EPE Association: EPE 2003 - Topic 12f: Adjustable Speed Generation Systems

EPE 2003 - Topic 12f: Adjustable Speed Generation Systems
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2003 - Conference > EPE 2003 - Topic 12: POWER ELECTRONICS IN GENERATION, TRANSMISSION AND DISTRIBUTION OF ELECTRICAL ENERGY > EPE 2003 - Topic 12f: Adjustable Speed Generation Systems

   [return to parent folder]

   Doubly fed induction machine: Operating regions and dynamic simulation
By J. Soens; K. de Brabandere; J. Driesen; R. Belmans [View]
[Download]

Abstract: The present cost and operating constraints of voltage-source power electronic converters (VSC) limit their applications in the control of variable speed motors and generators in the multi-megawatt power range. For high power applications where only a small continuous operating zone around the machine rated values is required, the doubly fed induction motor/generator (DFIM/DFIG) provides an economic solution. The operating limits of a doubly fed machine are mainly determined by the rating of the rotor power electronic converter. Until now, literature has stressed the relation between active power in the rotor and speed range of the machine. In this paper, the electric loading of the rotor windings and the frequency converter is more deeply examined, as a function of speed range and stator reactive power. This is done using an equivalent circuit of the doubly fed machine. In a next step, a dynamic simulation of a doubly fed induction generator is made. This allows assessing the impact of a grid disturbance on the machine behaviour.

   Power converter topologies for adjustable-speed cascaded induction generator systems
By S. Kato; N. Hoshi; K. Oguchi

Abstract: The effects of power converter topologies on the steady-state characteristics of cascaded induction generator systems are discussed by the use of an original simulation tool. The simulation results show that the input power factor of the generator systems using diode rectifiers becomes less than −0.6. Moreover, the power efficiency of those systems is lower than that of the PWM converter system by around 4%. For the generator system consisting of a PWM converter, the PWM converter capacity of 409 kVA that corresponds to 30% of the total generated power is necessary to generate electric power with negative unity input power factor when the slip of the cascaded induction generator is −0.4.

   Grid voltage fault proof doubly-fed induction generator system
By A. Dittrich; A. Stoev [View]
[Download]

Abstract: Regenerative energy systems are confronted with increasing demands for power quality and fail-safe operation at grid voltage failures, e.g. three-phase short circuits. The paper discusses the problems arising for systems with doubly-fed induction generators and proposes a frequency converter system which meets the respective requirements of grid operator companies, especially for continuous operation through transient grid voltage faults.

   4*300 MW variable speed drive for pump-storage plant application
By A. Bocquel; J. Janning [View]
[Download]

Abstract: The drive system of the new pump-storage station Glodisthal, Germany, is presented. Two of in total four electrical machines (300 MV A each) are designed as cyclo-converter driven doubly-fed induction machines. The cyclo-converter supplied by ALSTOM is one of the largest in the world. Major benefits of this innovative concept are the increase of the turbine efficiency and the high dynamic power control for the stabilisation of the grid. On the basis of simulations the operation principle, control and protection of the drive systels in case of grid faults are analysed. The high-dynamic control of the doubly-fed induction machine is capable of realizing step response times of less than 10 ms from zero to full rate torque.

   Modeling and simulation of doubly fed induction generators for variable speed wind turbines integrated in a distribution network
By S. El Aimani; B. Francois; F. Minne; B. Robyns [View]
[Download]

Abstract: Doubly fed induction generators can improve wind energy conversion systems, since they are able to generate controllable high power thanks to power converters with reduced rated power in comparison with other variable speed wind generator technologies. Many structures for the electrical feeding of the auxiliary winding may be considered. In this paper a classification of these structures are presented and ordered according to the obtained control possibilities. Then a wind doubly fed generator system whose wound rotor is connected to the grid via two back-toback voltage source inverters is investigated. An equivalent continuous dynamic model of the global system is presented in this paper and enables the control design. The control strategy consists in the capture of the maximum available energy from the wind, the control of the reactive power, the power quality of electrical variables and the control of the intermediary dc bus. The proposed global model is simulated with the help of Matlab-Simulink™, by considering a 1.5 MW wind generator. The generation system is connected to a distribution network, which is simulated with the help of the Sim Power System toolbox. The objectives are to evaluate technical requirements, impacts and limitations of integrating distributed wind generation onto the electrical distribution network.

   Control method for doubly-fed machine supplying unbalanced load
By M. Chomat; L. Schreier; J. Bendl [View]
[Download]

Abstract: The present paper analyses operation of a power unit with a doubly fed machine. A novel vector control method is investigated which enables independent control of both positive- and negativesequence components of stator currents or voltages. Operation of the system supplying unbalanced three-phase load is discussed.

   Steady state and transient performances of new variable speed generating set
By J. Al-Tayie; R. Seliga; N. Al-Khayat; W. Koczara [View]
[Download]

Abstract: This paper presents a variable speed integrated generator (VSIG) set incorporating reciprocating internal combustion diesel engine, permanent magnet axial generator and power electronics converter. The VSIG offers the benefits of compact size, fuel saving, reduce noise level, high power quality and wide load acceptance. Full analysis of VSIG set performance based on its steady-state and transient conditions taking into account wide load variation including linear and non linear loads, resistive, inductive and capacitive loads to be presented

   Experimental evaluation of high level control strategies in a variable speed wind turbine
By M. Rodriguez; G. Abad; H. Camblong [View]
[Download]

Abstract: In this paper, an analysis of different control designs is presented for a variable speed wind turbine (VSWT). Simulation studies are compared with experimental results in a laboratory system. An experimental rig is used, composed by a DC machine coupled with a wound rotor machine of 15KW. The DC machine with its control actuates as the wind turbine, and the doubly fed machine actuates as the generator. The study is focused in the control strategy for the emulation VSWT in terms of power quality, reduction of fatigue loads and optimal power generation. The analysis of the whole system (from wind to electric grid), allows understanding the phenomena that origin power quality, fatigue load and energetic yield problems. Once the causes are detected, improved control algorithms are proposed to optimize the behavior of the wind turbine.

   Control implementation and test of an 11 kW adjustable speed wind turbine using flexible development platform
By R. Teodorescu; F. Iov; F. Blaabjerg; E. Urlep [View]
[Download]

Abstract: This paper describes a flexible development platform used to implement and test a control strategy for a grid-connected 11 kW variable-speed wind generator system. A dSPACE controller is used providing a high degree of flexibility allowing entirely code development in Simulink. The flexibility of this development platform allowed relative complex control strategies to be implemented and tested in a short time. The control of a PWM grid converter with LCL filter is designed and tested. The filter design, current controller and dc-voltage controller designs are presented in details. Experimental results validate the good performances of the system.

EPE 2003 - Topic 12f: Adjustable Speed Generation Systems
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2003 - Conference > EPE 2003 - Topic 12: POWER ELECTRONICS IN GENERATION, TRANSMISSION AND DISTRIBUTION OF ELECTRICAL ENERGY > EPE 2003 - Topic 12f: Adjustable Speed Generation Systems
	[return to parent folder]

	Doubly fed induction machine: Operating regions and dynamic simulation By J. Soens; K. de Brabandere; J. Driesen; R. Belmans	[View] [Download]
Abstract: The present cost and operating constraints of voltage-source power electronic converters (VSC) limit their applications in the control of variable speed motors and generators in the multi-megawatt power range. For high power applications where only a small continuous operating zone around the machine rated values is required, the doubly fed induction motor/generator (DFIM/DFIG) provides an economic solution. The operating limits of a doubly fed machine are mainly determined by the rating of the rotor power electronic converter. Until now, literature has stressed the relation between active power in the rotor and speed range of the machine. In this paper, the electric loading of the rotor windings and the frequency converter is more deeply examined, as a function of speed range and stator reactive power. This is done using an equivalent circuit of the doubly fed machine. In a next step, a dynamic simulation of a doubly fed induction generator is made. This allows assessing the impact of a grid disturbance on the machine behaviour.

	Power converter topologies for adjustable-speed cascaded induction generator systems By S. Kato; N. Hoshi; K. Oguchi
Abstract: The effects of power converter topologies on the steady-state characteristics of cascaded induction generator systems are discussed by the use of an original simulation tool. The simulation results show that the input power factor of the generator systems using diode rectifiers becomes less than −0.6. Moreover, the power efficiency of those systems is lower than that of the PWM converter system by around 4%. For the generator system consisting of a PWM converter, the PWM converter capacity of 409 kVA that corresponds to 30% of the total generated power is necessary to generate electric power with negative unity input power factor when the slip of the cascaded induction generator is −0.4.

	Grid voltage fault proof doubly-fed induction generator system By A. Dittrich; A. Stoev	[View] [Download]
Abstract: Regenerative energy systems are confronted with increasing demands for power quality and fail-safe operation at grid voltage failures, e.g. three-phase short circuits. The paper discusses the problems arising for systems with doubly-fed induction generators and proposes a frequency converter system which meets the respective requirements of grid operator companies, especially for continuous operation through transient grid voltage faults.

	4300 MW variable speed drive for pump-storage plant application By A. Bocquel; J. Janning*	[View] [Download]
Abstract: The drive system of the new pump-storage station Glodisthal, Germany, is presented. Two of in total four electrical machines (300 MV A each) are designed as cyclo-converter driven doubly-fed induction machines. The cyclo-converter supplied by ALSTOM is one of the largest in the world. Major benefits of this innovative concept are the increase of the turbine efficiency and the high dynamic power control for the stabilisation of the grid. On the basis of simulations the operation principle, control and protection of the drive systels in case of grid faults are analysed. The high-dynamic control of the doubly-fed induction machine is capable of realizing step response times of less than 10 ms from zero to full rate torque.

	Modeling and simulation of doubly fed induction generators for variable speed wind turbines integrated in a distribution network By S. El Aimani; B. Francois; F. Minne; B. Robyns	[View] [Download]
Abstract: Doubly fed induction generators can improve wind energy conversion systems, since they are able to generate controllable high power thanks to power converters with reduced rated power in comparison with other variable speed wind generator technologies. Many structures for the electrical feeding of the auxiliary winding may be considered. In this paper a classification of these structures are presented and ordered according to the obtained control possibilities. Then a wind doubly fed generator system whose wound rotor is connected to the grid via two back-toback voltage source inverters is investigated. An equivalent continuous dynamic model of the global system is presented in this paper and enables the control design. The control strategy consists in the capture of the maximum available energy from the wind, the control of the reactive power, the power quality of electrical variables and the control of the intermediary dc bus. The proposed global model is simulated with the help of Matlab-Simulink™, by considering a 1.5 MW wind generator. The generation system is connected to a distribution network, which is simulated with the help of the Sim Power System toolbox. The objectives are to evaluate technical requirements, impacts and limitations of integrating distributed wind generation onto the electrical distribution network.

	Control method for doubly-fed machine supplying unbalanced load By M. Chomat; L. Schreier; J. Bendl	[View] [Download]
Abstract: The present paper analyses operation of a power unit with a doubly fed machine. A novel vector control method is investigated which enables independent control of both positive- and negativesequence components of stator currents or voltages. Operation of the system supplying unbalanced three-phase load is discussed.

	Steady state and transient performances of new variable speed generating set By J. Al-Tayie; R. Seliga; N. Al-Khayat; W. Koczara	[View] [Download]
Abstract: This paper presents a variable speed integrated generator (VSIG) set incorporating reciprocating internal combustion diesel engine, permanent magnet axial generator and power electronics converter. The VSIG offers the benefits of compact size, fuel saving, reduce noise level, high power quality and wide load acceptance. Full analysis of VSIG set performance based on its steady-state and transient conditions taking into account wide load variation including linear and non linear loads, resistive, inductive and capacitive loads to be presented

	Experimental evaluation of high level control strategies in a variable speed wind turbine By M. Rodriguez; G. Abad; H. Camblong	[View] [Download]
Abstract: In this paper, an analysis of different control designs is presented for a variable speed wind turbine (VSWT). Simulation studies are compared with experimental results in a laboratory system. An experimental rig is used, composed by a DC machine coupled with a wound rotor machine of 15KW. The DC machine with its control actuates as the wind turbine, and the doubly fed machine actuates as the generator. The study is focused in the control strategy for the emulation VSWT in terms of power quality, reduction of fatigue loads and optimal power generation. The analysis of the whole system (from wind to electric grid), allows understanding the phenomena that origin power quality, fatigue load and energetic yield problems. Once the causes are detected, improved control algorithms are proposed to optimize the behavior of the wind turbine.

	Control implementation and test of an 11 kW adjustable speed wind turbine using flexible development platform By R. Teodorescu; F. Iov; F. Blaabjerg; E. Urlep	[View] [Download]
Abstract: This paper describes a flexible development platform used to implement and test a control strategy for a grid-connected 11 kW variable-speed wind generator system. A dSPACE controller is used providing a high degree of flexibility allowing entirely code development in Simulink. The flexibility of this development platform allowed relative complex control strategies to be implemented and tested in a short time. The control of a PWM grid converter with LCL filter is designed and tested. The filter design, current controller and dc-voltage controller designs are presented in details. Experimental results validate the good performances of the system.