EPE Association: EPE 2015 - DS1f: Wind Energy Systems

EPE 2015 - DS1f: Wind Energy Systems
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2015 ECCE Europe - Conference > EPE 2015 - Topic 05: Renewable Energy Power Systems > EPE 2015 - DS1f: Wind Energy Systems

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   DFIG Wind turbines operating in a fixed reference frame
By Cord PRIGNITZ [View]
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Abstract: HVDC connected offshore wind farms represent a weak grid that causes stability issues in voltage orientedcontrolled converters. In addition the conventional line side converter control is not applicable forisland grids without an existing AC-voltage source. A Fixed Reference Frame (FixReF) control provedalready beneficial in full scale converter wind turbines.In this paper, the usage of FixReF in wind energy plants with doubly fed induction generators is investigated.

   Driving Two Induction Generators with One Frequency Converter Using Stator-Flux-Oriented Control Method
By Ulf SCHUEMANN [View]
[Download]

Abstract: This paper shows an approach for operating two induction generators with one frequency converter. With a stator flux-oriented speed-sensor less control method the torques of the two generators can be controlled. The flux estimator is based on voltage model observers. The estimation error is minimized by using an adapted low pass filter. The control strategy has been simulated, and validated on a test bench. The test bench consists of two drive motors and two 15kW generators which are controlled with a free programmable frequency converter.

   Low Dissipative Snubber using Flyback Type Transformer for 10 kV IGCT in 7 MW Wind Turbine Systems
By Siamak SHIRMOHAMMADI [View]
[Download]

Abstract: 10kV IGCT has been recently developed and has the potential to push wind turbine systems to higher power and voltage rating. Converters employing IGCTs need snubber and OVP circuit to limit the rate of rise of current and peak over voltage across IGCT during turn on and off state respectively. The conventional RCD snubber which is used in such power converter dissipates a significant amount of power. In order to reduce the amount of energy lost by conventional RCD snubber, this paper proposes a flyback-type snubber circuit that not only meets all of the IGCTs characteristics during on and off-state but also significantly saves the power loss. Loss analysis of conventional di/dt snubber and OVP circuit is performed for the 3-level NPC type back-to-back VSC supplied from grid voltage of 6.9kV. In comparison with the conventional snubber, flyback type snubber has a fewer number of components and improved efficiency leading to a reliable and efficient wind turbine systems.

   New ideas to reuse PC power supply for renewable energy applications
By Pascal MAUSSION [View]
[Download]

Abstract: This paper presents new ideas for re-using ATX PC power supplies. By successive and light modifications of the existing architecture, without any new PCB, these second-hand items can be used almost readily as power electronic converters in simple and limited power renewable energy systems. Developing countries are particularly targeted.

   Potential of RC-IGBTs in Three Level Converters for Wind Energy Application
By Sidney GIERSCHNER [View]
[Download]

Abstract: At medium voltage level the three level NPC converter is commonly used. As generator side converterin wind energy applications the diodes are most stressed and limit operation. The BIGT combines thefunctionality of the IGBT and the free-wheeling diode in one chip. The larger usable chip area in bothIGBT and diode mode decreases the maximum junction temperature as well as the junction temperatureripple compared to a conventional IGBT/diode module at the same output power. This leads to reducedpower cycling stress and improved lifetime. A lower maximum junction temperature enables an increasein output power. The potential of the BIGT in the NPC converter for wind energy applications is investigatedand compared to the conventional IGBT/diode module for a real wind speed over time profilemeasured at FINO 1 station in the German North Sea.

   Repetitive Control of Doubly-Fed Induction Generator For General Distorted Grid Voltage Disturbances Rejection
By Yu QUAN [View]
[Download]

Abstract: This paper proposed a new control strategy of doubly-fed induction generator (DFIG) with distorted grid voltage disturbances. In the strategy, a repetitive controller (RPC)-based stator current control loop is added to the classic PI controller-based rotor current control loop, and the good tracking of stator periodic reference currents can be achieved. Compared to the resonant controller-based selective harmonic control strategy, it can regulate the unbalance and all lower-order harmonic currents within the designed bandwidth. As the harmonic order existed in distorted grid voltage is changeful, the proposed strategy is more practical. Finally, the balanced and sinusoidal stator current is achieved under general distorted grid voltage conditions, which satisfies the accessing network demand. The availability of the proposed strategy is validated by simulation studies on Matlab/Simulink.

   Stability Characterization of Inverter Based Microgrids considering Configuration changes
By MYUNGCHIN KIM [View]
[Download]

Abstract: This paper studies the effect of configuration changes to a modular inverter-based microgrid using an inertia index. The inertia index is developed based on an analogy between the inertia constant of synchronous generators and control parameters of droop controlled inverters. The effect of modular operation on transient performance of microgrid frequency is studied by using the considered index for an islanded inverter-based microgrid. Based on the inertia index, a control approach that mitigates the change in a microgrid frequency dynamics caused by modular operation is also explored. The effectiveness of the inertia index and control approach is also verified.

EPE 2015 - DS1f: Wind Energy Systems
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2015 ECCE Europe - Conference > EPE 2015 - Topic 05: Renewable Energy Power Systems > EPE 2015 - DS1f: Wind Energy Systems
	[return to parent folder]

	DFIG Wind turbines operating in a fixed reference frame By Cord PRIGNITZ	[View] [Download]
Abstract: HVDC connected offshore wind farms represent a weak grid that causes stability issues in voltage orientedcontrolled converters. In addition the conventional line side converter control is not applicable forisland grids without an existing AC-voltage source. A Fixed Reference Frame (FixReF) control provedalready beneficial in full scale converter wind turbines.In this paper, the usage of FixReF in wind energy plants with doubly fed induction generators is investigated.

	Driving Two Induction Generators with One Frequency Converter Using Stator-Flux-Oriented Control Method By Ulf SCHUEMANN	[View] [Download]
Abstract: This paper shows an approach for operating two induction generators with one frequency converter. With a stator flux-oriented speed-sensor less control method the torques of the two generators can be controlled. The flux estimator is based on voltage model observers. The estimation error is minimized by using an adapted low pass filter. The control strategy has been simulated, and validated on a test bench. The test bench consists of two drive motors and two 15kW generators which are controlled with a free programmable frequency converter.

	Low Dissipative Snubber using Flyback Type Transformer for 10 kV IGCT in 7 MW Wind Turbine Systems By Siamak SHIRMOHAMMADI	[View] [Download]
Abstract: 10kV IGCT has been recently developed and has the potential to push wind turbine systems to higher power and voltage rating. Converters employing IGCTs need snubber and OVP circuit to limit the rate of rise of current and peak over voltage across IGCT during turn on and off state respectively. The conventional RCD snubber which is used in such power converter dissipates a significant amount of power. In order to reduce the amount of energy lost by conventional RCD snubber, this paper proposes a flyback-type snubber circuit that not only meets all of the IGCTs characteristics during on and off-state but also significantly saves the power loss. Loss analysis of conventional di/dt snubber and OVP circuit is performed for the 3-level NPC type back-to-back VSC supplied from grid voltage of 6.9kV. In comparison with the conventional snubber, flyback type snubber has a fewer number of components and improved efficiency leading to a reliable and efficient wind turbine systems.

	New ideas to reuse PC power supply for renewable energy applications By Pascal MAUSSION	[View] [Download]
Abstract: This paper presents new ideas for re-using ATX PC power supplies. By successive and light modifications of the existing architecture, without any new PCB, these second-hand items can be used almost readily as power electronic converters in simple and limited power renewable energy systems. Developing countries are particularly targeted.

	Potential of RC-IGBTs in Three Level Converters for Wind Energy Application By Sidney GIERSCHNER	[View] [Download]
Abstract: At medium voltage level the three level NPC converter is commonly used. As generator side converterin wind energy applications the diodes are most stressed and limit operation. The BIGT combines thefunctionality of the IGBT and the free-wheeling diode in one chip. The larger usable chip area in bothIGBT and diode mode decreases the maximum junction temperature as well as the junction temperatureripple compared to a conventional IGBT/diode module at the same output power. This leads to reducedpower cycling stress and improved lifetime. A lower maximum junction temperature enables an increasein output power. The potential of the BIGT in the NPC converter for wind energy applications is investigatedand compared to the conventional IGBT/diode module for a real wind speed over time profilemeasured at FINO 1 station in the German North Sea.

	Repetitive Control of Doubly-Fed Induction Generator For General Distorted Grid Voltage Disturbances Rejection By Yu QUAN	[View] [Download]
Abstract: This paper proposed a new control strategy of doubly-fed induction generator (DFIG) with distorted grid voltage disturbances. In the strategy, a repetitive controller (RPC)-based stator current control loop is added to the classic PI controller-based rotor current control loop, and the good tracking of stator periodic reference currents can be achieved. Compared to the resonant controller-based selective harmonic control strategy, it can regulate the unbalance and all lower-order harmonic currents within the designed bandwidth. As the harmonic order existed in distorted grid voltage is changeful, the proposed strategy is more practical. Finally, the balanced and sinusoidal stator current is achieved under general distorted grid voltage conditions, which satisfies the accessing network demand. The availability of the proposed strategy is validated by simulation studies on Matlab/Simulink.

	Stability Characterization of Inverter Based Microgrids considering Configuration changes By MYUNGCHIN KIM	[View] [Download]
Abstract: This paper studies the effect of configuration changes to a modular inverter-based microgrid using an inertia index. The inertia index is developed based on an analogy between the inertia constant of synchronous generators and control parameters of droop controlled inverters. The effect of modular operation on transient performance of microgrid frequency is studied by using the considered index for an islanded inverter-based microgrid. Based on the inertia index, a control approach that mitigates the change in a microgrid frequency dynamics caused by modular operation is also explored. The effectiveness of the inertia index and control approach is also verified.