Publications
424 results found
Davis RA, Dinh MM, Bein KJ, et al., 2014, Senior work-up assessment and treatment team in an emergency department: A randomised control trial, EMERGENCY MEDICINE AUSTRALASIA, Vol: 26, Pages: 343-349, ISSN: 1742-6731
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- Citations: 15
Bottrell N, Green TC, 2014, Comparison of current-limiting strategies during fault ride-through of inverters to prevent latch-up and wind-up, IEEE Transactions on Power Electronics, Vol: 29, Pages: 3786-3797, ISSN: 0885-8993
Transient stability of a power network requires that generators remain synchronized and return to normal power export once a fault is cleared. For inverter-interfaced generators, one must ensure that current and voltage limiters do not latch-up and that controller integrators do not wind-up. A comparison of current-limiting strategies during fault ride-through of inverters to prevent latch-up and wind-up is presented. A voltage-controlled inverter with an inner current controller is used in this paper. Instantaneous limiting (saturation) and latched limiting with a variety of reset strategies are tested to check for correct operation when a fault is applied and cleared. All the cases were tested on an experimental system using 10-kVA inverters and low-impedance three-phase faults. The experimental results showing the current and voltage waveforms of the inverter are presented to test whether each strategy correctly transitioned from current limiting to normal operation once the fault was cleared and to examine the extent to which controller wind-up was a problem. Conclusions are drawn as to which current-limiting strategies provide good performance in ride-through and recovery from faults.
Rogers DJ, Green TC, Silversides RW, 2014, A Low-Wear Onload Tap Changer Diverter Switch for Frequent Voltage Control on Distribution Networks, IEEE TRANSACTIONS ON POWER DELIVERY, Vol: 29, Pages: 860-869, ISSN: 0885-8977
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- Citations: 10
Merlin MMC, Green TC, Mitcheson PD, et al., 2014, The Alternate Arm Converter: A New Hybrid Multilevel Converter With DC-Fault Blocking Capability, IEEE Transactions on Power Delivery, Vol: 29, Pages: 310-317, ISSN: 0885-8977
This paper explains the working principles, supported by simulation results, of a new converter topology intended for HVDC applications, called the alternate arm converter (AAC). It is a hybrid between the modular multilevel converter, because of the presence of H-bridge cells, and the two-level converter, in the form of director switches in each arm. This converter is able to generate a multilevel ac voltage and since its stacks of cells consist of H-bridge cells instead of half-bridge cells, they are able to generate higher ac voltage than the dc terminal voltage. This allows the AAC to operate at an optimal point, called the “sweet spot,” where the ac and dc energy flows equal. The director switches in the AAC are responsible for alternating the conduction period of each arm, leading to a significant reduction in the number of cells in the stacks. Furthermore, the AAC can keep control of the current in the phase reactor even in case of a dc-side fault and support the ac grid, through a STATCOM mode. Simulation results and loss calculations are presented in this paper in order to support the claimed features of the AAC.
Plet CA, Green TC, 2014, Fault response of inverter interfaced distributed generators in grid-connected applications, ELECTRIC POWER SYSTEMS RESEARCH, Vol: 106, Pages: 21-28, ISSN: 0378-7796
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- Citations: 73
Merlin MMC, Judge PD, Green TC, et al., 2014, Alternate Arm Converter Operation of the Modular Multilevel Converter, IEEE Energy Conversion Congress and Exposition (ECCE), Publisher: IEEE, Pages: 1924-1930, ISSN: 2329-3721
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- Citations: 14
Luth T, Merlin M, Green T, 2014, A DC/DC Converter Suitable for HVDC Applications with Large Step-ratios, IEEE Energy Conversion Congress and Exposition (ECCE), Publisher: IEEE, Pages: 5331-5338, ISSN: 2329-3721
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- Citations: 9
Silversides R, Green T, Merlin MMC, 2014, A High Density Converter for Mid Feeder Voltage Regulation of Low Voltage Distribution Feeders, IEEE Energy Conversion Congress and Exposition (ECCE), Publisher: IEEE, Pages: 1972-1978, ISSN: 2329-3721
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- Citations: 4
Spallarossa CE, Green TC, Lin C, et al., 2014, A DC Voltage Control Strategy for MMC MTDC Grids incorporating Multiple Master Stations, IEEE PES T and D Conference and Exposition, Publisher: IEEE
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- Citations: 2
Merlin MMC, Green TC, Mitcheson PD, et al., 2014, Cell capacitor sizing in modular multilevel converters and hybrid topologies, Pages: 1-10
Junyent-Ferre A, Clemow P, Merlin M, et al., 2014, Operation of HVDC Modular Multilevel Converters under DC pole imbalances, Pages: 1-10
Luth T, Merlin MMC, Green TC, 2014, Modular multilevel DC/DC converter architectures for HVDC taps, Pages: 1-10
Moreno FJ, Merlin MMC, Trainer DR, et al., 2014, Control of an alternate arm converter connected to a star transformer, Pages: 1-10
Sheridan CE, Merlin MMC, Green TC, 2014, Reduced Dynamic Model of the Alternate Arm Converter, IEEE 15th Workshop on Control and Modeling for Power Electronics (COMPEL), Publisher: IEEE, ISSN: 2151-0997
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- Citations: 2
Clemow P, Judge P, Chaffey G, et al., 2014, Lab-scale experimental multilevel modular HVDC converter with temperature controlled cells, Pages: 1-10
Bottrell N, Green TC, 2013, An impedance-based method for the detection of over-load and network faults in inverter interfaced distributed generation
An impedance-based method is presented for detecting and differentiating over-load and fault conditions for an inverter-interfaced power generator. When the observed impedance falls below a threshold, current limiting occurs. The impedance-based method, unlike other current limiting strategies, is able to differentiate between an over-load and a network fault. The inverter presented in this paper exports a fixed current for detected over-loads and a higher fixed current for detected faults. An experimental system using a 10 kVA inverter was used to test three cases. The first demonstrates the response of the inverter when the impedance of the load is gradually decreased. The second demonstrates the output of the inverter when a three-phase fault is applied and the third demonstrates the output when a single-phase fault is applied. The impedance-based method is shown to be able to ride-thought the fault and return to normal operation once the fault has been cleared. © 2013 IEEE.
Bottrell N, Prodanovic M, Green TC, 2013, Dynamic Stability of a Microgrid With an Active Load, IEEE Transactions on Power Electronics, Vol: 28, Pages: 5107-5119, ISSN: 1941-0107
Rectifiers and voltage regulators acting as constant power loads form an important part of amicrogrid’s total load. In simplified form, they present a negative incremental resistance and beyondthat, they have control loop dynamics in a similar frequency range to the inverters that may supply amicrogrid. Either of these features may lead to a degradation of small-signal damping. It is known thatdroop control constants need to be chosen with regard to damping, even with simple impedance loads.Actively controlled rectifiers have been modelled in non-linear state-space form, linearised around anoperating point, and joined to network and inverter models. Participation analysis of the eigenvalues ofthe combined system identified that the low-frequency modes are associated with the voltage controllerof the active rectifier and the droop-controllers of the inverters. The analysis also reveals that whenthe active load DC-voltage controller is designed with large gains, the voltage controller of the inverterbecomes unstable. This dependency has been verified by observing the response of an experimentalmicrogrid to step changes in power demand. Achieving a well-damped response with a conservativestability margin does not compromise normal active rectifier design, but notice should be taken of theinverter-rectifier interaction identified.
Trainer DR, Crookes W, Green TC, et al., 2013, HVDC Converter Comprising Fullbridge Cells For Handling A DC Side Short Circuit
Bloemink JM, Green TC, 2013, Benefits of Distribution-Level Power Electronics for Supporting Distributed Generation Growth, IEEE TRANSACTIONS ON POWER DELIVERY, Vol: 28, Pages: 911-919, ISSN: 0885-8977
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- Citations: 153
Rogers DJ, Green TC, 2013, An Active-Shunt Diverter for On-load Tap Changers, IEEE TRANSACTIONS ON POWER DELIVERY, Vol: 28, Pages: 649-657, ISSN: 0885-8977
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- Citations: 19
Judge PD, Merlin MMC, Mitcheson PD, et al., 2013, Power Loss and Thermal Characterization of IGBT Modules in the Alternate Arm Converter, IEEE Energy Conversion Congress and Exposition (ECCE), Publisher: IEEE, Pages: 1731-1737, ISSN: 2329-3721
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- Citations: 11
Lueth T, Merlin MMC, Green TC, et al., 2013, Choice of AC Operating Voltage in HV DC/AC/DC System, General Meeting of the IEEE-Power-and-Energy-Society (PES), Publisher: IEEE, ISSN: 1944-9925
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- Citations: 3
Clemow P, Green TC, Merlin MMC, 2013, Partial Power Operation of Multi-level Modular Converters under Subsystem Faults, General Meeting of the IEEE-Power-and-Energy-Society (PES), Publisher: IEEE, ISSN: 1944-9925
Sheridan CE, Merlin MMC, Green TC, 2013, Study of a Resonant DC/DC Converter in Alternate Discontinuous Mode, General Meeting of the IEEE-Power-and-Energy-Society (PES), Publisher: IEEE, ISSN: 1944-9925
Collins ME, Silversides RW, Green TC, 2013, Control and Coordination of a Distribution Network via Decentralised Decision Making, General Meeting of the IEEE-Power-and-Energy-Society (PES), Publisher: IEEE, ISSN: 1944-9925
Spallarossa CE, Pipelzadeh Y, Green TC, 2013, Influence of Frequency-Droop Supplementary Control on Disturbance Propagation through VSC HVDC Links, General Meeting of the IEEE-Power-and-Energy-Society (PES), Publisher: IEEE, ISSN: 1944-9925
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- Citations: 2
Bloemink JM, Green TC, 2013, Effects of Power Electronic Compensation on Distribution Network Thermal and Voltage Violations, General Meeting of the IEEE-Power-and-Energy-Society (PES), Publisher: IEEE, ISSN: 1944-9925
Luth T, Merlin MMC, Green TC, et 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.
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