Abstract：Based on the low-speed communication network，a multi-energy storage operation method of DC

microgrid with improved power droop control was proposed so as to realize the balanced control in three aspects：

state of charge（SOC）balance，rational power distribution among energy storage units and stable bus voltage.

Firstly，considering that the operation of DC microgrid varies with the different system states，the operation mode of the system was divided into three working modes according to the state of energy storage unit and load. Secondly，in order to achieve the purpose of balanced distribution of SOC of each energy storage unit，an improved droop control method was introduced to modify the droop coefficient according to the size of SOC of energy storage unit. By increasing the voltage offset，the DC bus deviation was effectively reduced. Finally，the simulation model was built in Matlab/Simulink and the experimental platform was built in RTDS. The simulation and experimental results prove the effectiveness and correctness of the proposed control strategy.

      Key words：DC microgrid；droop control；state of charge（SOC）；low-speed communication