The Top & Tail Project ended in November 2015. The final impacts can be found on the Project Outcomes page.

Work Packages

   

Work Package 1.1:

Planning a Transcontinental Interconnected System

A number of recent studies (e.g. Czisch, Jacobson, and ECF) have concluded that dramatic developments of the electrical infrastructure will be required across the whole continent for a low-carbon power future. Already nine international GW-scale electrical interconnections from the UK are either in service, under construction or being planned. These are, however, point-to-point connections between AC systems and not an interconnected SuperGrid. The exploitation of the UK renewable energy resource on a much larger scale posses a grand challenge in the realisation of the network infrastructure and technology that makes a SuperGrid feasible, economic and reliable. With very long portions of routes being undersea or underground (for environmental reasons), this will necessitate use of HVDC for which some options presently exist but with major technology and plant level research required. More information...


Work Package 1.2:

Operation of a Transcontinental SuperGrid

The scale and level of connection of the transcontinental electrical system that is anticipated is without precedent. The deployment of HVDC and flexible AC Technologies will greatly increase the control capability of power networks. I t will also require a significant re-evaluation of power system stability and protection concepts. A key part of future operational designs will be means to access demand-side actions and improved observability and estimation of system state arising from scientific development in Information and Communication Technology. More information...


Work Package 1.3:

Super-Scale HVDC

High-level studies indicate that new transmission links of the order of 20 GW are required. Across the North Sea and English Channel these will clearly need to be sub-sea cable links. Across Pyrenees, under-ground cable is presently being used. HVDC is clearly required. There are existing point-to-point overhead line HVDC links using line-commutated converters (LCC) at 6.4 GW. However, there is nothing close to this rating using cables or the (self-commutated) voltage source converter, VSCs needed for interconnected DC. A SuperGrid network is going to require an increase in cable capacity of around a factor of 10 and an increase of VSC converter power rating of around a factor of 20. Furthermore, the changed generating patterns are likely to result in the creation of networks where the power flows associated with HVDC transmission will dominate any local AC generating capacity and interplay between transient stability and modularity must influence the design at circuit level. The next steps require game-changing technology advances. More information...


Work Package 2.1:

Starting with Demand

The demand for energy in the UK is dominated by two sectors, the built-environment and transport, which together account for the majority of primary energy demand. Both will undergo fundamental changes driven by a move to low carbon energy and pursued through energy vector displacement, accelerated technology deployment and societal change. Consequently, both will present radically different energy demand characteristics to future electrical and thermal energy networks and are likely to play a more interactive role within them. Our contention is that only by starting with a fundamental re-analysis of end-use demand characteristics and working back through to network design can one (a) adequately account for demand-side transformations in the planning and operation of future networks and (b) identify the opportunities for game changing within the new characteristics. More information...


Work Package 2.2:

The Last Mile Electric Network

With so much of the push to a low-carbon economy resting on electrification of building thermal requirements and vehicle transport, the provision of additional network capacity in distribution becomes a key problem and one which could be very expensive if we cannot do better than simply installing more or thicker wires. This seems to be especially true in the last mile of the electricity network where we do not have redundancy (as a passive means to provide security). What we have identified, though, is that in the last mile it is voltage-drop and not ampacity that limits a cable's capacity. A large amount of additional capacity could be released from legacy cables if we take a different approach to power quality and voltage regulation in particular. The benefit is clear: increased capacity without digging up every road and pavement in an urban area. To achieve this requires an understanding of load characteristics, an exploration of the power electronic approaches to voltage control and an understanding of cable behaviour under new operating regimes. More information...


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