Reconfigurable Distribution Networks

The "SmartGrid" is a concept that has emerged from its initial discussion in engineering circles into the wider public arena because its importance has been recognised for securing future electricity supply and facilitating the de-carbonisation of electricity. Much of the SmartGrid debate has so far focused customers with "smart homes" or "smart appliances" being engaged in managing the electricity system through their reactions to signals about price or availability of renewable energy. Behind the scenes, there is a parallel debate about how new control methods for existing electricity plant and equipment may enable electricity networks to offer the flexibility needed to incorporate low-carbon energy sources.

This proposal expands the SmartGrid debate in two directions. First, large numbers of people in developing countries suffer from an intermittent electricity supply. The supply companies use "rota disconnection" schemes to ration the limited energy available in some regions. Having electricity for, say, just 4 hours a day adversely impacts education, health care and economic development. "Micro-grids" able to run "off-gird" with local solar or micro-hydro energy are interesting in this context. Our proposal here is to design "on-off grids" in which supply companies adjust their rota disconnection to account for local resources in the micro-grids and the micro-grids are configured with power electronic interfaces that can manage the frequent transitions between on-grid and off-gird operation. The consortium members in India will build a demonstration version of such a micro-grid to allow control and optimisation ideas to be explored and assessed. The use of energy storage technology will be a key part of this scheme.

Second, developed countries do not suffer rota-disconnections except in emergencies. However, the security and adequacy of their existing electricity distribution networks may become compromised by the injection of significant amounts of solar energy at household level and the heavy loading anticipated from electric vehicle charging. Here we propose to develop power electronic equipment that enables the rapid reconfiguration of the possible supply routes in a network in order to optimise the power flows and voltage levels. The questions are not so much on can power electronic devices achieve this (we are confident they can) but rather how is it achieved efficiently and with a good equipment lifetime. The UK members of the consortium will design, build and test new forms of "soft meshing" power electronics to meet these objectives.

The "reconfigurable distribution network" presents a great opportunity in both the Indian and UK context. It also present research challenges on a number of fronts: innovation in power electronic equipment to reduce power losses and increase lifetime; the need to design new control algorithms to exploit the new flexible equipment to the benefit of consumers and network operators and the need to create new optimisation and planning tools to indicate where exactly the new equipment should be deployed and to determine how robust its business case can be.

Networks in developed nations such as the UK must deliver the increases in capacity and flexibility required to support extensive PV in-feed and the rapid growth in EV penetration and in developing nations such as India, shortfalls in generation and unreliable supplies to rural areas will continue to affect many millions of people, and this must be managed to enhance quality of life and facilitate economic development. Reconfigurable distribution networks, as envisioned by this proposal, are an important part of achieving both of these objectives in a cost effective manner. In developed countries, the move to a meshed network topology will increase the utilisation of existing network assets by allowing lightly loaded or generation rich feeders to support weak or heavily loaded parts of the network, avoiding or postponing costly network upgrades. In developing nations and rural areas, shortfall in generation may be managed through dynamic reconfiguration of the distribution network, ensuring critical loads remain connected and that local small-scale generation and storage is managed in an effective manner. The economic impact of a move towards fully reconfigurable distribution networks is clear in both contexts and the proposed research program seeks to address key issues on the way to delivering these networks.
Critical technology such as the Soft Open Point and hybrid dis-connector to be developed in this project will underpin much of the functionality of these networks. Both India and UK/Europe are well placed to design, manufacture and supply this type of equipment, for example, large power electronic systems are supplied by three major European headquartered companies (Siemens, ABB and Alstom Grid) and an emerging Indian industrial base.
Expertise in the planning, operation and control of reconfigurable distribution networks will be developed under the programme, assisting network operators themselves and engineering consultancies in the understanding of technology capabilities and their associated risks and benefits. In particular, an understanding of the competing objectives of increasing system reliability whilst achieving a reduction in the number of redundant devices will play an important role in determining the economic impact derived from a move to such network designs.
Reconfigurable distribution networks offer different societal benefits in developed and developing nations. It is well known that access to reliable electricity supplies play a critical role in improving quality of life in the developing world and is a basic requirement for effective industrialisation of rural areas. By providing options for the control of loads and by lowering the cost of supply through reduction of redundancy, reconfigurable distribution networks will help facilitate rapid electrification and increase economic output.