AUTONOMOUS POWER SUPPLY SYSTEM WITH MAXIMUM POWER POINT TRACKING OF PRIMARY ENERGY SOURCES

Heterogeneous and homogeneous energy sources with different characteristics are frequently used in autonomous power supply systems. The renewable energy sources such as solar, wind, geothermal and hydro energy mainly serve as primary energy sources of terrestrial autonomous power supply systems. A combination of different energy sources as a part of an autonomous power supply system allows reducing the dependence of the required generated power from unstable ambient conditions. Matching of the primary energy sources with different characteristics and operating conditions in the same power supply system leads to additional difficulties related to power control of energy sources. These difficulties determine the relevance of the study. The main aim of the study is to develop the primary energy sources combination and control techniques so that the primary energy sources with different characteristics and operating conditions could operate in the same power supply system. The objectives of the study are to develop the simulation model of the power supply system using MATLAB/Simulink software; to develop and test the primary energy source controllers operation algorithms that would allow maintaining the required battery charging current and operation of the primary energy sources in the maximum power point tracking mode and minimization of the maximum power point search time. Methods used in the study: the simulation of a power supply system with the use of MATLAB 7.9 Simulink software. Results. The authors have developed the simulation model of a power supply system that includes two primary energy sources with different characteristics. When there is an excess of power generated by the primary energy source, its controller operates in the battery charging mode. When the primary source power shortage occurs, its controller operates in the maximum power point tracking mode. The proposed power supply system structure allows controlling two energy sources independently, thus the primary energy source controllers could operate in different modes, providing more flexibility to the power supply system. The use of fuzzy logic control algorithm increases the accuracy and search speed of the maximum power point tracking algorithm. The results of simulation confirmed the efficiency of the proposed solar controller operation algorithms in all modes stated above. The efficiency of controller operation modes selection algorithm was confirmed in different operating conditions. The proposed algorithms allow controlling effectively the primary power sources power depending on the different power supply system operating conditions.