Analysis of a novel active filter for balancing and reactive power compensation

This paper presents the analysis of a three-phase active filter (AF), which establishes the superiority of PI control over other existing control techniques for power factor compensation and load balancing. A three-phase IGBT-based voltage source inverter with a DC bus capacitor is used as an active filter. An hysteresis-based carrierless PWM current control over the supply currents is employed resulting in reduction of load current sensors and derived gating signals are fed to the devices of AF. Thereby AF currents are such that they force supply currents to remain sinusoidal under varying load conditions. Continuously varying unbalanced lagging power factor load is considered as a sample load. A detailed dynamic model of the complete system is developed to study the steady state and transient behaviour of the active filter. This type of AF is also capable of converting single phase large RL loads into three phase balanced loads and eliminates the use of a transformer. Simulated results for the cases of single-phase, two-phase and three-phase loading are presented and discussed in detail to demonstrate the reactive power compensation and load balancing capabilities of the AF. The response of proposed AF with PI control is quite fast. It is envisaged that this compensator has great potential in several applications like supply utilities, process industries and cavity power generation systems