Thesis (M.S., Electrical and Computer Engineering) -- University of Idaho, December 2014 | High levels of intermittent renewable generation penetration, such as solar or wind, could lead to deviation of the power grid frequency from normal due to the randomness of the output of some renewable energy sources. Conventional peak load plants, i.e. gas turbine plants, lack of the ratings to stabilize the frequency, thus, grid storage is an option to provide extra load balance for renewable energy resources. Pumped hydroelectric storage is an excellent choice due to its low cost, acceptable efficiency, and reliability. This thesis develops models for a feasibility study of a proposed project to utilize a pumped hydro storage system to regulate the frequency of the power grid to meet the North American Electric Reliability Corporation Control Performance Standard Requirement 2 (NERC CPS2) in response to variable renewable energy output. The pumped hydro system should be able to vary the energy input and output to regulate the frequency within each 10 minute interval during its operation. To study this scenario, a dynamic model for the electrical and hydraulic systems is developed and tested using the MATLAB Script function. Simulations studies are performed using randomly generated variable wind generation output to test CPS2 compliance over period of 48 months. The simulation model is able to provide frequency regulation ability to the power grid to meet the CPS2 standard.