Publications
424 results found
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.
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- Citations: 17
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.
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.
Pipelzadeh Y, Chaudhuri NR, Chaudhuri B, et 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
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.
Piplezadeh Y, Chaudhuri B, Green TC, 2012, Control Coordination Within a VSC-HVDC Link for Power Oscillation Damping: A Robust Decentralized Approach Using Homotopy, IEEE Transactions on Control Systems Technology
Power oscillations can be damped effectivelythrough modulation of both active and reactive power of a voltage source converter based high voltage direct current link. The challenge, however, is how to coordinate the control action properly at the two ends of the link without using a centralised control scheme, which requires fast communication of control signals to remote actuator (converters) sites. A full centralised controller may result in a closed-loop performance worse than that of an open loop in case of a communication loss of feedback signal(s). Alternatively, with a block-diagonal control structure, the individual control loops are decoupled from each other, which is not only easier to implement in a decentralized way, but also shown to guarantee a certain level of performance. Here, the concept of homotopy is applied to obtain a single block-diagonal controller from a set of full controllers, individually designed to ensure specified closed-loop performance for a set of operating conditions. Simulation studies in DIgSILENT PowerFactory are carried out on two test systems to demonstrate both the robustness and control coordination in a decentralised framework.
Green TC, Merlin MMC, Okaeme N, et al., 2012, A Method of Voltage Source Converter Cell Voltage Balancing using Circulating Current, WO/2012/013248
Trainer DR, Crookes RW, Green TC, et al., 2012, Voltage Source Converter with Enhanced DC Fault Response, WO/2012/013248
Gross R, Heptonstall P, Leach M, et al., 2012, The uk energy research centre review of the costs and impacts of intermittency, Renewable Electricity and the Grid: The Challenge of Variability, Pages: 73-94, ISBN: 9781849772334
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- Citations: 7
Mitcheson PD, Green TC, 2012, Maximum Effectiveness of Electrostatic Energy Harvesters When Coupled to Interface Circuits, IEEE Transactions on Circuits and Systems Part 1: Regular Papers, Vol: 59, Pages: 3098-3111, ISSN: 1549-8328
Pipelzadeh Y, Chaudhuri B, Green TC, 2011, Coordinated Damping Control Through MultipleHVDC Systems: A Decentralized Approach, IEEE Power and Energy Society General Meeting 2011
The role of multiple HVDC links - both CSC and VSC - in improving the AC system dynamic performance is presented here. An Australian equivalent system with three critical interareamodes is considered to illustrate the case study on DIgSILENT PowerFactory. Subspace-based multi-input-multi-output(MIMO) system identification is used to estimate and validatelinearized state-space models through pseudo random binary sequence (PRBS) probing in DIgSILENT PowerFactory. Choice of appropriate input-output combinations is done through modalresidue analysis taking note of not only the magnitudes but also the phase angles. The decentralized control design is posed as an optimization problem and solved using an evolutionary technique. The results are validated through linear analysis andnon linear simulation in DIgSILENT for two extreme (light and heavy loading) operating conditions.
Pipelzadeh Y, Chaudhuri B, Green TC, 2011, The Impact of Significant Wind Penetration and HVDC Upgrades on the Stability of Future Grids: A Case Study on the Australian Power System, CIGRE International Symposium 2011
Wind power has been the fastest growing energy generation sector worldwide in recent years. Large on- and off-shore wind farms have a considerable impact on system security and stable system operation. Therefore its influence on the dynamic stability of the system must be addressed. For turbines above 1MW, doubly-fed induction generators (DFIG) are the most widely used concept. However in many countries such as U.K and Germany, full-rated converter (FRC) have also gained vast amount of market penetration.To address this, the paper presents studies performed in DIgSILENT PowerFactory aimed at ascertaining the impact that DFIG and FRC have on the oscillation modes of the power system. The feasibility, advantage and disadvantages of various options are discussed.Wind generators can be connected to existing power transmission networks spanning over long distances and ultimately causing interaction between wind-farms and transmission systems. The benefit of utilising HVDC (classical and/or Voltage- source) within an ac network for transporting large amounts of wind power to remote load locations is studied.Wind farms consist of large number of generators of relatively small size. Both types of variable speed wind generators (DFIG and FRC) have been modelled in detail in PowerFactory DIgSILENT. Model aggregation techniques are applied to reduce computation time. Different control strategies for VSC-HVDC and “classical” Thyristor-based HVDC links are presented and analyzed via network simulation. A case study is presented based on the equivalent SE Australian power system, an IEEE benchmark system for dynamic studies, with appropriate reinforcements introduced to accommodate wind generation and HVDC transmission systems.This paper is focused on the small-signal stability issues and analyses the impact of various aspects like generator technology, hybrid AC/HVDC transmission for getting a thorough understanding about the impact of these on the overall system sta
Junyent-Ferre A, Gomis-Bellmunt O, Green TC, et al., 2011, Current Control Reference Calculation Issues for the Operation of Renewable Source Grid Interface VSCs Under Unbalanced Voltage Sags, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 26, Pages: 3744-3753, ISSN: 0885-8993
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- Citations: 110
Dinh MM, Green TC, Newsome D, et al., 2011, Impact of technical assistants for venepuncture and intravenous cannulation on overall emergency department performance, EMERGENCY MEDICINE AUSTRALASIA, Vol: 23, Pages: 726-731, ISSN: 1742-6731
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- Citations: 1
Trainer DR, Soto-Sanchez DE, Green TC, et al., 2011, DC Network Active Filtering using VSC, WO 2,013,000,510
Plet CA, Green TC, Walton CM, 2011, Electrical Devices With Improved Fault Current Handling Capabilities
An electrical device comprising: first and second windings that are magnetically coupled such that, during normal operation, magnetic fields of the first and second windings interact and currents flow through the first and second windings; and a power controller arranged to control the current in the second winding in a fault situation, so as to reduce or limit the current magnitude flowing in the first winding or the second winding, or to synchronise the magnetic field of the second winding with the magnetic field of the first winding and thereby reduce their interaction; wherein the second winding incorporates a tap changer arrangement operable to reduce the number of turns in the second winding through which the current in the second winding flows, and thereby decrease the mutual inductance between the first and second windings and reduce the voltage magnitude required of the power controller in order to exercise control in the fault situation.Also provided is a method of operating such a device, and a tap changer arrangement that is well suited for use with such a device
Acha S, Green TC, Shah N, 2011, Optimal charging strategies of electric vehicles in the UK power market, 2011 IEEE PES Innovative Smart Grid Technologies (ISGT), Publisher: IEEE, Pages: 1-8
In order to gain the most from their deployment, it is imperative for stakeholders to exploit the main benefits electric vehicles bring to utilities. Therefore, this paper focuses on the aspects required to model the management of electricity supply for electric vehicles. The framework presented details a time coordinated optimal power flow (TCOPF) tool to illustrate the tradeoffs distribution network operators (DNO) might encounter when implementing various load control approaches of electric vehicles. Within an UK context, a case study is performed where the TCOPF tool functions as the intermediary entity that coordinates cost-effective interactions between power markets, network operators, and the plugged vehicles. Results depict the stochastic but optimal charging patterns stakeholders might visualise from electric vehicles in local networks as they are operated to reduce energy and emission costs. Furthermore, results show current emission costs have a negligible weight in the optimisation process when compared to wholesale electricity costs.
Plet CA, Green TC, 2011, A Method of Voltage Limiting and Distortion Avoidance for Islanded Inverter-Fed Networks under Fault, 14th European Conference on Power Electronics and Applications (EPE)/ECCE Europe Conference on Power Electronics and Adjustable Speed Drives - Towards the 20-20-20 Target, Publisher: IEEE, ISSN: 2325-0313
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- Citations: 14
Sokolov M, Green TC, Mitcheson PD, et al., 2011, Small-signal Model of Photovoltaic Power Converter for Selection of Perturb and Observe Algorithm Step Time, 14th European Conference on Power Electronics and Applications (EPE)/ECCE Europe Conference on Power Electronics and Adjustable Speed Drives - Towards the 20-20-20 Target, Publisher: IEEE, ISSN: 2325-0313
Soto-Sanchez D, Green TC, 2011, Control of a modular multilevel converter-based HVDC transmission system, 14th European Conference on Power Electronics and Applications (EPE)/ECCE Europe Conference on Power Electronics and Adjustable Speed Drives - Towards the 20-20-20 Target, Publisher: IEEE, ISSN: 2325-0313
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- Citations: 3
Bloemink JM, Green TC, 2011, Increasing Photovoltaic Penetration with Local Energy Storage and Soft Normally-Open Points, General Meeting of the IEEE-Power-and-Energy-Society (PES), Publisher: IEEE, ISSN: 1944-9925
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- Citations: 33
Plet CA, Brucoli M, McDonald JDF, et al., 2011, Fault Models of Inverter-Interfaced Distributed Generators: Experimental Verification and Application to Fault Analysis, General Meeting of the IEEE-Power-and-Energy-Society (PES), Publisher: IEEE, ISSN: 1944-9925
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- Citations: 19
Yang Q, Barria JA, Green TC, 2011, Communication Infrastructures for DistributedControl of Power Distribution Networks, IEEE Transactions on Industrial Informatics, Vol: 7, Pages: 316-327, ISSN: 1551-3203
Bloemink JM, Green TC, 2011, Reducing Passive Filter Sizes with Tuned Traps for Distribution Level Power Electronics, 14th European Conference on Power Electronics and Applications (EPE)/ECCE Europe Conference on Power Electronics and Adjustable Speed Drives - Towards the 20-20-20 Target, Publisher: IEEE, ISSN: 2325-0313
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- Citations: 8
Sudtharalingam S, Hawkes AD, Green TC, 2010, Feasibility of domestic micro combined heat and power units with adjusted real time pricing, IEEE PES General Meeting
Pipelzadeh Y, Chaudhuri B, Green TC, 2010, Wide-area Power Oscillation Damping Control through HVDC: A case study on the Australian equivalent network, IEEE Power and Energy Society General Meeting 2010, Minnesota, USA
Clemow P, Green TC, 2010, Wind farm output smoothing through coordinated control
This paper presents a new method of using coordinated control and short term wind speed prediction to smooth the output of an array of wind turbines. The proposed controller uses knowledge of the kinetic energy storage potential in the rotor disc to allow production of pre-determined power profiles for periods of around 60s from variable wind inputs. Previous studies have shown that there are large peaks in wind power variability in the minutes timescale which is within the ability of a control system to reduce. This variation will cause issues with balancing systems within the local grid, as such it is beneficial to remove it. Results of tests to the system are presented which show a significant reduction in wind farm output power variability without a significant drop in output power. Comparisons with the natural smoothing effect are also presented and show that despite the significant smoothing found in large and distributed wind farms, there is still a possibility to improve the output.
Pipelzadeh Y, Chaudhuri B, Green TC, 2010, Decentralised Control for Damping Multi-Modal Oscillations through CSC/VSC Based HVDC Transmission Technologies, The 9th international conference on AC and DC power transmission (ACDC 2010)
Pipelzadeh Y, Chaudhuri B, Green TC, 2010, Stability Improvement through HVDC Upgrade in the Australian Equivalent System, UPEC 2010
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