Coordinated Voltage Fluctuation Suppression Strategy for MPET in Hybrid AC/DC Distribution Network Based on Dynamic Control Mode Switch

Due to the intermittent and uncertain nature of wind power and photovoltaics, voltage fluctuations frequently occur in hybrid AC/DC distribution networks. This paper proposes a voltage fluctuation suppression strategy using the flexible port control capability of the power electronic transformer (PET). Firstly, the control capability of PET ports on node voltage is quantified under grid-following and grid-forming control modes. Then, the impact of various combinations of multiple PET control modes on node voltage fluctuations is investigated. To calculate the corresponding relationship between control mode combinations and the outputs of wind and photovoltaic power, a dynamic combination switch optimization model for multiple PET control modes is developed. Subsequently, a two-layer control strategy is constructed to suppress voltage fluctuation in hybrid AC/DC distribution networks. Finally, the proposed strategy is validated using the improved IEEE33 test system of the hybrid AC/DC distribution network, and its effectiveness in mitigating voltage fluctuations is compared with traditional methods.