Using AC-fed PWM converters as instantaneous reactive power compensators

A general control method that fully utilizes the inherent capability of AC-fed PWM (pulse-width-modulated) converters to compensate for reactive and harmonic currents absorbed by other loads is presented. Suitable definitions of instantaneous active and reactive current and power terms are introduced. Optimum modulation laws are then derived according to a general control theory valid for PWM multiconverter systems, which also results maximum system efficiency. Simulated results demonstrate the capabilities of the proposed compensation method. This method can also be implemented in existing systems, since only modifications of the control section are needed.