| Nowadays,the energy problem is becoming increasingly serious.The carbon dioxide pollution brought by traditional energy has seriously threatened human survival.China has promised the world to strive to achieve carbon peak in 2030 and carbon neutrality by 2060.In order to better build a community with a shared future for mankind and achieve sustainable economic development,the development of new energy industry has become the general trend.New energy power generation represented by solar power generation is greatly affected by the external environment and will have an uncontrollable impact on the power grid.If energy storage equipment is added,this problem can be effectively solved.The "peak shaving and valley filling" function of energy storage inverter effectively solves the problem of "power access" and effectively ensures the safe,economic and reliable operation of public power grid.Adding energy storage system to the development of new energy will help to promote the sound and rapid development of new energy.Therefore,energy storage equipment is the core of building energy Internet.Therefore,this paper studies a single-phase photovoltaic energy storage inverter system,which is mainly composed of three subsystems:MPPT controller,bidirectional DC/DC battery charge and discharge circuit and bidirectional AC/DC rectifier inverter circuit.Because the traditional battery charging and discharging circuit is not simple enough and has poor stability,this paper proposes a new combined double active bridge charging and discharging circuit based on full bridge parallel on the low voltage side and winding series on the high voltage side,which can effectively improve the power density of the system and obtain high cost performance.Considering that the single phase-shifting control can not achieve soft switching under light load,and the single PWM plus phase-shifting control has circulating current loss under light load,this paper analyzes the internal and external phaseshifting,and gives a dual compound phase-shifting control strategy.While realizing wide voltage and full load soft switching,it ensures the minimum inductance current under light load and minimizes the circulating current loss.For the bidirectional AC/DC rectifier and inverter circuit,based on the study of the working principle of the rectifier and inverter circuit,this paper puts forward the rectifier modeling based on power balance and the unified control strategy of rectifier and inverter,which improves the reliability of the whole photovoltaic energy storage inverter system.Aiming at the circulating current problem caused by the parallel improvement of system capacity by inverters,this paper adopts the non master-slave phase synchronization scheme to eliminate the active circulating current in the parallel system,and eliminates the reactive circulating current through CAN fieldbus communication,which not only expands the power supply capacity of the system,but also improves the stability and reliability of the power supply system.According to the operation function and actual operation environment of photovoltaic energy storage inverter,this paper studies the energy management strategy of single-phase photovoltaic energy storage inverter system,and analyzes the energy control method of the system with or without PV modules,energy storage batteries,power grid and diesel engine,so as to ensure the safe and stable operation of energy storage inverter under the condition of meeting the requirements.Finally,based on the theoretical analysis,the design method of the main parameters in the system is given.With the help of PSIM simulation software,the simulation models of battery charge and discharge circuit and rectifier inverter circuit are built,and the prototype of 5 kW single-phase photovoltaic energy storage inverter is made.The simulation and experimental results show that the theory and design method studied in this paper are correct. |
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