Rotor current control method of double-fed wind driven generator under power grid faults

Abstract

The invention belongs to the field of controlling a power conversion device of a wind driven generator, relating to a rotor current control method of a double-fed wind driven generator under power grid faults. The method comprises the following steps: obtaining the stator voltage and the rotor current under a two-phase static coordinates by utilizing the detected three-phase stator voltage and the three-phase rotor current through a 3 / 2 conversion module; calculating the stator magnetic flux linkage and the position angle; calculating the slip frequency angle and the slip frequency angular velocity; summating the stator magnetic flux linkage position angle and the rotor position angle, and then carrying out differentiation to obtain the sum of the magnetic flux linkage angular velocity and the rotor angular velocity; calculating the rotor current set values under the two-phase static coordinates of a rotor; respectively subtracting the rotor current set values under the two-phase static coordinates of the rotor with the rotor current under the two-phase static coordinates and obtaining the reference value of the rotor voltage under the two-phase static coordinates through the calculation by utilizing a performance requirement (PR) controller; and generating the switching signal of a control power device. The rotor current control method has the advantages that the rotor current oscillation of a double-fed induction generator (DFIG) resulted from power grid faults can be effectively inhibited, the grid in-service operation of the double-fed wind driven generator, and the operation performance of the DFIG under the power grid faults is enhanced.

Description

technical field [0001] The invention relates to a control method for a rotor-side inverter of a doubly-fed wind power generator (DFIG) under a grid failure, and belongs to the field of wind power generator control. Background technique [0002] Since the stator side of the doubly-fed induction generator (DFIG) is directly connected to the grid, it is very sensitive to grid faults. Power grid faults will cause sudden changes in the stator voltage of the generator, and the stator current will oscillate. At the same time, the active and reactive power and electromagnetic torque of the generator stator will also oscillate. In addition, due to the strong coupling between the rotor and the stator, the abrupt stator voltage will cause large fluctuations in the rotor current, which will affect the operating state of the doubly-fed machine. When the grid failure reaches a certain level, in order to protect the safe operation of the frequency conversion device, the wind turbine will ...

AI Technical Summary

Problems solved by technology

This method protects the excitation converter and the rotor winding when the power grid fails, but at this time the generator runs in the induction motor mode and needs to absorb a large amount of reactive power from the power grid, which will further deteriorate the power grid; second, the protection circuit The switching operation will have a transient impact on the system; in addition, adding a new protection device increases the system cost

Some scholars have introduced a new topology structure. The control of this scheme is complex, and because the scheme operates off-grid when the power transmission system fails, it does not actively support the restoration of normal operation of the power grid; similarly, this scheme needs to increase the cost of the system

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