Passivity-Based Controller Design of LCL-Filtered Selective-Harmonic Resistive-Active Power Filter

Passive property of grid-tied converter's output admittance is widely recognized as favorable to stability. However, the admittance of active power filter (APF) is dependent on the nonlinear load (NLL) applied. Thus, the passivity-based design of APF is also dependent on the specific NLL. To deal with this problem, this article suggests replacing APF with resistive active power filter (RAPF) whose admittance is unrelated to NLL. Virtual impedance or virtual admittance control schemes are examined in this article. It turns out that none of them is stable. Then, a new control scheme is proposed which emulates desired virtual immittance at selected frequencies. Passivity-based controller design for proposed RAPF is then formulated. Meanwhile, a simpler calculation method for compensation angle of resonant controller is proposed. The effectiveness and correctness of the proposed control scheme is finally verified by experiments.