Design of Voltage and Frequency Regulator for a Wind Turbine-Induction Generator System
Date Issued
2006
Date
2006
Author(s)
Chen, Woei-Luen
DOI
zh-TW
Abstract
Voltage regulator and frequency regulator are designed for a wind turbine-induction generator system. Much effort has been placed on control strategy exploration and controller design of the static synchronous compensator (STATCOM) and the variable blade pitch in a wind energy conversion system (WECS).
An output feedback linear quadratic controller is designed for the STATCOM and the variable blade pitch in order to reach the voltage and mechanical power control. Then a systematic approach based on pole assignment technique is used to refine the weighting matrix for the linear quadratic controller such that satisfactory damping characteristic can be achieved for the closed-loop system. To attain the decoupled real and reactive power control loops for the output feedback controller, a two-reference-frame transformation is proposed to convert the STATCOM currents from the coupled d-q plane to another decoupled d-q plane. In addition, to ensure zero steady-state voltage errors for the output feedback controller, the integrals of generator bus voltage deviation and DC capacitor voltage deviation are employed as the additional state variables.
An important conclusion obtained from steady-state analysis results for an isolated induction generator is that the stator frequency is proportional to the rotating speed at constant stator voltage. The advantage is that, through the action of the speed governor, the stator frequency can be regulated precisely. Besides, in another frequency control strategy, the relative rotating speed measured by the rate of change of voltage phase angle at generator terminal, is used to estimate stator frequency.
To demonstrate the effectiveness of the proposed approaches, both time domain simulations and experiments are conducted. Dynamic response curves for the system subjected to various disturbances are presented. It is found that the proposed approaches can provide effective voltage and frequency control for induction generators.
Subjects
葉片旋角
頻率調整器
感應發電機
靜態同步補償器
電壓調整器
風力發電系統
Blade pitch angle
frequency regulator
induction generator
static synchronous compensator (STATCOM)
voltage regulator
wind energy conversion system (WECS).
Type
thesis
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