Digital Substation Design and Architecture for Power Grid Modernization

Substation is considered as the heart of the power grid where the brain (intelligence) behind the protection, control, automation, monitoring and metering of various parameters related to primary equipment’s are present. At the same time major transformation of grid parameters like voltage, current, frequency, real power, reactive power, power factor, stability etc. is done by various controllers in the substation as per the loading conditions. Over the years, conventional substations have been designed to operate in a rule-based environment. Secondary equipment’s connected and communicated with primary equipment’s and SCADA using hard-wired cables resulted in reducing the overall reliability, safety with increased operational costs. Digital Substations along with Intelligent Electronic Devices (IED’s) has emerged over the past few years along with development of IEC 61850 international standard to design, upgrade and operate the substation in a secure, reliable, and flexible communication mechanism. At the same time various issues related to interoperability, complex engineering processes, ease of maintenance, data handling and reporting has been addressed. Station and Process Bus architectures forms the critical networking hub of digital substations along with intelligent controllers and scalable communications. In this paper, we discuss on overall Digital Substation architecture, case study with special emphasis on Process Bus which is still in the early stages of adoption in Indian grid.