<p>The optimization of power and frequency control in off-grid small hydropower plants is critical for ensuring system stability, particularly during islanding operations. This study presents a comparative analysis of control governor systems designed for power and frequency optimization in such scenarios for Hhaynu Small-hydropower plant in Mbulu—Tanzania. The research evaluates conventional control system using Proportional-Integral-Derivative (PID) control action alongside other control system strategies, including model Pseudo-derivative (PDF) controller, Mechanical system controller and Load control based system. Key performance metrics such as response time, frequency deviation, power quality, and adaptability under varying load conditions have been assessed through simulations and comparative analysis. The key findings reveal that Proportional-Integral-Derivative (PID controller demonstrate superior performance with the fast (quickest) stability response time (few seconds) in mitigating frequency deviations and maintaining optimal power output, especially during transient states caused by sudden load changes or system disturbances. The results analysis also shows a close similarity in terms of stability response time between Proportional-Integral-Derivative (PID and Pseudo-derivative (PDF) controller while Mechanical and Load controller demonstrates a delayed (slow) stability response time (several seconds). This study provides valuable insights into the selection and implementation of effective control strategies to enhance the reliability and efficiency of small hydropower plants operating in isolated environments.</p>