Design of A Novel IEC 61850 Based Merging Unit for Substation Automation

Substation Automation System (SAS) is a key component of the power distribution system of a so called “Smart City”. IEC 61850 is the modern and most popular international standard for substation automation because of its high degree of interoperability among systems from different vendors. Merging Unit (MU) is an essential building block of an IEC 61850 based SAS. A conventional MU, acquires current and voltage signals from various current and voltage transformers in the switchyard, converts them into digital form and sends the digital equivalents as sampled values through the process bus. A novel concept is envisaged in this MU design which has the additional function that it serves as a control unit with the capabilities of realtime decision making as well. This paper discusses the details involved in the design of a MU based on IEC 61850, as part of the ongoing design and development activity to bring out an indigenous solution for smart cities, executed by Centre for Development of Advanced Computing (C-DAC) and funded by Ministry of Electronics and Information Technology (MeitY). The paper outlines the features implemented in the hardware & firmware and also discusses preliminary results of the lab testing carried out at C-DAC, Thiruvananthapuram, to validate the same.