Reactive power compensator with switched-LC networks

Static compensators based on thyristor controlled reactors (TCR) are well suited for power factor correction under sinusoidal supply voltage and time-varying load situations, but they inject unwanted harmonic currents in the electric lines. Passive RLC networks can be the best choice to avoid this problem, but they are unable to follow load changes. Thus, a new reactive power compensator consisting of a set of parallel LC branches, which can be automatically switched, is proposed. This permits operation under nonsinusoidal conditions and time-varying loads. A control system, which measures the equivalent admittance on the load side, and sets the optimal LC configuration to minimize the reactive component of the line current, has been used. So, the synthesized compensator presents an equivalent harmonic-susceptance which is approximately equal (as given by its discrete structure) to that of the load (with opposite sign) within the adequate frequency margin. The results of numerical simulation and experimental results are presented.