Design of automatic energy flow shift control system in standalone solar power system

Abstract

Based on a national survey in Indonesia done by SAIDI and SAIFI, in 2020, power outages occurred 12.72 hours or a total of 9.25 times per customer. However, this value is still far from the standard of electric power system service at SPLN and IEEE. Therefore, this study aims to design an automatic transfer switch (ATS) system that can automatically transfer energy flows between solar power and State Electricity Company (PLN) grid to meet electrical energy needs. The control method that will be designed makes it possible to turn solar power off-grid to become a backup for PLN electricity. The state of charge (SOC) on the battery is calculated using the Open Circuit Voltage (OCV) method. The solar power system in this study will work if the battery voltage is at 12.93 V (SOC 90%). Meanwhile, PLN grid will work when the battery voltage is at 12.08 V (SOC <40%) or has a percentage of 40%. Based on the test results, the ATS system has worked well where the system can transfer electrical energy sources automatically according to the logic that has been designed. Solar power can work for 5 hours 45 minutes during the test. The total time for using solar power shows that the efficiency level of using it reaches 42% of the total time of testing.