A 1-phase Static VAr Compensator with Low Current THD and Wide Control Range

A 1-phase Static VAr Compensator (SVC) topology is proposed using a tapped Thyristor Controlled Reactor (TCR) and a third harmonic tuned filter. The TCR is controlled by firing angle delay over a limited range initially and its tapping is changed to create operation using different equivalent value of effective reactance, such that the amount of harmonics generated is limited. The third harmonic filter attenuates the corresponding harmonics to low magnitude and also presents a capacitive reactance at the fundamental frequency for VAr compensation. Such an arrangement prevents the third harmonics from entering into the supply system while some major characteristic harmonics are kept limited, along with control of VAr through the TCR. Thus, without using any additional complex set of individual harmonic filters, or additional capacitor bank, this scheme enables reactive power control with a low current THD over a reasonable range of control, meeting requisite harmonics standards. Simplicity in construction and operational requirements of the proposed topology makes it a viable and cost effective solution. Its modeling, analysis and performance assessment are presented. Simulation and experimental results support the theoretical proposition.