POWER SYSTEM PROTECTION USING MODERN COMPUTER AIDED TECHNIQUES

Abstract

Protecting transmission lines is an important task to safeguard human lives and electric power systems. Following the occurrence of a fault, the utility tries to minimize the damage, outage time, loss of revenue, and restore the faulted line to normal as quickly as possible to improve system transient stability and reliability. All these factors are increasingly important to the utilities facing challenges in today's market that req uire increasing in transmiSSion capabilities. Transmission lines are subjected to many types of fault. Some faults are temporary, some are permanent. Also, some switching processes may generate fault- like performance over a transmission line. Therefore, a fast and accurate fault classification is essential for the protection scheme to perform successfully. Moreover, transmission line faults must be allocated accurately to allow maintenance crews to arrive at the scene and repair the faulted section as soon as possible. Rugged terrain and geographical layout cause some sections of power transmission lines to be difficult to reach. Therefore, robustness of the accurate fault location determination under a variety of power system operating constraints and fault conditions is an important task. For these reasons, the degree of accuracy should be increased than that usually obtained using conventional techniques; even a small measurement error may require detailed local examination over several kilometers of a typical line. So, faults in transmission lines need to be detected, classified (whether permanent or temporary), located accurately, and cleared as fast as possible.