Design Of Distributed Battery Energy Storage System

The social life habit leads to a certain regularity of the grid demand in the time dimension.It shows that the electricity demand is usually concentrated in users’ active period and the grid current will remain at a high level for a long time.Eventually,it led to the contradiction that the load of the distribution network is too heavy during the peak period and the electricity is surplus during the valley period.The uneven distribution of electricity demand will bring many harms.The country also proposed a policy for peak–to–valley electrical energy,which did not wholly change the imbalanced of electricity demand in the time dimension,but increased the cost of living.In order to alleviate the pressure on the distribution network during peak periods,increase the utilization rate of electric energy and reduce household electricity energy costs.The paper proposes a distributed battery energy storage system based on lead–acid batteries to realize the secondary utilization of distribution network energy.The system stores electricity energy during the valley electricity period and meet the demand of user equipment electricity energy during peak period.The system consists of charging circuit,discharge circuit,control circuit and energy storage battery.The charging circuit adopts parallel boost APFC and half–bridge LLC resonance DC–DC step–down circuit to realize grid energy conversion into low–voltage direct electricity.the charging circuit power up to 2000 W and the efficiency up to 92%.The discharge circuit adopts a push–pull DC–DC boost circuit,and unipolar SPWM full–bridge DC–AC circuit to convert the energy storage battery’s energy into220V/50 Hz AC electricity,the discharge circuit power up to 2000 W and the efficiency up to 90%.The energy storage battery adopts the 4–section of DJM12100 S lead–acid battery pack produced by Lishi Company.The control circuit uses STM32F407ZGT6 as the main control chip,based on the UCOSIII embedded real–time operating system to realize the functions of working mode switching,battery information collection,TFTLCD touch screen and WIFI communication control.Finally,the system meets the expected goals through independent performance testing of the charging and discharging circuits and the overall function verification.