A Harmonic Current Self-Compensation Control Strategy of DC Active Power Filter

Due to the diversity of nonlinear loads, the harmonic frequency of the dc microgrid is unpredictable, which poses a challenge to traditional dc active power filters (dc-APF). Firstly, the harmonic compensation mechanism and characteristics of the dc-APF with classical control strategy are analyzed. For the classical dc-APF, the voltage control and harmonic extraction are independent of each other, which may lead to their conflict and reduce the harmonic compensation performance. To address this issue, a harmonic current self-compensation control strategy of dc-APF is proposed, which uses a 1st-order inertia controller in the voltage loop and can simultaneously achieve voltage control and harmonic extraction. Then, the mechanism, characteristics, and parametric design method of the proposed harmonic current self-compensation control are introduced in detail. Compared with the classical dc-APF, the proposed dc-APF does not require any harmonic extraction filter and has better harmonic current compensation performance. Finally, the proposed control strategy and theoretical analysis are verified by simulation and experiment.