Dynamic Performance of DFIG under Unbalance Grid Voltage Condition

Abstract

The global electrical energy consumption is rising and there is steady increase of the demand on power generation. So in addition to conventional power generation units a large no. of renewable energy units is being integrated into the power system. A wind electrical generation system is the most cost competitive of all the environmentally clean and safe renewable energy sources in world. The recent evolution of power semiconductors and variable frequency drive technology has aided the acceptance of variable speed generation systems.
Both fixed-speed squirrel-cage induction generator and variable speed double fed induction generator are used in wind turbine generation technology. Therefore, a detailed model of induction generator coupled to wind turbine system is presented in the thesis. Modeling and simulation of induction machine using vector control computing technique is done in MATLAB/SIMULINK platform. The significant result of the analysis is also shown and being compared with the existing literature to validate approach.
DFIG–wind turbine is an integrated part of distributed generation system. Therefore, any abnormalities associates with grid are going to affect the system performance considerably.
Taking this into account, the performance of double fed induction generator (DFIG) variable speed wind turbine under network fault is studied using simulation developed in MATLAB/SIMULINK results show the transient behavior of the double fed induction generator when a sudden short circuit at the generator. After the clearance the short circuit fault the control schemes manage to restore the wind turbine’s normal operation. The controller performance is demonstrated by simulation result both during fault and the clearance of the fault. A crowbar is used to protect the rotor converter against short-circuit current during faults.