An improved LCL filter control strategy based on instantaneous reactive power theory

Traditional LCL filters control harmonics using multi-rotating coordinate system transformation and PI regulators, and resonant control schemes are also employed. But these have a drawback: as harmonic orders increase, the computational burden rises. The new control strategy is based on instantaneous reactive power theory and comprehensively uses proportional-integral control, proportional-resonant algorithm, and repetitive control algorithm to achieve optimized LCL control with fixed calculation. The repetitive control algorithm can effectively compensate for model and steady-state errors caused by periodic disturbances. Dynamic and static experiments on the LCL experimental platform show that the newly-developed predictive current control scheme has good control performance in both steady-state and load-changing conditions and can achieve compensation for high-order harmonics.