One of the most interesting issues for power system operators is the load curve variability and non-uniformity that causes the power system to have higher operation costs. Power systems usually use high capacity and long-lasting storage units for operational storage and high speed response storage for frequency saving. To compar operation storage and frequency and to evaluate their impact on cost-effective power system operation, This paper attempts to analyze the role of pumped storage, compressed air storage and battery storage systems in an IEEE standard 118-bus test system (54 thermal units) by GAMS software. The simulation results show that the pumped storage units are more cost-effective opration performance than other two types of storage equipments. However, battery storage due to their lower start-up cost units are better than compressed air energy storage with higher capacit