Method and device for controlling uninterruptible operation of wind generator system in case of faulted power grid voltage

Abstract

The invention provides a method and device for controlling uninterruptible operation of a wind generator system in case of faulted power grid voltage. An existing doubly-fed motor rotor-side frequency converter and a CROWBAR circuit are utilized to realize the uninterruptible operation of a DFIG (doubly-fed induction generator) wind generator system when the power grid generates the serious voltage faults. The method at least comprises the following steps: 1) detecting the voltage of the power grid; 2) triggering CROWBAR protection; 3) waiting a voltage of the power grid to recover; 4) cutting off the CROWBAR protection; 5) starting a grid-side current transformer; and 6) starting a motor-side current transformer. In the invention, motor time sequences of corresponding states of the current transformer are given when the power grid voltage is seriously asymmetrical and when the motor is in a non-voltage state; the CROWBAR protection circuit of the current transformer is used to finishthe protection for the wind generator system and the current transformer; and the method and device provided by the invention are suitable for various faults of the power grid such as a symmetric voltage fault of the power grid, an asymmetric fault of a small voltage value of the power grid, a seriously asymmetric voltage fault of the power grid and a non-voltage fault of the power grid, and meets grid-connected requirements of the wind generator system formulated by a power grid corporation. Mechanical installation of equipment is simple and the installation is convenient and quick.

Description

technical field [0001] The invention belongs to a control method and device adapted to the power grid, in particular to a control method and device capable of realizing the uninterrupted operation of the doubly-fed induction motor wind turbine when the voltage is seriously faulty, and is mainly used to overcome the severe asymmetry of the power grid voltage or In the event of a zero-voltage fault, the uninterrupted operation of the doubly-fed induction motor wind turbine is guaranteed. technical background [0002] When the power grid failure causes a small symmetrical drop in the output terminal voltage of the generator or a three-phase unbalance, it should be considered to realize the uninterrupted operation of the wind turbine by improving the operation control of the doubly-fed induction motor (or DFIG) power generation system. , many related patent papers have been reported. Representative ones are as follows: [0003] 1. The patent application number is: 200810163510...

AI Technical Summary

Problems solved by technology

[0007] Aiming at the inability of the existing technology to overcome the shortcomings of DFIG wind turbines running uninterruptedly when the grid voltage is severely asymmetric or zero-voltage faults, a low-cost, no impact on the grid, simple system structure, high reliability, and wide application range are proposed. Control method for uninterrupted operation of DFIG wind turbine when grid voltage is seriously faulted

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