IMPACT OF DISTRIBUTED GENERATION ON DIRECTIONAL OVERCURRENT PROTECTION IN DISTRIBUTION NETWORKS

Abstract

Ambitious targets on climate change set by the UK has led to an increased penetration of low carbon generation technologies directly connected to the hitherto passive distribution network while optimising cost and meeting acceptable levels of security of supplies. Literature review of the problems associated with the increased penetration of distributed generation (DG) in distribution networks in chapter 2 of this thesis has revealed among other things, the possibility of reverse power flow through the network which will impact on the reliability and stability of the power grid. One problem identified is that one of the legacy protection systems widely used on the UK distribution system, the directional overcurrent (DOC) relay, is susceptible to mal-operation in such networks associated with reverse power flow. In response to the problem, the electricity supply industry and relay manufacturers have developed a solution in the form of a load blinding relay as further explained in chapter 5. As it is not possible to immediately replace the thousands of DOC relays on the system, and coupled with the fact that the performance of newly installed load blinding relays have not been well established, there is need for a methodology to manage the transition from the old protection scheme or relay application to a new one. This doctoral research aims to establish, analyse and investigate the impact of reverse power flow on DOC systems in networks with significant penetration of DG. Also, an assessment of the performance of newly installed load blinding relays was carried out with recommendations made for improvements. Finally, a more dependable solution was proposed which separates the protection function of a DOC relay from the control of excessive reverse power flow.

Date of Award	31 Dec 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Ian Cotton (Supervisor) & Mathaios Panteli (Supervisor)