Ensuring system security and stability is an ever-present concern in power system engineering due to the crucial importance of reliable power supply in modern society. The growth of renewable energy increases the number of power electronic converters present in the power network since they are needed to interface non-conventional forms of generation to standard 50 or 60 Hz system. This changes the network's physical structure and causes new threats to security. Compared to conventional power equipment, power electronic converters are subject to rigid capacity constraints which make them prone to lose functionalities during large disturbances and trigger fault cascading. On the other hand, converters have higher flexibility and faster response which enable more versatile patterns of dynamic control. Therefore, a new methodology for both converter design and system operation is needed to take advantage of the strengths and mitigate the weaknesses of converters in supporting grid security. This problem is difficult because power electronic converters have sophisticated internal dynamics which further interact with a complex power network with a vast number of nodes and uncertain disturbance scenarios. What adds to the difficulty is that converters and networks are created by very different owners and supply chains that newly come together but still have different perspectives and technical languages. This fellowship aims to establish a common technology framework for converter manufacturers and network operators, and find a systematic methodology and practical tools for grid-supportive converter design and converter-based grid security management. The proposed research sets out to do three things. First, it will find analytical methods to quantify the support provided by and stress placed on converters regarding network security, from which converter design guidelines will be derived to optimize the security support functions in a cost-effective way. Second, it will build computational platforms for network operators to use a vast number of converters synergistically for real-time security management. Third, it will develop proof-of-concept prototypes, demonstrate their application potential in a complex power system, and promote commercialization and standardization.

Ensuring system security and stability is an ever-present concern in power system engineering due to the crucial importance of reliable power supply in modern society. The growth of renewable energy increases the number of power electronic converters present in the power network since they are needed to interface non-conventional forms of generation to standard 50 or 60 Hz system. This changes the network's physical structure and causes new threats to security. Compared to conventional power equipment, power electronic converters are subject to rigid capacity constraints which make them prone to lose functionalities during large disturbances and trigger fault cascading. On the other hand, converters have higher flexibility and faster response which enable more versatile patterns of dynamic control. Therefore, a new methodology for both converter design and system operation is needed to take advantage of the strengths and mitigate the weaknesses of converters in supporting grid security. This problem is difficult because power electronic converters have sophisticated internal dynamics which further interact with a complex power network with a vast number of nodes and uncertain disturbance scenarios. What adds to the difficulty is that converters and networks are created by very different owners and supply chains that newly come together but still have different perspectives and technical languages. This fellowship aims to establish a common technology framework for converter manufacturers and network operators, and find a systematic methodology and practical tools for grid-supportive converter design and converter-based grid security management. The proposed research sets out to do three things. First, it will find analytical methods to quantify the support provided by and stress placed on converters regarding network security, from which converter design guidelines will be derived to optimize the security support functions in a cost-effective way. Second, it will build computational platforms for network operators to use a vast number of converters synergistically for real-time security management. Third, it will develop proof-of-concept prototypes, demonstrate their application potential in a complex power system, and promote commercialization and standardization.

There are increasing concerns about the safety and security of critical infrastructure such as nuclear power plants, the electricity grid and other utilities in the face of possible cyber attacks. As ageing controllers are replaced by smart devices based on Field-Programmable Gate Arrays (FPGAs) and embedded microprocessors, the safety of such devices raises many concerns. In particular, there is the very real risk of malicious functionality hidden in the silicon or in software binaries, dormant and waiting to be activated. Current hardware and software systems are of such complexity that it is impossible to discover such malicious code through testing. We aim to address this problem by closely connecting the system design specification with the actual implementation through the use of a formal design methodology based on type systems with static and dynamic type checking. The type system will be used as a formal language to encode the design specification so that the actual implementation will automatically be checked against the specification. Static type checking of data types and multiparty session types can ensure the correctness of the interaction between the components. However, as static checking assume full access to the design source code it cannot be used to protect against potential threads issuing from third-party functional blocks (know as ``Intellectual Property Cores'' or IP cores) that are commonly used in hardware design: the provider of the IP core can claim adherence to the types and protocols, so that the IP core will meet the compile-time requirements, but the run-time the behaviour cannot be controlled using static techniques. The same applies to third-party compiled software libraries. Therefore we propose to use run-time checking of data types as well as session types at the boundaries of untrusted modules ("Border Patrol"), so that any intentional or unintentional breach of the specification will safely be intercepted.

The aerospace industry is the key sector for growth of the UK economy. The potential market share of the UK, which is specialised in the most complicated and high tech aircraft parts, is estimated to be around $600 billion. This enormous market demand was also driven by the environmental issue, which requires the lightweight composite aircraft structures to meet the future CO2 emission regulations. The automated fibre placement (AFP) process is the core technology that underpins the UK's aerospace industry. This process can lay up carbon fibre tape (or tow) materials on a three dimensional mould surface using a robotic or a computer-controlled gantry machine at high speed, which is mainly used in the aerospace industry to manufacture composite structural components such as fuselages, wings, and spars. The AFP machine's capability of feeding individual tows at different speeds enables steering the fibres within the tows along curved paths, and such fibre steering allows for manufacturing composite structures with complex geometry as well as realising ultra-high structural efficiency beyond the limit of the conventional straight fibre lay-up design. However, it has a few fundamental limitations in fibre steering to produce complex composite components. First, since the AFP machine steers the fibres by bending the tow tape, fibre-buckling defects are always generated. Second, it needs to frequently cut the tows when laying up on a doubly-curved surface that cannot be perfectly tessellated with the finite width tows, which also creates defects such as fibre discontinuity and resin pockets. Such process-induced defects are a critical barrier that reduces the production speed and complicates the design process in the aerospace industry. Furthermore, as the shape of the composite components becomes more complex, the minimisation of such defects in fibre steering process is getting more important. This project aims to develop a new game-changing fibre placement technology that can produce defect-free doubly-curved composite components, based on fundamental understanding of the impregnation and deformation characteristics of tow materials. The new head mechanism to be developed will be capable of producing variable width tows on-the-fly to cover tessellated sections of a complex 3D surface without gaps. The scientific knowledge on tow-level deformation characteristics will be integrated with an advanced head mechanisms as well as a new head control algorithm in order to realise the buckling free fibre steering using the continuous tow shearing mechanism on complex 3D surfaces. Finally, a prototype head will be tested on a robotic platform programmed using the developed head control algorithm, and the lay-up quality and accuracy will be evaluated using various inspection methods. This establishes a proof-of-concept manufacturing process for complex 3D composite components. Although the industry is making various attempts to solve the quality problems by modifying the process parameters or the tow material, there are no existing AFP technologies that can either steer the tow without defects or control the tow width. The successful development of this unique and disruptive AFP process will provide the UK aerospace industry with a fundamental solution to the quality problems that they are facing, which enable the UK to be at the forefront of next-generation automated composites manufacturing technology.

The movement of electrical energy from generators to customers, through electricity networks, has historically been based on High Voltage Alternating Current (HVAC) technology. This has been a major success of the twentieth century, enabling reliable and stable energy supplies across the developed world. The technology dominated partly as a result of the ability to change voltage levels readily and efficiently using transformers. The alternative technology of High Voltage Direct Current (HVDC) has historically only been used for point-to-point links because of particular advantages in this situation. Now however, with the advent of power electronics, utilisation of HVDC systems is rapidly increasing across the world. This has been accelerated with the growth of renewable distributed energy supplies, such as offshore wind farms in the UK. As a result, local and international energy supplies are becoming dependent on HVDC. Consequently, the reliability of DC technologies is becoming critical as they become more embedded in supply networks. However, in comparison to AC systems, the understanding of insulation and plant reliability under HVDC is still in its infancy. At the same time, the working environment for DC plant is not well documented and, in reality, DC systems have AC ripple, impulses and voltage variation just as in any other system, and these time-varying waveforms are likely to control plant ageing and reliability. This project comprises internationally leading researchers from The University of Manchester, The University of Strathclyde and Imperial College. They bring complementary expertise to form a unique team to address the problem. Prof Tim Green (Imperial) is an expert in the use of power electronics to enhance the controllability and flexibility of electricity networks; Prof Simon Rowland (Manchester) is an authority on ageing of high voltage insulation materials; and Prof Brian Steward (Strathclyde) has unique experience in condition monitoring and insulation diagnostics for high voltage systems. The project is designed to embed the work into the global community and in particular is linked to researchers in China where the largest systems are being developed. This project will firstly identify the voltage profiles experienced by plant insulation in a real HVDC network or link, because in real systems the voltage on the network is not a constant, fixed value. The power converters that feed a DC network create intrinsic "noise" in the form of high frequency elements as part of their normal operation, and also create voltage disturbances in their responses to fault conditions and emergency overloads. Characterising these is the first step in the overall study of how DC power quality impacts the lifetime of HV insulation. The team will then, through laboratory exploration, develop life models for polymeric insulation subject to known levels of DC power quality. The focus will be on AC ripple over a wide frequency range. In addition, the influence of fast transient signals of varying levels and durations will be considered, as identified above. The third experimental theme is to develop tools for monitoring transient signals and power quality in a real DC cable setting, and enable subsequent interpretation. Finally, we will develop input for utility policy documents on acceptable DC power quality. We will also provide evidence for optimal insulation design for equipment manufacturers and asset management recommendations for utilities. Through these means we hope to de-risk the UK's growing dependence on DC networks, and optimise equipment and system design and operation.