Research On Control Strategies Of Grid-conneted Inverter Of Wind Power Generation

Nowadays, since the energy resources become more and more scarce, wind power generation runs on the mainstream trend, and variable speed constant frequency wind power generation system has played a dominant role in this field. So far, double PWM "back to back" full power converter topology has been applied in a great range,the inverter is the vital component of grid connected power system, research of its control strategy has significances on power quality improvement.Grid connected inverter has a vital function in energy conversion and transfer, to ensure stability of the grid, decrease harmonic distortion and improve voltage utilization rate,this paper focuses on further research of control technology in wind power grid connected inverter.Taking the three-phase voltage source PWM inverter as the object of study, establish mathematical model to analyze functional principal, Three-phase voltage-type PWM inverter for the study,a mathematical model analysis theory,and a detailed study based on SVPWM modulation loop control strategy and direct power control strategy are two main network inverter control method,in Based on theoretical analysis on the establishment of a system simulation model, simulation verify the correctness of the theory, and summarizes the advantages and disadvantages of the two control methods.Firstly, summarize practical significance, development and research status of wind the permanent magnet direct drive wind power generation system, and select double PWM"back to back" converter topology, after analyzing the circuit structure and principal of grid side inverter, found mathematical models separately in three coordinate systems. With generally introduce the development situation of inverter control strategy, the research direction of this paper is made clear.Secondly, design the control pattern of current inner loop and voltage outer loop, explain the implementation procedure of SVPWM with the help of display the details of space vector pulse width modulation (SVPWM) principle,simulation results show that the control pattern has impressive advantages such as good current waveform and low current harmonic distortion, its application effect shows preponderance.Further more, direct power control strategy is introduced, then analyzed and explained the principle and implementation procedure of direct power control strategy that based on voltage oriented and virtual flux, predictive direct power control algorithm was proposed to deal with the switching frequency instability of direct power control strategy, principle and actuation duration processing method of predictive direct power control are studied particularity.Finally, in the MATLAB / Simulink environment were built system simulation model,simulation results demonstrate the direct power control algorithm theoretical analysis. The technical method adopted achieves satisfying performances in both grid control and unit power factor function and even sinusoidal effect of current on line side, gets the anticipated objective. Merits and drawbacks of the control strategies, and accommodation are analyzed and summarized.