Research On Key Technologies Based On Embedded Digital Photoelectric Sunlight Recorder

Sunshine duration is a basic item of observation at surface meteorological stations,which is of great significance to solar energy utilization,guidance of agricultural production and protection of ecological environment.At present,the chinese meteorological department mainly uses the focused and dark-tube type sunshine recorder to observe the data of sunshine.With the increasing demand for sunshine observation data in the fields of solar power generation,climate prediction and agricultural production services,traditional observation instruments can not meet the demand of operational observation.Therefore,it is necessary to develop an embedded photoelectric sunshine recorder which is recorder low-cost,stable performance,easy maintenance and high observation accuracy,in order to realize the automation and digitalization of sunshine observation equipment.In this paper,the embedded photoelectric sunlight recorder studied in this paper is a special instrument for obtaining the sunshine duration by directly measuring the global solar radiation and diffuse solar radiation to obtain the sunshine duration.In this paper,the measurement method and principle of sunshine radiation are described in detail,and the research and design of embedded photoelectric sunlight recorder are carried out.Finally,the structure design based on dichotomous sky method is adopted.In this paper,the control circuit,photoelectric signal conversion circuit,low temperature heating circuit,clock circuit,data storage circuit and other hardware parts with STM32F4 as the core are designed and the corresponding software and irradiance compensation procedures are designed.The remote initialization parameter setting and the sunshine radiation monitoring function of the embedded photoelectric sunshine recorder are realized by designing the host computer program based on Labview.In view of the technical problems that the current photoelectric sunshine meter needs to manually adjust the pitch angle and the midday irradiance measurement error,the key technologies including solar radiation measurement,celestial coordinate system establishment and cosine response characteristics are studied in this paper.The analysis shows that the cosine response error of the photoelectric sensor and the scattering radiation error are the main error sources.In order to correct this part of the error,a new method based on the solar elevation angle and azimuth angle to correct the cosine response error and scattering radiation error is proposed in this paper.The application of this method can nearly double the accuracy of sunshine duration measurement of embedded photoelectric solar radiometer for total radiation,and meet the measurement requirements of the meteorological department with sunshine duration better than 10%.Finally,the embedded photoelectric sunlight recorder has been tested in the outdoor field for half a year,the test results show that all the indexes meet the requirements.