Theses and Dissertations Collection

In this thesis, a Type III (Doubly Fed Induction Generator) wind generation system

is analyzed and modeled. The results of this analysis are used to design and build

a testbed for protection design and testing. The specic generator modeled is the

four-pole, 10HP DFIG driven by a four-pole, 10HP induction machine powered by an

adjustable speed drive. The testbed is made for research and development to analyze

the DFIG during fault conditions. A future goal for the overall project is to design

protection equipment for wind farms.

The thesis presents the steady-state modelling and dynamic modelling of the

DFIG, followed by a detailed switching model of the two-level voltage source con-

verter (VSC). Two VSCs form a back-to-back converter which connects between the

rotor windings and the power system. The grid side converter (GSC) interacts with

the power system and the DC bus and is designed to maintain a constant DC bus

voltage. The GSC is controlled to exchange power between the DC bus and the power

system while tracking the system frequency. The power circuit, sensor circuit and con-

trol circuit for GSC are rst designed and validated in simulation, then implemented

in hardware. The protection logic is designed to protect the power electronics from

overcurrent and overvoltage. The power control of the DFIG is achieved by rotor side

converter (RSC) control strategies. The functionality of the RSC control is validated

with simulation and could be implemented in hardware with similar hardware setups

as the GSC.