UK distribution system protection issues

In the light of anticipated changes in the UK distribution system leading towards active networks with high penetration levels of distributed generation (DG), a number of major challenges must be addressed with respect to power system protection. Accordingly, the primary objective of this paper is to raise awareness of the potential bottlenecks that may act to inhibit further integration of renewables and other types of generation in distribution systems because of insufficient protection system provisions. The paper presents a UK industry view, formulated using the outcomes of questionnaires, seminars and other academic-industry exchanges carried out under the auspices of the Department of Trade and Industry (DTI) funded centre for DG and sustainable electrical energy (CDG&SEE), of the present and anticipated future protection system challenges in active distribution networks. A systematic methodology for opinion recording and priority assessment based on a carefully designed questionnaire has been proposed and applied to the distribution system protection domain. The industrial consultation involved all UK distribution network operators (DNOs) and a selection of protection system manufacturers and developers. The results of this exercise provide a unique insight into the key challenges facing the ongoing development of effective power system protection systems for distribution systems including DG. In particular this paper supports the assertion that, in order of decreasing significance, the resolution of loss of mains, islanding and certain protection discrimination issues would facilitate the integration of increased levels of DG.