EPE Association: NORpie 2004 - Topic 09: Wind Farms

NORpie 2004 - Topic 09: Wind Farms - DC Distribution
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   New topology for more efficient AC/DC converters for future offshore wind farms
By S. Meier; S. Norrga; H.-P. Nee [View]
[Download]

Abstract: The concept of a novel soft-switching AC/DC converter is applied for use in future offshore wind farms. A voltage source converter with capacitive snubbers and cycloconverters, connected via a medium frequency AC bus, promises substantial benefits. This paper presents this new topology and describes its principle of operation. Furthermore, a comparison with state-ofthe- art adjustable speed generators reveals the potential of this new concept.

   Evaluation of wind farm layouts
By S. Lundberg [View]
[Download]

Abstract: In this paper, layouts of various large-scale wind farms, using both AC as well as DC, are investigated. The criteria in this investigation is the energy production cost. The energy production cost is defined as the total investment cost divided with the total energy production of the wind farm. To determine the energy production and the total investment cost, loss and cost models for the components in the wind farm are used (the most important models are presented in this paper). Of the investigated wind farm configurations, a wind farm with series connected DC wind turbines seems to have the best potential to give the lowest energy production cost, if the transmission distance is longer then 10-20km.

   Small-Signal Modeling and Analysis of DC Distributed Power Systems
By P. Karlsson [View]
[Download]

Abstract: DC power systems have been discussed for connection of renewable, small-scale power generation units. This paper addresses small-signal analysis of distributed DC power systems with emphasis on converter modeling and DC bus voltage control. Droop control is utilized to distribute the load between the source converters. The dynamic properties in terms of small-signal stability are investigated both for the converters and for a small DC distribution system. It is found that the converter models do not have to be taken into account. It is also found that the negative equivalent small-signal resistance of constant power loads does not cause problems, for the proposed converter and DC bus parameters.

   Optimization of Electrical System for a Large DC OffshoreWind Farm by Genetic Algorithm
By M. Zhao; Z. Chen; F. Blaabjerg [View]
[Download]

Abstract: This paper proposes an optimization platform based on Genetic Algorithm, where the main components of the electrical systemof a wind farm and key technical specifications are used as input parameters and the topology of the electrical system is to be optimized for a minimum cost and high reliability. A method to encode and decode an electrical system is studied. The reliability evaluation for a given network is also investigated. Genetic Algorithm is implemented to find the optimum network design for a large DC wind farm. It is concluded that different topologies may cause very different cost and reliability, and the Genetic Algorithm is capable of finding the optimum solution.

   A Probabilistic Method for Sizing of Isolated Wind-Electrolyzer Systems
By L. N. Grimsmo; M. Korpäs; T. Gjengedal; S. Möller-Holst [View]
[Download]

Abstract: Wind Power is currently the fastest growing energy source in the world. Norway is one of the best-situated European countries for using wind power, and several large-scale wind farms are given concession. If wind power is combined with other energy sources and/or energy storage systems, wind power may also be a realistic energy source in isolated energy systems. This paper has focused on a small windhydrogen system comprising of a wind turbine, a battery storage, an electrolyser, a compressor, a hydrogen storage tank and a filling station for hydrogen vehicles. Wind conditions are changing with time of day, season and year. At the same time, the electrolyser may require stable and strict operational conditions, which might impose limitations on the dynamic utilisation of the electrolyser. This paper has presented a new methodology for taking the stochastic nature of the wind into account when dimensioning the system. The method was implemented in MatLab and was used on a small case study, with focus on component sizing and the cost of delivered hydrogen.

   A Short Review of Models for Double-Fed Variable Speed Wind Turbines
By M. Hokkanen; H. J. Salminen; T. Vekara [View]
[Download]

Abstract: A short review is given on some public simulation models for double-fed, variable speed horizontal axis wind turbines to enable studying the effects of wind power in grid connection. Most recent Nordic literature is reviewed. The paper assesses the background for atmospheric, fluid dynamic and stochastic models, as well as technology-related aerodynamic models for wind turbines, which are needed in order to produce realistic input to the electromechanical system. The stochastic nature of wind represents special challenges in connection of wind power to the grid. Models contain features from engineering and physics.

NORpie 2004 - Topic 09: Wind Farms - DC Distribution
You are here: EPE Documents > 05 - EPE Supported Conference Proceedings > NORpie - Proceedings > NORpie 2004 > NORpie 2004 - Topic 09: Wind Farms - DC Distribution
	[return to parent folder]

	New topology for more efficient AC/DC converters for future offshore wind farms By S. Meier; S. Norrga; H.-P. Nee	[View] [Download]
Abstract: The concept of a novel soft-switching AC/DC converter is applied for use in future offshore wind farms. A voltage source converter with capacitive snubbers and cycloconverters, connected via a medium frequency AC bus, promises substantial benefits. This paper presents this new topology and describes its principle of operation. Furthermore, a comparison with state-ofthe- art adjustable speed generators reveals the potential of this new concept.

	Evaluation of wind farm layouts By S. Lundberg	[View] [Download]
Abstract: In this paper, layouts of various large-scale wind farms, using both AC as well as DC, are investigated. The criteria in this investigation is the energy production cost. The energy production cost is defined as the total investment cost divided with the total energy production of the wind farm. To determine the energy production and the total investment cost, loss and cost models for the components in the wind farm are used (the most important models are presented in this paper). Of the investigated wind farm configurations, a wind farm with series connected DC wind turbines seems to have the best potential to give the lowest energy production cost, if the transmission distance is longer then 10-20km.

	Small-Signal Modeling and Analysis of DC Distributed Power Systems By P. Karlsson	[View] [Download]
Abstract: DC power systems have been discussed for connection of renewable, small-scale power generation units. This paper addresses small-signal analysis of distributed DC power systems with emphasis on converter modeling and DC bus voltage control. Droop control is utilized to distribute the load between the source converters. The dynamic properties in terms of small-signal stability are investigated both for the converters and for a small DC distribution system. It is found that the converter models do not have to be taken into account. It is also found that the negative equivalent small-signal resistance of constant power loads does not cause problems, for the proposed converter and DC bus parameters.

	Optimization of Electrical System for a Large DC OffshoreWind Farm by Genetic Algorithm By M. Zhao; Z. Chen; F. Blaabjerg	[View] [Download]
Abstract: This paper proposes an optimization platform based on Genetic Algorithm, where the main components of the electrical systemof a wind farm and key technical specifications are used as input parameters and the topology of the electrical system is to be optimized for a minimum cost and high reliability. A method to encode and decode an electrical system is studied. The reliability evaluation for a given network is also investigated. Genetic Algorithm is implemented to find the optimum network design for a large DC wind farm. It is concluded that different topologies may cause very different cost and reliability, and the Genetic Algorithm is capable of finding the optimum solution.

	A Probabilistic Method for Sizing of Isolated Wind-Electrolyzer Systems By L. N. Grimsmo; M. Korpäs; T. Gjengedal; S. Möller-Holst	[View] [Download]
Abstract: Wind Power is currently the fastest growing energy source in the world. Norway is one of the best-situated European countries for using wind power, and several large-scale wind farms are given concession. If wind power is combined with other energy sources and/or energy storage systems, wind power may also be a realistic energy source in isolated energy systems. This paper has focused on a small windhydrogen system comprising of a wind turbine, a battery storage, an electrolyser, a compressor, a hydrogen storage tank and a filling station for hydrogen vehicles. Wind conditions are changing with time of day, season and year. At the same time, the electrolyser may require stable and strict operational conditions, which might impose limitations on the dynamic utilisation of the electrolyser. This paper has presented a new methodology for taking the stochastic nature of the wind into account when dimensioning the system. The method was implemented in MatLab and was used on a small case study, with focus on component sizing and the cost of delivered hydrogen.

	A Short Review of Models for Double-Fed Variable Speed Wind Turbines By M. Hokkanen; H. J. Salminen; T. Vekara	[View] [Download]
Abstract: A short review is given on some public simulation models for double-fed, variable speed horizontal axis wind turbines to enable studying the effects of wind power in grid connection. Most recent Nordic literature is reviewed. The paper assesses the background for atmospheric, fluid dynamic and stochastic models, as well as technology-related aerodynamic models for wind turbines, which are needed in order to produce realistic input to the electromechanical system. The stochastic nature of wind represents special challenges in connection of wind power to the grid. Models contain features from engineering and physics.