Use of superconducting magnetic energy storage device in a power system topermit delayed tripping

Use of a superconducting magnetic energy storage (SMES) device in an electr ic power system can extend the time margin required for clearing a fault wi thout any loss of stability of the synchronous generators in the system. Ne cessary mathematical model and computer simulation results have been presen ted. A wider time margin would be beneficial in many ways, such as precludi ng unwanted line tripping following temporary earth fault or transient swin gs, deferring costly replacement of the existing relays and breakers by the faster ones, and making a fair decision on tripping, taking into considera tion a large volume of on-line data, constraints and complicated policies l ikely to be encountered in operating a power system under deregulation or a competitive market environment.