Optimum Performance of Protection IEDs at OOS in Power System

Abstract

Protective equipment's in high voltage substations should be providing fast, reliable, localizes faults and selectivity. But, some abnormal conditions in power system such as Out of Step (OOS) condition which that the mechanical power for the generator not equalize with electrical power for the loads, this case is not a real fault but the protection equipment will consider this condition is a fault. This situation will cause the loss of synchronism between areas within the power system or between interconnected systems, that's will lead to blackout for the system. This paper study the out of step condition, philosophy of protection relay device at this case and how to overcome this condition by the optimal method to avoid the false operation for distance protection function by Out of Step Blocking (OSB) to improve the stability of the power system.