Francis,Eligard, KOmari, Arthur M., John, John.P2025-03-042025-03-042022https://repository.must.ac.tz/handle/123456789/266This Journal Article was published by Scientific Research Publishing .A grid connected microgrid connects to the grid at a point of common coupl ing. Due to the great inertia of the grid which accelerates and decelerates the generator when its frequency tends to deviate, the grid connected microgrid operates at a frequency of the infinity bus. Frequency instability is one of the major challenges facing the grid connected microgrid during islanding. The power demand variation causes the variation in rotor speed, resulting to fre quency deviation. Frequency can be brought back to standard by varying the power generation to match with the varying load. The performance of the fre quency stability control system at Mwenga hydroelectric microgrid has been studied. Through site visitation, the power demand and generation status da ta were collected and analysed for model preparation. The results of the study indicate that, during islanding, the Mwenga rural electrification project is ob served to be subjected to power imbalance which leads to frequency instabili ty. Although the frequency control system tries to keep the system at a no minal frequency by maintaining the continuous balance between generation and varying load demand, however the system still operates with large mag nitude of overshoot, undershoot and longer settling time.enArticle