Independent control of active and reactive power for grid connected DFIG using reference power based improved field-oriented control scheme

Abstract

The increase in the wind speed or rotor speed will decrease the doubly-fed induction generators (DFIG) terminal voltage which will increase the undesired reactive power flow from it. Hence, in this paper extraction of optimal power and control of reactive power is analysed. For this, independent control of real and reactive power is done using the proposed reference power-based improved field-oriented control scheme. The rotor side controller is designed to run the rotor at specified optimal speed and also control of reactive power from the rotor side based on the grid requirement. In this work, only a wind speed sensor is required, and there is no need for rotor speed sensor, real power sensor, and torque sensor and hence, is cost-effective and lesser parameter dependency. Rotor speed and torque are predicted using measured stator voltage and stator and rotor current and also using the derived rotor flux. The performance of the DFIG system is examined in a simulation environment for rapid changes in rotor speed, wind speed, grid reactive power. There is smoother rotor speed changing, and rapid reactive power support from the DFIG.