Monitoring System for Small-Scale Photovoltaic Plants
Abstract
This study presents the results of research aimed at developing and creating a monitoring system for solar photovoltaic power plants; this system would allow measuring values of key output parameters (generated power, current and voltage, photovoltaic module, and ambient temperatures). The presented monitoring system consists of a measuring device, a computer, a shunt, and thermal sensors. The measuring device was made on the basis of an STM32F415RGT6 microcontroller. It is shown that an operational amplifier with a programmable gain can be used in which the gain can be changed via the SPI interface to 1, 2, 3, 4, 5, 8, 10, 12, 16, or 32. When high and low voltages are measured, this gain is programmatically switched to lower and, vice versa, higher levels. This makes it possible to measure the voltage smoothly in the entire range to high precision and without manual switching. The DS18B20 temperature sensors are used to measure the temperature from –55 to 125ºC. Several programs based on C++Builder are developed to display graphs and the MySQL database and save the measurement results on a computer. Every 15 min the software collects data from the measuring device, displays them in the form of tables, graphs, and also records and stores the data in a MySQL database for further processing and analysis.