Novel Multiple-Loop Composite Control Strategy for Active Power Filter

Active power filter is a reliable and effective technology for harmonic elimination and reactive power compensation. Based on the traditional control strategy for detecting load harmonic current, a new multiple-loop composite control strategy is proposed. The new control strategy has five control loops, which are used for calculating reference voltage signal of the inverter by detecting the load harmonic current, the supply harmonic current, the output harmonic current of the inverter, the DC bus voltage and the supply voltage synchronously. They are contributed to harmonic suppression and reactive power compensation, suppress high frequency oscillation between the supply and the active power filter, control DC bus voltage of the active power filter and adjust the reactive power supplied from the active power filter, respectively. In order to prove the performance of the new control strategy, the simulations has been done by using PSCAD / EMTDC. Results indicate the optimal effect for harmonic suppression and reactive compensation and the proposed control strategy is suitable entirely for the 3-phase sinusoidal and non-sinusoidal power systems. It is shown that the new control strategy has good prospect of application.