PI control has been the most common way to control the parameters because it is easy to set up and works well for controlling many different processes. However, the vast majority of conventional PI tuning approaches depend on trial and error for complicated processes with limited system knowledge, which may not give the ideal PI settings. In a number of situations, the tuning of PI controllers has been accomplished with excellent results by using optimization techniques. In this research, a simulation model of a hydropower plant was developed via MATLAB/Simulink software and the connection of models for the various power plant components. The objective is to determine how it performs and how it reacts to an unstable environment. By implementing a BWO (Black Widow Optimization) tuned PI controller, model voltage fluctuations have been reduced, while the voltage has been stabilized and errors have been minimized (MSE, MAE, MAPE, and RMSE).