Electricity is so deeply ingrained in everyday life that when it is not available many things, essential and simply pleasurable, cease working. Finding ways to better manage faults in electricity distribution systems is a key way of improving the quality of supply offered to customers. Society also faces choices about its sources of energy and we need to find ways to remove technical barriers to the connection of small scale renewable generation without large cost penalties. The reasons that both of these tasks are difficult are (i) that the low voltage part of the distribution system was designed for simple operation without active control and (ii) the distribution system is very large and overall central control is not realistic. Solutions are also constrained by the large amount of existing equipment that is only part way through a long service life and is too expensive to replace prematurely. This project will explore a means to gradually devolving control authority from the existing central control room (which is semi-automated and semi-manual) and use a peer-to-peer network of controllers/decision-makers placed at each substation. The controllers can open and close remotely controlled switches to reallocate loads to different parts of the network and take various voltage correction actions. There is a strong need for communication to obtain feedback information and to allow a controller with only a partial view of the system to cooperate in finding an optimal set of actions to take in the event of a fault, an out-of-tolerance voltage or a generator whose output is being limited by network constraints. The project is challenging because it requires integration of research in distributed control, decision making, network analysis and communications. For this reason we have assembled a team drawn from 7 universities and 3 major international companies in the power industry.

The ever increasing demand for electricity consumption accompanied by environmental pressures impose a continuing need for electrical systems modification and growth, partly because of changing operational practices resulting from de-regulation and, partly, due to the increased use of distributed generation, which is changing the demands on transmission and, especially, distribution lines. But for many years now, the opportunities for installation of new lines have become very limited because of public concern over visual and other environmental impacts, and it is clear that extensions to system capacity will have to be met substantially without new lines.The voltage rating and the insulation coordination of transmission and distribution lines is determined by a combined consideration of the voltage stress applied to the line and its electrical strength. The stress arises from overvoltages due to switching transients or lightning surges. The magnitude of the switching overvoltage is controlled by the characteristics of the system components, and is more critical at the highest operating voltages. Lightning overvoltages, on the other hand, are of much larger magnitudes and are more onerous to distribution systems.IEC 60071 makes recommendations for the gaps and clearances to be used for specific voltage levels, and individual operators will then adopt safety factors above and beyond these recommendations, depending upon local conditions. Pollution, for instance, may reduce the breakdown voltage by up to 50%. These adopted clearances are usually very generous and can be optimised using modern equipment and practice.The investigators have researched for many years the possibilities for compact lines and substations through improved co-ordination of insulation and the use of polymeric insulators and more effective protective devices such as ZnO surge arresters. This programme, therefore, proposes to apply the compact line concepts to the up-rating of existing lines. It will involve statistical studies of switching and lightning surges that account for various parameters which affect the overvoltage magnitudes, such as closing times for circuit breakers and analysis of the possible state of the line in order to minimize the risk of re-closing onto trapped charge. The statistical variations of stress and strength of the system will be combined in a voltage-frequency plot to determine the risk of failure, which has to be minimized within economic constraints. The stress will be presented as the probability of a certain overvoltage occurring, and its distribution along a line will be controlled by the judicious placement of modern ZnO surge arresters. Electrical strength, on the other hand, can be presented as a probabilistic breakdown curve. It will be primarily derived from consideration of the breakdown curves taking into account the critical clearances at the tower and along the line. These principles have been studied over the years, but present-day pressures are causing a re-evaluation of the conventional limits and methodology. This is also supported by the excellent performance of modern ZnO surge arresters in controlling overvoltages and the superior pollution performance of new polymeric insulators. The programme will also include laboratory and field experimental programmes to test and characterise the new devices and configurations to be used for the compact design of the uprated lines. The main output of the programme is to establish well researched fundamental principles that will allow an efficient and safe design for the future transmission and distribution lines.The basis of this programme has been proposed by HIVES, Cardiff University and then moderated by discussions with an industry group involving National Grid, four UK DNOs, ESB and three line construction companies, whose views are embedded in the proposed programme.