Flux Based Sensorless Speed Sensing and Real and Reactive Power Flow Control with Look-up Table based Maximum Power Point Tracking Technique for Grid Connected Doubly Fed Induction Generator

This aim of this paper is to design controller for Doubly Fed Induction Generator (DFIG) converters and MPPT for turbine and a sensor-less rotor speed estimation to maintain equilibrium in rotor speed, generator torque, and stator and rotor voltages. It is also aimed to meet desired reference real and reactive power during the turbulences like sudden change in reactive power or voltage with concurrently changing wind speed. The turbine blade angle changes with variations in wind speed and direction of wind flow and improves the coefficient of power extracted from turbine using MPPT. Rotor side converter (RSC) helps to achieve optimal real and reactive power from generator, which keeps rotor to rotate at optimal speed and to vary current flow from rotor and stator terminals. Rotor speed is estimated using stator and rotor flux estimation algorithm. Parameters like tip speed ratio; coefficient of power, stator and rotor voltage, current, real, reactive power; rotor speed and electromagnetic torque are studied using MATLAB simulation. The performance of DFIG is compared when there is in wind speed change only; alter in reactive power and variation in grid voltage individually along with variation in wind speed

Tip Speed Ratio Based MPPT Algorithm and Improved Field Oriented Control for Extracting Optimal Real power and Independent Reactive Power Control for Grid Connected Doubly Fed Induction Generator

Doubly Fed Induction Generator (DFIG) needs to get adopted to change in wind speeds with sudden change in reactive power or grid terminal voltage as it is required for maintaining synchronism and stability as per modern grid rules. This paper proposes a controller for DFIG converters and optimal tip speed ratio based maximum power point tracking (MPPT) for turbine to maintain equilibrium in rotor speed, generator torque, and stator and rotor voltages and also to meet desired reference real power during the turbulences like sudden change in reactive power or voltage with concurrently changing wind speed. The performance of DFIG is compared when there is change in wind speed only, changes in reactive power and variation in grid voltage along with variation in wind speed

Mitigation of voltage dip and power system oscillations damping using dual STATCOM for grid connected DFIG

During grid fault, transmission lines reach its thermal limit and lose its capability to transfer. If this fault current enters generator terminals, it will lead to dip in stator voltage and consequently produces torque and real power oscillations. This further affects in the form of internal heat in rotor windings and finally damages the generator. A new control strategy is proposed to limit fault current using dual STATCOM, which will damp power oscillations and mitigate the voltage dip due to a severe symmetrical fault. It is achieved by diverting the fault current to the capacitor using the dual-STATCOM controller. It is best suitable to maintain power system stability with uninterrupted power supply, effective power transfer capability and rapid reactive power support and to damp inter-area oscillations. The effectiveness of SG and DFIG due to the transmission line short circuit symmetrical fault was studied