Research On Solar Tracking System For Photovoltaic Power Generation

With the progress of human society,the development and utilization of solar energy,wind energy,tidal energy,nuclear energy and other primary energy sources have received extensive attention.The solar tracking control system can effectively improve the utilization rate of solar energy in the process of receiving solar energy by photovoltaic panels to generate electricity.The common control methods of solar tracking system contain open-loop tracking and closed-loop tracking.Open-loop tracking is easy to generate cumulative errors,and the closed-loop tracking effect is greatly affected by the sensor reception angle.In order to further improve the tracking effect of the system and improve the utilization rate of solar energy,this paper designs a solar tracking experiment platform and studies the control strategy of the solar tracking system on this basis.Firstly,the hardware experiment platform of the sun tracking system is designed and built.A two-dimensional turntable is designed to place photovoltaic panels and track the sun.The stepper motor is selected according to the requirements of torque.The model of the motor is 57HS11242A4.In order to realize the closed-loop control of the system,a sensor is designed to detect whether the photovoltaic panel and the solar incident light are perpendicular.A light intensity detection circuit is designed to analyze and compare the solar energy utilization rate under different tracking modes.Secondly,the characteristics of open-loop tracking mode and closed-loop tracking mode are compared,and the motion control strategy of the phased tracking system is proposed.For the tracking mode,the phased control is adopted.The tracking system adopts open-loop tracking control when the initial rotation and direct sunlight are not strong,while the closed-loop tracking control is adopted in other time periods.The variable step control strategy is designed to solve the problem that the motor starts frequently when the error angle is large.The way of motor control adopts phased control.When the error angle is large,variable step motor control is adopted.When the error Angle is small,constant step motor control is adopted.On this basis,the phased control method of solar tracking system for photovoltaic power generation is realized.Finally,based on the sun tracking experiment platform,a comparative experiment of tracking control mode is carried out.The tracking accuracy of the system is obtained by measuring the shadow length parallel to the normal screw of the photovoltaic panel.By measuring the intensity of sunlight received by the photovoltaic panel,the total solar energyreceived by the tracking system can be obtained.The tracking precision of the system and the daily solar energy received by the photovoltaic panel under three modes of no-tracking control,open-loop tracking control and phased tracking control in the same weather condition were measured and compared.The experimental results show that the phase angle error of tracking system can be controlled at about 5°,sectional tracking control can effectively improve the tracking precision of the tracking system and solar accept total.