Study on the Coordinated Control Strategy of Electric-hydrogen Microgrid

Hydrogen energy is regarded as an important trend in the future of the energy field because of its environmental protection, high energy density and long-term storage characteristics. With the addition of hydrogen energy to the DC microgrid, the electrolysis hydrogen production unit can absorb photovoltaic energy in a long cycle and on a large scale. In order to ensure the reliable and stable operation of this electric-hydrogen DC microgrid, it is particularly critical to develop a set of appropriate control strategies. General electricity-hydrogen micro grid coordination control strategy is widely used system converter combined droop control, through the droop coefficient of different units, the current value as the characteristics of power change, after the two compared with the given power value, to complete the power distribution between the units, realize the network power balance, but the droop control strategy may reduce the dc bus voltage control ability. In some cases, the stability of the bus voltage may be sacrificed to maintain power balance. In this study, a system-level coordinated control strategy based on the bus voltage signal, uses the DC bus voltage signal for regulation. By analyzing the operation characteristics and basic control strategy of each unit in the microgrid, the DC bus voltage is subdivided into five levels and six intervals, and the converter adopts five different working modes in these intervals, so as to realize the balanced distribution of power within the DC microgrid. The correctness and stability of the theoretical analysis and the proposed control strategy are verified by simulation.