var region to lead var region and vice versa for switching delay angle of around 90°. A mathematical model has been developed to find out the expression of the critical resistance. The effects of other parameters such as commutating capacitor, variations of supply frequency and voltage etc. on the performance of the compensator have also been presented.