Research On Optimal Grid-connected Control Of Permanent Magnet Synchronous Power Generation System Based On Z-source Inverter

At present,the global energy and environmental problems are serious,the development of new energy is the product of this situation.Among them,wind energy is one of the renewable energy with large reserves,no pollution and increasingly mature power generation technology.The converter plays an important role in various grid-connected power generation systems.Among them,the z-source inverter is applied to the wind power generation system as a power converter,mainly responsible for converting the input dc energy into ac energy that can be incorporated into the power grid system.It has a unique topological structure,without increasing the dead zone time,when the state of the upper and lower switch tube changes with the conduction of the bridge arm at the same time,it will not cause damage to the equipment,can achieve single-stage weight lifting and pressure relief,so it is widely used in wind power systems,etc.,which is greatly affected by environmental changes.The main research object of this paper is the grid-connected z-source inverter in permanent magnet synchronous power generation system,and the main research work is to optimize its grid-connected control strategy.This paper first analyzes the basic operating principle of z-source inverter,the low frequency of the operating cycle is to establish a mathematical model,and then the whole zsource low frequency mathematical model combined with the power generation system is by the z-source topology and operating principle of the power generation system.At the same time,the basic composition of permanent magnet synchronous power generation system is introduced,the permanent magnet synchronous generator in the system is analyzed,and the mathematical model of permanent magnet synchronous power generation system is established.On this basis,the optimal grid-connected control technology of permanent magnet synchronous power generation system based on z source inverter is studied.Electric network,the first is the traditional vector control,on the basis of the current inner loop control is introduced into the equivalent of the sliding mode control law based on index reaching law,then introduce the fuzzy center of gravity method for fuzzy sliding mode control switch vector controller of sliding mode plane function and its differential fuzzy processing,to get accurate to solve the sliding coefficient of sliding mode control law.At the dc end,it is equivalent to the sliding mode control based on the switching control law to introduce the control of capacitor voltage to realize the change of capacitor voltage and dc input voltage.After that,the inverter with rapidly enhanced performance and stable dc chain voltage can improve the non-minimum phase problem of z-source network and improve the quality of grid-connection and antiinterference ability of the system.At the same time,the z-source inverter SVPWM modulation method is studied,and the basic working principle of SVPWM is analyzed.Then,based on the direct segmentation of SVPWM modulation,the modified ZSVM6 modulation method is proposed.By analyzing the simulation results,it is concluded that the modified modulation strategy has good performance and high utilization rate of harmonic and dc voltage.Finally,the main circuit parameters of the 5k W z-source grid-connected inverter are designed,and the simulation model of the fuzzy sliding mode controller designed by zsvm6-ii modulation mode is established under the selected system parameters.The simulation results verify the theoretical correctness and effectiveness of the optimized grid-connected controller.