In order to stabilize the power fluctuation caused by distributed energy and load access to bipolar-type DC micro-grid

we proposed a control strategy for hybrid energy storage system（HESS） of bipolar-type DC micro-grid. First

according to the characteristics of bipolar-type DC bus

we designed a hybrid energy storage architecture consisting of double supercapacitors and lithium battery. Then

the operation state of the double supercapacitors was used to coordinate the work of lithium battery and voltage balancer in cascade control mode. In this way

the output current of the lithium battery was smoothed

and the frequency of the voltage balancer was reduced. At the same time

the adaptive droop curve of double supercapacitor was adjusted by setting the voltage reference value of the double DC bus. The experimental results show that the lithium battery and the voltage balancer can respond correctly to the operation of the double supercapacitors. The control strategy can effectively maintain the voltage level buses within the allowable fluctuation range

and achieve multiple complementary functions between the two buses. Therefore

the proposed strategy can further improve the power quality of bipolar-type DC micro-grid and the efficiency of the system can also be improved.