Research of the Mathematical Model of Heated Greenhouses

Large-scale greenhouse production is currently developing along the path of introducing technologies for intensive cultivation of vegetable crops and using automated control systems for technological processes based on micro and minicomputers. One of important technological processes is watering and feeding plants with mineral fertilizers. The need to automate this process is associated with laboriousness of process of preparing solutions, accurately maintaining given concentration of substances in them, timely supply and uniform dosing over the entire area of greenhouse under various disturbances of external environment. The article shows a technological scheme of a heated greenhouse of the simplest design. A method for constructing balance models is presented; model can be transformed for more complex schemes. Three main models in spacestate (continuous, discrete, operator) are considered. Information about processes is recorded discretely, therefore, we first identify discrete form of the model, then we obtain parameters of the discrete form. Further, using equation of constraints, a matrix of discrete and continuous forms, we obtain transfer functions for the internal airtemperature. Due to simplicity of setting parameters, it can be easily reproduced for many different designs and systems of greenhouse complexes, as well as for various scenarios of changing environmental conditions. Proposed balanced dynamic models allow the most complete use of computers for studying heat consumption modes of heated greenhouses, as well as for synthesis of temperature controllers. In this case, vector-matrix algebra is used as a mathematical apparatus, standard programs for which are widely used on computers for various purposes.