Harmonic instability analysis method for double-fed fan grid-side converter

Abstract

The invention discloses a harmonic instability analysis method for a double-fed fan grid-side converter, comprising the following steps: firstly, building a harmonic model for the double-fed fan grid-side converter; secondly, only considering influence of a current control loop and grid-side impedance, and building an output admittance small signal model under a d axis according to the model in the step 1; thirdly, building a return ratio matrix under the influence of the d axis according to the model in the step 2; fourthly, obtaining an output impedance closed loop transfer function under adq axis and a return ratio matrix thereof according to the model in the step 2; and fifthly, respectively extracting characteristic values of the return ratio matrixes obtained in the step 3 and the step 4, and carrying out harmonic instability analysis on each parameter according to a generalized Nyquist criterion. The method disclosed by the invention can simply and visually judge and control influence of parameters as well as conversion trends of inductances and resistances at a grid side and an alternating current side on system stability.

Description

technical field [0001] The invention relates to the field of converter harmonic stability, in particular to a method for analyzing harmonic instability of a double-fed wind turbine grid-side converter. Background technique [0002] Wind energy is currently one of the renewable energy sources with the most mature development technology and the most large-scale development conditions, and the double-fed wind turbine is one of the current mainstream models; the grid-side converter of the double-fed wind turbine is used as a power electronic component. There may be a large number of harmonics; in addition to the harm caused by the harmonic itself to the power system, when the harmonic distortion reaches a certain level, it will cause harmonic instability, which seriously endangers the normal operation of the system; in order to prevent the occurrence of harmonic instability , to improve the operating environment of the double-fed fan; it is of great significance for the harmonic...

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Problems solved by technology

[0003] Regarding the analysis of harmonic instability, there have been literatures that have carried out comprehensive modeling based on the characteristics of wind farms combined with the LCL filter at the outlet of the voltage source converter, but the analysis process focuses on theoretical research and focuses on the consequences of instability It is described; the frequency sweep method is also used to deduce the impedance characteristics of the AC side frequency of the converter, and the influence of different short-circuit ratios on harmonic instability is studied, but the root cause of instability is not revealed; there are few current analysis methods It involves the influence trend and scope of each parameter on harmonic stability, and lacks the judgment of the critical point of instability

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