A Calculation Method for Maximum Increment of Rotor Current When Terminal Voltage Drops in Doubly-fed Induction Generator

Abstract

The invention relates to a method for calculating maximum increment of rotor current of a doubly-fed induction generator in case of terminal voltage drop. The method is characterized in that subject to 'rotor exciting voltage and rotor speed remaining unchanged', a current transient process excited by terminal voltage drop in stator and rotor windings of the DFIG (doubly-fed induction generator) is analyzed scientifically and reasonably, a physical process and a rotor current incremental frequency component of the doubly-fed induction generator after terminal voltage drop are analyzed, and based on the superposition principle, the method for calculating maximum increment of the rotor current excited by terminal voltage drop while crowbar protection idles is provided; on such basis, the stator and rotor winding resistance is omitted, effectiveness of an analytical calculation model under fixed wind speed and different wind speeds is deducted and verified, and the method has the advantages of simplicity in calculation, quickness in calculation and the like.

Description

technical field [0001] The invention relates to the field of doubly-fed wind power generator interlocking off-grid, and relates to a method for calculating the maximum increment of rotor current when the terminal voltage of a doubly-fed induction generator drops. Background technique [0002] In recent years, global wind power has developed rapidly. Under the background of large-scale centralized development and utilization of wind power, it is convenient and accurate to quantitatively analyze and evaluate the fault characteristics of grid-connected wind turbines when the power grid is faulty, so as to provide reference for wind farm planning, design and protection configuration. important meaning. [0003] Double-fed induction generator is one of the mainstream models used in wind power generation at present. The rotor winding is excited through back-to-back four-quadrant converters, so that the double-fed induction generator can achieve variable speed and constant frequenc...

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Problems solved by technology

[0004] At present, it is mostly assumed that the Crowbar protection action occurs at the moment of machine terminal voltage drop, and then the DFIG rotor current fault characteristic analysis is transformed into the fault current analysis of conventional asynchronous motors. , it takes a certain amount of time for the rotor current to increase to the Crowbar protection action value, and the growth time varies according to the severity of the fault, so that the transient characteristics of the DFIG rotor current are still related to the control of the converter at the initial stage of the grid fault. Therefore, based on the "machine-side The research results obtained under the assumption that the Crowbar protection operates at the moment of voltage drop cannot fully reflect the fault characteristics of the DFIG rotor current

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