EPE Association: EPE 2005 - Topic 14-1 - LS: Control of doubly fed induction generators

EPE 2005 - Topic 14-1 - LS: Control of doubly fed induction generators
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2005 - Conference > EPE 2005 - Topic 14: POWER ELECTRONICS IN ELECTRICAL ENERGY GENERATING SYSTEMS > EPE 2005 - Topic 14-1 - LS: Control of doubly fed induction generators

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   Active filtering applied to a doubly-fed induction generator supplying nonlinear loads on isolated grid
By MONMASSON Eric; VASIC Dejan; PATIN Nicolas; LOUIS Jea [View]
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Abstract: Variable speed and constant frequency (VSCF) generators are widely used in industry (e.g. embedded applications and renewable energy systems). Doubly-fed induction generators (DFIG) allows a such operation. Moreover, this kind of machines can be driven by a low power converter in comparison to the power provided to the grid. On isolated grid, a efficient controller is needed in order to maintain quasi-sinusoidal voltages with an important amount of nonlinear load. The aim of this paper is to present a new design methodology based on the inversion of the dynamical model of the system. It also uses an original representation of the system called dynamical equivalent circuit. Thus, a hierarchical controller is designed and validated by simulation.

   Control of a Doubly-fed Induction Wind Generator Under Unbalanced Grid Voltage Conditions
By BREKKEN Ted; MOHAN Ned [View]
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Abstract: Wind energy is often installed in rural, remote areas characterized by weak, unbalanced power transmission grids. In induction wind generators, unbalanced three-phase stator voltages cause a number of problems, such as overheating, over-current, and stress on the mechanical components from torque pulsations. Therefore, beyond a certain amount of unbalance, induction wind generators are switched out of the network. This can further weaken the grid. In doubly-fed induction generators, control of rotor currents allows for adjustable speed operation and reactive power control. In addition, it is possible to control the rotor currents to correct for the problems caused by unbalanced stator voltages, including torque pulsations and unbalanced stator currents. This paper presents a novel voltage mode controller design for a doubly-fed induction generator that provides variable speed, reactive power control. Also, under stator voltage unbalance conditions, the proposed control eliminates torque pulsations and draws more balanced currents from the utility.

   Sensorless Direct Voltage Control Method for Stand-Alone Slip-Ring Induction Generator
By Grzegorz Iwanski; Wlodzimierz Koczara [View]
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Abstract: A control method for stand alone mode operation of doubly fed induction generator is presented. The method bases on the stator voltage vector control represented in the synchronously rotated polar coordinates. The generated stator voltage is controlled by rotor currents. Amplitude of stator voltage and its frequency are controlled independently. The output signals from the voltage and the frequency regulators are the reference signals for the rotor current amplitude and frequency. This way, in spite of the variable generator speed, the fixed stator voltage amplitude and frequency, and controlled voltage phase are achieved. Developed Direct Voltage Control method permits the DFIG the stand alone and the grid connected operation. After the mains outage the DFIG instantly supplies loads. Methods of supply grid voltage faults detection are developed. One method bases on the generated voltage vector amplitude, whereas a second bases on the voltage frequency. Both methods allows soft transients of generator disconnection from the grid. The controlled voltage phase permits for soft synchronization and grid connection after the mains reappearing. This way the load is protected from voltage phase rapid change. Applied methods allows the load to be uninterruptible supplied. Topology of power system, controller operation and results from laboratory tests of the DFIG are presented in the paper.

EPE 2005 - Topic 14-1 - LS: Control of doubly fed induction generators
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2005 - Conference > EPE 2005 - Topic 14: POWER ELECTRONICS IN ELECTRICAL ENERGY GENERATING SYSTEMS > EPE 2005 - Topic 14-1 - LS: Control of doubly fed induction generators
	[return to parent folder]

	Active filtering applied to a doubly-fed induction generator supplying nonlinear loads on isolated grid By MONMASSON Eric; VASIC Dejan; PATIN Nicolas; LOUIS Jea	[View] [Download]
Abstract: Variable speed and constant frequency (VSCF) generators are widely used in industry (e.g. embedded applications and renewable energy systems). Doubly-fed induction generators (DFIG) allows a such operation. Moreover, this kind of machines can be driven by a low power converter in comparison to the power provided to the grid. On isolated grid, a efficient controller is needed in order to maintain quasi-sinusoidal voltages with an important amount of nonlinear load. The aim of this paper is to present a new design methodology based on the inversion of the dynamical model of the system. It also uses an original representation of the system called dynamical equivalent circuit. Thus, a hierarchical controller is designed and validated by simulation.

	Control of a Doubly-fed Induction Wind Generator Under Unbalanced Grid Voltage Conditions By BREKKEN Ted; MOHAN Ned	[View] [Download]
Abstract: Wind energy is often installed in rural, remote areas characterized by weak, unbalanced power transmission grids. In induction wind generators, unbalanced three-phase stator voltages cause a number of problems, such as overheating, over-current, and stress on the mechanical components from torque pulsations. Therefore, beyond a certain amount of unbalance, induction wind generators are switched out of the network. This can further weaken the grid. In doubly-fed induction generators, control of rotor currents allows for adjustable speed operation and reactive power control. In addition, it is possible to control the rotor currents to correct for the problems caused by unbalanced stator voltages, including torque pulsations and unbalanced stator currents. This paper presents a novel voltage mode controller design for a doubly-fed induction generator that provides variable speed, reactive power control. Also, under stator voltage unbalance conditions, the proposed control eliminates torque pulsations and draws more balanced currents from the utility.

	Sensorless Direct Voltage Control Method for Stand-Alone Slip-Ring Induction Generator By Grzegorz Iwanski; Wlodzimierz Koczara	[View] [Download]
Abstract: A control method for stand alone mode operation of doubly fed induction generator is presented. The method bases on the stator voltage vector control represented in the synchronously rotated polar coordinates. The generated stator voltage is controlled by rotor currents. Amplitude of stator voltage and its frequency are controlled independently. The output signals from the voltage and the frequency regulators are the reference signals for the rotor current amplitude and frequency. This way, in spite of the variable generator speed, the fixed stator voltage amplitude and frequency, and controlled voltage phase are achieved. Developed Direct Voltage Control method permits the DFIG the stand alone and the grid connected operation. After the mains outage the DFIG instantly supplies loads. Methods of supply grid voltage faults detection are developed. One method bases on the generated voltage vector amplitude, whereas a second bases on the voltage frequency. Both methods allows soft transients of generator disconnection from the grid. The controlled voltage phase permits for soft synchronization and grid connection after the mains reappearing. This way the load is protected from voltage phase rapid change. Applied methods allows the load to be uninterruptible supplied. Topology of power system, controller operation and results from laboratory tests of the DFIG are presented in the paper.