Independent Operation Control Method of DC Type Double-Fed Wind Power System with Energy Storage on the Rotor Side

A doubly-fed wind power generation system with battery energy storage directly connected to the rotor side is proposed. The stator side of the doubly-fed motor is connected to the DC load through a diode uncontrolled rectifier bridge, and the rotor side is connected to the energy storage battery through a converter. On the one hand, Compared with connecting the energy storage battery through a bidirectional DC-DC converter, the cost is greatly saved. On the other hand, it is possible to flexibly control and change the stator frequency directly with the help of the rotor-side converter of the doubly-fed motor, and to change the slip power in a timely manner to control the charging and discharging of the battery. Based on the study of the relationship among battery current, stator frequency, and rotor speed, a battery current control method is proposed, which can realize the stability of the DC load voltage and adjust the stator frequency to achieve accurate control of battery charging and discharging. Finally, the feasibility of the proposed control strategy is verified by the simulation of a 1.5MW double-fed wind power generation system.