lee holdsworth

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Aalborg University

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University of Alberta

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University Of Carthage

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Ecole Nationale d'Ingénieurs de Tunis (ENIT)

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Rajshahi University of Engineering and Technology

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The University of Dodoma, Tanzania

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Federal University of Amapá

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National Technical University of Athens

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University of Windsor

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Universitatea Tehnica Cluj Napoca

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Papers by lee holdsworth

An investigation into the inherent robustness and optimal harmonic performance of the advanced static var compensator (ASVC)

For many years, it was generally understood that a.c. transmission systems could not be controlle... more For many years, it was generally understood that a.c. transmission systems could not be controlled fast enough to handle dynamic system conditions. The dynamic system problems were usually handled by over-design, which resulted in under utilisation of the system. Flexible AC Transmission System (FACTS) devices play an important role in improving the dynamic performance of a power system and hence achieve better utilisation of the available system. They are principally employed to 'rapidly' control one or more of the three main parameters directly affecting a.c. power transmission, namely the system impedance, magnitude and phase angle of the system voltage. The Voltage Source Inverter (VSI) is the basic building block of most FACTS devices. The multi-level VSI topologies are becoming the favourite power circuits for the 2nd generation of FACTS shunt compensators. The research reported in this thesis is to investigate the reliability of Voltage Source Inverter topologies that...

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DFIG control performance under fault conditions for offshore wind applications

18th International Conference and Exhibition on Electricity Distribution (CIRED 2005), 2005

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A new adaptive discharge-path-protection-switch clamped multilevel inverter

Proceedings. International Conference on Power System Technology

Since the initial proposal of the diode clamped voltage source inverter (VSI), various inverter t... more Since the initial proposal of the diode clamped voltage source inverter (VSI), various inverter topologies and associated control strategies have been studied. The industrially favored topology has been the multilevel bridge, e.g. 3, 5, 7 levels. Investigations so far have concentrated on the normal operation of the multilevel inverter. It is an accepted practice that the inverter, comprising many semiconductor

Power system frequency response from fixed speed and doubly fed induction generator-based wind turbines

Wind Energy, 2004

Throughout Europe there is an increasing trend of connecting high penetrations of wind turbines t... more Throughout Europe there is an increasing trend of connecting high penetrations of wind turbines to the transmission networks. This has resulted in transmission system operators revising their grid code documents for the connection of large wind farms. These specifications require large MW capacity wind farms to have the ability to assist in some of the power system control services currently carried out by conventional synchronous generation. These services include voltage and frequency control. It is now recognized that much of this new wind generation plant will use either fixed speed induction generator (FSIG)-or doubly fed induction generator (DFIG)-based wind turbines. The addition of a control loop to synthesize inertia in the DFIG wind turbine using the power electronic control system has been described. The possibility of deloading wind turbines for frequency response using blade pitch angle control is discussed.A pitch control scheme to provide frequency response from FSIG and DFIG wind turbines is also described. A case study of an FSIG wind turbine with frequency response capabilities is investigated.

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Dynamic selective harmonic elimination of a three-level inverter used for static VAr compensation

IEE Proceedings - Generation, Transmission and Distribution, 2002

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Comparison of fixed speed and doubly-fed induction wind turbines during power system disturbances

IEE Proceedings - Generation, Transmission and Distribution, 2003

The dynamic modelling of large (MW) capacity fixed and variable speed induction generator wind tu... more The dynamic modelling of large (MW) capacity fixed and variable speed induction generator wind turbines is discussed. A reduced order dynamic machine model is derived suitable for modelling both k e d speed and douhly-fed asynchronous generator wind turbines, Control schemes for variable speed turbines. using doubly-fed induction generators (DFIG), are described and simulated. Speed control characteristics and converter protection of the DFIG are Research and MCEE. UMIST. UK J.B. Ekanayake is with the Dept. ofElcc1tic;d and Electronic Eng., University of

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Co-ordinated voltage control strategy for a doubly-fed induction generator (DFIG)-based wind farm

IEE Proceedings - Generation, Transmission and Distribution, 2004

Page 1. Co-ordinated voltage control strategy for a doubly-fed induction generator (DFIG)-based w... more

Dynamic modeling of doubly fed induction generator wind turbines

IEEE Transactions on Power Systems, 2003

It is now recognized that many large wind farms will employ doubly fed induction generator (DFIG)... more It is now recognized that many large wind farms will employ doubly fed induction generator (DFIG) variable speed wind turbines. A number of such wind farms are already in operation and more are planned or under construction. With the rising penetration of wind power into electricity networks, increasingly comprehensive studies are required to identify the interaction between the wind farm(s) and the power system. These require accurate models of doubly fed induction generator wind turbines and their associated control and protection circuits. A dynamic model has been derived, which can be used to simulate the DFIG wind turbine using a single-cage and double-cage representation of the generator rotor, as well as a representation of its control and protection circuits. The model is suitable for use in transient stability programs that can be used to investigate large power systems. The behavior of a wind farm and the network under various system disturbances was studied using this dynamic model. The influence of the DFIG control on the stability of the wind farm was also investigated by considering different control gains and by applying network voltage control through both stator side and rotor side converters.

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Comparison of 5th order and 3rd order machine models for doubly fed induction generator (DFIG) wind turbines

Electric Power Systems Research, 2003

With increasing concern over climate change, a number of countries have implemented new renewable... more With increasing concern over climate change, a number of countries have implemented new renewable energy targets, which require significant amounts of wind generation. It is now recognized that much of this new wind generation plant will be variable speed type using doubly fed induction generators (DFIG). In order to investigate the impacts of these DFIG installations on the operation and control of the power system, accurate models are required. A fifth order and reduced order (3rd) machine models are described and the control of the wind turbine discussed. The capability of the DFIG for voltage control (VC) and its performance during a network fault is also addressed.

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Control of DFIG wind turbines

Power Engineer, 2003

The generation of electrical power using sustainable sources of energy is developing rapidly. The... more

An investigation into the inherent robustness and optimal harmonic performance of the advanced static var compensator (ASVC)