Protection redundancy in a digital network within a high voltage utility substation based on IEC 62439-3

The advancement of optical sensors primarily called as Non Conventional Instrument Transformers (NCITs) and processes controlled by microprocessors have a greater reliability in providing robust protection to the substation primary plant equipment. The NCITs provide dependable protection of primary plant equipment using digital instrumentation within a substation environment. The application of NCITs are realized as a part of the solution to reduce substation expenditures by decreasing the maintenance cost and increasing the safety of the primary plant of a conventional or Gas Insulated Substation. Recently, the improvement in digital technology has dramatically evolved the application of Merging Units and Intelligent Electronic Devices (IEDs) in protection schemes. Digital equipment is much preferred due to its high accuracy. It reduces fault diagnosis downtime which makes it an easy option for substituting in place of a conventional instrument transformer. These digital equipment offer number of potential advantages, such as better accuracy, transient response, and wider bandwidth, etc. It is anticipated that the NCITs will grow significantly in future due to its high reliability in protection schemes, less maintenance, safety to the operator and equipment in the next decade. However, there are few challenges related to interoperability and delay in receiving communication packets due to latency in receiving the data packets. In this report, we have simulated the interoperability issues between NCITs and IEDs using an Optimized Network Engineering Tool or Riverbed modeller