Introduction: There are varied types of power flow limitation in modern power systems. If the problem can be solved by a relatively large increase in the thermal rating of an overhead line, re-conductoring the line with High Temperature Low Sag (HTLS) conductor is a possible solution. These conductors are capable of high temperature operation with minimal change in electrical and mechanical properties and have low sag at high temperature when compared to conventional conductors.

In order to increase a lines thermal rating without rebuilding or replacing its structures and foundations, the original conductor can be replaced with a special HTLS conductor having the a similar dimensions and properties as the original, but which can be operated safely and reliably at much higher temperatures with far greater ampacity.

The 3M Company was established in 1902 with $27 Billion Sales in 2010 over 80,000 employee’s world wide.

ACCR conductor has over 10 years service history with no reported failures in service and no failures during installation. To date there are 90 successful installations, in over 60 different countries, with more scheduled for 2011, 2012 & 2013. With the most recent installation being in National Grid USA, as part of the Western Massachusetts Transmission Reinforcement Strategy, 3M are currently investing in expanding manufacturing capacity to meet demand.

Objectives: Key learning to be delivered by the project is the understanding of the circumstances under which the Superconducting Fault Current Limiter (SCFL) can be used to mitigate fault level issues which are a barrier to Distributed Generation (DG) connection and how the SFCL can then be designed into and operated.

Specifically the following learning outcomes would be expected:

• Identification of network and physical circumstances where use of the SFCL could be used to mitigate fault level issues and address potential future DG connection issues

• Identification of design, construction, commissioning, protection, control and operational issues associated with use of such equipment. If the trial proves successful in mitigating faults this could also reduce the need for transmission reinforcements across GB

• Assessment of actual carbon benefits/confirmation of initial carbon case

• Assessment of impact of equipment on policies, codes of practice, section level procedures, financial authorisation processes (including the financial justification) and identification of required revisions.

• Dissemination will be through the production of a manual that details the new knowledge outlined above.

Demonstration Objectives:

This project trials a specific piece of new equipment that has a direct impact on the operation and management of the distribution system and potentially the transmission system.

Phase 1. To identify suitable locations for the SFCL installation and undertake a feasibility and systems readiness study to analyse the network, outline the optimum application and specification, and confirm the business and carbon cases. This has been completed.

Phase 2. To design, build, install and commission a three-phase 33kV SFCL on the CE distribution network. It is proposed, subject to site surveys and agreement with National Grid and other partner organisations, that the unit is installed at a 275/33kV substation in South Yorkshire to limit the fault current to within the rating of the 33kV switchgear. This is currently managed through an operational management switching procedure which in some circumstances may increase the risk of loss of supplies to customers.