Abstract
Modern power system substations are undergoing a fundamental transition from conventional copper-wired protection architectures to digital substation technologies based on the IEC 61850 standard. While IEC 61850 sampled value-based protection offers significant advantages including elimination of up to 80% of copper wiring, reduced current transformer burden, and improved interoperability, utilities require rigorous comparative data on how these systems perform relative to conventional direct wired relay protection before committing to deployment.This thesis presents a systematic, hardware-in-the-loop performance evaluation of a conventional bus differential protection relay against an IEC 61850-9-2 sampled values based relay, conducted using a Real-Time Digital Simulator (RTDS) testbed. The testbed replicates a double-bus, single-breaker substation arrangement with four feeders and integrates commercially available protective relays, merging units and network switches.
Test scenarios evaluated relay performance across a range of fault scenarios by varying fault location, point-of-wave fault incidence angle, and fault resistance. Additionally, the thesis investigates the impact of network congestion or adversarial IEC 61850 sampled values protocol data manipulation and data stream manipulation. Results demonstrate that the trip time for the IEC 61850-9-2 sampled values-based relay will be slower than the conventional relay, where the network latency corresponds. The data manipulation tests IEC 61850-9-2 sampled values-based relay blocks tripping if more than three consecutive packets are dropped. To address this challenge of signal reconstruction under the packet loss conditions, a Kalman filter based dynamic state estimator was implemented to estimate reconstruct the lost packets. The approach was tested within the testbed environment.