Current source converters for megawatt wind energy conversion systems
Notice bibliographique
Résumé
The rapid growth of wind energy market has propelled the research and development of high-power wind turbines in the megawatt range. At this power level, current source converter (CSC) topologies possess favorable features such as simple structure, grid friendly waveforms, controllable power factor, and reliable grid short-circuit protection. This dissertation proposes the use of current source converters for permanent magnet synchronous generator based megawatt wind energy conversion systems (WECS). Related research in terms of converter topology, modulation scheme, control strategy and grid integration are carried out to adapt the proposed configuration for megawatt wind applications. Various current source converter topologies are compared for wind applications. Detailed feasibility study and performance evaluation are conducted based on theoretical analysis and simulation results. Among all, the back-to-back pulse-width modulated (PWM) current source converter is identified as the most promising converter configuration for megawatt WECS due to its high performance, control flexibility and compliance with grid connection codes. A novel multi-sampling space vector modulation (MS-SVM) scheme with superior harmonic performance and controllability is proposed to operate the PWM CSC. The device switching frequency under MS-SVM is investigated and methods to eliminate additional switching are presented. The proposed scheme is compared with the conventional modulation schemes. It is demonstrated that the MS-SVM scheme provides superior performance at low switching frequency. It not only offers high control flexibility but also substantially reduces the low-order harmonics existing in the conventional schemes. System modeling and controller design for the current source converter based WECS are then presented. Dynamic, steady-state and small-signal models are developed for analysis and controller design. An optimum de-link current control scheme is developed to achieve the best dynamic performance and maximize the system overall efficiency. Control strategies such as decoupled active and reactive power control and power feed-forward control are also proposed to further improve the system dynamic performance. Grid integration issues, especially the low-voltage ride-through capability of the current source converter based WECS, are addressed. Challenges for the grid-connected current source converter are identified based on grid code requirements. A unified de-link current control scheme is proposed to assist the system to ride through grid low-voltage faults while maintaining the control capability of active and reactive power during and after the fault. The unified de-link controller can be well embedded in the system control structure. Smooth transitions between normal and fault operations are achieved. Simulation and experimental verifications for various objectives are provided throughout the dissertation. The results validate the proposed solutions for the main challenges of using current source converter in a megawatt WECS.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».