Comparison of direct-drive and geared generator concepts for wind turbines
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Citations
A direct drive generator for marine current energy conversion - first experimental results
Low Voltage Ride-through Scheme of the PMSG Wind Power System Based on Coordinated Instantaneous Active Power Control
A supplementary controller for improvement of small signal stability of power system with wind power penetration
Hybrid Generator for Wind Generation Systems
Air-Gap Flux Density Characteristics Comparison and Analysis of Permanent Magnet Vernier Machines With Different Rotor Topologies
References
Design of Direct-driven Permanent-magnet Generators for Wind Turbines
Electric machines and drives
Efficiency of three wind energy generator systems
Optimized Permanent Magnet Generator Topologies for Direct-Drive Wind Turbines
Related Papers (5)
A Review of the State of the Art of Power Electronics for Wind Turbines
Frequently Asked Questions (18)
Q2. What are the future works mentioned in the paper "Comparison of direct-drive and geared generator concepts for wind turbines" ?
Very important design aspects for which further work is needed are reliability and availability [ 20 ].
Q3. What is the phasecurrent in the PMG1G generator?
The phasecurrent is in the middle between the terminal voltage and the voltage induced by the magnets in order to reduce the saturation and to get a compromise between the converter rating and the generator rating.
Q4. What is the phase current in the DDSG?
The phase current leads the phase voltage a little in order to reduce saturation and excitation losses while a larger rating of the converter is not necessary.
Q5. What are the advantages of the DFIG3G?
Manufacturers supplying the DFIG3G use generator and converter components which are close to industrial standards yielding benefits in standardization, cost, and reliability.
Q6. How much is the rated speed of the generator?
With a gear ratio of 80, the rated speed of the generator is 1200 r/min, so that at rated speed, there is still some margin for control purposes.
Q7. What is the simplest way to calculate the parameters of the second equivalent circuit?
The parameters of the second equivalent circuit can be calculated from the parameters of the first in the following way [15]:Ls = Lsσ + Lsm;RR = RrL2 sL2smLL = LsσLs Lsm + LrσL2 sL2sm . (15)To simplify the calculations, the second equivalent circuit has been used.
Q8. What is the wind turbine's pitch angle?
Using these characteristics, the available shaft power P can be calculated as a function of the wind speed as [2], [10]P = 1 2 ρairCp(λ, θ)πr2v3w (1)where ρair is the mass density of air, r is the wind turbine rotor radius, vw is the wind speed, and Cp(λ, θ) is the power coefficient or the aerodynamic efficiency, which is a function of the tip speed ratio λ (tip speed divided by wind speed) and the pitch angle θ.
Q9. What is the popular type of wind turbine?
The only commercially successful large direct-drive wind turbine manufacturer, Enercon, uses this system but they claim other benefits from the system.
Q10. What is the average annual energy dissipation in the generator system?
The losses in the gearbox dominate the losses in this generator system: Roughly 70% of the annual energy dissipation in the generator system is in the gearbox.
Q11. What is the reluctance of the iron of the magnetic circuit?
The factor representing the reluctance of the iron of the magnetic circuit is calculated as [17]ksat = 1 + 1Hggeff ∫ lFe 0 HFedlFe (7)where HFe is the magnetic field intensity in the iron, estimated from the BH curve.
Q12. Why is the DFIG1G the expensive generator?
Because it is mainly built from standard components consisting of copper and iron, major improvements in performance or cost reductions cannot be expected.
Q13. What is the current of the DFIG1G?
The magnetizing current of this induction machine is rather large due to the considerable air gap and the high number of pole pairs.
Q14. Why are the numbers in Table The authornot extensively validated?
Because the paper concentrates on the generator system, these numbers are not extensively validated and must be seen only as indicators.
Q15. What is the BH of a permanent magnet?
In permanent-magnet machines, this factor representing saturation is much smaller than in the other machines because the effective air gap is much larger due to the low permeability of the magnets.
Q16. What is the annual energy yield of the DDSG?
The annual energydissipation, determined from a combination of the losses with the Weibull distribution, is also depicted in Fig.
Q17. What is the energy dissipation of the DFIG1G?
The annual energy dissipation, determined from a combination of the losses with the Weibull distribution, is also depicted in Fig. 13.
Q18. What is the smallest part of the losses in the generator?
Iron losses are not negligible; at wind speeds up to 8 m/s, they are larger than the copper losses and over 15% of the annual dissipation in the generator system is in the iron.