DFIG Based Wind Turbine System

The significant growth of the wind power in modern electric power system increased the demand of sophisticated control algorithms which are capable to achieve high performance for the generator under variable operating conditions. Double-fed induction generator, as one type of wind power generation system, needs effective control of its power electronic interfaces to ensure stable operating characteristics, efficient power generation and satisfactory power quality. This paper designs a proposed current controller for rotor-side converter (RSC) of DFIG-based wind energy conversion system, particularly discussing the parameter tuning and performance evaluation of proportional-integral (PI) controller for stability and accuracy. The dynamic model for the wind turbine generation system has been developed and studied under both normal and abnormal conditions by using MATLAB/Simulink. Vector-oriented control strategy is adopted in the system control framework where real power and reactive power injected to the grid are individually controlled. In this case, the rotor-side converter provides electromagnetic torque and control the amount of reactive power, and grid-side converter is applied to ensure stability of DC-link voltage and reliable transmission of power. An indirectly power-based control structure is applied for rotor circuit, which helps generator to adapt to rapid changes in reactive power and increase its transient dynamics. With the proposed PI-based current control scheme, fluctuations in rotor currents are diminished and undesired fluctuations in power generation are suppressed. In addition, resonance in control scheme is introduced so that to increase the tracking ability of AC reference currents and minimize the steady state error for the specific frequencies. Simulation is carried out on a 1.5 MW DFIG wind power system and the result demonstrate the practicability, robustness and advanced control performance of the proposed approach for the application.