Doubly Fed Induction Generator Fault Simulation
Author
Leban, Krisztina
Term
4. term
Education
Publication year
2009
Abstract
Dette projekt modellerer, hvordan en vindmølle opfører sig under kortvarige netfejl. Møllen anvender en dobbeltfødet induktionsgenerator (DFIG), en udbredt konstruktion der gør det muligt at styre effekten ved varierende rotomhastighed. Vi undersøgte to fault ride‑through‑situationer, som afprøver om møllen kan forblive tilsluttet nettet under kortslutninger. For at begrænse skadelige strømme modellerede vi to standardbeskyttelser: en dumpmodstand (der afleder overskydende energi) og en crowbar (der midlertidigt kortslutter generatoren for at beskytte konverterne). For hver situation opbyggede vi en enkel ækvivalentmodel af net, transformer, linje og generator ved hjælp af basale kredsløbselementer—modstande (R), spoler (L), kondensatorer (C) og spændingskilder. Under den meget korte varighed af en trefaset kortslutning antog vi, at møllens mekaniske dele ikke kan nå at reagere. Fejlmodellerne blev forenklet, så de kan udtrykkes med synkrone maskinparametre. De forenklede crowbar‑ og dumpmodstandsmodeller blev sammenlignet med detaljerede simuleringer opbygget af biblioteksundersystemer i SimPower Systems (Simulink). Vi skitserede desuden grundlaget for en tilstandsrumrepræsentation og systemets overføringsfunktion og dokumenterede trin‑ og impulssvar for fejlmodellen. Dette arbejde er første skridt mod en fuld stabilitetsanalyse.
This project models how a wind turbine behaves during brief grid faults. The turbine uses a doubly fed induction generator (DFIG), a common design that allows control of power while rotor speed varies. We examined two fault ride‑through situations, which assess whether the turbine can stay connected to the grid during short‑circuits. To limit damaging currents, we modeled two standard protection circuits: a dump resistor (which dissipates excess energy) and a crowbar (which temporarily shunts the generator to protect its converters). For each case, we built a simple equivalent circuit of the grid, transformer, line, and generator using basic elements—resistors (R), inductors (L), capacitors (C), and voltage sources. During the very short duration of a three‑phase short‑circuit, we assumed the mechanical parts of the turbine cannot respond. The fault models were simplified so they can be expressed using synchronous machine parameters. We compared the simplified crowbar and dump‑resistor models with detailed simulations created from library subsystems in the SimPower Systems (Simulink) environment. We also outlined the basis for a state‑space representation and a transfer function of the system, and documented the step and impulse responses of the fault model. This modeling work is a first step toward a full stability analysis.
[This abstract was generated with the help of AI]
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