In areas with rapidly changing loads of large magnitude, utility companies often experience large deviations in frequency and area control error. Inadvertent tie-line power flow also occurs. The purpose of this research is to examine the effects a large scale energy storage device has on the system response to a rapidly changing load. Two control areas connected by a tie-line are modelled and simulations are performed to determine the response to a step change in load and also to a five-stand rolling mill load. For each type of load, three cases are studied: no energy storage in the system, a superconducting magnetic energy storage device in the system, and a battery energy storage device in the system. Each case is analyzed and the improvements in system operation for each of the energy storage devices is discussed