Optimised MV neutral treatment and earth fault management

Abstract

A wide range of neutral earthing techniques are in successful operation worldwide. SARS-CoV-2 (COVID-19) has normalised remote working; many electricity users in rural areas now have higher requirements for electricity service continuity. The drive to de-carbonise is promoting the adoption of e-transport and e-heat. Both further raise the criticality of supply continuity and reliability. Mitigating the risk of ignition of wildfires is a further driver. These drivers are increasing the number of utilities migrating from low resistance to high impedance neutral earthing at medium voltage (MV). Such migrations present challenges around changes to protection and operating regimes. This paper reviews common historical practice, then focuses on enhanced compensated neutral treatments, including active injection and faulted phase earthing. Outcomes of trial migration are included. Such solutions provide high levels of safety, supply continuity, supply quality, low energy release and operational simplicity. This paper does not address fault causes or repairs.