According to the characteristics of double fed induction generator (DFIG), starting from the rotor kinetic energy, the relationship between the rotating kinetic energy and load shedding power of the wind turbine is coordinated by controlling the load shedding operation mode of DFIG, the release process of rotor energy is controlled, and the rotating kinetic energy of the rotor is fully utilized, which can improve the capacity of frequency modulation in wind turbine grid. On the basis of integrated inertia control, this paper proposes that the rotor kinetic energy can be better released by adding a D-value of rotor speed compensation loop control module for the first time, so that DFIG can further make full use of the rotational kinetic energy stored in the rotor to provide short-term power support for the power grid, realize the normal operation, reserve part of the power, as well as taking part in the frequency regulation in the power grid actively. Meanwhile, different given speed values are used to realize the quantitative output control of backup power, so as to meet the digital transformation requirements of the power industry. The simulation results show that the control strategy with D-value of rotor speed compensation loop is obviously superior to the integrated inertia control in the primary frequency regulation characteristics of the power grid, which improves the frequency regulation ability, and can effectively reduce the impact of large-scale wind turbine grid-connection on the frequency stability of the power system.
Keywords: DFIG, rotor rotation energy, D-value of rotor speed compensation, quantitative output of backup power, digital transformation