EPE Association: EPE-PEMC 2002: Special Session: Windenergy and Offshore Windparks

EPE-PEMC 2002: Special Session: Windenergy and Offshore Windparks
You are here: EPE Documents > 04 - EPE-PEMC Conference Proceedings > EPE-PEMC 2002 - Conference > EPE-PEMC 2002: Special Session: Windenergy and Offshore Windparks

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   Comparison of the energy yield of wind turbines with individual ac/dc/ac converters and wind turbines connected to a common ac/dc/ac converter
By I. Nusimovich; J. G. Slootweg; S.W.H. De Haan [View]
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Abstract: For optimal energy extraction, wind turbines should operate at variable speed, with the rotor speed depending on wind speed. In large wind farms, the wind speed will in general not be the same for all wind turbines. To enable variable speed operation of wind turbines with (induction) generators and optimal energy extraction, each turbine should preferably be equipped with its own ac/dc/ac converter. Utilising a common ac/dc/ac converter in wind farms may reduce cost but requires all turbines to operate at the same speed. This rotational speed can still be proportional to the average wind speed, but no longer to the wind speed at each individual wind turbine. In this paper, the energy yield of these two connection schemes is compared. For both schemes the optimal control strategy is determined, based on wind speed and spatial wind speed distribution within the farm. Further the difference in energy yield is determined for various wind speed regimes. The results obtained showed that the reduction in energy yield found in the parallel-connected scheme is 1.44%, compared to the total production of the individual connected scheme. Other aspects such as differences in costs and mechanical stresses due to wind speed variations are not considered.

   Modelling and simulation of hybrid wind-photovoltaic generating system
By L. Leclercq; B. François; B. Robyns; Y. Pankow [View]
[Download]

Abstract: An equivalent continuous model of an hybrid wind-photovoltaic generating system is proposed in this paper. The model of the solar generating system is particularly developed. It is shown that this model is interesting for analysing the dynamic behaviour of the system and for synthesising the control strategy. The proposed global model is simulated with the help of Matlab-SimulinkTD, by considering a 4.5 kW wind generator and a 3.6 kW solar generator.

   Reliability Normalization of Autonomous System for Transforming the Wind’s Energy in Electrical
By R. S. Dimova; N. G. Georgieva; A. Sl. Georgiev [View]
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Abstract: Nowadays the utilization of the nature energy resources is an important problem for energy independence of the modern society. Unfortunately high reliability of autonomous systems for transforming the wind’s energy (ASTWE) often contradicts with the achieving good characteristics of the system. This paper presents an optimal compromise between reliability and the other characteristics of ASTWE. Scalar and vector approaches to reliability normalization are compared. The results show that vector approach is more flexible and adaptive.

   Reliability Study of The Synchronous Machine Variables at The Junction of WECS to a Weak Energy Grid Under Different Wind Velocities
By E. C. Tsimplostephanakis; A. N. Safacas [View]
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Abstract: In this paper, a weak hybrid energy system consisting of a conventional power plant and a wind energy conversion system is investigated via simulation. A general dynamic mathematical model, which enables to investigate the dynamic behavior of the system’s variables for various systems perturbations, such as the connection and the disconnection of the WECS, the wind speed variation, the load variation and faults at the grid or at the electrical subsystems is developed. Specific attention is paid to the reliability study of the S.G.’s electromechanical variables at the connection of WECS to the grid under different wind velocity. Using this model some useful characteristic results of the system’s variables for the previous cases are presented.

   Sensorless Direct Power Control of a Doubly Fed Induction Generator for Variable Speed Wind Turbines
By S. Arnalte; J.L. Rodríguez-Amenedo [View]
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Abstract: This paper presents a sensorless direct power control (DPC) scheme of a doubly fed induction generator (DFIG) applied to a wind generation systems as an alternative to the widely used field oriented control (FOC). The aims of the control system are the control of the power drawn from the wind turbine and the control of the reactive power interchanged between the generator and the grid. DPC is used to control a wound rotor induction generator by means of a rotor connected VSI. The proposed control scheme is based on the direct torque control (DTC) concept, but using active and reactive power as control variables instead of torque and rotor flux. Simulation results show that DPC gives excellent dynamic performance.

   Windenergy and Offshore Windparks: State of the Art and Trends
By S.W.H. De Haan; M.R. Dubois; P. Bauer [View]
[Download]

Abstract: Wind energy and cost effective transmission and distribution of wind power generated electricity presents a stimulating engineering challenge. Several aspects such as generators, converters and power electronics, cables are addressed in the paper. Offshore wind parks and application of wind energy perform the latest development of the wind energy applications. Special attention is paid to the electrical infrastructure of offshore wind parks.

EPE-PEMC 2002: Special Session: Windenergy and Offshore Windparks
You are here: EPE Documents > 04 - EPE-PEMC Conference Proceedings > EPE-PEMC 2002 - Conference > EPE-PEMC 2002: Special Session: Windenergy and Offshore Windparks
	[return to parent folder]

	Comparison of the energy yield of wind turbines with individual ac/dc/ac converters and wind turbines connected to a common ac/dc/ac converter By I. Nusimovich; J. G. Slootweg; S.W.H. De Haan	[View] [Download]
Abstract: For optimal energy extraction, wind turbines should operate at variable speed, with the rotor speed depending on wind speed. In large wind farms, the wind speed will in general not be the same for all wind turbines. To enable variable speed operation of wind turbines with (induction) generators and optimal energy extraction, each turbine should preferably be equipped with its own ac/dc/ac converter. Utilising a common ac/dc/ac converter in wind farms may reduce cost but requires all turbines to operate at the same speed. This rotational speed can still be proportional to the average wind speed, but no longer to the wind speed at each individual wind turbine. In this paper, the energy yield of these two connection schemes is compared. For both schemes the optimal control strategy is determined, based on wind speed and spatial wind speed distribution within the farm. Further the difference in energy yield is determined for various wind speed regimes. The results obtained showed that the reduction in energy yield found in the parallel-connected scheme is 1.44%, compared to the total production of the individual connected scheme. Other aspects such as differences in costs and mechanical stresses due to wind speed variations are not considered.

	Modelling and simulation of hybrid wind-photovoltaic generating system By L. Leclercq; B. François; B. Robyns; Y. Pankow	[View] [Download]
Abstract: An equivalent continuous model of an hybrid wind-photovoltaic generating system is proposed in this paper. The model of the solar generating system is particularly developed. It is shown that this model is interesting for analysing the dynamic behaviour of the system and for synthesising the control strategy. The proposed global model is simulated with the help of Matlab-SimulinkTD, by considering a 4.5 kW wind generator and a 3.6 kW solar generator.

	Reliability Normalization of Autonomous System for Transforming the Wind’s Energy in Electrical By R. S. Dimova; N. G. Georgieva; A. Sl. Georgiev	[View] [Download]
Abstract: Nowadays the utilization of the nature energy resources is an important problem for energy independence of the modern society. Unfortunately high reliability of autonomous systems for transforming the wind’s energy (ASTWE) often contradicts with the achieving good characteristics of the system. This paper presents an optimal compromise between reliability and the other characteristics of ASTWE. Scalar and vector approaches to reliability normalization are compared. The results show that vector approach is more flexible and adaptive.

	Reliability Study of The Synchronous Machine Variables at The Junction of WECS to a Weak Energy Grid Under Different Wind Velocities By E. C. Tsimplostephanakis; A. N. Safacas	[View] [Download]
Abstract: In this paper, a weak hybrid energy system consisting of a conventional power plant and a wind energy conversion system is investigated via simulation. A general dynamic mathematical model, which enables to investigate the dynamic behavior of the system’s variables for various systems perturbations, such as the connection and the disconnection of the WECS, the wind speed variation, the load variation and faults at the grid or at the electrical subsystems is developed. Specific attention is paid to the reliability study of the S.G.’s electromechanical variables at the connection of WECS to the grid under different wind velocity. Using this model some useful characteristic results of the system’s variables for the previous cases are presented.

	Sensorless Direct Power Control of a Doubly Fed Induction Generator for Variable Speed Wind Turbines By S. Arnalte; J.L. Rodríguez-Amenedo	[View] [Download]
Abstract: This paper presents a sensorless direct power control (DPC) scheme of a doubly fed induction generator (DFIG) applied to a wind generation systems as an alternative to the widely used field oriented control (FOC). The aims of the control system are the control of the power drawn from the wind turbine and the control of the reactive power interchanged between the generator and the grid. DPC is used to control a wound rotor induction generator by means of a rotor connected VSI. The proposed control scheme is based on the direct torque control (DTC) concept, but using active and reactive power as control variables instead of torque and rotor flux. Simulation results show that DPC gives excellent dynamic performance.

	Windenergy and Offshore Windparks: State of the Art and Trends By S.W.H. De Haan; M.R. Dubois; P. Bauer	[View] [Download]
Abstract: Wind energy and cost effective transmission and distribution of wind power generated electricity presents a stimulating engineering challenge. Several aspects such as generators, converters and power electronics, cables are addressed in the paper. Offshore wind parks and application of wind energy perform the latest development of the wind energy applications. Special attention is paid to the electrical infrastructure of offshore wind parks.