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  • Patent
    Green TC, Merlin MMC, Okaeme N, Trainer DRet al., 2010,

    Modular Multilevel Converter
  • Conference paper
    Merlin MMC, Green TC, Mitcheson PD, Trainer D, Critchley R, Crookes RWet al., 2010,

    A New Hybrid Multi-Level Voltage-Sourced Converter with DC Fault Blocking Capability

    , IET Conference on AC/DC Transmission
  • Journal article
    Astolfi A, 2010,

    Model Reduction by Moment Matching for Linear and Nonlinear Systems

    , IEEE TRANSACTIONS ON AUTOMATIC CONTROL, Vol: 55, Pages: 2321-2336, ISSN: 0018-9286

    The model reduction problem for (single-input, single-output) linear and nonlinear systems is addressed using the notion of moment. A re-visitation of the linear theory allows to obtain novel results for linear systems and to develop a nonlinear enhancement of the notion of moment. This, in turn, is used to pose and solve the model reduction problem by moment matching for nonlinear systems, to develop a notion of frequency response for nonlinear systems, and to solve model reduction problems in the presence of constraints on the reduced model. Connections between the proposed results, projection methods, the covariance extension problem and interpolation theory are presented. Finally, the theory is illustrated by means of simple worked out examples and case studies.
  • Journal article
    Junyent-Ferre A, Gomis-Bellmunt O, Sumper A, Sala M, Mata Met al., 2010,

    Modeling and control of the doubly fed induction generator wind turbine

    , SIMULATION MODELLING PRACTICE AND THEORY, Vol: 18, Pages: 1365-1381, ISSN: 1569-190X
  • Journal article
    Angeli D, De Leenheer P, Sontag E, 2010,

    Graph-theoretic characterizations of monotonicity of chemical networks in reaction coordinates

    , JOURNAL OF MATHEMATICAL BIOLOGY, Vol: 61, Pages: 581-616, ISSN: 0303-6812
  • Journal article
    Gomis-Bellmunt O, Junyent-Ferre A, Sumper A, Galceran-Arellano Set al., 2010,

    Maximum generation power evaluation of variable frequency offshore wind farms when connected to a single power converter

    , APPLIED ENERGY, Vol: 87, Pages: 3103-3109, ISSN: 0306-2619
  • Journal article
    Chaudhuri NR, Domahidi A, Majumder R, Chaudhuri B, Korba P, Ray S, Uhlen Ket al., 2010,

    Wide-area power oscillation damping control in Nordic equivalent system

    , IET GENERATION TRANSMISSION & DISTRIBUTION, Vol: 4, Pages: 1139-1150, ISSN: 1751-8687
  • Journal article
    Zhong WX, Ho WC, Hui SYR, 2010,

    Generalized self-driven AC-DC synchronous rectification techniques for single- & multiphase systems

    , 2010 International Power Electronics Conference - ECCE Asia -, IPEC 2010, Pages: 2098-2105

    This paper extends the single-phase self-driven synchronous rectification (SDSR) technique to multiphase and multi-level AC-DC systems. Power MOSFETs with either voltage or current self-sensing and self-driven gate drives are used to replace diodes in the rectifier circuits. The generalized methodology allows multiphase SDSRs to be designed to replace multiphase diode rectifiers. Unlike traditional SR designed for high-frequency power converters, the SDSR proposed here can be direct replacement of power diode bridges for both low and high frequency operations. The SDSR utilizes its output dc voltage to power its control circuit. No start-up control is needed because the body diodes of the power MOSFETs provide the diode rectifier for initial start-up stage. The generalized method is demonstrated in 2kW 1-phase and 3-phase SDSRs. Power loss reduction in the range of 50% to 69% has been achieved for inductive, capacitive and resistive loads. © 2010 IEEE.
  • Patent
    Rogers DJ, Green TC, 2010,

    Method And Apparatus For Performing On-Load Mechanical Switching Operations

    An electrical device comprising: a first current path having a primary switch therein, and means for coupling to an electrical supply; and a diversionary current path having semiconductor switching means therein, the semiconductor switching means being operable to bypass the primary switch; the device being arranged such that, in use, a first current flowing from the supply along the first current path can be diverted, on the operation of the semiconductor switching means, along the diversionary current path, bypassing the primary switch; wherein the diversionary current path comprises a controllable electrical supply operable to supply a second current whilst the semiconductor switching means are in a state of conduction, the second current being such as to cause substantially zero current to flow through the primary switch, such that the primary switch can then be opened under a condition of substantially zero load current. A corresponding method of operating a mechanical switch in such a device is also provided.The disclosure further provides a controllable electrical supply comprising: an electrical source; an amplifier having two output terminals and comprising a plurality of semiconductor devices; and control logic arranged to operate the amplifier such that it can selectively present both current and voltage source behaviour at the terminals.
  • Conference paper
    Rogers DJ, Green TC, 2010,

    Zero-current zero-voltage switching for on-load tap changers

    We present a new on-load tap changer (OLTC) design that provides the traditional advantages of the semiconductor-assisted OLTC over the classic, mechanical OLTC. The design provides zero-current, zero-voltage operation of both diverter switches at all times, eliminating contact wear due to arcing. The design of the diverter sub-circuit is discussed, including the introduction of a voltage source and corresponding control loop that provides the necessary shunt current or voltage to create the desired zero conditions in the diverter switches. The design differs from existing semiconductor-assisted OLTC systems by the fact that the semiconductor portion of the system is connected in a purely shunt configuration to the main current path. Under normal conditions the load current flows only in the selector and diverter switches making the system very low loss.
  • Conference paper
    Ahmadi AR, Green TC, 2010,

    Voltage versus Power Factor Regulation for enhancement of renewable generation capacity

    The connection of Distributed Generators (DGs) to distribution network creates technical concerns for Distribution Network Operators (DNOs) which primarily include power flow management, loss increase and voltage management problems. Active Network Management (ANM) system provides monitoring and control of the distribution network as well as providing the infrastructure and technology for full integration of DGs to the distribution network. Optimal Power Flow (OPF) is a valuable tool in providing optimal control solutions for active network management system applications. In this paper, Terminal Voltage Regulator Mode (TVRM) and fixed Power Factor Regulation Mode (PFRM) were incorporated in the main optimisation routine to extract the maximum real power output capacity. The main contribution was to test different droop characteristics including one with local voltage regulator dead-bands associated to a particular DG. The DG operation methods of PFRM and TVRM are then compared together. Numerical result obtained from tests on two U.K. representative distribution networks show that TVRM has the potential in offering more capacity exploitation and improving network flexibility for additional DG connection.
  • Journal article
    Moreno R, Strbac G, Porrua F, Mocarquer S, Bezerra Bet al., 2010,

    Making Room for the Boom

    , IEEE POWER & ENERGY MAGAZINE, Vol: 8, Pages: 36-46, ISSN: 1540-7977
  • Journal article
    Jones BL, Kerrigan EC, 2010,

    When is the discretization of a spatially distributed system good enough for control?

    , AUTOMATICA, Vol: 46, Pages: 1462-1468, ISSN: 0005-1098
  • Journal article
    Sassano M, Carnevale D, Astolfi A, 2010,

    Observer design for range and orientation identification

    , AUTOMATICA, Vol: 46, Pages: 1369-1375, ISSN: 0005-1098
  • Journal article
    Jabr RA, Pal BC, Martins N, JCR Fet al., 2010,

    Robust and coordinated tuning of power system stabiliser gains using sequential linear programming

    , IET Generation, Transmission and Distribution, Vol: 4, Pages: 893-904, ISSN: 1751-8687

    This study presents a linear programming (LP)-based multivariable root locus following technique for coordinating the gain settings of power system stabilisers (PSSs). The stabiliser robustness is accounted for in the design problem by simultaneously considering the state-space representations and multivariable root loci corresponding to different operating scenarios. The proposed technique computes a curve in the PSS gain parameter space such that when the PSS gains move along this curve to their optimal values, the branches of the corresponding multivariable root loci terminate at satisfactory points in the complex plane. The curve in the gain parameter space is computed via a linear program that successively minimises the Euclidean distance between the unsatisfactory and satisfactory eigenvalue locations. The design method is demonstrated on a 39-bus test system with 14 operating scenarios. A comparison is carried out between the coordination results of two PSS structures, one involving two phase-lead blocks and the other comprised of two phase-lead blocks and a phase-lag block.
  • Journal article
    Jabr RA, Pal BC, Martins N, 2010,

    A Sequential Conic Programming Approach for the Coordinated and Robust Design of Power System Stabilizers

    , IEEE Transactions on Power Systems, Vol: 25, Pages: 1627-1637

    This paper shows that conic programming is an effective tool to solve robust power system stabilizer (PSS) design problems, namely coordinated gain tuning and coordinated phase and gain tuning. Design robustness is achieved by simultaneously considering several operating scenarios. The method is implemented through a sequence of conic programming runs that define a multivariable root locus along which the eigenvalues move. Specifically, the eigenvalues corresponding to the unstable and poorly damped modes are moved to a conic sector in the left half of the s-plane, whereas the eigenvalues corresponding to the well damped modes are constrained to stay within the boundaries of this conic sector. At each step of the solution, the PSS design parameters are restricted in a trust-region such that the computation of the eigenvalue shift based on the residue method holds valid. The proposed method is demonstrated on a 68-bus test system with nine different operating conditions. Comparisons are carried out between conic programming implementations for PSS coordinated gain tuning and for simultaneous tuning of gain and phase characteristics
  • Journal article
    Singh R, Manitsas E, Pal BC, Strbac Get al., 2010,

    A Recursive Bayesian Approach for Identification of Network Configuration Changes in Distribution System State Estimation

    , IEEE Transactions on Power Systems, Vol: 25, Pages: 1329-1336

    This paper deals with the identification of network configuration changes in distribution system state estimation (DSSE). The models of critical network configurations are stored in the form of a model bank. A recursive Bayesian approach which utilizes the output of the state estimation function of each model in the bank is used to identify the correct configuration of the network. The concept is demonstrated on a part of the U.K. Generic Distribution System (UKGDS) model.
  • Journal article
    Angeli D, 2010,

    A Modular Criterion for Persistence of Chemical Reaction Networks

    , IEEE TRANSACTIONS ON AUTOMATIC CONTROL, Vol: 55, Pages: 1674-1679, ISSN: 0018-9286
  • Journal article
    Hui SYR, Liu X, 2010,

    Semiconductor transformers

    , Electronics Letters, Vol: 46, Pages: 947-949, ISSN: 0013-5194

    A semiconductor transformer concept in which all parts of the transformer are made of semiconductor materials is described. This proposal transforms the conventional concept of 'magnetic transformers' to 'semiconductor transformers' for easy circuit integration. © 2010 The Institution of Engineering and Technology.
  • Journal article
    Choi WP, Ho WC, Liu X, Hui SYRet al., 2010,

    Bidirectional communication techniques for wireless battery charging systems & portable consumer electronics

    , Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC, Pages: 2251-2257

    Simultaneous power and signal transfer in a wireless/contactless system is an emerging technology for portable electronics. This paper aims at exploring simple and cost effective ways for such applications for a wide range of the portable consumer electronic devices such as mobile phones. Frequency-shift keying (FSK) and amplitude-shift keying (ASK) techniques for an inductive battery charging platform have been successfully implemented for simultaneous power and signal transfer in an 10W wireless charging system. The proposed techniques provide effective bidirectional communication between the charging platform and the loads and form the basis for load identification and battery monitoring in wireless charging system. Considerations of these methods for compatibility among a wide range of portable products are discussed. ©2010 IEEE.
  • Journal article
    Hui SYR, Lin DY, Ng WM, Yan Wet al., 2010,

    A "class-A2" ultra-low-loss magnetic ballast for T5 fluorescent lamps

    , Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC, Pages: 1346-1351

    This paper shows that magnetic ballasts for high-voltage T5 lamps are not only feasible but their luminous and ballast-loss performance can be better than those of electronic ballasts. A computer-aided design and practical implementation of an ultra-low-loss magnetic ballast system for T5 28W lamps is presented. The high-voltage & low-current features of T5 lamps imply that the copper and core losses of the magnetic ballast can be greatly reduced. Its total system power is 30W (with a ballast loss of only 2.42W) is less than the 32W upper limit specified for Class A2 of energy-efficient electronic ballast for T5 28W lamps. High luminous efficacy of 74.8 lumen/W can be achieved. This important breakthrough has the potential of reversing the existing trend of using electronic ballasts as the energy-saving technology in lighting industry. With a better luminous efficacy, lower product and maintenance costs, much longer lifetime and the use of recyclable metallic materials over its electronic counterparts, this patent-pending proposal provides a truly sustainable lighting solution to the lighting industry. ©2010 IEEE.
  • Journal article
    Zhong WX, Ho WC, Liu X, Hui SYRet al., 2010,

    Self-driven AC-DC synchronous rectifier for power applications - A direct energy-efficient replacement for traditional diode rectifier

    , Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC, Pages: 994-1001

    Synchronous rectification has previously been adopted in switched mode circuits for reducing the conduction losses particularly in low-voltage and high-current applications. This paper presents a generalized "self-driven" AC-DC synchronous rectification technique that can be used to develop AC-DC synchronous rectifier that behaves like a diode bridge, but with much reduced conduction losses and without control integrated circuits. This generalized concept can be extended from single-phase to multi-phase systems. Experiments based on 1kW and 2kW single-phase systems have been successfully conducted for capacitive, inductive and resistive loads. Very significant power loss reduction (over 50%) has been achieved in the rectification stage at both 110V and 220V AC mains operations. This patent-pending circuit can be regarded as a direct replacement of general-purpose diode rectifier. Due to the reduction of power loss, further reduction in the size and cost of the heatsink or thermal management for the power circuit becomes possible. ©2010 IEEE.
  • Journal article
    Hui SYR, Li SN, Tao XH, Chen W, Ng WMet al., 2010,

    A novel passive off-line light-emitting diode (LED) driver with long lifetime

    , Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC, Pages: 594-600

    This paper describes a patent-pending passive offline LED driver that has no semiconductor switches, electrolytic capacitors, auxiliary power supply and control board. It can provide a fairly smooth current from the ac mains to drive LED strings. The new circuit has the advantages of high input power factor, high energy efficiency and luminous efficacy, long lifetime, stable luminous output and high robustness against extreme weather conditions. In addition, over 90% of the driver material is recyclable, leading to reduction of electronic waste. It is particularly suitable public LED lighting systems such as road lighting systems. Experimental results based on a 50W system are included in the paper to confirm the validity of the proposal. Due to the circuit simplicity, an energy efficiency exceeding 93.6% has been achieved. ©2010 IEEE.
  • Journal article
    Su YP, Liu X, Lee CK, Hui SYRet al., 2010,

    Relationship of quality factor and hollow winding structure of Coreless Printed Spiral Winding (CPSW) inductor

    , Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC, Pages: 86-91

    The principle of using hollow spiral winding is not novel, but the study on this topic is far from complete. In this paper, how hollow the central region of the Coreless Printed Spiral Winding (CPSW) inductor should be in order to achieve the maximal quality factor value Qmax is explored. A new parameter, namely the ratio of the inner hollow radius and the outer winding radius τ = Rin / Rout, is proposed as an indicator for optimization and used to quantify how hollow a spiral winding is. With the aid of Finite Element Analysis (FEA), the relationship between τ and Q max, which depends on the operating frequency and the dimensional parameters of CPSW inductor, is established. For a specific operating frequency, it is discovered that if the conductor width is comparable with the skin depth, or the conductors are placed relatively far away from each others, the hollow design of the CPSW inductor has little improvement on Q but reduces the inductance. On the contrary, if the conductor width is much larger than the skin depth and the conductors are placed relatively close, the hollow spiral design is recommended. The optimal range of τ with which the Qmax can be achieved is found to be around 0.45 to 0.55. ©2010 IEEE.
  • Software
    E J Van Wyk, P Falugi, E C Kerrigan, 2010,

    ICLOCS

    Solves nonlinear optimal control problems subject to constraints.
  • Journal article
    Carnevale D, Karagiannis D, Astolfi A, 2010,

    A Condition for Certainty Equivalence Output Feedback Stabilization of Nonlinear Systems

    , IEEE TRANSACTIONS ON AUTOMATIC CONTROL, Vol: 55, Pages: 1180-1185, ISSN: 0018-9286
  • Journal article
    Chaudhuri NR, Chaudhuri B, Ray S, Majumder Ret al., 2010,

    Wide-area phasor power oscillation damping controller: a new approach to handling time-varying signal latency

    , IET GENERATION TRANSMISSION & DISTRIBUTION, Vol: 4, Pages: 620-630, ISSN: 1751-8687
  • Journal article
    Ledyaev YS, Vinter RB, 2010,

    Discontinuous feedback in nonlinear control: Stabilization under persistent disturbances

    , PROCEEDINGS OF THE STEKLOV INSTITUTE OF MATHEMATICS, Vol: 268, Pages: 222-241, ISSN: 0081-5438
  • Journal article
    Parisini T, 2010,

    Control Systems Technology: Towards a Systems-of-Systems Perspective?

    , IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, Vol: 18, Pages: 249-250, ISSN: 1063-6536
  • Journal article
    Lee CK, Hui SYR, 2010,

    Experimental comparison of traditional and alternating winding method for planar spiral inductor

    , Electronics Letters, Vol: 46, Pages: 238-239, ISSN: 0013-5194

    Two planar winding structures have been built to compare the characteristics of traditional and alternating winding methods. The alternating winding method reduces the potential difference of adjacent conductors, thus reducing substantially the self-capacitance in the winding. Measurements confirmed that the two inductors have similar equivalent inductance and low-frequency series resistance. However, the alternating winding method has a higher self resonant frequency. It is also evident that the reduction of self-capacitance in the winding not only increased the operating bandwidth of the device but also reduced the power losses of the inductor at high frequency. © 2010 The Institution of Engineering and Technology.

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