Under the isolated island mode of DC microgrid

in view of such shortcomings as frequent switching of energy storage control mode and large voltage fluctuation existing in the common hierarchical control

a kind of control strategy based on power signal discrimination is proposed in this paper.The DC microgrid composed of photovoltaic array

hybrid energy storage system and fuel cell is taken as the study object

the power magnitude and direction in DC microgrid are judged through real-time acquisition of information such as photovoltaic output power

DC bus voltage and current

and SOC（state of charge） of hybrid energy storage system.The balance state of system power of the microgrid is reached through coordinated control of various distributed power sources

thus keeping stability of DC busbar voltage.The simulation model is set up based on the simulation platform of Matlab/Simulink

the effectiveness of different mode switching control strategies in the microgrid is verified and it is shown that the control strategy is obviously superior to the commonly used hierarchical control strategy.