Research On Grid Connected Control Strategy Of Two Stage Matrix Converter

As the energy crisis and environmental pollution problems are becoming more and more serious, the rapid development and use of renewable energy to grid power generation is an effective measure to alleviate the above problems. Wind power is an important part of renewable energy, and it is also the most rapid development of renewable energy sources. In order to realize wind energy integrated into the grid, the back-to-back PWM converter usually is used as the main circuit topology. However, compared with the back to back converter, dual stage matrix converter has no intermediate DC link, without the DC bus capacitor, high life, small volume, facilitate modular and compact design and other advantages. Therefore, the dual stage matrix converter used in wind power generation system has important practical significance and engineering value. In this paper, a dual stage matrix converter direct drive permanent magnet synchronous wind power generation system as the research object, the paper mainly research the dual stage matrix converter grid control method to achieve maximum power tracking.The mathematical model of wind turbine is established, the operation characteristics of wind turbine are studied, and the three stage operation mode of wind power generation system is analyzed. The mathematical model of the abc coordinate system, the a(3 coordinate system and the dq coordinate system of the permanent magnet synchronous motor and the two stage matrix converter are established.The equivalent mechanism between the two stage matrix converter and the conventional matrix converter is analyzed, and the space vector modulation strategy with zero vectors and no zero vectors for the two stage matrix converter is studied. The selection principle of duty cycle, sector and action time is given. The simulation model of space vector modulation strategy of dual stage matrix converter is built by using Matlab/Simulink, the simulation research is carried out on the condition of the expected voltage and frequency variation.The maximum power tracking control principle of wind power generation system is analyzed, the maximum power tracking control diagram also is given, and the implementation process is analyzed in detail. The synchronization phase-locked loop technology is researched, the PLL control principle is analyzed, PI regulator parameters of phase locked loop is designed, the simulation model of the synchronization phase-locked loop is established, and the feasibility of the method is studied.The simulation model of the dual stage matrix converter for direct drive permanent magnet synchronous wind power generation system is built, and the simulation is carried out under the conditions of fixed average wind speed, wind speed change and gradual change wind speed. The simulation results show that the maximum power tracking can be realized under the condition of the change of wind speed. The reference value of reactive power variation is simulated, the simulation results show that the reactive power can quickly track the given value, the system dynamic and static performance is good.