Sensitivity analysis of symmetrical direct control of torque and power variables of doubly-fed induction generator

The torque and power outputs of a doubly-fed induction generator (DFIG) are differentiated once to obtain a linear relationship with the rotor voltage vectors, which are the control input quantities. The derived model is used to develop direct control of the torque and power of the DFIG whereby the rotor voltage quantities are generated at a constant switching frequency. Decoupled control of torque and power is obtained by field orientation and voltage alignment, respectively. Sensitivity of the direct control schemes to system parameter variation is investigated using small signal analysis. Results for a 5 hp machine indicate that the vector control is more affected by system parameter mismatch.