Roadmap for Digital Control System (DCS) Implementation in Utility Substations

Abstract

Traditional protection systems in substations were predominantly based on standalone electromechanical relays. During the 1970s, with advancement in technology and increasing requirements from grid operations, static relays and RTU based Substation Automation Systems (SAS) evolved. Further, the 90s saw the evolution of Intelligent Electronic Device (IED) s with much higher processing capability and advanced protection functionality based on digital processing techniques. IEDs also performed additional tasks such as fault recording, reporting, remote control and metering. The need for communicating with the IEDs became a necessity which resulted in development of proprietary protocols creating an issue of interoperability among the various products and applications. The 2000s saw remarkable progress in the field of substation automation with advent of IEC 61850 Edition 1, which brought standardized configurability, object oriented data models, simple architecture, the promise of interoperability and adaptability with evolving future smart grid developments making it a popular option for substation automation. To leverage the benefits of new standards, electrical utilities implemented IEC 61850 based SAS. Progressively IEC 61850 evolved overcoming the shortcomings and technical issues associated with Edition 1 and new functionalities emerged in Edition 2 to cater to the requirements of grid operations. Utilities which implemented SAS based on IEC 61850 Edition 1 face challenges pertaining to standardization of SAS design/implementation, in defining maintenance strategies and most importantly in defining future strategy to leverage the benefits of latest technological development in standards and bringing SAS implementation to a common/standard design. An important step in defining the roadmap for digitally enabling SAS is to assess the current landscape and identify technologies and standards to be implemented. This paper presents the assessment of Digital Control System (DCS)/SAS generally implemented across power Utilities, based on the IEC 61850 Edition 1, bringing the view of global SAS implementations and industry best practices. The assessment is with respect to electrical functionalities, system architecture, time synchronization and cyber security. The paper further defines a strategy for future implementations to leverage the benefits of latest technological developments in IEC 61850, to stay at par with industry trends/standards and most importantly to bring SAS implementations to a standard design. A maintenance strategy for handling multivendor SAS products, operational cost optimization, dealing with ageing infrastructure, extending functionality required to meet power system infra-structure enhancements with minimal effort and cost, maintaining high availability of equipment is also discussed.