Design On House-hold Stand-alone Photovoltaic Generation System

The limited fossil energy can no longer meet the continuous development of the society,then the new energtic technologies had emerged.With the deepening of photoelectric technology research,the cost of photovoltaic power generation systems has been reduced,pollution has been reduced,and renewable energy sources have emerged.It led to a hot spot of applied research:House-hold Stand-alone Photovoltaic Generation Systems.This paper designed a 500W house-hold stand-alone photovoltaic generation system with single-phase power frequency sine wave inverter as the core.The system design was divided into four parts:power generation module,energy storage module,DC-DC conversion module,and DC-AC conversion module.The model simulation analysis,parameter index design and system function implementation of the system were elaborated in detail.First,the power generation link of the system was to describe the intrinsic characteristics of the photovoltaic cell through multiple angles through the equivalent circuit model,mathematical model,and P-R characteristic curve of the crystalline silicon cell.Using Simulink as a platform,based on the mathematical model of the photovoltaic cell,a simulation module for photovoltaic cell output currentand output voltage Ucharacteristics under standard test conditions of irradiance was established.The application of Lusaka(15°25'S 28°17'E)in southern Africa,which is rich in sunshine but poor in electricity generation,was designed by mathematical analysis and software analysis as the background of the system.The performance parameters of the 8 of 65W-18p PV modules required for the system,with a component azimuth of 4°,a component inclination of 19°and a minimum footprint of 4.26 m~2.Secondly,after analyzing the model parameters of the four types of photovoltaic energy storage cells,the energy storage link used the two factors of maintenance-free lead-acid batteries'self-discharge rate and ambient temperature as the application analysis object,and designs two 12V 10Ah CP12100 battery pack for this system.Finally,the Simulink platform simulates and analyzes the maximum power point tracking control module based on a fixed-step conductance increment method connected in series.The DC-DC step-up module and DC-AC inverter module were designed as a two-stage inverter with 24V DC~310V DC boost converter and 310V DC~220V AC inverter control module.A pre-push-pull step-up converter and post-stage full-bridge inverter circuit were designed for the inverter in four modular circuit designs:1.Push-pull DC-DC step-up converter based SG3525 PWM boost drive control circuit and MOS transistor and rectifier diodes and other components of the parameter design;2.Based on IPA15F2K61S2 chip full-bridge inverter DC-AC inverter drive control circuit including dead time,H-bridge drive and its component parameters design 3.Based on IPA15F2K61S2 chip unipolar SPWM drive module SPWM wave control circuit and feedback signal circuit and control the main program,interrupt program design,etc.;4.The design of the protection circuit module consist of the soft start circuit,over-voltage sampling protection,short circuit protection and other components.After the design of DC-DC and DC-AC modules,the DC-DC step-up converter push-pull DC boost circuit schematic and the SG3525 PWM drive control schematic,DC-AC inverter,were drawn using Altium Designer 17 Variable H4 bridge inverter circuit schematic and SPWM drive control schematic,protection circuit schematic and corresponding module PCB diagram.Take the exported BOM as a reference,performed component welding on the PCB.Then connected the burner with microcontroller.After the main program and the interrupt subroutine are compiled,the hexadecimal(.hex)file is processed by the STC-isp+V6.8 software to download to microcontroller IPA15F2K61S2.The single-phase industrial frequency inverter and the household off-grid photovoltaic power generation system were designed for debugging and performance tests.The experimental test platform built for the 750W peak power inverter output voltage no-load debugging and load output voltage debugging,the voltage waveform data into Matlab using FFT-Analysis test at start time=0 or 0.015s,THDs were less than 3%,so the output voltage waveform was relatively smooth.Operated with two loads,the power conversion efficiency?1=86.4%(>85%)can meet the system design requirements.Based on the criteria of the design procedure for small photovoltaic power generation systems,a small-scale household off-grid photovoltaic power generation system with a rated power of 500 W was built.The designed off-grid photovoltaic power generation system was continuously operated with LED lamp loads and high-power purely resistive loads.The power conversion efficiency?was more than 70%under the conditions,thus verifying the applicability of the designed photovoltaic system.