| 1. |
- Harnefors, Lennart, 1968, et al.
(författare)
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Current controller design for passivity of the input admittance
- 2009
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Ingår i: 2009 13th European Conference on Power Electronics and Applications, EPE '09; Barcelona; Spain; 8 September 2009 through 10 September 2009. - 9781424444328 ; , s. 1-8
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Konferensbidrag (refereegranskat)abstract
- Current controller design for three-phase voltage-source converters, by which a passive input admittance is ideally obtained, is considered. Two design alternatives, with and without voltage feedforward, respectively, are shown to give similar performance. It is demonstrated how additional parts can be added to the controller while preserving the passivity property. This is applied particularly to resonant controllers.
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| 2. |
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| 3. |
- Harnefors, Lennart, 1968, et al.
(författare)
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Input-admittance calculation and shaping for controlled voltage-source converters
- 2007
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Ingår i: IEEE Transactions on Industrial Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0278-0046 .- 1557-9948. ; 54:6, s. 3323-3334
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Tidskriftsartikel (refereegranskat)abstract
- A controlled power electronic converter can cause local instabilities when interacting with other dynamic subsystems in a power system. Oscillations at a certain frequency cannot, however, build up if the converter differential input admittance has a positive conductance (real part) at that frequency, since power is then dissipated. In this paper, input-admittance expressions for a voltage-source converter are derived. It is seen how the admittance can be shaped in order to get a positive real part in the desired frequency regions by adjusting the controller parameters.
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| 4. |
- Harnefors, Lennart, 1968, et al.
(författare)
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Regenerating-mode stabilization of the "statically compensated voltage model''
- 2007
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Ingår i: IEEE Transactions on Industrial Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0278-0046 .- 1557-9948. ; 54:2, s. 818-824
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Tidskriftsartikel (refereegranskat)abstract
- Reversal of rotation under load of sensorless induction motor drives is very challenging, as there is often an unstable region in the low-speed regenerating mode. In this paper, a variant of the classical "voltage model," i.e., the "statically compensated voltage model," is modified for stable regenerating-mode operation with accurate model motor parameters. The mechanisms behind two low-speed instability phenomena are thereafter, explored, and methods for avoiding instability with inaccurate model parameters are developed. Experimental results verify the theory and show adequate performance.
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| 5. |
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| 6. |
- Petersson, Andreas, 1974, et al.
(författare)
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Evaluation of Current Control Methods for Wind Turbines Using Doubly-Fed Induction Machines
- 2005
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Ingår i: IEEE Transactions on Power Electronics. - 0885-8993 .- 1941-0107. ; 20:1, s. 227-235
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, different rotor current control methods are investigated with the objective of eliminating the influence of the back electromotive force (EMF), which is that of, in control terminology, a load disturbance, on the rotor current. It is found that the method that utilizes both feed-forward of the back EMF and so-called "active resistance" manages best to suppress the influence of the back EMF on the rotor current, particularly when voltage sags occur, of the investigated methods. This method also has the best stability properties. In addition it is found that this method also has the best robustness to parameter deviations.
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| 7. |
- Petersson, Andreas, 1974, et al.
(författare)
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Modeling and Experimental Verification of Grid Interaction of a DFIG Wind Turbine
- 2005
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Ingår i: IEEE Transactions on Energy Conversion. - Chalmers Univ Technol, Dept Energy & Environm, SE-41296 Gothenburg, Sweden. Malardalen Univ, Dept Comp Sci & Elect, SE-72123 Vasteras, Sweden. NACHI Czech, Louny, Czech Republic. : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1558-0059 .- 0885-8969. ; 20:4, s. 878- 886
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Tidskriftsartikel (refereegranskat)abstract
- The response of the doubly fed induction generator (DFIG) wind turbine system to grid disturbances is simulated and verified experimentally. The results are compared to the response that a fixed-speed wind turbine would have given. A voltage sag to 80% (80% remaining voltage) is handled very well, which is not the case for a fixed-speed wind turbine. A second-order model for prediction of the response of DFIG wind turbines is derived, and its simulated performance is successfully verified experimentally. The power quality impact by the DFIG wind turbine system is measured and evaluated. Steady-state impact, such as flicker emission, reactive power, and harmonic emission, is measured and analyzed. It is found that the flicker emission is very low, the reactive power is close to zero in the whole operating range, and the current THD is always lower than 5%.
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| 8. |
- Wallmark, Oskar, 1976, et al.
(författare)
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Post-fault operation of fault-tolerant inverters for PMSM drives
- 2005
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Ingår i: European Conference on Power Electronics and Applications. - 9075815085 - 9789075815085
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Konferensbidrag (refereegranskat)abstract
- This paper considers post-fault operation of permanent-magnet synchronous motor drives equipped with a fault-tolerant inverter. In post-fault mode, the faulted phase is isolated and the neutral point is connected either to an additional inverter leg or to the midpoint of the dc bus. Different methods of controlling the neutral point voltage are presented and compared. Furthermore, operation without a position sensor (i.e., sensorless control) is considered and a modification to an estimator previously reported in the literature is proposed in order to take into account the effect of the asymmetry introduced due to the isolation of the faulted phase in post-fault mode. Simulations and experimental results are provided to support the theory and demonstrate the practical impact of the modifications proposed.
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