A Substation Automation System Architecture for Migrating From Decentralized to Centralized Protection and Control in Smart Substations

The protection of the power system component is crucial for the healthy and reliable operation of the entire grid. Depending upon the equipment being protected and the type of fault it may encounter, various protection functions need to be employed. The paper presents a detailed overview of the evolution of the SAS structure in smart substations facilitating the centralization of multiple protection and control functions. The description detailing the evolution of the substation automation system (SAS), driven by the IEC61850 standard, enabling the transition from conventional substations to digital substations has been highlighted in this paper. The centralized protection and control (CPC) technique, representing an innovative strategy that consolidates all protection and control functions within a single device at the substation level, has been presented in detail. Moreover, the guidelines on the implementation of the CPC architecture in substations along with the approach involved in migration from a decentralized protection scheme to CPC architecture have been proposed considering the existing substation in a power grid. The protection functions employed in the line and transformer bays of the substation have been mathematically described using the actual parameters of the substation equipment. Their effectiveness has been confirmed by analyzing disturbance reports of faults that occurred in both the line and transformer feeders.