Resonance analysis and active damping strategy for shipboard DC zonal distribution network

In this paper, an impedance analysis method and resonance suppression strategies are proposed for the distributed controlled DC zonal distribution network. By combining with the grid impedance model and the node impedance matrix, the resonance mechanism of shipboard DC distribution network is investigated. The resonance damping is estimated using an aggregated RLC circuit. The proposed method is validated by the time-domain small signal model. Moreover, a multi-bus analysis method is proposed for the stability assessment of the system with multi-parallel, multi-cascade and ring-type structure, and the influence factors on the resonance are investigated. Further, a voltage feedforward approach is introduced, which can adjust the impedance characteristic of line regulating converter (LRC) at the resonance-frequency band effectively. Besides, a virtual capacitor control strategy analogized with virtual synchronous generator (VSG) is proposed to enhance the system inertia. By analyzing the control system stability, the appropriate controller parameters are selected. The simulation results show the effectiveness of the proposed analysis method and the control strategies.