Grid-related protection for distributed energy resource balancing voltage and frequency ride-through capabilities with rapid fault isolation

As the penetration rate of distributed energy resources (DERs) in distribution grids continues to increase, their voltage and frequency support capabilities during system disturbances and grid faults become increasingly critical, necessitating compliance with low-voltage ride-through (LVRT) standards. However, this requirement conflicts with the need for DERs to be selectively and rapidly shed during grid faults and islanding operations. To address this issue, this study proposes a grid-related protection scheme for DERs that balances the enhancement of grid frequency and voltage support capabilities with rapid fault isolation. First, based on meeting the LVRT standards and anti-islanding protection requirements for DERs, and considering the impact of DERs on system security and reclosing during grid faults, we propose differentiated grid-related protection operation requirements for scenarios including system disturbances, islanding operation, and grid faults. Second, the scheme refines operational scenarios, analyzes electrical quantity differences at DER grid connection points, and extracts key characteristic threshold values to distinguish different operational states. Finally, a multi-criteria grid protection scheme based on the voltage change rate is proposed, integrating characteristic indicators such as the rate of change of frequency (RoCoF), frequency, and voltage, along with differentiated action time. Theoretical analysis and simulation results demonstrate that this approach ensures rapid and selective disconnection of DERs affecting system security and reclosing during system faults or islanding operations while simultaneously preserving the grid’s frequency and voltage enhancement capabilities. This achieves a balanced integration of DERs within the system’s disturbance ride-through capability, anti-islanding protection, and fault protection capabilities.