A method of inertia control for doubly-fed wind turbines based on slip feedback

Abstract

The invention discloses an inertia control method for a double-fed wind turbine generator capable of improving the frequency inertia characteristic of a wind power grid-connected system based on virtual rotational inertia of a double-fed wind generator rotor, and belongs to the control technical field of new energy power generation. The inertia control method comprises the steps of enabling a frequency measured value to pass through a high-pass filter, then defining a transient state changing process of a slip ratio through proportion and differential links to be used as a reference value of a slip ratio feedback link; enabling a slip ratio feedback value to be compared with the slip ratio reference value to obtain a slip ratio deviation signal, and obtaining a rotor current q-axis component fine tuning value through an incomplete differential PD controller; and enabling the obtained fine tuning value to be overlaid to a rotor current instruction of an active power control ring, and performing adjustment on the active output of the wind turbine generator so as to realize inertia control. By adoption of the method, secondary fall off of power grid frequency can be avoided while the rotary speed recovery speed is high; and in addition, the frequency deviation amplitude and the changing speed after frequency disturbance can be effectively lowered, and the frequency stability of an electric power system can be improved.

Description

technical field [0001] The invention relates to the technical field of new energy power generation, and in particular to an inertia control method of a doubly-fed wind turbine that improves the frequency-inertia characteristics of a wind power grid-connected system by using the virtual moment of inertia of the rotor of the double-fed wind turbine. Background technique [0002] With the development of new energy technology, the proportion of wind energy in the power energy structure is increasing, and the large-scale grid connection of wind power has already had an impact on the security and stability of the frequency of the power grid. In fact, in order to maximize the utilization of wind energy, the existing doubly-fed wind turbines generally work under the maximum wind energy tracking control, and achieve independent decoupling control of the active and reactive power output by the wind turbine through vector control of the back-to-back converters. . , so that the double-...

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Problems solved by technology

[0004] In order to solve the existing problem of frequency secondary drop phenomenon, the present invention is based on the mathematical model of the doubly-fed wind turbine, analyzes its inertial characteristics, and selects the operating parameter slip rate that can truly reflect the wind turbine rotor speed and grid frequency characteristics as the control The input of the controller is used to propose an inertia control strategy for doubly-fed wind turbines based on slip feedback

This strategy can effectively improve the problems that the existing control strategy easily causes the frequency to drop twice and the speed recovers slowly

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