Calculation method for sub-frequency harmonic compensation of APF under multiple synchronous rotating reference frames

The invention discloses a calculation method for sub-frequency harmonic compensation of an APF under multiple synchronous rotating reference frames. The calculation method comprises the following steps that after two-phase Clarke transformation is carried out on system voltage, positive-sequence Park transformation and negative-sequence Park transformation are carried out respectively, so that DC components VPd and VPq under a positive-sequence coordinate system and DC components VNd and VNq under a negative-sequence coordinate system are obtained, positive-sequence and negative-sequence decoupling filtering processing is carried out on the DC components VPd and VPq under the positive-sequence coordinate system and the DC components VNd and VNq under the negative-sequence coordinate system at a D_Couple module, and therefore the feedforward quantity of reference voltage output by the APF is obtained. Phase-locked loop calculation is used for obtaining the phase of the system voltage, so that the phase of the feedforward quantity of the reference voltage output by the APF is provided. Compared with the prior art, the method has the advantages that the calculation method for sub-frequency harmonic compensation of the APF under the multiple synchronous rotating reference frames prompts that each order of harmonic current is independently processed and quickly responded, and it is guaranteed that compensation for each order of harmonic is independently set.