A more robust reverse blocking scheme using IEC61850 GOOSE messaging

In substations, the busbar is a critical component, and both main and backup protections are essential for reliability and safety. However, traditional busbar protection methods can be costly and complex, requiring specialized current transformers (CTs), intricate wiring, and challenging maintenance. A simpler alternative is reverse blocking protection, which detects faults within the protected zone while blocking faults outside it. The Intelligent Electronic Device (IED) monitors fault current direction and triggers a trip signal using CTs and voltage transformers (VTs). While reverse blocking is used in smaller substations, it is rarely applied in primary substations due to the complexities of parallel systems. To address this, we developed a system incorporating reverse blocking for primary substations operating in parallel. Using the IEC 61850 GOOSE messaging protocol, we eliminated the need for hardwires, improving system stability, speed, and selectivity. This approach reduces wiring complexity and utilizes cost-effective devices, such as the Directional Overcurrent Element Function (OCEF), in IEC 61850-compliant IEDs. Protection stability is enhanced by cross-checking information between IEDs, with all logic implemented within the devices. The system uses existing CTs designed for OCEF protection IEDs. Our project included designing an optimal protection scheme, developing a comprehensive testing methodology, and confirming relay compatibility with different manufacturers.