Combined System for Harmonic Suppression and Reactive Power Compensation

In this paper, a combined system of static Var compensator (SVC) and active power filter (APF) was proposed. The system has the function of power factor correction, voltage stability, and harmonic suppression. The SVC, which consists of delta-connected thyristor-controlled reactor (TCR) and Y-connected passive power filter (PPF), is mainly for voltage stability and power factor correction. The small rating APF is used to filter harmonics generated by the nonlinear load and the TCR in the SVC and to suppress possible resonance between the grid and the PPFs. The configuration and principle of the combined system were discussed first, and then, the control method of the combined system was presented. An optimal nonlinear proportional-integral control was proposed to improve the dynamic response and decrease the steady-state error of the SVC. Harmonic detection with precompensation method and improved generalized integrator control were proposed to improve the performance of APF. The new combined system is compared to classical SVC. It is implemented in a 200-kVA prototype in the laboratory. Simulation and experimental results show that the proposed combined configuration can effectively stabilize system voltage, correct power factor, and suppress harmonic currents.