The battery is one of the vital components in the substation because the battery is the only component that is the source of DC current supply to the substation if there is a disturbance in the substation that causes the loss of the main AC current source. An example of the disturbance that most affects the process of distributing the electric power system at the substation is a blackout. A blackout can result in disruption of the process of distributing electric power at the substation and protection at the substation. The purpose of writing this research is to analyze the performance of the battery unit 1 110 V Substation 150 kV Duri Kosambi which experienced a decrease in battery capacity, knowing how to optimize the performance of the battery unit by using battery cells that are still in good condition with Matlab software simulation, knowing the performance of the battery unit after removing the damaged battery cells from the battery unit circuit. From the results of the battery capacity test carried out, a value of 201 Ah from 300 Ah was obtained where the measured efficiency of the battery was 67% this was due to the
presence of 6 damaged battery cells so that a simulation experiment was carried out using Matlab Simulink to increase the efficiency of the battery unit's performance by using 78 battery cells. After the simulation, a battery efficiency value of 100% was obtained with a voltage value of 103 VDC from 110 VDC so that the load worked in under voltage conditions but in emergency conditions this method can still be done by prioritizing the supply from the battery unit to vital loads at the substation, but under normal conditions the load is not recommended to be supplied in under voltage conditions because it will shorten the life of the equipment