A new one-cycle controlled FACTS element with the function of STATCOM and active power filter

Active power filters and STATCOMs are indispensable elements in distributed generation (DG) power system. In recent years, research and applications of active power filter (APF) and STATCOM using voltage-source converters have attracted great attention due to the increased energy awareness in the world. Many topologies and control approaches have been reported. Previously proposed control methods realize only one function, either APF or STATCOM, furthermore they require fast and real-time calculation; therefore, a high-speed digital microprocessor and high performance A/D converters are necessary, yielding high complexity, high cost, and low reliability. The theory and experiments reported in [K. Ma Smedley, 1991] have demonstrated that one-cycle control is a unified PWM control method in the power electronics field. Functioning as an analog computer, it can control all basic power converters at low cost, simple circuitry and high reliability. In this paper a new control approach based on one-cycle control is proposed that realizes both APF and STATCOM's functions by controlling a three-phase voltage source converter. As a result, the cost for DC can be greatly reduced. Theory, simulation, and experiment have proved that the new control approach is a high performance and low cost solution for DG applications.