A Novel Solution for Overcoming Conflicts Between Line Protection and LVRT in MV Solar PV Interconnections

Abstract

The implementation of low-voltage-ride-through (LVRT) requirements for distributed generation (DG) sources in medium voltage (MV) distribution networks introduce challenges for the existing protection systems. These challenges stem from coordination issues between line protection systems (fuses and reclosers) when the DG may continue to operate in line with LVRT requirements during faults in the network. To address this challenge, we propose an enhanced voltage protection module (EVPM) for DG interconnection protection relays (IPR). EVPM employs a space phasor model (SPM) of three-phase voltages at the point of common coupling (PCC) to detect faults in the distribution network and the consequent recloser operation. This allows for prompt isolation of the DG from the faulty network in coordination with the reclosing relays, by over-riding the LVRT requirement. This reduces the time required for reclosing and ensures recloser fuse coordination without changing the settings of the existing protection systems based on DG penetration levels. To assess the EVPM performance under different scenarios, transient simulation studies are carried out in three case study networks. The results validate the efficacy of the proposed EVPM.

Keywords

• Distributed generation (DG)
• enhanced voltage protection module (EVPM)
• interconnection protection relay (IPR)
• inverter-based DG-units (IBDGs)
• low voltage ride through (LVRT)
• medium voltage (MV)