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  • 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
    Ahmed S, Kerrigan EC, Jaimoukha IJ, Ahmed S, Kerrigan EC, Jaimoukha IMet al., 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.
  • 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
  • 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.
  • Conference paper
    Segundo Sevilla FR, Jaimoukha I, Chaudhuri B, Korba Pet al., 2012,

    Fault-tolerant Wide-area Control for PowerOscillation Damping

    , IEEE PES General Meeting 2012
  • Journal article
    Lin D, Yan W, Zissis G, Hui SYRet al., 2012,

    Methodology for developing a low-pressure discharge lamp model with electron density variation and ambipolar diffusion

    , IET SCIENCE MEASUREMENT & TECHNOLOGY, Vol: 6, Pages: 229-237, ISSN: 1751-8822
  • Journal article
    Luis Dominguez-Garcia J, Gomis-Bellmunt O, Trilla-Romero L, Junyent-Ferre Aet al., 2012,

    Indirect vector control of a squirrel cage induction generator wind turbine

    , COMPUTERS & MATHEMATICS WITH APPLICATIONS, Vol: 64, Pages: 102-114, ISSN: 0898-1221
  • Conference paper
    Kuenzel S, Kunjumuhammed LP, Pal BC, Erlich Iet al., 2012,

    Wind Power Plants Inertial Response Capability Considering Wake Effect

    , 11th International Workshop on Large-Scale Integration of Wind Power into Power Systems as well as on Transmission Networks for Offshore Wind Power Plants, Lisbon
  • Journal article
    Su Y, Liu X, Lee CK, Hui SYRet al., 2012,

    On the Relationship of Quality Factor and Hollow Winding Structure of Coreless Printed Spiral Winding (CPSW) Inductor

    , IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 27, Pages: 3050-3056, ISSN: 0885-8993
  • Conference paper
    Pinuela M, Yates DC, Mitcheson PD, Lucyszyn Set al., 2012,

    Current State of Research at Imperial College London in RF Harvesting and Inductive Power Transfer

    , 2nd International Workshop on Wireless Energy Transport and Harvesting, Pages: 1-4

    This paper presents simulation and experimental results for ambient RF energy harvesting and Inductive Power Transfer systems. End-to-end and dc-load efficiency measurements and calculations were performed to demonstrate the capabilities of both systems, respectively. An RF spectral survey was conducted across all the 270 underground stations in London. DTV, GSM900, GSM1800 and 3G were selected as the highest contributors and single banded rectennas were fabricated for all frequencies. Ground level measurements demonstrate that more than 50 stations have suitable channel power levels per band to allow ambient RF energy harvesting. Efficiencies of up to 40% were achieved with a single banded rectenna operating at GSM 900, and efficiencies higher than 20% were achieved for TV and 3G. Furthermore a high frequency, semi-resonant Class-E driver was used to transfer 60 W of power across a 30 cm distance with a dc-load efficiency of 66%.
  • Patent
    GREEN TC, MERLIN MMC, OKAEME N, TRAINER DR, otherset al., 2012,

    MODULAR MULTILEVEL CONVERTER
  • Conference paper
    Vasilakos C, Strbac G, Pudjianto D, Gammons S, Druce R, Moreno Ret al., 2012,

    European Transmission Tariff Harmonization: A Modeling Analysis

    , 9th International Conference on the European Energy Market EEM12
  • Journal article
    Angeli D, Kountouriotis P-A, 2012,

    A Stochastic Approach to "Dynamic-Demand" Refrigerator Control

    , IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, Vol: 20, Pages: 581-592, ISSN: 1063-6536
  • Journal article
    Bianchi FD, Egea-Alvarez A, Junyent-Ferre A, Gomis-Bellmunt Oet al., 2012,

    Optimal control of voltage source converters under power system faults

    , CONTROL ENGINEERING PRACTICE, Vol: 20, Pages: 539-546, ISSN: 0967-0661
  • Journal article
    Falugi P, Kountouriotis P-A, Vinter RB, 2012,

    Differential Games Controllers That Confine a System to a Safe Region in the State Space, With Applications to Surge Tank Control

    , IEEE Transactions on Automatic Control, Vol: 57, Pages: 2778-2788, ISSN: 1558-2523

    Surge tanks are units employed in chemical processing to regulate the flow of fluids between reactors. A notable feature of surge tank control is the need to constrain the magnitude of the Maximum Rate of Change (MROC) of the surge tank outflow, since excessive fluctuations in the rate of change of outflow can adversely affect down-stream processing (through disturbance of sediments, initiation of turbulence, etc.). Proportional + Integral controllers, traditionally employed in surge tank control, do not take direct account of the MROC. It is therefore of interest to explore alternative approaches. We show that the surge tank controller design problem naturally fits a differential games framework, proposed by Dupuis and McEneaney, for controlling a system to confine the state to a safe region of the state space. We show furthermore that the differential game arising in this way can be solved by decomposing it into a collection of (one player) optimal control problems. We discuss the implications of this decomposition technique, for the solution of other controller design problems possessing some features of the surge tank controller design problem.
  • Journal article
    Tao X, Hui SYR, 2012,

    Dynamic Photoelectrothermal Theory for Light-Emitting Diode Systems

    , IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol: 59, Pages: 1751-1759, ISSN: 0278-0046
  • Journal article
    Chen HT, Tao XH, Hui SYR, 2012,

    Estimation of Optical Power and Heat-Dissipation Coefficient for the Photo-Electro-Thermal Theory for LED Systems

    , IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 27, Pages: 2176-2183, ISSN: 0885-8993
  • Journal article
    Tao X, Chen H, Li SN, Hui SYRet al., 2012,

    A New Noncontact Method for the Prediction of Both Internal Thermal Resistance and Junction Temperature of White Light-Emitting Diodes

    , IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 27, Pages: 2184-2192, ISSN: 0885-8993
  • Journal article
    Azcondo FJ, Marcos Alonso J, Hui SYR, 2012,

    SPECIAL SECTION ON MODERN BALLAST TECHNOLOGY AND LIGHTING APPLICATIONS

    , IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol: 59, Pages: 1686-1688, ISSN: 0278-0046
  • Journal article
    Datta S, Chakraborty D, Chaudhuri B, 2012,

    Partial Pole Placement with Controller Optimization

    , IEEE TRANSACTIONS ON AUTOMATIC CONTROL, Vol: 57, Pages: 1051-1056, ISSN: 0018-9286
  • Journal article
    Li SN, Zhong WX, Chen W, Hui SYRet al., 2012,

    Novel Self-Configurable Current-Mirror Techniques for Reducing Current Imbalance in Parallel Light-Emitting Diode (LED) Strings

    , IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 27, Pages: 2153-2162, ISSN: 0885-8993

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