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  • Conference paper
    Chaudhuri B, Pal B, 2004,

    Robust damping of multiple swing modes employing global stabilizing signals with a TCSC

    , IEEE-Power-Engineering-Society General Meeting, Publisher: IEEE, Pages: 1709-1709
  • Book chapter
    Rodriguez H, Astolfi A, Ortega R, 2004,

    On the control of a class of electromechanical systems

    , Lagrangian and Hamiltonian methods for nonlinear control : a proceedings volume from the 2nd IFAC Workshop, Seville, Spain, 3-5 April, 2003, Editors: Astolfi, Gordillo, Schaft, Publisher: Elsevier, Pages: 165-170, ISBN: 9780080442785
  • Conference paper
    Laiou MC, Astolfi A, 2004,

    Local transformations to generalized chained forms

    , 16th international symposium on mathematical theory of networks and systems (MTNS 2004)
  • Conference paper
    Anaparthi KK, Pal BC, 2004,

    Coprime factorization approach to multi-input PSS design for damping SSR and local modes

    , New York, International conference on power system technology (POWERCON 2004), Singapore, Singapore, 21 - 24 November 2004, Publisher: IEEE, Pages: 684-689
  • Conference paper
    Mitcheson PD, Miao P, Stark BH, Yeatman EM, Holmes AS, Green TCet al., 2004,

    MEMS electrostatic micropower generator for low frequency operation

    , Publisher: Elsevier, Pages: 523-529, ISSN: 0924-4247

    This paper describes the analysis, simulation and testing of a microengineered motion-driven power generator, suitable for application in sensors within or worn on the human body. Micro-generators capable of powering sensors have previously been reported, but these have required high frequency mechanical vibrations to excite a resonant structure. However, body-driven movements are slow and irregular, with large displacements, and hence do not effectively couple energy into such generators. The device presented here uses an alternative, non-resonant operating mode. Analysis of this generator shows its potential for the application considered, and shows the possibility to optimise the design for particular conditions. An experimental prototype based on a variable parallel-plate capacitor operating in constant charge mode is described which confirms the analysis and simulation models. This prototype, when precharged to 30 V, develops an output voltage of 250 V, corresponding to 0.3 μJ per cycle. The experimental test procedure and the instrumentation are also described.
  • Conference paper
    Petropoulos T, Yeatman EM, Mitcheson PD, 2004,

    MEMS coupled resonators for power generation and sensing

    , Micromechanics Europe, Leuven, Belgium, 5 - 7 September 2004, Pages: 261-264
  • Conference paper
    Chaudhuri B, Korba P, Pal BC, 2004,

    Damping controller design through simultaneous stabilization technique

    , World automation congress, Seville, 28 June - 1 July 2004, Pages: 1-8
  • Journal article
    Andersson G, Green T, Pal B, Rehtanz Cet al., 2004,

    Advanced FACTS control

    , ABB Review, Vol: 4, Pages: 21-26, ISSN: 1013-3119

    FACTS devices – power electronics based devices for controlling var compensation and power flow in electricity supply networks – require specific control algorithms in order for their benefits to be realized in a broad portfolio of applications. To gain the benefits that can arise from the use of more than one FACTS device within a specific network area, ABB has initiated a joint project with the Swiss Federal Institute of Technology and Imperial College London. The project sets out to answer, in an industrially applicable way, questions that arise when coordinating wide area control for power flow control and damping of oscillations
  • Conference paper
    Shafiu A, Bopp T, Chilvers I, Strbac G, Jenkins N, Li Het al., 2004,

    Active managment and protection of distribution networks with distributed generation

    , General meeting of the IEEE Power Engineering Society, Denver, CO, Publisher: IEEE; 2004, Pages: 1098-1103
  • Journal article
    Lee STS, Chung HSH, Hui SYR, 2003,

    An Electrode Power Control Scheme for Dimmable Electronic Ballasts

    , IEEE Transactions on Industrial Electronics, Vol: 50, Pages: 1335-1337, ISSN: 0278-0046

    A novel electrode power control scheme for dimmable ballasts is proposed. Dimming of the fluorescent lamp and control of electrode power are achieved by simultaneously adjusting the dc-link voltage and the switching frequency of the output inverter. The electrode power is derived by considering the near-orthogonal property of the lamp current and the resonant tank circuit current.
  • Journal article
    Tam PW, Lee TS, Hui SYR, Chung HSH, Liu YSet al., 2003,

    Practical Evaluation of Dimming Control Methods for Electronic Ballasts

    , Conference Record - IAS Annual Meeting (IEEE Industry Applications Society), Vol: 2, Pages: 799-804, ISSN: 0197-2618

    The authors compare and evaluate (i) the traditional frequency-control dimming method and (ii) a recently-patented voltage-control dimming method in electronic ballasts for fluorescent lamps. The power factor, energy efficiency, electronic loss, lux/Watt and crest factor of 2×36W electronic ballasts based on these two dimming methods are recorded and compared over a wide dimming range. It is found that the voltage dimming control approach is much better than the frequency control method in most of the compared aspects as the lamp is dimmed. In particular, voltage dimming approach has much higher energy efficiency and lux per watt than the frequency control one. Unlike frequency dimming method, voltage dimming control has a distinctive feature that its electronic loss decreases with. decreasing lamp power.
  • Journal article
    Chryssochoos I, Vinter RB, 2003,

    Optimal control problems on manifolds: a dynamic programming approach

    , JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS, Vol: 287, Pages: 118-140, ISSN: 0022-247X
  • Journal article
    Yip SC, Qiu DY, Chung HSH, Hui SYRet al., 2003,

    A Novel Voltage Sensorless Control Technique for a Bidirectional AC/DC Converter

    , IEEE Transactions on Power Electronics, Vol: 18, Pages: 1346-1355, ISSN: 0885-8993

    A novel voltage sensorless control technique for a bidirectional ac/dc converter is presented. Only a single current sensor that measures the inductor current is needed in the whole system. The sensed inductor current is used for two functions. The first one is for shaping the current waveform at the ac side and the second one is for deriving the inductor voltage by determining the rate of change of the inductor current. The ac-side and dc-side voltages, which are used for ac current synchronization and dc voltage regulation, respectively, are obtained by extracting the envelopes of the derived inductor voltage. Apart from reducing the number of sensing elements, the proposed method has additional advantages of 1) inherent electrical isolation and reducing noise coupling between the power circuit and the controller; 2) wide operating range. Design criteria for the differentiator and the envelope detector circuit has been described. The applicability of the proposed method is verified with the experimental results of a laboratory prototype.
  • Journal article
    Angeli D, Sontag ED, Wang Y, 2003,

    Input to state stability with respect to inputs and their derivatives

    , International Journal of Robust and Nonlinear Control, Vol: 13, Pages: 1035-1056
  • Journal article
    Arutyunov AV, Vinter RB, 2003,

    A finite-dimensional approximation method in optimal control theory

    , DIFFERENTIAL EQUATIONS, Vol: 39, Pages: 1519-1528, ISSN: 0012-2661
  • Journal article
    Green TC, Hernández-Arámburo CA, Smith AC, 2003,

    Losses in grid and inverter supplied induction machine drives

    , IEE PROCEEDINGS-ELECTRIC POWER APPLICATIONS, Vol: 150, Pages: 712-724, ISSN: 1350-2352
  • Journal article
    Karagiannis D, Mendes E, Astolfi A, Ortega Ret al., 2003,

    An experimental comparison of several PWM controllers for a single-phase AC-DC converter

    , IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, Vol: 11, Pages: 940-947, ISSN: 1063-6536
  • Journal article
    Prieur C, Astolfi A, 2003,

    Robust stabilization of chained systems via hybrid control

    , IEEE TRANSACTIONS ON AUTOMATIC CONTROL, Vol: 48, Pages: 1768-1772, ISSN: 0018-9286
  • Journal article
    Antonelli R, Astolfi A, 2003,

    Continuous stirred tank reactors: easy to stabilise?

    , AUTOMATICA, Vol: 39, Pages: 1817-1827, ISSN: 0005-1098
  • Journal article
    Galbraith GN, Vinter RB, 2003,

    Optimal control of hybrid systems with an infinite set of discrete states

    , J DYN CONTROL SYST, Vol: 9, Pages: 563-584, ISSN: 1079-2724

    Hybrid control systems are described by a family of continuous subsystems and a set of logic rules for switching between them. This paper concerns a broad class of optimization problems for hybrid systems, in which the continuous subsystems are modelled as differential inclusions. The formulation allows endpoint constraints and a general objective function that includes "transaction costs" associated with abrupt changes of discrete and continuous states, and terms associated with continuous control action as well as the terminal value of the continuous state. In consequence of the endpoint constraints, the value function may be discontinuous. It is shown that the collection of value functions (associated with all discrete states) is the unique lower semicontinuous solution of a system of generalized Bensoussan-Lions type quasi-variational inequalities, suitably interpreted for nondifferentiable, extended valued functions. It is also shown how optimal strategies and value functions are related. The proof techniques are system theoretic, i.e., based on the construction of state trajectories with suitable properties. A distinctive feature of the analysis is that it permits an infinite set of discrete states.
  • Journal article
    Angeli D, Sontag ED, 2003,

    Monotone Control Systems

    , IEEE Transactions on Automatic Control, Vol: 48, Pages: 1684-1698
  • Journal article
    Vinter RB, Zheng H, 2003,

    Some finance problems solved with nonsmooth optimization techniques

    , JOURNAL OF OPTIMIZATION THEORY AND APPLICATIONS, Vol: 119, Pages: 1-18, ISSN: 0022-3239
  • Journal article
    Lu HY, Zhu JG, Hui SYR, 2003,

    Experimental determination of stray capacitances in high frequency transformers

    , IEEE Transactions on Power Electronics, Vol: 18, Pages: 1105-1112, ISSN: 0885-8993

    This paper presents practical techniques for determining stray capacitances in a two-winding high frequency transformer for circuit simulation and computer-aided design purposes. These techniques fall into two categories: 1) the two-port network approach; 2) the step-response approach. The first approach can be employed for high frequency transformer circuit models with the effect of stray capacitances modeled as a π-shape network of three lumped stray capacitances. The second approach is useful for the transformer circuit model with the overall effects of stray capacitances modeled as lumped stray-capacitance connected cross the primary side. These techniques have been verified in the modeling and numerical simulation of a 500 W 25 kHz two winding E-core transformer. The merits and limitations of these techniques are also discussed.
  • Conference paper
    Mitcheson PD, Stark BH, Miao P, Yeatman EM, Holmes AS, Green TCet al., 2003,

    Analysis and optimisation of MEMS electrostatic on-chip power supply for self-powering of slow-moving sensors

    , Guimaraes, Eurosensors 03, 17th European conference on sensors and actuators, University of Minho Guimaraes, Portugal, 21 - 24 September 2003, Publisher: University of Minho, Pages: 48-51
  • Journal article
    Green TC, Marks JH, 2003,

    Ratings of active power filters

    , IEE PROCEEDINGS-ELECTRIC POWER APPLICATIONS, Vol: 150, Pages: 607-614, ISSN: 1350-2352
  • Journal article
    Lee CK, Leung JSK, Hui SYR, Chung HSHet al., 2003,

    Circuit-level comparison of STATCOM technologies

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 4, Pages: 1777-1784, ISSN: 0275-9306

    This paper performs a circuit-level evaluation of four modern STATCOM systems, namely True-48-Pulse and Quasi-48-Pulse STATCOMs, Cascade Multilevel and Binary Multilevel Inverters. The comparison is based on a number of factors including circuit topology, harmonic distortion, system losses, GTO quantities, their specific applications and other considerations. The theoretical results are verified by simulation with the use of MATLAB-Simulink Power System Blockset.
  • Journal article
    Qiu DY, Hui SY, Chung SH, 2003,

    Parameter monitoring of high-frequency electronically operated discharge lamp systems

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 3, Pages: 1341-1346, ISSN: 0275-9306

    Arc discharge loads such as discharge lamps require high ignition voltage (several kilo-volt to 20 kilo-Volts), but have low on-state voltage (typically 100V). For discharge arc monitoring purposes, it is difficult or uneconomical to Implement voltage sensor to cover such a wide range of voltage. In this paper, a non-intrusive and electrically isolated method, based on the single-sensor principle, is used to derive the system parameters and variables for system monitoring and control purposes. Only one coupled winding is used to derive the converter inductor voltage, from which the lamp power, lamp arc resistance and inverter dc link voltage can be accurately derived. The proposal is verified with good agreement between derived values and measurements in an electronic ballast - fluorescent lamp system. The proposal can be useful in applications in which sensing the voltage across the load is either difficult or costly.
  • Journal article
    Lee SST, Chung HSH, Hui SYR, 2003,

    A comparative study of random switching schemes for eliminating visible striations in fluorescent lamps

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 3, Pages: 1006-1011, ISSN: 0275-9306

    This paper presents a comparative study of using random switching modulation schemes for the resonant inverter in electronic ballasts to eliminate visible striation (appearance of black and white bands along the tube) in fluorescent lamps. As striations can be eliminated by superimposing a small amount of dc current or low frequency ac current to the electrodes to produce composite current waveform through the lamp, the underlying principle of this work is based on the fact that random switching introduces low-frequency harmonics at the inverter output. Although this inherent low-frequency generation characteristics is generally undesirable for switching converters requiring high quality output, it provides a favorable means to eliminate striations in this particular application. Modulation schemes under investigation include random pulse position modulation, randomized pulse width modulation (RPWM) and randomized carrier frequency modulation. Issues addressed include the effectiveness of each scheme in eliminating the striations and the randomness level on lamp flickers. Among the schemes, RPWM is found to be the best choice as it introduces largest amount of low-frequency lamp current. The validity of the analyses Is confirmed experimentally by using a T8 36W prototype.
  • Journal article
    Lee SST, Chan S, Chung HSH, Hui SYRet al., 2003,

    Use of saturable inductor to improve the dimming characteristics of frequency-controlled dimmable electronic ballasts

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 3, Pages: 988-993, ISSN: 0275-9306

    This paper presents an investigation into the use of saturable inductor to improve the dimming characteristics of frequency-controlled dimmable electronic ballasts with a half-bridge series-resonant parallel-loaded inverter. The concept is based on the fact that the effective resonant frequency increases as the inductor current increases, if the unsaturable inductor in the resonant tank circuit is replaced with a saturable one. Susceptibility of the lamp power to the switching frequency variation at low luminous level can be reduced. This can lessen the problem of lamp flickers at dimmed level, resulting in a wider dimming range and improved controllability. The method gives a simple solution of improving the dimming characteristics without changing the circuit structure. Theoretical predictions are verified with the experimental results of a 36W T8 prototype.
  • Journal article
    Chaudhuri B, Pal BC, Zolotas AC, Jaimoukha IM, Green TCet al., 2003,

    Mixed-sensitivity approach to <i>H</i><sub>∞</sub> control of power system oscillations employing multiple FACTS devices

    , IEEE TRANSACTIONS ON POWER SYSTEMS, Vol: 18, Pages: 1149-1156, ISSN: 0885-8950

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