This thesis describes the use of nonlinear adaptive control to design the cooling system ofrnhydropower generators. The increasing load demands are posing serious threats to reliablernoperation of power systems. These days, in the light of the attention given to reduction of carbonrndioxide emissions and efficient usage of raw materials, high-efficiency electric generators are inrnthe lime light over the world. As all losses generate heat it is important to have a cooling systemrnthat can maintain a sufficiently low operating temperature within all parts of the generator. rnrnThe objective of this research was to model, design and simulate a reliable and efficient coolingrnsystem for hydropower generators using nonlinear adaptive control. As the load on a generatorrnvaries with time, the generators heat dissipation also varies. This variation in the heat causes therntemperature of the air surrounding the generator in the closed generator room to vary. In thisrnthesis this variation of temperature is studied and heat transfer analysis method is used torndetermine the heat loss of the generators. Following that appropriate size of butterfly valve isrnchosen which is driven by a DC servomotor and a tubular heat exchanger is designed usingrndimensionless number analysis method which includes determining the Reynolds number,rnPrandtl number, and Nusselt number. Then the required amount of cooling water is suppliedrnthrough the tubular heat exchanger according to the load on the generator. rnrnIn this research the cooling system is designed to keep the generator temperature below 50 rnC inrnother words keeping the temperature of the surrounding air inside the generator room below 27 rn0rn0rnC. Matlab Simulink software is applied for performance analysis of the designed coolingrnsystem. The simulation results show that the designed cooling system keeps the surrounding airrnat a temperature of 27 rnC with a settling time of 0.6 seconds and without any overshoot when itrnexceeds this set point (27 rn0rnC). For this study we choose the Koka Hydropower Plant and thernrequired data for the design is collected from there. The butterfly valve opening angle forrnadjusting the valve at the desired position in order to allow the required flow rate is related withrnthe temperature of the generator room in a non-linear way specifically having an exponentialrnrelation. Thus an ANN controller is used which accounts for this process nonlinearity so thatrnincreasing model robustness and reducing the generator stoppage time due to cooling systemrnfailure. This results in increasing the efficiency of the hydropower plant as a whole.