DFIG Fault Ride Through Control
Authors
Gavriluta, Catalin ; Spataru, Sergiu
Term
4. term
Education
Publication year
2011
Submitted on
2011-05-31
Pages
92
Abstract
This thesis addresses the fault ride-through (FRT) capability of doubly-fed induction generator (DFIG) wind turbines in the context of increasingly stringent grid codes. The objective is to enhance DFIG performance during symmetrical voltage dips while preserving the technology’s economic advantages. Two vector-oriented control strategies in the synchronous reference frame are developed and implemented, and assessed alongside common protection devices, namely a DC-link chopper and rotor or stator crowbars. A full wind turbine model comprising the grid, aerodynamics, generator, filters, and back-to-back converters is built, and time-domain simulations of a 2 MW system are carried out in MATLAB/Simulink for medium and low symmetrical voltage drops. The results are interpreted with respect to the latest Danish FRT requirements. The proposed methods exhibit complementary behavior: the first provides satisfactory reactive current support during faults, while the second improves transient response and mitigates electrical and mechanical stress. A 7.5 kW laboratory-scale setup is also established to implement and test parts of the proposed controls. Overall, the study outlines practical control options to improve DFIG FRT performance and offers a basis for further development toward grid-code-compliant operation.
Dette speciale undersøger fault ride-through (FRT) for vindmøller med dobbeltsidet asynkrongenerator (DFIG) i lyset af stadig strengere netkoder. Målet er at forbedre DFIG-anlæggenes evne til at ride igennem symmetriske spændingsdyk uden at miste den økonomiske fordel ved teknologien. Der udvikles og implementeres to vektororienterede reguleringsstrategier i det synkrone referenceplan, som evalueres sammen med typiske beskyttelseskomponenter, herunder DC-link chopper samt rotor- og statorcrowbar. En fuld model af vindkraftanlægget (net, aerodynamik, generator, filtre og back-to-back konvertere) opbygges, og tidsdomænesimuleringer af et 2 MW system gennemføres i MATLAB/Simulink for middelstore og lave symmetriske spændingsdyk. Resultaterne analyseres i relation til de nyeste danske FRT-krav. Metoderne viser komplementær adfærd: den første leverer tilfredsstillende reaktiv strømstøtte under fejl, mens den anden forbedrer transientresponsen og mindsker elektrisk og mekanisk belastning. Der etableres desuden en laboratorieopstilling på 7,5 kW som eksperimentel ramme til at implementere og afprøve dele af reguleringsstrategierne. Arbejdet peger på praktiske reguleringsmuligheder til at styrke DFIG-baserede anlægs FRT-egenskaber og giver et grundlag for videre udvikling mod netkodekompatibel drift.
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Keywords
DFIG ; FRT ; symmetrical