Instruments and Systems: Monitoring, Control, and Diagnostics Annotation << Back Development of a combined digital system for controlling the temperature of the curd at the cooler outlet V.S. KUDRYASHOV, S.V. RYAZANTSEV, E.A. HROMYH, I.A. KOZENKO, A.R. GNEDNEVA The use of single-loop automatic control systems, which form the basis of most modern automated control systems for the company`s technological processes, leads to untimely and incomplete elimination of the influence of disturbing influences. This circumstance is the reason for the decrease in the quality of regulation and the products obtained. One of the dairy productions, characterized by the features described above, is the production of cottage cheese, in which one of the most important operations is the cooling of cottage cheese. Based on the description and features of the cooling process of cottage cheese, the task is to develop a digital system for controlling the temperature of cottage cheese in a screw cooler, since it is the most perfect. The development of a mathematical description of the cooling process of cottage cheese is carried out using a deterministic approach. The disturbing quantity is the consumption of cottage cheese through the cooler, the control is the flow of cooling water. Based on the found transfer functions obtained on the basis of the heat balance equations and the relationship between the controlled quantity and the control and disturbing effects, it is proposed to use a combined control system. The structure of the model includes a regulator, an actuator with a regulating organ, a control object, a compensator and a sensor, since their dynamic characteristics have a significant influence on the functioning of the control system. Calculation of the digital compensator in the presented combined system is carried out on the basis of the invariance principle. And since the proposed system is implemented on the means of digital computers, the calculation and modeling is proposed to be carried out in the time domain using finite-difference equations. To study the combined digital control system, a PD regulator is used, since the analysis of the quality of regulation has shown its advantage over the PID regulator. A comparative analysis of the study of a single-loop and combined control system by reference and simultaneous submission of a task and a disturbance shows a 2% decrease in the integral-quadratic error, which indicates the advisability of using a combined system in the presence of a disturbance in comparison with a single-loop one. Keywords: production of cottage cheese, screw cooler, mathematical model, deterministic approach, PD regulator, combined control system. DOI: 10.25791/pribor.02.2019.466 Contacts: E-mail: kudryashovvs@mail.ru Pp. 28-36.