Enhancing Distributed Energy Resource Integration and Supply Reliability: The Two-to-One rule

Society’s increasing dependence on small renewable resources, generating less than 10 MVA, for sustainable electricity brings forth a unique challenge. Unlike large and centralized generation facilities, these resources often remain unconnected to the transmission system because there are prohibitive costs associated with high-voltage interconnection equipment. Consequently, they find their connection in medium- or low-voltage distribution systems, originally designed for customer supply rather than for securing the integration of generation resources. This shift transforms the distribution feeder from a single source to a double-sourced (or multisourced) line, necessitating protection requirements like the transmission system. However, traditional transmission protection solutions prove too costly to integrate these small-generation resources into the distribution system.