EPE Association: EPE-PEMC 2008 - Topic: Wind Turbine Generating System

EPE-PEMC 2008 - Topic: Wind Turbine Generating System
You are here: EPE Documents > 04 - EPE-PEMC Conference Proceedings > EPE-PEMC 2008 - Conference > EPE-PEMC 2008 - Topic: Wind Turbine Generating System

   [return to parent folder]

   A Cooperative Control Method for Output Power Smoothing and Hydrogen Production by Using Variable Speed Wind Generator
By Rion Takahashi [View]
[Download]

Abstract: This paper presents a combination system of wind energy conversion and hydrogen production. Hydrogen is expected as alternative energy sources in the future, and it is the best way to produce it from renewable energy like wind energy. On the other hand, the output of a wind generator, in general, fluctuates greatly due to wind speed variations, and thus the output fluctuations can have a serious influence on the power system. In the proposed system, a variable speed wind generator is adopted, and an electrolyzer is installed in parallel with it for hydrogen production. Output power from the wind generator is smoothed and supplied to the power system as well as to the electrolyzer based on the cooperative control method. The performance of the proposed system is evaluated by simulation analyses, in which simulations are performed by using PSCAD/EMTDC.

   A New Interconnecting Method for Wind Turbine/Generators in a Wind Farm and Basic Characteristics of the Integrated System
By Shoji Nishikata [View]
[Download]

Abstract: A new interconnecting method for a cluster of wind turbine/generators is proposed, and some examples of the basic characteristics of the integrated system are shown. This method can be achieved with wind turbine generating system using a shaft generator system. A group of wind turbine-generators can be interconnected easily with the proposed method, and high reliability and electric output power with high quality are also expected. Moreover, since this method enables to send generated power through a long-distance DC transmission line, the optimum site for wind turbines can be selected so as to acquire the maximum wind energy.

   Flicker Study on Variable Speed Wind Turbines with Permanent Magnet Synchronous Generator
By Weihao Hu [View]
[Download]

Abstract: Grid connected wind turbines are fluctuating power sources that may produce flicker during continuous operation. This paper presents a simulation model of a MWlevel variable speed wind turbines with a permanent magnet synchronous generator (PMSG) and a full-scale converter developed in the simulation tool of PSCAD/EMTDC. Flicker emission of this system is investigated during continuous operation. The dependence of flicker emission on wind characteristics (mean speed, turbulence intensity), 3p torque oscillations due to wind shear and tower shadow effects and grid conditions (short circuit capacity, grid impedance angle) are analyzed. Flicker mitigation is realized by output reactive power control of the variable speed wind turbines with PMSG. Simulation results show the output reactive power control is an effective measure to mitigate the flicker during continuous operation of grid connected wind turbines.

   Power Output Characteristics Analysis of Wind Energy Converter Control Methods
By Bingchang Ni [View]
[Download]

Abstract: The stochastically fluctuating offer of wind energy limits the supply capacity in electrical grids by means of technical and economical reasons. This paper analyses the influence of the control method on the power output characteristic of wind energy converters. Conventional controls, like optimal rotor speed control, and a new control, the stochastic dynamic optimization, are compared in regard of their grid impact. The results show the superior performance of the stochastic dynamic optimization. The power gradient and the deviation from the mean power output value are significantly lowered, reducing the wind energy converter's impact on the grid stability.

   Torque Transient Alleviation in Fixed Speed Wind Generators by Indirect Torque Control with STATCOM
By Marta Molinas, Jon Are Suul and Tore Undeland [View]
[Download]

Abstract: Gearboxes for wind turbines must ensure high reliability over a period of 20 years withstanding cumulative and transient loads. Grid disturbances affecting wind turbines with induction generators directly connected to the grid generates electromagnetic torque transients that will result in significant stresses and fatigue of the gearbox. This paper presents a technique by which the transient torques during recovery after a grid fault can be smoothed for fixed speed wind turbines with induction generators directly connected to the grid. The technique labeled Indirect Torque Control (ITC) is suggested in order to reduce the drive train mechanical stresses caused by the characteristics of the induction machine when decelerating through the maximum torque region. The basis of the approach consists of controlling the induction generator terminal voltage by the injection/absorption of reactive current using a STATCOM. By controlling the terminal voltage with the STATCOM, the electromagnetic torque of the generator is indirectly smoothed. The control concept is shown by simulations on a wind generation system model built in PSCAD, where the smoothing effect of the proposed technique is seen during the recovery after a three phase to ground fault condition. The influence of shaft stiffness and mutual damping on the proposed control is further investigated on a two mass model of the wind generation system.

EPE-PEMC 2008 - Topic: Wind Turbine Generating System
You are here: EPE Documents > 04 - EPE-PEMC Conference Proceedings > EPE-PEMC 2008 - Conference > EPE-PEMC 2008 - Topic: Wind Turbine Generating System
	[return to parent folder]

	A Cooperative Control Method for Output Power Smoothing and Hydrogen Production by Using Variable Speed Wind Generator By Rion Takahashi	[View] [Download]
Abstract: This paper presents a combination system of wind energy conversion and hydrogen production. Hydrogen is expected as alternative energy sources in the future, and it is the best way to produce it from renewable energy like wind energy. On the other hand, the output of a wind generator, in general, fluctuates greatly due to wind speed variations, and thus the output fluctuations can have a serious influence on the power system. In the proposed system, a variable speed wind generator is adopted, and an electrolyzer is installed in parallel with it for hydrogen production. Output power from the wind generator is smoothed and supplied to the power system as well as to the electrolyzer based on the cooperative control method. The performance of the proposed system is evaluated by simulation analyses, in which simulations are performed by using PSCAD/EMTDC.

	A New Interconnecting Method for Wind Turbine/Generators in a Wind Farm and Basic Characteristics of the Integrated System By Shoji Nishikata	[View] [Download]
Abstract: A new interconnecting method for a cluster of wind turbine/generators is proposed, and some examples of the basic characteristics of the integrated system are shown. This method can be achieved with wind turbine generating system using a shaft generator system. A group of wind turbine-generators can be interconnected easily with the proposed method, and high reliability and electric output power with high quality are also expected. Moreover, since this method enables to send generated power through a long-distance DC transmission line, the optimum site for wind turbines can be selected so as to acquire the maximum wind energy.

	Flicker Study on Variable Speed Wind Turbines with Permanent Magnet Synchronous Generator By Weihao Hu	[View] [Download]
Abstract: Grid connected wind turbines are fluctuating power sources that may produce flicker during continuous operation. This paper presents a simulation model of a MWlevel variable speed wind turbines with a permanent magnet synchronous generator (PMSG) and a full-scale converter developed in the simulation tool of PSCAD/EMTDC. Flicker emission of this system is investigated during continuous operation. The dependence of flicker emission on wind characteristics (mean speed, turbulence intensity), 3p torque oscillations due to wind shear and tower shadow effects and grid conditions (short circuit capacity, grid impedance angle) are analyzed. Flicker mitigation is realized by output reactive power control of the variable speed wind turbines with PMSG. Simulation results show the output reactive power control is an effective measure to mitigate the flicker during continuous operation of grid connected wind turbines.

	Power Output Characteristics Analysis of Wind Energy Converter Control Methods By Bingchang Ni	[View] [Download]
Abstract: The stochastically fluctuating offer of wind energy limits the supply capacity in electrical grids by means of technical and economical reasons. This paper analyses the influence of the control method on the power output characteristic of wind energy converters. Conventional controls, like optimal rotor speed control, and a new control, the stochastic dynamic optimization, are compared in regard of their grid impact. The results show the superior performance of the stochastic dynamic optimization. The power gradient and the deviation from the mean power output value are significantly lowered, reducing the wind energy converter's impact on the grid stability.

	Torque Transient Alleviation in Fixed Speed Wind Generators by Indirect Torque Control with STATCOM By Marta Molinas, Jon Are Suul and Tore Undeland	[View] [Download]
Abstract: Gearboxes for wind turbines must ensure high reliability over a period of 20 years withstanding cumulative and transient loads. Grid disturbances affecting wind turbines with induction generators directly connected to the grid generates electromagnetic torque transients that will result in significant stresses and fatigue of the gearbox. This paper presents a technique by which the transient torques during recovery after a grid fault can be smoothed for fixed speed wind turbines with induction generators directly connected to the grid. The technique labeled Indirect Torque Control (ITC) is suggested in order to reduce the drive train mechanical stresses caused by the characteristics of the induction machine when decelerating through the maximum torque region. The basis of the approach consists of controlling the induction generator terminal voltage by the injection/absorption of reactive current using a STATCOM. By controlling the terminal voltage with the STATCOM, the electromagnetic torque of the generator is indirectly smoothed. The control concept is shown by simulations on a wind generation system model built in PSCAD, where the smoothing effect of the proposed technique is seen during the recovery after a three phase to ground fault condition. The influence of shaft stiffness and mutual damping on the proposed control is further investigated on a two mass model of the wind generation system.