Small Signal Stability Analysis Of The Asynchronous Induction Generator Wind Power System With Full-scale Converter

As one kind of renewable energy in today’s society, wind energy is receivingmore attention because of double pressure of energy crisis and environment pollution,and thus its technology is developing in a rapid speed. Common wind generators canbe seen as double-fed wind turbine, permanent magnet direct drive wind turbine andfull-scale asynchronous wind turbine. In recent years, with the continuousdevelopment of power electronics technology, the capacity of the full-scaleasynchronous wind turbine also increases. As a result, advantages of asynchronousinduction generator like simple structure, reliable operation, easy to maintain makefull-scale asynchronous wind power system is gaining more attention in whole windenergy generation industry. The aim of this paper is to analyze and study full-scaleasynchronous wind turbine system.To begin with, this paper describes full-scale asynchronous wind power system’sbasic structure, operating principles and operating characteristics. After that,mathematical models of wind turbine, transmission system, pitch angle control system,induction generator and double PWM converters are established. When wind turbineis connected to the grid through double PWM converters, the converters are in need ofcontrol. According to the Park coordinate transformation, vector decoupling controlprinciple and mathematical model of the wind turbine, this paper proposes a controlstrategy of the generator side converter based on rotor flux oriented. Meanwhile,based on a mathematical model of the grid-side converter and grid-side convertercontrol requirements, a vector control strategy based on grid-side voltage oriented isproposed.With a brief introduction of the basic principles and methods of the power systemsmall signal stability analysis, this paper linearizes the dynamic differential equationsdescribing the whole full-scale asynchronous wind power system and then gets smalldisturbance equation which is easy to analyze. Through calculation, values of eachcomponent in the small disturbance equation matrix are clear. Based on calculatedeigenvalue, this paper analyzes the stability of asynchronous wind power systemunder small disturbance.Finally, model of whole full-scale asynchronous wind power system is builtthrough Matlab/Simulink simulation platform. Based on previously derived mathematical model of wind power system, this paper develops simulation models foreach part of the system. Establish a wind turbine with asynchronous single machineinfinite bus system and three nine-node system model. From detailed simulation andanalysis of asynchronous wind turbine’s operating characteristics, output result, andstability under small disturbance, conclusions drawn above are verified.