Protection against sub-synchronous oscillations, a relay model

Abstract

With increased integration of renewable energy resources, FACTs devices and series compensation, sub-synchronous oscillations (SSO) have become more common in electrical power systems in recent years. Specially designed relaying devices are often employed to detect and isolate harmful SSO conditions as when unconstrained, they can lead to widespread equipment damage and system instability. This paper presents design and implementation of a SSO relay model that can effectively extract sub-synchronous components in system measurements to quickly detect SSO conditions. Dependability and security of the developed relay model are validated using electro-magnetic transient (EMT) type simulations. In addition, performance of the developed relay model is compared against a commercial (physical) SSO relay. Obtained results demonstrate the effectiveness of the implemented relay model in detecting SSO and protecting electrical power systems against SSO conditions.