Voltage Stability Improvement Method of Multi-port Energy System Based on Impedance Remodeling

To solve the voltage instability problem caused by a large number of power electronic converters connecting to the same dc bus in multi-port energy control system, a voltage stability enhancement method based on impedance remodeling is proposed. The impedance models of power conversion units with different topologies are bulit respectively. The variation rules of source load impedance under different control modes and working conditions are analyzed, and the reason for the instability of bus voltage and its unstable frequency band are obtained. On this basis, the low frequency disturbance bus voltage instability is corrected, and the impedance remodeling control strategy based on sag control is adopted. According to the characteristics of different provenances, the output impedance was reshaped respectively. The idea of impedance reshaping is to reduce the impedance near 100Hz when the source discharge is in a low frequency band, which effectively increases the stability margin of bus voltage and improves the stability of the dc bus. Finally, the effectiveness of the proposed method is verified based on the PLECS simulation platform.