Back-stepping direct power control method of DFIG

Abstract

The invention discloses a back-stepping direct power control (DPC) method of a DFIG. According to the method, on the basis of combination of a back-stepping algorithm and a DPC technology, calculation is carried out by using a power reference value, an actual value, and a stator side voltage so as to obtain a reference value of a rotator side output voltage; and then modulation is carried out by a SVPWM module to obtain switching signals Sa, Sb, and Sc. The whole control process is carried out under a stationary coordinate system without the need of coordinate rotation and conversion; and independent and effective control of the active power and reactive power of the DFIG can be realized only by adjusting two adjustable parameters kp and kq, so that the control structure becomes simple. With inheriting of the excellent dynamic performance of the traditional DPC, the current harmonic wave and the power fluctuation can be reduced and the constant switching frequency can be obtained; and the good steady-state and dynamic performances are also realized.

Description

technical field [0001] The invention belongs to the technical field of motor control, and in particular relates to a reverse thrust direct power control method of DFIG. Background technique [0002] Modern wind power generation systems mainly use two types of doubly-fed induction generators and permanent magnet synchronous generators. In order to improve the power generation efficiency, both variable-speed and constant-frequency power generation operation modes are adopted. Among them, DFIG has the most applications and the most mature technology, and is the current mainstream model. DFIG system structure such as figure 1 shown. The DFIG scheme can realize variable speed constant frequency control, reduce the capacity of the converter, and can also realize the decoupling control of active and reactive power, and can output corresponding inductive or capacitive reactive power according to the requirements of the power grid. This kind of reactive power control is flexible. ...

AI Technical Summary

Problems solved by technology

DPC based on PI controller and space vector modulation (SVM) can obtain smaller power fluctuation and constant switching frequency, but the introduction of PI controller makes it have the same problems as VC. In addition, this method has no effect on the mathematical model The parameter dependence degree is high, so the robustness is not strong

Predictive direct power control (P-DPC) that selects three vectors in one sampling time can also obtain better steady-state and dynamic performance, and the switching frequency is constant, but it needs to calculate the action time of the three vectors in real time, and the calculation amount is relatively large. Large, vector selection is more complicated

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