Reliability Design And Implementation Of Data Collector For Solar Water Heating Project

As the main application form of heat utilization,sustained development of solar hot water system(SHWS)has become an important way of clean energy in China.In order to monitor the operation status and to real-time control the system,a real-time data acquisition technology is necessary.The reliability of the data acquisition system(DAS)is essential for a remote date acquisition of the SHWS,especially in the harsh environment.Aiming at the unfavorable factors when acquiring data,such as data acquisition losing,communication being jammed,program crashing and software function instability,a reliability design of DAS by using impedance matching,circuit filtering and PCB optimization design technology is carried out.The reliability testing of hardware and software show that the new DAS meets the requirements of high stability,wide applicability,and high reliability.The research mainly includes the following three aspects.(1)In order to improve the electromagnetic compatibility of DAS,a Samsung Exynos 4 Quad core board based on ARM9 architecture is selected.Some measures,such as using isolating,grounding,filtering,surge protecting for power interface,RS485 interface,RS-232A interface,USB interface and Ethermet interface,are taken to design circuit schematics.The power supply module,communication module,storage module and measurement module are designed with some technology,such as reducing noise source level,blocking interference propagation path,and enhancing anti-interference ability of sensitive devices.PCB layout and wiring are designed,and the hardware reliability design of data collector was completed.(2)The reliability and characteristics of the software system are analyzed,and then the U-boot boot program and Linux kermel are transplanted to the data collector to build a stable and reliable application-running environment.Then the system functional reliability design is completed,which includes the following four parts:building SSH server to achieve convenient remote login;building MySQL database to achieve data distributed storage and backup;building NFS client to achieve remote file updates;using the framework of B/S and C/S architecture to achieve safe and efficient web pages publishing.Finally,the Docker tool is used to package the system into a mirror and store it in a container to achieve rapid attribute design.(3)The system reliability is analyzed by using the average fault-free time,and the reliability prediction results are given.Then the EMC immunity test is carried out on the hardware of DAS.The test results show that the new designed DAS has higher noise immunity than the old one.The new one meets the reliability requirements of the hardware of the data acquisition device.Finally,some tests of the functions of remote login,data storage,web page publishing and file updating are taken,the results satisfy the requirements of software's reliability.The new designed DAS designed achieves the expectation in properties of hardware immunity and software function,and meets the reliability requirements in practical engineering.