Research On Networking And Monitoring Of Multiple Flyback Photovoltaic Micro-inverters

Global energy has been developing towards low-carbon direction,and distributed photovoltaic power generation plays an increasingly important role in solar power generation.Micro-inverter has the advantages of small size,long life and high conversion efficiency,and has become the mainstream product in the market of photovoltaic grid-connected power generation.However,the difficulty of unified management and monitoring of multiple micro inverters and the low degree of intellectualization restrict the further development of micro inverters.Therefore,intelligent monitoring becomes the research focus of photovoltaic microinverter.This paper takes photovoltaic micro-inverter and intelligent monitoring of network as the research object,and studies the grid-connected control,power generation prediction,multi-unit network and monitoring of micro-inverter.Finally,a prototype with a fixed amount of power of 180 W was developed,and a power generation system composed of multiple photovoltaic micro-inverters for mobile monitoring of smart phones was realized.The main research contents of this paper are as follows:(1)The topology structure of photovoltaic micro-inverter was studied,and modular design of hardware structure was carried out.The power supply module and sampling detection circuit are verified,and the main circuit topology is verified by means of Simulink tool.(2)The prediction algorithm of photovoltaic power generation system was studied,and a prediction algorithm based on IWD optimization support vector machine was proposed.By seeking the optimal solution of SVM parameters to further improve the accuracy of the prediction model,combined with the LIBSVM tool to train short-term prediction models under different weather conditions,and the final test results show that the prediction error of all models is less than 7%.(3)The grid-connection strategy of photovoltaic micro-inverter was studied,and a gridconnected current control strategy of "quasi-proportional resonance and repetitive control" was proposed.Two parallel control algorithms is used to realize better dynamic and steady state characteristics of grid-connected current.At full load,FFT tool was used to analyze the total harmonic output rate of 2.46%,which verified the effectiveness of the algorithm.(4)Study the system monitoring scheme,and a zigbee-based networking combined with gateway module and cloud server communication scheme was proposed.ZigBee network was established to realize the joint monitoring of multiple photovoltaic micro-inverters.Gateway module was designed based on ZigBee,STM32 chip and GPRS,and monitoring APP was developed based on Android platform.The communication test of each link of data transmission is carried out,and the photovoltaic power generation system of mobile monitoring for smart phones is realized.(5)Relevant hardware and software test platform was established to verify some functions of the prototype and APP developed.The test results are as follows: grid-connected current and grid voltage are of the same frequency and phase,and the efficiency of the whole machine reaches more than 95% at full load;When the prototype is input in low voltage range,it can realize automatic reduction;When the grid deviates from normal operation,the prototype has a 2-minute delay start time;Realized the APP function designed based on monitoring requirements of power generation system,and successfully carried out unified cloud monitoring and management of multiple photovoltaic micro-inverters.