Simulation Modeling of an Autonomous Power Supply System Based on Solar Panels in Real Time

Abstract

During the last decade, solar energy showed rapid development. So, in 2021, production volumes increased by 19 percent, which is the highest rate among renewable energy sources, and in the last ten years, by 714. And this growth will continue. And according to forecasts, similar development will continue in the coming years, the projected growth of total capacity over the next five years is from 112 to 188 percent, and the growth of investments until 2050 will be 68 percent. This, as well as the introduction of green tariffs, which encourage the use of renewable energy sources by purchasing surplus energy obtained with their help, increases the number of installed solar power plants and power supply systems based on them. But the use of renewable energy sources obliges users to report on the projected level of production. Computer modeling is one of the methods of analyzing processes in electrical systems in real time and is less complicated than mathematical calculation methods. The work presents a structural diagram of an autonomous power supply system based on solar panels, as well as a description of its main elements. The stability of the solar panel-boosting pulse-width converter system was investigated using the Nyquist criterion. A block diagram of the method of selecting the maximum power from the solar panel based on the current at the output of the solar panel, which is used in the simulation, was also given, a set of positions of the maximum power points depending on the insolation with a discreteness of 50 W/m^2 is shown, the function of the dependence of the current on insolation using the cubic interpolation method, compared the results obtained using this dependence with previous data, estimated the average absolute error of the method. A model of the stand-alone power system is assembled in MATLAB Simulink, which can be used for real-time forecasting. Simulations were carried out using data for a day from a real household and insolation data from the LARES laboratory in Zagreb with a discreteness of 1 min, oscillograms of the output power of the solar panel, power consumption, as well as an oscillogram of the change in the state of battery charge during the day with such data are given. The simulation results were analyzed and recommendations were given regarding the behavior of users of such an autonomous power supply system during certain periods of the day when the generation capacity exceeds consumption or vice versa, affecting the state of battery charge.