BIFURCATION PHENOMENA IN VOLTAGE CONVERTER WITH FREQUENCY-PULSE CONTROL FOR A WIND GENERATOR

Abstract

The relevance of the paper is determined by the need to improve energy efficiency parameters of power converting devices for the needs of alternative energy, in particular for a wind generator. One of the difficulties of converting wind energy is the low level of energy efficiency of this process. Due to the variable value of the rotational speed of the blades of the wind turbine in a certain time interval, the parameters of the received energy are variable, therefore, the settings of the secondary converters of electric energy must correspond to the time intervals for generating the signal. Improving the functioning of alternative power sources is possible through the use of multi-frequency stabilization modes of the converter. The article considers a model of a pulse-modulation step-down voltage converter based on pulse‑frequency modulation. The authors have studied and proposed the methods for changing the width of the working zone of a single-frequency stabilization mode. The main aim of the study is to analyze the changing modes of the secondary voltage converter of a wind generator and to develop approaches to the study of bifurcation phenomena that occur in a converter with pulse‑frequency modulation by constructing a mathematical model and numerically-analytical modeling of a buck voltage converter to improve the reliability of the system under consideration. Methods: study of literature on standard energy conversion schemes in wind turbines with an intermediate DC link; mathematical modeling and conducting numerical experiments to change the operational parameters of a buck converter with pulse‑frequency modulation to identify bifurcation in it; construction of bifurcation diagrams for various parameters of the transducer in order to increase the reliability of operation. The results. The authors obtained the mathematical models and numerical-analytical technique for constructing and identifying dynamic modes of a voltage converter with pulse‑frequency modulation acting as a DC link of a wind generator set and constructed the bifurcation diagrams for voltage stabilization at different parameters of the control system. The simultaneous presence of single-frequency and burst-packed modes was shown, bifurcation of period division was identified; the influence of the system parameters on the operating modes was studied, and methods for changing the width of the working zone of the single-frequency stabilization mode were proposed.

Keywords

• wind generation
• buck voltage converter
• pulse-frequency modulation
• switching function
• bifurcation diagram
• single-frequency mode of stabilization