EPE Association: 001 - EPE Wind Energy Chapter Seminar (2008)

001 - EPE Wind Energy Chapter Seminar (2008)
You are here: EPE Documents > 03 - EPE Seminar Papers > 001 - EPE Wind Energy Chapter Seminar (2008)

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   Multipolar double fed induction generator
By L. Ribickis; G. Dilevs; N. Levins; V. Pugachevs [View]
[Download]

Abstract: This paper concerns the design and practical application of the multipolar induction generator which can be applied to small power directly driven wind generators (1 â€“ 30 kW). All the windings of this generator are placed on the stator. The overturned rotor is tooth-like without windings on it. The stator is placed inside the rotor. This construction helps to reduce the weight of the generator for about 15 - 17% comparing with conventional design.

   VECTOR CONTROL OF A DOUBLY FED INDUCTION GENERATOR FOR STANDALONE WIND ENERGY APPLICATION
By H. M. EL-helw; Sarath B. Tennakoon [View]
[Download]

Abstract: Indirect and direct vector control strategies can be applied to a stand alone Doubly Fed Induction Generator (DFIG) for wind energy applications. The control algorithm allows generating constant frequency and voltage with variable mechanical speed. The maximum power tracking can only be realised by controlling the load power. In this study the load was modelled as a controlled rectifier supplying an RL load. Simulation results for a 9 MW wind farm modelled as one aggregated DFIG machine are presented.

   Loss and Rating Considerations of a Wind Energy Conversion System with Reactive Compensation by Magnetic Energy Recovery Switch (MERS)
By J. A. Wiik; A. Kulka; T. Isobe; K. Usuki; M. Molinas; T. Takaku; T. Undeland; R. Shimada [View]
[Download]

Abstract: Electrical conversion system for permanent magnet wind generators is challenging due to the large rating of power electronics devices needed and the associated costs. Additionally, due to the large inductance present in the generator (synchronous reactance), voltage drops results with resistive load and the generator output power is limited. A solution utilizing an active series compensation device called magnetic energy recovery switch (MERS) for cancelling the voltage drop across the synchronous reactance is investigated. MERS is a simple configuration with low switching losses. Due to the special characteristics of the configuration, a new IGBT with low on-state voltage has been applied. The performance of the configuration has been confirmed with experiments on a 50 kW multi-pole permanent magnet generator. Numerical investigations on large scale system indicate potential for loss reductions and rating reduction compared to using a conventional active rectifier solution.

   New HVDC-Concept for power transmission from offshore wind farms
By T. VÃ¶lker; C. Mehler; H. Raffel; B. Orlik [View]
[Download]

Abstract: The future for wind power generation in Germany is offshore wind energy. The preferred concept for power transmission over long distances from the offshore wind farm to the mainland is the High Voltage Direct Current (HVDC) power transmission. In this paper a new transmission concept based on HVDC is presented.

   Simulation of CMV-minimized Direct Power Control for Doubly Fed Induction Generators
By B. Rueckert; W. Hofmann [View]
[Download]

Abstract: Nowadays the doubly fed induction machine is often used as generator in high power windenergy systems. Because of the use of two converters in the generatorâ€™s rotor circuit bearing damages can occure specially for this type of machine. So the aim is to reduce the common mode voltage as one cause of bearing currents. Instead of a classic space vector modulation this paper presents the simulation of an enhanced direct power control.

   Energy storage, a condition when feeding the electrical grid from natural sources
By W. Leonhard [View]
[Download]

Abstract: Sustainability by using regenerative sources is a longterm political goal, the reasons are the finite fossil resources and the avoidance of toxic emissions and waste. Of the natural energy sources, wind energy is considered in Europe to offer best promise for contributing in the coming decades a substantial portion of the electrical supply. It is discussed, how the environment-oriented policy in Germany of feeding with priority large quantities of subsidized wind power into the supply affects the stability of the grid and whether it can substitute the dependance on fossil and nuclear fuels. Generation of storable secondary energy carriers such as hydrogen for decoupling the fluctuating supply and demand may be a preferable alternative. The possibility of processing the CO2 - emissions of coal power stations with regenerative hydrogen, similar to natural photosynthesis, is briefly discussed.

   Stiffness and load free transmission error for the Multi-Flexible-Body-Dynamics Simulation of a wind turbine gearbox using a FE-based tooth contact analysis
By C. Brecher; T. RÃ¶thlingshÃ¶fer; C. Gorgels [View]
[Download]

Abstract: In most MFBD-Systems it is possible to use a gear element to create a dynamic model of a wind turbine gearbox. This article shows a possibility to calculate the stiffness and the load free transmission error for this element using a FE-based tooth contact analysis.

   Promising Direct-Drive Generator System for Large Wind Turbines
By DJ Bang; H. Polinder; G. Shrestha; J.A. Ferreira [View]
[Download]

Abstract: The aim of this paper is to review direct-drive generators and to suggest promising direct-drive generator concepts for large wind turbines. Different large direct-drive generators are compared based on the mass and the torque. Features of different PM machines are investigated to find promising machine type for direct-drive. The requirements and alternative solutions are suggested for both electromagnetic and mechanical design.

   Experiment of a wind generator participation to frequency control
By V. COURTECUISSE; M. EL MOKADEM; C. SAUDEMONT; B. ROBYNS; J. DEUSE [View]
[Download]

Abstract: In this paper, a primary frequency control strategy based on fuzzy logic designed for variable speed wind generators is proposed and tested on a 2,2 kW test bench. The fuzzy logic supervisor ensures a regular primary reserve on a large range of wind speed without any wind speed measurement. This supervisor controls simultaneously the generator torque and the pitch angle to keep the primary reserve; it determines in real time the generator power reference value. The fuzzy logic supervisor is compared with a classical strategy which maximises the power efficiency.The experiments point out the regularity of the power reserve and the ability to contribute to frequency control.

   Future Interconnection, Control and Balancing of Large Wind Parks
By G. Brauner [View]
[Download]

Abstract: Report from ETG-meeting on Wind Energy, Regulation and Stability.

   Modeling of Battery-Charging Wind Turbines with Yaw Axis Furling
By J. Reed; G. Venkataramanan [View]
[Download]

Abstract: Design of small wind turbines is typically dictated by considerations of cost, manufacturing and maintenance and often follows heuristically driven trade-offs. Definitive and simple analytical models that provide performance prediction can enable optimization of the design process. This paper describes a wind turbine system model based on the Blade Element Method adapted for use with yawed turbines, integrated with a model of the furling system. Analytical development of the system model is presented along with selected laboratory experimental results.

   Resonance in the AC-Connected Offshore Wind Farms
By J. Plotkin; U. Schaefer; R. Hanitsch [View]
[Download]

Abstract: Possible power quality problem for the AC-connected offshore wind farms is discussed on the example of a 132 MW onshore wind farm with a similar structure. A resonant circuit formed by the wind farm components is found to be responsible for a low power quality at the output. Various compensation strategies are proposed and analyzed.

001 - EPE Wind Energy Chapter Seminar (2008)
You are here: EPE Documents > 03 - EPE Seminar Papers > 001 - EPE Wind Energy Chapter Seminar (2008)
	[return to parent folder]

	Multipolar double fed induction generator By L. Ribickis; G. Dilevs; N. Levins; V. Pugachevs	[View] [Download]
Abstract: This paper concerns the design and practical application of the multipolar induction generator which can be applied to small power directly driven wind generators (1 â€“ 30 kW). All the windings of this generator are placed on the stator. The overturned rotor is tooth-like without windings on it. The stator is placed inside the rotor. This construction helps to reduce the weight of the generator for about 15 - 17% comparing with conventional design.

	VECTOR CONTROL OF A DOUBLY FED INDUCTION GENERATOR FOR STANDALONE WIND ENERGY APPLICATION By H. M. EL-helw; Sarath B. Tennakoon	[View] [Download]
Abstract: Indirect and direct vector control strategies can be applied to a stand alone Doubly Fed Induction Generator (DFIG) for wind energy applications. The control algorithm allows generating constant frequency and voltage with variable mechanical speed. The maximum power tracking can only be realised by controlling the load power. In this study the load was modelled as a controlled rectifier supplying an RL load. Simulation results for a 9 MW wind farm modelled as one aggregated DFIG machine are presented.

	Loss and Rating Considerations of a Wind Energy Conversion System with Reactive Compensation by Magnetic Energy Recovery Switch (MERS) By J. A. Wiik; A. Kulka; T. Isobe; K. Usuki; M. Molinas; T. Takaku; T. Undeland; R. Shimada	[View] [Download]
Abstract: Electrical conversion system for permanent magnet wind generators is challenging due to the large rating of power electronics devices needed and the associated costs. Additionally, due to the large inductance present in the generator (synchronous reactance), voltage drops results with resistive load and the generator output power is limited. A solution utilizing an active series compensation device called magnetic energy recovery switch (MERS) for cancelling the voltage drop across the synchronous reactance is investigated. MERS is a simple configuration with low switching losses. Due to the special characteristics of the configuration, a new IGBT with low on-state voltage has been applied. The performance of the configuration has been confirmed with experiments on a 50 kW multi-pole permanent magnet generator. Numerical investigations on large scale system indicate potential for loss reductions and rating reduction compared to using a conventional active rectifier solution.

	New HVDC-Concept for power transmission from offshore wind farms By T. VÃ¶lker; C. Mehler; H. Raffel; B. Orlik	[View] [Download]
Abstract: The future for wind power generation in Germany is offshore wind energy. The preferred concept for power transmission over long distances from the offshore wind farm to the mainland is the High Voltage Direct Current (HVDC) power transmission. In this paper a new transmission concept based on HVDC is presented.

	Simulation of CMV-minimized Direct Power Control for Doubly Fed Induction Generators By B. Rueckert; W. Hofmann	[View] [Download]
Abstract: Nowadays the doubly fed induction machine is often used as generator in high power windenergy systems. Because of the use of two converters in the generatorâ€™s rotor circuit bearing damages can occure specially for this type of machine. So the aim is to reduce the common mode voltage as one cause of bearing currents. Instead of a classic space vector modulation this paper presents the simulation of an enhanced direct power control.

	Energy storage, a condition when feeding the electrical grid from natural sources By W. Leonhard	[View] [Download]
Abstract: Sustainability by using regenerative sources is a longterm political goal, the reasons are the finite fossil resources and the avoidance of toxic emissions and waste. Of the natural energy sources, wind energy is considered in Europe to offer best promise for contributing in the coming decades a substantial portion of the electrical supply. It is discussed, how the environment-oriented policy in Germany of feeding with priority large quantities of subsidized wind power into the supply affects the stability of the grid and whether it can substitute the dependance on fossil and nuclear fuels. Generation of storable secondary energy carriers such as hydrogen for decoupling the fluctuating supply and demand may be a preferable alternative. The possibility of processing the CO2 - emissions of coal power stations with regenerative hydrogen, similar to natural photosynthesis, is briefly discussed.

	Stiffness and load free transmission error for the Multi-Flexible-Body-Dynamics Simulation of a wind turbine gearbox using a FE-based tooth contact analysis By C. Brecher; T. RÃ¶thlingshÃ¶fer; C. Gorgels	[View] [Download]
Abstract: In most MFBD-Systems it is possible to use a gear element to create a dynamic model of a wind turbine gearbox. This article shows a possibility to calculate the stiffness and the load free transmission error for this element using a FE-based tooth contact analysis.

	Promising Direct-Drive Generator System for Large Wind Turbines By DJ Bang; H. Polinder; G. Shrestha; J.A. Ferreira	[View] [Download]
Abstract: The aim of this paper is to review direct-drive generators and to suggest promising direct-drive generator concepts for large wind turbines. Different large direct-drive generators are compared based on the mass and the torque. Features of different PM machines are investigated to find promising machine type for direct-drive. The requirements and alternative solutions are suggested for both electromagnetic and mechanical design.

	Experiment of a wind generator participation to frequency control By V. COURTECUISSE; M. EL MOKADEM; C. SAUDEMONT; B. ROBYNS; J. DEUSE	[View] [Download]
Abstract: In this paper, a primary frequency control strategy based on fuzzy logic designed for variable speed wind generators is proposed and tested on a 2,2 kW test bench. The fuzzy logic supervisor ensures a regular primary reserve on a large range of wind speed without any wind speed measurement. This supervisor controls simultaneously the generator torque and the pitch angle to keep the primary reserve; it determines in real time the generator power reference value. The fuzzy logic supervisor is compared with a classical strategy which maximises the power efficiency.The experiments point out the regularity of the power reserve and the ability to contribute to frequency control.

	Future Interconnection, Control and Balancing of Large Wind Parks By G. Brauner	[View] [Download]
Abstract: Report from ETG-meeting on Wind Energy, Regulation and Stability.

	Modeling of Battery-Charging Wind Turbines with Yaw Axis Furling By J. Reed; G. Venkataramanan	[View] [Download]
Abstract: Design of small wind turbines is typically dictated by considerations of cost, manufacturing and maintenance and often follows heuristically driven trade-offs. Definitive and simple analytical models that provide performance prediction can enable optimization of the design process. This paper describes a wind turbine system model based on the Blade Element Method adapted for use with yawed turbines, integrated with a model of the furling system. Analytical development of the system model is presented along with selected laboratory experimental results.

	Resonance in the AC-Connected Offshore Wind Farms By J. Plotkin; U. Schaefer; R. Hanitsch	[View] [Download]
Abstract: Possible power quality problem for the AC-connected offshore wind farms is discussed on the example of a 132 MW onshore wind farm with a similar structure. A resonant circuit formed by the wind farm components is found to be responsible for a low power quality at the output. Various compensation strategies are proposed and analyzed.