Design And Implementation Of A Smart Household Photovoltaic Energy Storage System

The proportion of solar photovoltaic power generation in renewable energy power generation and installed capacity is gradually increasing,becoming one of the essential methods to achieve the goal of carbon neutrality.Distributed photovoltaic power generation has developed rapidly due to its advantages,such as a small footprint and the ability to rely on buildings.Photovoltaic power generation is affected by factors such as light intensity.It has certain randomness and volatility,which will cause problems such as unstable power supply and affect the voltage of the distribution network.This thesis focuses on researching and designing power conversion and intelligent control of household photovoltaic energy storage systems.This thesis designs a household photovoltaic energy storage system,which includes four parts:photovoltaic power generation,energy storage battery,inverter circuit,and control circuit.(1)Photovoltaic power generation consists of solar cells and DC-DC converters.Improve solar cells’ utilization rate and achieve different power level output using a parallel distributed converter structure.Analyzing the Output Characteristics of Solar Cells by Simulation.Using the four-switch BUCKBOOST circuit to realize the output conversion of photovoltaic cells.The four-switch BUCK-BOOST provides three working modes of boost,buck,and buck-boost to adapt a wide voltage range of photovoltaic output and improve conversion efficiency.(2)Energy storage batteries use lead-acid batteries to store,release,and manage household energy.(3)The inverter circuit uses a two-stage single-phase inverter structure,converting the output of battery or photovoltaic power generation into alternating current to supply power for electrical equipment.The front stage uses a multi-transformer push-pull boost circuit in which the primary side of the transformer connects in parallel and the secondary side in series.And the latter stage is a sinusoidal pulse width modulation(SPWM)full bridge inverter Transformation circuit.(4)The control part uses the STM32 microcontroller as the core to design information detection circuits,state control circuits,communication module circuits,and power supply circuits.Mains input detection circuits to realize system operating state detection,working state switching,and battery charge and discharge protection.Combining the ampere-hour integration method and the open circuit voltage method to detect the state of charge of the battery,and switch the power supply mode according to the system operation information and the state of charge of the battery.The 4G cellular network connects the system to the ONENET Internet of Things cloud platform and designs the upper computer and display screen to monitor and control the system status.Test the whole system and its parts.The maximum output power of the four-switch BUCKBOOST circuit is 600 W when the input is 72 V,the output is 50 V,and the efficiency is greater than96%.Inverter circuit 50 V input,220V/50 Hz AC maximum output power is 3.3k W,efficiency greater than 90%.Meet the system charging and discharging optimization design requirements.The functional test of the household photovoltaic energy storage system is in line with the expected results.