Device and method for cooperatively controlling unbalanced current of doubly-fed converter

Abstract

The invention relates to a device and a method for cooperatively controlling unbalanced current of a doubly-fed converter. The control method comprises a machine side converter control method and a grid side converter control method, wherein the machine side converter control method comprises the following steps: detecting the negative sequence component of a present stator voltage vector, calculating a rotator negative-sequence current needed for limiting a current unbalance, taking the value of the rotator negative-sequence current as the reference input of a rotator current negative-sequence control to perform the rotator current negative-sequence control; and the grid side converter control method comprises the steps of detecting the negative-sequence component of the present stator current and taking the negative-sequence component of the stator current as the reference input of a grid side current negative-sequence control to perform the grid side current negative-sequence control. The control method has the advantages that the unbalance of the stator current can be effectively inhibited, the loss of a generator set is reduced, the problems of a reactive power pulsation and an active power pulsation are solved; and at the same time, the unbalance degree of a system total-grid current is reduced, so that the power quality and the grid adaption capacity of the generator set are improved.

Description

technical field [0001] The invention relates to an unbalanced current coordinated control device and a control method thereof, in particular to a doubly-fed converter unbalanced current coordinated control device and a control method thereof. Background technique [0002] With the development of wind power generation, power grids around the world have higher and higher requirements for the grid adaptability of wind turbines, and wind turbines must be able to adapt to more complex grid conditions. Since the AC excitation frequency converter of the doubly-fed unit only needs to supply the slip power, the requirement for the capacity of the frequency converter is greatly reduced, making the doubly-fed wind turbine one of the main models in the field of wind power generation. [0003] The existing control technology of doubly-fed units is generally only based on ideal grid considerations. When the power grid is unbalanced, because the stator of the doubly-fed generator is direc...

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Problems solved by technology

[0004] In view of this, the present invention provides a doubly-fed converter unbalanced current cooperative control device and its control method to solve the problems caused by grid voltage asymmetry and doubly-fed generator winding and doubly-fed converter internal device parameter asymmetry Problems such as stator current unbalance, increased loss, increased heat generation, torque pulsation, fatigue loss of gearbox and mechanical transmission shaft, reactive power pulsation, and power quality degradation caused by torque pulsation

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