Implications of fault current limitation for electrical distribution networks

This paper explores the potential future need for fault current limitation in the UK's power system, and some of the technical implications of this change. It is estimated that approximately 300-400 distribution substations will require fault current limitation, based on the statistical analysis of the projected fault level "headroom" (or violation). The analysis uses a UK electrical system scenario that satisfies the Government's target for an 80% cut in CO2 emissions by 2050. A case study involving the connection of distributed generation (DG) via a superconducting fault current limiter (SFCL) is used to illustrate the potential protection and control issues. In particular, DG fault ride-through, autoreclosure schemes, and transformer inrush current can be problematic for SFCLs that require a recovery period. The potential solutions to these issues are discussed, such as the use of islanding or automation to reduce the fault level