Introduction to DC0079
The Accelerated Loss of Mains Change Programme
The DC0079 Accelerated Loss of Mains Change Programme (ALoMCP) is being rolled out by National Grid ESO and the UK DNOs (Distribution Network Operators) and iDNOs (independent Distribution Network Operators) to accelerate compliance with the Distribution Code.
The purpose of the initiative is to consider Accelerated Loss of Mains Change Programme (ALoMCP) protection and their settings. The aim being to reduce the risk of inadvertent tripping and reduce system balancing issues by giving National Grid ESO greater latitude with regards to system RoCoF limits.
Your generator will have been connected to the Distribution Network under technical standards that require it to be tripped off at times of network disturbances. This is commonly referred to as the “G59 trip” or “G59 relay”, as G59 was the number of the Energy Networks Association Engineering Recommendation adopted by all DNOs/iDNOs. When your generator was commissioned, the G59 relay would have been programmed with the settings prescribed at the time, then tested and possibly witnessed by the DNO/iDNO.
As more and more distributed generation as been connected to the grid, concerns increase about the amount of generation that can be lost during a system disturbance, due to the G59 relays doing what they were programmed to do. As well as that, nationwide experience has shown that Vector Shift loss of mains protection has not provided results as predictable as had been hoped for.
The DC0079 programme aims to reduce the likelihood of large amounts of distributed generation being lost on system disturbance by making changes to settings in G59 relays to reduce the sensitivity to tripping, and to migrate any relays still using Vector Shift onto Rate of Change of Frequency (ROCOF)
National Grid ESO and the DNOs/iDNOs is starting to send out invitations to participate in the programme. The set of slides below provided by National Grid ESO and the Energy Networks Association, on behalf of all DNOs/iDNOs gives the background to the programme, as well as the proposed method and timescales of implementation.
The Energy Networks Association has published a webpage (link below) to provide more information.
Bryan J Rendall (Electrical) Ltd (BJRE) have been carrying out G59 related works for almost 20 years, having carried out testing on relays in Orkney as early as 2000 for the emerging wind energy industry. Since then, we have carried out hundreds of installations and tests, witnessed by relevant DNOs. As such, we have the wealth of experience needed to be considered as a “Certified Contractor” as detailed in the above slideshow, and are listed on the ENA website above as a Loss of Mains Protection Support Organisation.
The Energy Networks Association have opened up the portal for registration to the Accelerated Loss
This attached PDF contains the recent modifications made to the Distribution Code, and Engineering
Please refer to our Terms and Conditions
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