There are two very particular places in energy networks where existing network technology and infrastructure needs radical change to move us to a low carbon economy. At the Top of network, i.e. the very highest transmission voltages, the expected emergence of transcontinental energy exchange in Europe (and elsewhere) that is driven by exploitation of diversity in renewable sources and diversity in load requires radical innovation in technologies. Many of these proposed interconnectors will be submarine or underground cable and High Voltage Direct Current (HVDC) must be used. Power ratings for the voltage source AC/DC converters for HVDC use are presently around 500 MW while the need is for links of up to 20 GW. A change of this magnitude requires radical innovation in technology. To focus our research in HVDC cable technology and power converters we have defined target ratings of 1 MV and 5 kA. The Tail of the network is the so-called last mile and behind the meter wiring into customer premises. More than half the capital cost of an electricity system is sunk in the last mile and cost and disruption barriers have made it resistant to change. Not only have recent changes in consumer electronics yet to impact network design, there are radical changes in future heat and transport services that need to be met. The challenge is to reengineer the way in which the last mile assets are used without changing the most expensive part: the cables and pipes in the ground. To get this right means starting with a fresh look at the energy services required and seeing what flexibility there is to meet the service expectation differently. A consortium of universities has been brought together to address this transformation of our energy networks. Several of the bid partners have had leading roles in Supergen consortia in the networks area but this consortium includes new partners whose expertise, especially in the power electronics field, is strongly indicated as game-changing. For the first time, the power electronics researchers in Warwick, Nottingham, Imperial and Strathclyde and the insulation materials groups in Manchester and Southampton are proposing to work together bringing developments of underpinning technologies to bear on network issues. These technology developments are folded into the energy network planning and operations work of Strathclyde, Manchester, Cardiff and Imperial. Birmingham brings energy economics expertise and Imperial expertise in energy policy and the social science of consumer acceptance. Several important industrial companies are engaged with this programme to form our scientific advisory board and to pick up and use results that emerge. These in clued network operators such as National Grid and Central Networks, equipment manufacturers such as Alstom Grid and Converteam and component manufacturers such as Dynnex and Dow Chemicals.Although the proposed project will address major challenges of technology, we recognise that transforming our energy networks is not merely a technical question. Members of the consortium already have links with civil servants and advisors in a number of administrations in the UK including DECC, the Scottish Government, WAG and NIE. These links allow us to understand the context in which energy policy is made. Consortium members have given advice to Ofgem on the Low Carbon Networks Fund, Parliamentary Select Committees and have been active in projects commissioned through the Energy Technologies Institute. Thus although the focus of your project is on a timescale of 20-40 years the results of our research will impact network development much earlier. Discussions to date with our partners in these organisations suggest a great deal of excitement about what work on the Energy Networks Grand Challenge can contribute.

There is an urgent need to expand the use of renewable energy generation systems to meet UK government targets. The expansion of grid-connected renewable energy sources must be done in a way which does not reduce the security of the power distribution system. Integral to power distribution system security is the ability of distributed generators to reliably detect a loss of grid condition. This is important to prevent unwanted islanded sections of the system which continue to be energised after the grid connection is lost. An islanding system occurs when a part of the grid system become disconnected from the rest of the network but continues to be energised by localised distributed generation systems. Islanded systems are (i) potentially hazardous to power system workers, (ii) may operate outside voltage and frequency tolerance, (iii) may be inadequately grounded and (iv) may not re-synchronise properly leading to undesirable protection trips. The existing approaches to islanding detection either have operational regions in which they fail to work or are required to have artificial signals injected into the grid which can impact on power quality. The most difficult operational condition is when there is a power balance between a distributed generator and its local load network. During this condition many systems will not detect that the grid connection has been lost because the fundamental frequency quantities are not altered by the event. Many renewable generation systems require a grid-connected inverter to transfer power into the grid. This is necessary because the generating source itself is rarely capable of producing power at grid frequency. A grid-connected inverter must be able to detect the loss of grid event. This proposal will investigate a novel approach using pattern recognition with a high sampling rate. The pattern recognition system is required to analyse the inverter output voltages and currents to determine if a loss of grid event has taken place. The novelty in this proposal is to include the high frequency information due to PWM effects in the real-time analysis. The benefit of doing this is that information will still be available to the pattern recognition system when a power balance condition exists. There is concern that many islanded detection systems are not immune from the effects of other neighbouring equipment. This equipment may be power electronic loads or other grid-connected inverters. The basis of the proposed approach is that the pattern recognition system will be able to discriminate between the presence and absence of the grid connection despite potential interference signals from neighbouring equipment. A major advantage of the proposed scheme is that it makes use of high frequency signals generated by the PWM switching in the inverter. These signals are extracted from the output voltages and currents by using high sampling rates where a number of samples are taken during one PWM cycle. These signals will still be present when a balance load condition exits and therefore will provide valuable diagnostic information during this difficult condition. These high frequency signals will add to the signals associated with the fundamental frequency components to detect the loss of grid event. It is important that this scheme is demonstrated experimentally and therefore a test rig will be produced which contains a range of typical loads and other grid-connected generators. The rig will be used to evaluate the performance of the proposed scheme in the presence of other neighbouring power electronic equipment. If successful the research will have major impact on the integration of renewable energy generation into power distribution systems. There will be significant benefits to power distribution system security and to the manufacturers of grid-connected inverters.

Urban energy systems play a crucial role in the economic, social and environmental performance of large towns and cities. There are many dense newly built urban areas in China, with limited space for renewables but resilience and clean energy with less air pollution are key issues. The UK has legacy urban energy infrastructure and decarbonisation has priority. All these challenges will place unprecedented requirements on the load demand and distributed generation of urban energy systems. Although the driving forces and the objectives of development of urban energy systems are different in the UK and China, sustainable, cost effective and reliable urban power supply is one of the key research topics in both countries. This project will focus on novel methods for sustainable power supply, and will address the following two key research challenges, each of which has associated objectives. (1) Conventional control approaches for urban power supply do not address the emerging opportunities offered by increased measurement and control of urban energy systems, do not consider the flexibility provided by other energy vectors, and do not proactively and self-adaptively deal with the inevitable uncertainties associated with the fast-evolving urban energy systems; and (2) current urban energy systems rely on external bulk power supply with low resilience, i.e. interruption of external power supply will have catastrophic consequences, and supply restoration from such abnormal events will be difficult and time consuming. Coupling of different energy vectors to maximise the benefits of system integration must be coordinated with decoupling of electricity networks (create islandable urban energy systems) during abnormal events to increase the system resilience by maintaining energy supply to un-faulted urban areas. The objectives of the project are to combine research strengths of the leading institutions in the UK and China to respond to the above challenges and: (1) investigate multi-zone and multi-energy evolving system and control architecture of urban energy systems. Digital twins will be used to model and analyse each multi-energy system that is connected to the urban electric power network. Their system coupling and system-integration potential will be identified and flexibility provision quantified; (2) develop a novel method for both current situational awareness and future situational forecasting of an urban energy system, based on the digital twin of each multi-energy system and network measurements; (3) investigate smart interconnection of different urban zones using Soft Open Points in medium voltage (MV) electricity networks for accurate, real-time and resilient power flow control, and smart interconnection of multiple players using distributed ledger technology (DLT) for fully decentralised trust-based control; (4) develop a multi-energy control strategy for an urban energy system, which employs situational awareness and smart interconnection methods to significantly improve performance and resilience of the urban energy system by setting up coordinated control and energy islanding capability; and (5) validate the effectiveness of the proposed multi-energy control using hardware-in-the-loop (HiL) test facilities and selected case studies, and provide cost and benefit analysis (CBA). The MC2 project will provide strategic direction for the future of sustainable urban power supply in the 2030-2050 time frame and deliver methodologies and technologies of alternative network control in order to facilitate a cost effective evolution to a resilient, affordable, low carbon and even net-zero future. The complementary, cross-country expertise will allow us to undertake the challenging research with substantially reduced cost, time and effort. The two-nation cross-fertilisation will make sure that the value of our research is for both developed and developing nations.

UK Research Councils have set up a RCUK Energy Programme, investing more than £530 million in research and skills to pioneer a low carbon future. Energy is also a major application area funded by TSB. Several major global companies, including BP, Caterpillar, EDF Energy, E.On, Rolls-Royce and Shell, have joined their forces with the UK government to establish the Energy Technologies Institute, creating a potential £1billion investment fund for new energy technologies. The ongoing research programmes cover various aspects of energy from generation, transmission to end use, in order to create affordable, reliable and sustainable energy for heat, power and transport. Increasing the share of renewable energy, e.g. wind, solar, marine and biomass, and improving energy efficiency are the two most important ultimate goals for all energy-related programmes. The renewable energy needs to be connected to the grid, preferably, via inverters in order for them to take part in the grid regulation, in particular, for large-scale renewable installations. However, the capacity of individual power inverters is limited and multiple inverters are needed to be operated in parallel to achieve the power capacity needed. For a 5GW offshore wind power site, 1000 of 5MW inverters are needed. How to make sure that the inverters will share the load proportionally/evenly is a challenge. It should not be assumed that inverters could be connected in parallel automatically. Without proper mechanisms in place, circulating currents may appear and some inverters may be overloaded, which may cause damage. The system may even become unstable and lead to unwanted behaviours. The parallel operation of inverters has been a major problem in industry that prevents the large-scale utilisation of renewable energy sources. This is a simple problem which has not been solved properly for many years. The conventional droop control strategy is a promising technology but the sharing accuracy cannot be guaranteed. Very recently, the PI has revealed that the conventional droop control scheme and its variants do not possess a mechanism to make sure that the sharing accuracy is robust against numerical computational errors, parameter drifts and component mismatches. A robust droop controller is then proposed, which is able to maintain accurate sharing of real power and reactive power at the same time and also to maintain good voltage regulation when the inverters are of the same type. The problem is still unsolved when the inverters are different. The major aims of the project are to develop fundamental understanding about parallel-operated inverters and to develop enabling contorl technologies to facilitate the large-scale utilisation of renewable energy and distributed generation. The ultimate goals of the project are to develop universal control strategies that allow the parallel operation of inverters with different types of output impedances and to develop a fundamental theory to guarantee the stable operation of power systems with parallel-operated inverters.

In pursuit of Carbon net-zero, it is imperative to develop technologies that enhance the efficiency and reliability of energy conversion, e.g. in drivetrain and rapid chargers of electric vehicles (EVs). To put this into context, the larger battery size (i.e. 350 kWh at 800 V & 440 A for higher consumption) and long-range driving nature of heavy-duty EVs mandate ubiquitous access to extremely fast chargers at 350 kW for financially justifiable charging delays. These are proposed to directly connect to 11 kV feeders by high-frequency solid-state-transformers (SST), needing energy-dense fast power modules. Literature indicates that the emergence of wide-bandgap semiconductor devices, especially Silicon Carbide devices, enables us to deliver ultra-efficient reliable converters that deliver the next leap. Wide-bandgap power electronics is, however, currently being slowed down due to issues such as high dV/dt, common-mode interference and degradations. This means the full potential of wide-bandgap devices is still far from being obtained. The IEEE International Technology Roadmap for Wide-Bandgap Power Semiconductors (ITRW) has indicated that to unlock this potential, these limitations must be broken-through by 2028. As the UK is leading toward automotive electrification with a ban on the sale of new petrol & diesel engines by 2030, the UK needs to develop this technology locally, and earlier than this, to remain a global competitor in 'driving the electric revolution'. Research on SiC devices has shown that they are prone to progressive degradations, with a 'memory' effect that leads to a drift of electrothermal parameters away from the datasheet values. This can lead to failures in long-term operations. Nevertheless, it is demonstrated that under certain conditions the devices can recover to close to the initial state, if the devices are subjected to specific electrical and thermal conditions. This proposal, in a nutshell, aims to take advantage of these findings to explore ways of controlling and reversing degradation in devices using non-contact sensors which feed information to smart, active gate drivers, which, in turn, control the recovery of the power devices. To this end, this New Investigator Award project aims to make the power electronic core of these power converters responsive to operating conditions and functional degradations. This will be achieved by closing the loop between detection of change in SiC devices and how devices are controlled via their gates. This would permit SiC devices to be operated safely at higher switching speeds and thus efficiencies, than current datasheet limits allow. This is because datasheet nominal values are conservative in order to take every situation into account, whereas new situational awareness will allow these limits to be safely exceeded when appropriate. This is so important, particularly in the case of SiC power conversion, because whilst it is successfully taking over from silicon, it is also known that the potential performance of SiC is over an order higher than today's systems. Being able to safely break through these nominal limitations will reduce converter volume in cars and aircraft 2x or more, and bring a similar reduction in power loss in wind and solar power generation. Perhaps most importantly, it will reduce operational risk, by changing to safer driving modes as devices age or overheat. For example, this will reduce the cost of offshore wind power generation by generating more power at a lower risk of damage, and allow maintenance to be pre-empted. In the future, responsive power conversion with awareness of operating conditions and degradation could allow electric vehicles to detect the onset of drive failure, and activate a safe mode to get people home.