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  • Journal article
    Abraham E, Kerrigan EC, 2013,

    Optimal Active Control and Optimization of a Wave Energy Converter

    , IEEE Transactions on Sustainable Energy, Vol: 4, Pages: 324-332, ISSN: 1949-3029
  • Journal article
    Chang H, Pistikopoulos EN, Astolfi A, 2013,

    Robust Multi-parametric Model Predictive Control for Discrete-time LPV Systems

    , 2013 AMERICAN CONTROL CONFERENCE (ACC), Pages: 431-436, ISSN: 0743-1619
  • Journal article
    Yin J, Lee CK, Hui SYR, Shravastava Yet al., 2013,

    A New Algorithm for Instantaneous Speed and Position Estimation of Surface-Mounted Permanent Magnet Synchronous Motors

    , 2013 IEEE ECCE ASIA DOWNUNDER (ECCE ASIA), Pages: 518-524
  • Conference paper
    Aunedi M, Strbac G, 2013,

    Efficient System Integration of Wind Generation through Smart Charging of Electric Vehicles

    , 8th International Conference and Exhibition on Ecological Vehicles and Renewable Energies (EVER), Publisher: IEEE
  • Conference paper
    Mitcheson PD, 2013,

    Adaptable, High Performance Energy Harvesters Can Energy Harvesting Deliver Enough Power for Automotive Electronics?

    , Design, Automation and Test in Europe Conference and Exhibition (DATE), Publisher: ASSOC COMPUTING MACHINERY, Pages: 482-482, ISSN: 1530-1591
  • Conference paper
    P Falugi, D Q Mayne, 2012,

    Tracking performance of model predictive control

    , Proc. 51st IEEE Conference on Decision and Control, Pages: 2631-2636
  • Conference paper
    Arana C, Evangelou SA, Dini D, 2012,

    Pitch Angle Reduction for Cars under Ac- celeration and Braking by Active Variable Geometry Suspension

    , 51st Conference on Decision and Control; CDC2012
  • Conference paper
    Shabbir W, Evangelou SA, 2012,

    Efficiency Maximizing and Charge Sustaining Supervisory Control for Series Hybrid Electric Vehicles

    , 51st Conference on Decision and Control; CDC2012
  • Conference paper
    Abraham E, Kerrigan EC, 2012,

    Optimal Active Control of a Wave Energy Converter

    , 51st IEEE Annual Conference on Decision and Control (CDC), Publisher: IEEE, Pages: 2415-2420, ISSN: 0743-1546

    This paper investigates optimal active control schemes applied to a point absorber wave energy converter within a receding horizon fashion. A variational formulation of the power maximization problem is adapted to solve the optimal control problem. The optimal control method is shown to be of a bang-bang type for a power take-off mechanism that incorporates both linear dampers and active control elements. We also consider a direct transcription of the optimal control problem as a general nonlinear program. A variation of the projected gradient optimization scheme is formulated and shown to be feasible and computationally inexpensive compared to a standard NLP solver. Since the system model is bilinear and the cost function is non-convex quadratic, the resulting optimization problem is not a convex quadratic program. Results will be compared with an optimal command latching method to demonstrate the improvement in absorbed power. Time domain simulations are generated under irregular sea conditions.
  • Conference paper
    Spallarossa CE, Pipelzadeh Y, Chaudhuri B, Green TCet al., 2012,

    Assessment of Disturbance Propagation between AC Grids through VSC HVDC Links using Reduced Great Britain Mode

    , IET Conference on AC and DC Power Transmission, Publisher: IET
  • Conference paper
    Luth T, Merlin MMC, Green TC, Barker CD, Hassan F, Critchley RW, Crookes RW, Dyke Ket al., 2012,

    Performance of a DC/AC/DC VSC System to Interconnect HVDC Routes

    , IET AC and DC Transmission Conference, Publisher: IET

    Interconnection of High Voltage Direct Current (HVDC) links into networks is key to a future HVDC grid spanning large parts of Europe. Different factors including the evolution of cable technology will lead to a variety of DC voltages and a need to provide a DC/DC step up/down at high power ratings (beyond 500 MW). This paper analyses a High Voltage (HV) DC/DC converter utilising an intermediated AC link between two modular multi-level converters (MMC) based on the Alternate Arm Converter (AAC) topology. System operation is demonstrated using a detailed simulation. Power loss estimates derived from the simulation are provided to illustrate the dependence of efficiency on design choices and operating point. Furthermore, the system is shown to block a DC-side fault and prevent its affect from propagating through the system.
  • Conference paper
    Sheridan CE, Merlin MMC, Green TC, 2012,

    Assessment of DC/DC converters for use in DC nodes for offshore grids

    With increasing offshore wind generation, there is a strong argument for implementing a multi-terminal DC grid offshore by the interconnection of individual HVDC links. The point of intersection of three or more lines can be used to interconnect projects with different voltage levels and to control power distribution. It is being proposed that these points, or nodes, be implemented using DC devices. A highvoltage, high-power DC/DC converter will therefore be an important component of a DC node. This paper reviews possible DC/DC converter topologies, looking at device requirement, different voltage conversion ratio and fault management. The suitability of the converters considered, for use in a node in a HVDC offshore grid, is discussed. A resonant DC/DC converter topology is considered in detail and is modelled at a conversion ratio of two, and demonstrates high power efficiency.
  • Journal article
    Yalcin Y, Astolfi A, 2012,

    Immersion and invariance adaptive control for discrete time systems in strict feedback form

    , SYSTEMS & CONTROL LETTERS, Vol: 61, Pages: 1132-1137, ISSN: 0167-6911
  • Journal article
    Zhong WX, Lee CK, Hui SYR, 2012,

    Wireless Power Domino-Resonator Systems With Noncoaxial Axes and Circular Structures

    , IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 27, Pages: 4750-4762, ISSN: 0885-8993
  • Journal article
    Hui SYR, Chen HT, Tao XH, 2012,

    An Extended Photoelectrothermal Theory for LED Systems: A Tutorial From Device Characteristic to System Design for General Lighting

    , IEEE Transactions on Power Electronics, Vol: 27, Pages: 4571-4583
  • Journal article
    Dicken J, Mitcheson PD, Stoianov I, Yeatman EMet al., 2012,

    Power-Extraction Circuits for Piezoelectric Energy Harvesters in Miniature and Low-Power Applications

    , IEEE Transactions on Power Electronics, Vol: 27, Pages: 4514-4529, ISSN: 0885-8993
  • Journal article
    Hasan A, Kerrigan EC, Constantinides GA, 2012,

    Control-theoretic forward error analysis of iterative numericalalgorithms

    , IEEE Transactions on Automatic Control, Vol: 58, Pages: 1524-1529, ISSN: 0018-9286

    It has been known for at least five decades that control theorycan be used to study iterative algorithms. However, little work can be foundin the control systems literature on numerical algorithms, especially on thestudy of finite precision effects. In this technical note, we consider numericaliterative algorithms in finite precision as dynamical systems and studythe effects of finite precision using control theory. By using the control toolsof input-to-state stability and results from the study of quantization in controlsystems, we present new systematic ways to find bounds on the forwarderror for iterative algorithms. The advantages of the proposed schemes areshown by applying them to find bounds for the classical iterative methodsfor solving a system of linear equations.
  • Patent
    Pinuela M, Mitcheson PD, Lucyszyn S, Yates DCet al., 2012,

    Maximising DC to load efficiency for inductive power transfer
  • Conference paper
    Bottrell N, Green TC, 2012,

    Modeling microgrids with active loads

    It is known that active rectifier loads present a negative incremental resistance and have control loop dynamics similar to inverters that may supply a microgrid. To investigate this, a small-signal model of an active rectifier load within a microgrid is developed. The active rectifier load and microgrid are modeled in the synchronous (DQ) reference frame. A participation analysis of the model is performed and modes of the system are identified. The model is verified in a laboratory using rapid prototyping power converters where a set of load perturbations are performed to identify the modes predicted by the participation analysis. © 2012 IEEE.
  • Journal article
    Shahzad A, Kerrigan EC, Constantinides GA, 2012,

    A Stable and Efficient Method for Solving a Convex Quadratic Program with Application to Optimal Control

    , SIAM Journal on Optimization, Vol: 22, Pages: 1369-1393, ISSN: 1052-6234
  • Journal article
    Sassano M, Astolfi A, 2012,

    Dynamic Approximate Solutions of the HJ Inequality and of the HJB Equation for Input-Affine Nonlinear Systems

    , IEEE TRANSACTIONS ON AUTOMATIC CONTROL, Vol: 57, Pages: 2490-2503, ISSN: 0018-9286
  • Conference paper
    Collins ME, Silversides RW, Green TC, 2012,

    Multi-Agent System Control and Coordination of an Electrical Network

    , Universities Power Engineering Conference, Publisher: IEEE

    Multi-Agent Systems (MAS) have the potential to solve Active Network Management (ANM) problems arising from an increase in Distributed Energy Resources (DER). The aim of this research is to integrate a MAS into an electrical network emulation for the purpose of implementing ANM. Initially an overview of agents and MAS and how their characteristics can be used to control and coordinate an electrical network is presented. An electrical network comprising a real-time emulated transmission network connected to a live DER network controlled and coordinated by a MAS is then constructed. The MAS is then used to solve a simple ANM problem: the control and coordination of an electrical network in order to maintain frequency within operational limits. The research concludes that a MAS is successful in solving this ANM problem and also that in the future the developed MAS can be applied to other ANM problems.
  • Conference paper
    Moreno C, Tomas-Rodriguez M, Evangelou SA, 2012,

    Dynamical Analysis of a Duolever Suspension System

    , UKACC
  • Journal article
    Pipelzadeh Y, Chaudhuri NR, Chaudhuri B, Green TCet al., 2012,

    System stability improvement through optimal control allocation in voltage source converter-based high-voltage direct current links

    , IET GENERATION TRANSMISSION & DISTRIBUTION, Vol: 6, Pages: 811-821, ISSN: 1751-8687
  • Journal article
    Hui SYR, Lee CK, Wu F, 2012,

    Electric Springs — A New Smart Grid Technology

    , IEEE Transactions on Smart Grid, Vol: 3, Pages: 1552-1561, ISSN: 1949-3053
  • Journal article
    Jerez JL, Ling KV, Constantinides GA, Kerrigan ECet al., 2012,

    Model predictive control for deeply pipelined field-programmable gate array implementation: algorithms and circuitry

    , IET Control Theory and Applications, Vol: 6, Pages: 1029-1041, ISSN: 1751-8652

    Model predictive control (MPC) is an optimisation-based scheme that imposes a real-time constraint on computingthe solution of a quadratic programming (QP) problem. The implementation of MPC in fast embedded systems presents newtechnological challenges. In this paper we present a parameterised field-programmable gate array implementation of acustomised QP solver for optimal control of linear processes with constraints, which can achieve substantial acceleration overa general purpose microprocessor, especially as the size of the optimisation problem grows. The focus is on exploiting thestructure and accelerating the computational bottleneck in a primal-dual interior-point method. We then introduce a new MPCformulation that can take advantage of the novel computational opportunities, in the form of parallel computational channels,offered by the proposed pipelined architecture to improve performance even further. This highlights the importance of theinteraction between the control theory and digital system design communities for the success of MPC in fast embedded systems.
  • Journal article
    Buchstaller D, Kerrigan EC, Constantinides GA, 2012,

    Sampling and controlling faster than the computational delay

    , IET Control Theory and Applications, Vol: 6, Pages: 1071-1079
  • Journal article
    Casagrande D, Sassano M, Astolfi A, 2012,

    Hamiltonian-Based Clustering ALGORITHMS FOR STATIC AND DYNAMIC CLUSTERING IN DATA MINING AND IMAGE PROCESSING

    , IEEE CONTROL SYSTEMS MAGAZINE, Vol: 32, Pages: 74-91, ISSN: 1066-033X
  • Journal article
    Ahmed S, Kerrigan EC, Jaimoukha IJ, 2012,

    A Semidefinite Relaxation-Based Algorithm for Robust Attitude Estimation

    , IEEE Transactions on Signal Processing, Vol: 60, Pages: 3942-3952, ISSN: 1053-587X

    This paper presents a tractable method for solving a robust attitude estimation problem, based on a weighted least squares approach with nonlinear constraints. Attitude estimation requires information of a few vector quantities, each obtained from both a sensor and a mathematical model. By considering the modeling errors, measurementnoise, sensor biases and offsets as infinity-norm bounded uncertainties, we formulate a robust optimization problem, which is non-convex with nonlinear cost and constraints. The robust min-max problem is approximated with a non-convex minimization problem using an upper bound. A new regularization scheme is also proposed to improve the robust performance. We then use semidefinite relaxation to convert the suboptimal problem with quadratic cost and constraints into a tractable semidefinite program with a linear objective function and linear matrix inequality constraints. We also show how to extract the solution of the suboptimal robust estimation problem from the solution of the semidefinite relaxation. Further, a mathematical proof supported by numerical results is presented stating the gap between the suboptimal problem and its relaxation is zero under a given condition, which is mostly true in real life scenarios. The usefulness of the proposed algorithm in the presence of uncertainties is evaluated with the helpof examples.
  • Conference paper
    Pipelzadeh Y, Chaudhuri B, Green TC, 2012,

    Inertial Response from Remote Offshore WindFarms Connected Through VSC-HVDC Links: ACommunication-less Scheme

    , IEEE Power and Energy Society General Meeting 2012

    A communication-less scheme that allows remoteoffshore wind farms connected through HVDC links to participatein primary frequency control and contribute to systeminertia is discussed in this paper. As a HVDC link decouples theoffshore system from the onshore side, real-time communicationof onshore frequency is normally required for the primaryfrequency control loop of the wind farms. Dependance on remotecommunication which could be unreliable at times is a problem.To obviate the need for communication, appropriate droopcontrol on the offshore and onshore converters is used in thispaper to translate the variation in onshore frequency to anequivalent variation on the offshore end. Thus the need for communicatingonshore frequency to the offshore side is mitigatedwhich ensures reliable operation. Such a communication-lessscheme is compared against the conventional approach involvingremote communication of onshore grid frequency to the windfarm site. Along side physical and analytical justification, a casestudy is presented to demonstrate that the communication-lessscheme performs similar to the conventional one in terms ofreducing grid frequency variations.

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