Summary: The operations of interconnected power networks are facing unprecedented challenges which are primarily driven by new intermittent sources of generation that are replacing centralised flexible generation. Such intermittency in generation inevitably leads to difficulties in achieving reliable operation. The existing weak high voltage AC system in China suffers from stability-related problems and as a result, in 2010 17% of the electricity produced in China's top 10 wind power bases was curtailed with curtailment reaching as much as 25% in the Gansu province. A single grid fault on the 24th of February 2011 caused the disconnection of 598 wind turbines in Northwest China, resulting in a system frequency dip of 0.178 Hz, highlighting the inadequacy of the control technology currently used. A similar incident of generation outage in the UK on the 2nd of September 2010 led to a rapid decline in frequency, which disconnected about 350 MW embedded generation (mainly wind) through the action of the rate of change of frequency (RoCoF) protection. These are two of the many incidents that highlight the need for new approaches in fast system monitoring for enhanced stability and control. Energy storage is essential to address the balance between generation and demand at different time scales. However, the description of the dynamic performance of energy storage under varied loading, and their state of charge and health monitoring are currently open problems. Complex dynamic behaviour, such as hysteresis, may manifest in storage systems. Therefore it is not clear how storage may impact power system operation, particularly with respect to stability. There have been instances of loss of generation because of the inadequate control of the power converter interface between intermittent generation and network. When the existing power converter technology is duplicated to act as an interface between storage and the grid, the poor performance is inevitable without improved understanding of local and global dynamics. Another key barrier is the lack of robust enabling technology for monitoring and control that can integrate the capabilities of storage in a time critical manner. Fast dynamic security assessment has been attempted through the energy function approach - but existing tools fail to compute the true stability margin because of the complexity of power system dynamic characteristics. All these barriers may be overcome through underpinning research in monitoring, modelling and control of storage to stabilise interconnected power network operations. The challenges lie in fast computation, fault detection and robust control design of the interface between storage and the network. The approach proposed here is decentralised stability monitoring, assessment and control of the network. Existing network operation practice relies heavily on slow and centralised control architectures through large SCADA/EMS. The methodologies that are being proposed will thus need to rely little on system wide communication infrastructure. In addition, distributed approach to dynamic system monitoring, decentralised approaches to system wide disturbances and dynamic security assessment through distributed energy function are novel approaches. The innovations include cutting edge representations of high power low energy storage; energy functions to include asynchronous and synchronous generation with storage with resistive elements, practical applications of ground breaking decentralised fault detection and robust and reliable control between intermittent generation and the rest of the system. Because the successful operation of interconnected power grids requires fast computation and control, as well as energy storage domain knowledge, the power system and energy storage experts in this consortium are joined by a number of leading control theory experts with experience in power networks - definitely a very unique strength of the team.

This project studies various aspects of integration of large renewable power parks with DC networks which include DC/DC converters. UK and China alike have enormous wind power potential which theoretically can exceed total national energy demand. Much of this energy is located offshore or in remote sites like North Scotland and North West China which have no electrical grid or have very weak grid infrastructure. These factors together with wind energy intermittency cause integration challenges, demand new approaches in developing transmission/collection grids and call for substantial use of power electronics. There is large number of point to point High Voltage Direct Current (HVDC) links worldwide and HVDC has proven beneficial for interconnecting wind energy. Nevertheless DC transmission has not evolved into widespread DC grids because of a range of technical challenges such as difficulties with DC voltage stepping and DC fault isolation. It is expected that DC grids will have same security level as AC systems, but all grid functions, topologies, operation and control will be different and need substantial further studies. The DC networks may not adopt AC grid topologies because of high costs and losses associated with DC/DC voltage stepping and DC fault isolation components. However unlike AC transformers, the DC/DC converters will be highly controllable and flexible since they will be based on power electronics. This controllability enables DC/DC electronic units to take numerous other functions like controllable voltage stepping, circuit breaker and a power regulator in a single component. In this project we study the development of DC grids exploring the power electronics DC/DC components. This project will investigate development of DC grids by considering the essential requirements (AC systems experience) like security, stability, reserve, fault responses loss minimization. To meet these requirements we explore in depth power electronics DC/DC components and consider also semiconductor-based DC CB and mechanical DC CB. The main aims of this project are: 1. To study integration technologies and control strategies of large scale renewable power parks with DC networks incorporating DC/DC converters, 2. To study key technologies required for DC grids including a multifunctional and multiterminal electronic DC/DC substation (power electronics unit connecting multiple DC lines), 3. To investigate meshed and hybrid DC grid topologies, their security and interface with national AC grids, 4. To develop new wind generator topologies, converters and controls suitable for connecting to DC grids, 5. To strengthen existing and build new lasting collaborative links between UK and China institutions. The offshore DC grid is recognized as being highly important for UK energy sector. The interconnections with EU grid will increase security of electricity supply, reduce the spinning reserve concerns with wind energy and provide access points for offshore renewable sources. The offshore wind power in round 3 program has the potential to supply significant portion of the UK energy needs and thus to reduce greenhouse emissions and avoid building of new Nuclear power plants. It is projected that energy for transport and heating will be more dependent on the electricity grid, demanding strengthening of transmission grid and only offshore DC grid can meet these requirements in short-medium time frame. In China, there is now large number of LCC (Line Commutated Converter) HVDC lines operating solely as point-to-point links and new lines are planned for connecting large wind resources in north regions and offshore. There would be significant performance/operational and cost benefit if multiple wind parks could be tapped along these DC lines or if DC lines could be interconnected on the DC side The main beneficiaries of this research include high power converter manufacturers, grid operators and renewable energy developers.

Reliable electricity supply forms a one of the basic requirements of modern 21st Century life. Sustaining this reliable supply is one of the key challenges for the coming decades. A solution is not straight-forward and will have many parts. Integrating offshore wind energy generation as cheaply as possible is one part. Linking our electricity transmission network to the generation and services of other European countries is another part. Reinforcing the onshore electricity network to cope with new power flows, is a further part. Addressing these challenges requires an offshore electricity network, which is controlled to support our existing infrastructure. Such an offshore network disrupts far less of the onshore countryside and living environment than conventional onshore solutions. Enabling this necessary offshore network is the goal of this proposal. The technology needed to achieve such a solution is so-called Voltage-Source High-Voltage DC Transmission (VSC-HVDC): DC connections using converter stations with the latest state-of-the-art, high-voltage semiconductor power processing technology. Only such stations have the required flexibility, compactness offshore and ability to transmit power over long sub-sea cables. However our experience with such technology is limited to point-to-point systems. No small networks (so-called multi-terminal systems) have been built. No large networks (so-called DC grids) have been constructed. Very little research has been published into how to control such systems. There is a dearth of information on how to make large offshore networks 'work'. However many industrial and academic organizations have highlighted the substantial potential benefits in terms of reduced cost, improved reliability and greater functionality which could be offered by such DC offshore networks to our existing electricity infrastructure. This project will undertake the research urgently required to assess the best way to control and mange such networks. Since telecommunications, controller architecture and control are intimately linked, research to assess and include the impact of these constraints will also be incorporated. Candidate networks will be formulated, analyzed and simulated using state-of-the-art models. These models will be improved to include the effects of distributed control and telecommunications effects/Quality of Service. New techniques will be developed that allow similar benefits to 'perfect' (idealized Master) control to be achieved with more realistic distributed hardware systems. The transformative goals of this project are thus: 1. To establish how Master and Distributed Master controllers can improve VSC-HVDC-grid performance and offer robust and reliable services to AC onshore networks. 2. To investigate advanced controls, and effective exploitation of state-of-the-art and developing telecommunication technologies, to integrate this control with local station control and to overcome conventional operational speed limitations. Better system understanding, models, and improved control will result. This in turn should allow the creation of a cheaper, more effective offshore network.

Industrial computer-based control systems are crucial to society, they control the water we drink, the power we use, the cars we drive as well as railways and air transportation. These systems need to be trusted and trustworthy. They are often networked into complex and interconnected systems of systems and control and protect the UK national infrastructure. An important aspect of infrastructures is their interactions and interdependencies: the functioning of one infrastructures service often depends on the functioning of another. As the infrastructure becomes layered and there are secondary services layered on top of these primary infrastructures and as the network becomes dynamic and controlled by computer networks and systems there is considerable potential for unforeseen interaction and dependencies. As Industrial control systems become more networked, the previous strategy of making them secure by isolating them from the world becomes ineffective. In addition those who might harm the system either out of maliciousness or misplaced curiosity proliferate and their expertise increases, so the importance of security for the availability and integrity of services and systems is becoming ever more significant. The research focuses on the importance of dependencies and interdependencies in this security context. These have been studied for a number of years and it is known that unforeseen interdependencies are a source of threat to systems and an important factor in our uncertainty of risk assessment, particularly risk due to cascade failures in which the rate and size of loss is amplified. However there two faces to interdependencies, while we are concerned about how they might make attacking the system easier and a source of unforeseen behaviours, it is also central to providing tolerance to attack and failure. Redundancy, diversity, defence in depth are deliberately engineered into control systems to increase dependability and are an important mechanism for adaptation and overall resilience. Any risk assessment of computer based control systems has to take into account uncertainty about the structure of the system. It is not just the uncertainty of when events might happen but uncertainty about the world, so-called epistemic uncertainty. For example, audits for the US DHS states that they find, on average, 11 unexpected connections between the SCADA system and the enterprise network for each audit A key part of risk assessment is communication to stakeholders and society as appropriate. We will develop a security informed (or cyber-informed) enhancement to evaluating and communicating business and other risks from lack of control system integrity and availability based on a claims, arguments, evidence (CAE) framework. Our focus will be to include cyber informed dependency analysis within these assessments. The research to do this will follow an impact driven, threat-informed and vulnerability-focused strategy. We will also develop probabilistic models that address explicitly the evolving relationship between an adversary and attacks on the one hand and of the consequences of a successful attack as well as the dependencies between the mitigations and barriers. We are particularly interested in modelling and evaluating defence in depth as a fundamental part of any resilient and trustworthy system yet estimating its effectiveness given uncertainties in the system structure and the attack space is enormously difficult. We will develop a modelling toolset based on existing tools we have developed within EU, Artemis and TSB projects that integrate stochastic and deterministic (e.g. of power flow). We will conduct case studies based on problems provided by our project partners Adelard (a specialist SME that evaluates ICS systems and components) and Alsthom.

25 million rural Indian households do not have access to electricity and the rest of the rural households face 4-5 hours of daily load shedding. In the UK, 17.2% rural households are fuel poor and it takes 10 times longer to restore power supply in rural areas than in the cities. While in India it is the inadequacy of infrastructure, the UK scene is dominated by network operation and control issues. Most of these remote regions have local power resources but mainly intermittent in nature. Running such system in isolation requires storage and thus pushing the overall cost up. On and off grid through hybrid AC/DC micro grid concept is very revolutionary in this context. However, the operation in such mode does not come unchallenged. The technical issues are low inertia because of small synchronous generators and inverter based generation, unbalanced demand, asymmetric network, false tripping of DG during mode transition, excessive harmonic distortion because of power electronics driven customer loads, etc. The challenges represent a major test of the power engineering community. This is because, in order to solve them, experts from different specialities - distribution system operation and control, power electronic converter design and control, energy storage must come together and fuse different enabling technologies for making smart distribution grid truly functional. This consortium, drawing in experts from each of these technical areas, proposes to undertake fundamental technical research to fuse these technologies to make a community grid a reality. The overarching aim of this proposal is to invent appropriate, cost effective, scalable, secure and reliable local energy system. The innovations include cutting edge converter topology, control design, practical application of ground breaking voltage and frequency control, innovation in thermal storage in demand management and the output of DG intermittency and advanced system operation tools. Four prototype laboratory based systems will be designed tested and validated to reflect four different geographical and climate situations influencing the resource availability and consumption trends. In the short to medium term this project will establish and strengthen the collaborations between the leading UK and Indian universities engaged in research in power electronics, renewable energy, power distribution operation and control and energy storage. This will promote mutual understanding of the challenge facing the power system practices in order to meet the growing energy demand through increasingly intermittent local energy resources in the years ahead. Strong collaboration between the scientists in two countries will allow rigorous evaluation of challenges, technology and approach to address the problem of reliably operating power distribution systems of both countries. This will lead to novel and scientific understanding validated on different contexts and systems, which could not be possibly achieved by either side working in isolation. The research outcome will be well publicized in journal and conferences. While it is clear that the uptake of this research primarily benefit the community living in the remote region, the other inevitable impact is employment opportunity for local people, business opportunity for various companies such as EoN, GE Energy, Siemens, ALSTOM GRID, ABB in the UK and in India, to name a few. In a time when there is a universal crisis for power engineers, the project will deliver trained researchers with broader expertise of working in this multinational collaborative project. Many of the investigators on both the UK and Indian side already enjoy healthy collaborative working relationships with industrial and utility partners primarily within their own countries. This programme will clearly move the research frontier and will drive technology development through such true multinational research collaboration.