Harmonics Suppression and Stability Improvement for Power Router in Nonideal Grid Conditions: A Multiport Passivity-Based Collaborative Control Scheme

The multiport power router (PR) is becoming an indispensable part of modern power systems. However, in the case of severe three-phase voltage imbalance and grid voltage distortion, it becomes challenging to simultaneously suppress harmonics on both the ac side and the dc side merely by relying on the grid-tied port. Consequently, this article proposes a multiport passivity-based collaborative control (PBCC) scheme considering simultaneous suppression of ac and dc harmonics, takes the grid-connected port (GTP), energy storage port (ESP), and ac load port of PR as the research objects. First, only through the collaboration of GTP and ESP can the multiple goals of mitigating grid-side current harmonics, compensating for current imbalances, and eliminating dc-bus voltage ripple simultaneously be achieved. Therefore, the hybrid passivity-based control (PBC) laws for the GTP and ESP are reconstructed separately based on internal model control and resonance control. Then, a dc bus power compensation controller is also introduced, based on the collaboration of the GTP and ESP, which is capable of adaptively compensating for dc power based on varying grid voltage drop depths to suppress grid-side over-current. In addition, the impedance stability analysis of GTP, ESP, and dc bus are developed to verify the impedance matching between port–port and port–bus under the proposed PBCC scheme. Finally, a three-port-based PR prototype was built and tested, and the results proved that the proposed PBCC method can decouple the ac and dc harmonics of the PR system, exhibiting strong robustness and anti-interference ability compared with the existing control methods.