Transmission distribution coordination for DER fault ride through support

Rapid renewable energy sources (RESs) deployments in transmission and distribution networks have changed power systems’ operation and control mechanisms. This fundamental shift makes the interaction between transmission and distribution systems more sensitive and requires robust TSO–DSO coordination to ensure system stability and ancillary services for the entire network. This paper uses an electromagnetic transient (EMT) simulation tool using a real-time digital simulator (RTDS) to investigate the dynamic transmission–distribution coordination with a high share of RESs in fault ride-through (FRT) capability of distributed energy resources (DERs). Then, the paper implements fault current injection (FCI), incorporating inverter-based resources (IBRs) in the transmission system to support dynamic voltage responses for the distribution system. Different reactive current control schemes are examined to evaluate the FRT performance of DERs under different fault locations. Additionally, hardware in the loop simulation for the under-voltage protection relay is implemented to validate the low-voltage ride-through capability of DERs. The comparison results show that the transmission system can provide dynamic voltage support for the distribution system through FCI from IBRs to help DER ride through. The FCI from the transmission system also significantly enhances fault-induced delayed voltage recovery of voltage-sensitive load in the distribution system.