Behavior of responding to sudden change of standalone dc load supplied by a DFIG with different frequency in AC side

This paper presents a wind-driven DC power generation and control system modified by a doubly fed induction generator (DFIG), which stator is connected with a full-power diode rectifier to supply DC power to a stand-alone load and rotor is connected to the DC link with a PWM converter in charge of regulation of frequency and voltage on stator side. The transient character and behavior of current, voltage and electro-magnetic torque are studied under different frequency condition as the control system responds to sudden change of the DC load. The stator flux orientation control method is applied in this paper, which d-axis rotor current is used to regulate the flux and frequency of the stator, and q-axis rotor current is used to keep the dc voltage constant. Simulation results show that frequency regulation can be realized with stator flux leakage, and meanwhile the dc voltage can be kept. Load change will cause different dc voltage variation under different frequency conditions.