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At the heart of the UK Gas Industry

Gemini Changes

CP4368 – EU Gas Capacity Conversion Change ­- NOW LIVE!


EU legislation to create a harmonised European internal energy market came into law on the 3rd March 2011. At Xoserve we have been implementing changes to processes and systems since 2013. The Capacity Allocation Mechanism (CAM) Code requires a capacity conversion mechanism to be offered to users at Interconnection Points (IPs). Modification 616 Capacity Conversion mechanism for Interconnection Points introduces this requirement to the Uniform Network Code (UNC).


Shippers who hold unbundled capacity on one side of an IP may wish to acquire matching unbundled capacity on the other side of the IP. Priority is given to offering Bundled Capacity, so the Shipper may find they have to buy a new bundled product to acquire capacity on both sides of the IP, which means the Shipper will have purchased Capacity twice.


National Grid (NG) will be using the existing buyback functionality in the Gemini system to process conversion requests when they are received from Shippers. NG will then manage a manual process to ensure that data remains accurate to maintain compliancy with the EU obligation. A minor system change has now been implemented in Gemini to allow NG users to do this. The change was made live on the 18th February 2018.

Xoserve Invoices – A new Entry Method of Sale has been introduced to support this change which has resulted in the requirement for two new charge types to be set up on the NTS Entry invoice. The two new charge types are:

  • CEC Capacity Conversion Entry Charge
  • CEA Capacity Conversion Entry Adjustment

These charge types are effective from the 1st March 2018 and so will appear on the February 2018 invoice.


CP4376 – GB Charging & Incremental (IP PARCA)

This is a large project, with a key element being the delivery of changes from the GB Charging Review. This is a significant change to how National Grid Gas Transmission (NGGT) will receive its revenue and is likely to impact future UK Link releases as well as Gemini.

The project has been split into two parts, A and B.

Part A is due to complete its Analysis & Design phase in April 2018 and is due to be implemented  by end of April 2018.

The majority of the changes are included in Part B; the Analysis & Design phase commences in May 2018 and is due to be implemented in September 2019.

COR4149 – NG Gateway Migration

National Grid Gas Transmission (NGGT) is in the process of setting up a new internet gateway – Virtual Secure Transco Internet Gateway (VSTIG). This will replace the existing internet gateways STIG 1 and STIG 2 which support National Grid (NG) business critical systems and network traffic flows to other systems, including those managed by Xoserve.  This project is to reduce the operational risk as the legacy STIG environments are over utilised and comprise of physically aged network environments for which there is limited support.

The Gemini Project team is supporting National Grid Information Services (NG IS) with this change: co-ordinating infrastructure activity and ensuring that interface changes are tested appropriately, minimising the risk of impacts to NG and Xoserve systems.

The current target cutover is May 2018.

CP4550 – Gemini Re-Platform

The Gemini system is sitting on ageing hardware and so during 2017 a health assessment was carried out. The findings included a recommendation to re-platform the Gemini system onto new hardware. In December 2018 National Grid initiated the Gemini Re-Platform project which is in the early planning stage. The aim of the project is to relocate the system in order to maintain the Gemini service for a number of years. Xoserve will be working with National Grid in order to understand the key requirements for hosting the Gemini system and any potential impacts to customers and interfacing systems. This project will not implement before the GB Charging changes that are due to implement in 2019.

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