Improving energy efficiency in residential space heating has a key role to play for achieving the goal of carbonneutrality. Condensing boilers for providing heating can achieve significantly higher efficiency than conventional ones due to possibility to recover latent heat of vaporization from the flue gas. But it can be achieved when return temperature of heating system is sufficiently low (below the dew temperature of the flue gas), which directly depends on real thermal modes of the heating system. So, development of methods and tools that can use data under real operating conditions and have possibilities to find the most efficient modes is crucial for improving performance of such system. Implementation of these methods should be based on mathematical modeling or simulation. The model should be automatically fitted to current measurements. The paper presents development of a digital twin-based smart heating system, which includes a condensing boiler. The proposed framework of a digital twin (DT) takes advantage of the latest technologies in information technology, which could be applied for real-time information interchange between the physical system and its virtual copy to achieve energy efficient operation modes. A methodology and a user-friendly interface, which are easy to use and navigate, have been developed for estimation of energy efficient solutions in the studied system. It has been demonstrated that the biggest increase in boiler efficiency (by 6.6 %) can be achieved by switching to low-temperature heating systems. Applying intermittent heating is in second place in terms of the possibility of increasing boiler efficiency (up to 1.5 %).

This works aims at evaluating the impact of different ratios of heating design loads to cooling ones on the thermodynamic efficiency of a R290 air-to-water reversible heat pump with the aid of an exergy analysis.The potential improvements of the investigated solution were also assessed.The heat pump was sized for a twopipe fan-coil system designed with supply/return water temperatures of 45/40 °C in winter and 7/12 °C in summer.The outdoor air was cooled from -7 ℃ to -12 ℃ in heating mode and heated from 30 ℃ up to 35 ℃ in cooling mode, respectively.The heating loads were varied in a range from 8 kW to 13 kW, whereas the cooling loads were ranged between 6 kW and 15 kW, respectively.The results obtained showed that heat exchanger sizing plays a significant impact on the distribution of exergy destruction within the system components.As the system was sized based on the cooling load, the air-based heat exchanger was found to be oversized and the water-based heat exchanger was observed to be undersized for covering the heating loads and vice versa.It was also found that for the ratios of heating design loads and cooling ones less than 1.2 the system should be sized based on the cooling design loads.In this case lower system exergy destruction could be obtained.Furthermore, in this case the thermodynamic improvement of the air-based heat exchanger, the water-based heat exchanger and the compressor had approximately the same potential of increasing the efficiency of the system.As the ratios of heating design loads and cooling ones were higher than 1.2, the heating load should have been used for sizing the system components due to higher thermodynamic efficiency of the system compared to the previous case and technical possibilities to be operated.Removing the avoidable irreversibilities within the air-based heat exchanger offered the biggest decrease of the exergy destruction within the system.

The article is aimed at the development of modern automatic control systems, which should provide high-performance indicators in the conditions of variable operating modes of industrial equipment due to effective control structures and algorithms. The purpose of the study is to reduce the cost of the basic oxygen furnace steel, which is a consequence of the increase in the share of scrap metal due to the enhanced post-burning of CO to CO2 in the cavity, by optimal controlling the duty mode parameters using model-predictive control. The blowing mode of the basic oxygen furnace was considered as a technological object of control, and the problem of controlling blowing parameters in conditions of non-stationarity of the rate of metal decarburization was analyzed. The use of a model-predictive controller made it possible to improve the quality of control for the oxygen flow circuit by 39% and the maximum dynamic deviation of the CO2 content in the gases was reduced by 16.5% compared to the PID control. The implementation of a software-hardware control system using model-predictive control based on a programmable logic controller is considered.

The aim of the research. This article discusses the use of the Digital Twin in automation and its impact on the resulting solution. The research aims to illuminate the Digital Twin concept explanation and systematise the knowledge base and fulfill information gaps. Research results. The paper overviews the history of the concept and determines the main phases of Digital Twin development. The significant attention was paid to the classification issue to show the huge variation depending on Digital Twin‘s purpose, lifecycle phase, the scale of the physical twins and data amount in order to explain the twin‘s relation and the hierarchy of complex system. The defined capabilities and values of the concept identify the possible use cases and explain the potential benefits of Digital Twin implementation. Also, this paper takes a look at the use of Digital Twin in the area of building automation. This concept potentially may act as the integration platform for building management systems (BMS) and building information modelling (BIM) technologies with IoT solutions. The discussion of Digital Twin implementation for the building automation complex is presented. We conclude that the Digital Twin can integrate human factor to the control system by using the indexes of climate satisfaction, the feedback functionality and human-machine interfaces. As a result, the improvement of system efficiency depends on the coordination and orchestration of equipment operating mode. Conclusion. The Digital Twin has a high potential for energy efficiency improvements, as it considers many factors, integrates a huge amount of data and continuously improves themselves with real-world data.

Fan coils are widely used in heating and air conditioning systems in both residential buildings and commercial areas. This article deals with the creation of a mathematical model of the fan coil for use in control systems, building digital twins, etc. The development of models of components of building engineering systems contributes to the introduction of more sophisticated control algorithms and analytics to coordinate the operation of equipment and as a result improve the energy efficiency of systems, the ability to investigate the dynamics of systems, etc. In this paper, a system of heat balance equations for the water, air and walls of the heat exchanger was used, which allows for simulating the operation of the system in transient modes. Considerable attention was paid to the calculation of the coolant and air parameters, including specific heat capacity, heat transfer coefficients, water and air thermal conductivity, kinematic viscosity coefficients, density, etc. The use of dynamic calculation of the coolant and air characteristics was proposed, an algorithm using the Python programming language and the CoolProp, SciPy, and NumPy libraries were implemented, and simulation results were presented. To assess the effectiveness of the proposed solutions, an analysis of the simulation results for the system with constant values of the coolant and air parameters, determined from the averaged initial values of the input and output parameters of the model, compared to the system with dynamic calculation, was performed. Finally, we investigated the dynamics of the external factor influence on the simulation results and presented an analysis of the influence of the model input variables on the output temperature values due to implicit relationships in the calculation of the parameters characterizing the heat transfer fluid and the air in the fan coil. According to the results of the comparison, the deviations in the simulation results of the models under study were estimated for the calculated value of heat output on the air side in absolute and relative units.

Background. Model predictive control (MPC) approach is the basic feedback scheme, combined with high adaptive properties, which determines its successful use in the practice of design and operation of control systems. These advantages allow managing multidimensional objects with a complex structure, including nonlinearity, optimizing processes in real time within the constraints on controlled and managed variables, taking into account uncertainties in the task of objects and perturbations. Objective. The purpose of the paper is to design and analyse control system of carbon monoxide oxidation in the convector cavity based on MPC with linear-quadratic cost functional with constraint. Methods. The design of MPC is based on mathematical model of an object (relatively simple). At the current step, the prediction of object dynamic response on some final period of time (prediction horizon) is carried out; control optimization is performed, the purpose of which is to approximate the control variables of the prediction model to the corresponding setpoint on the predict horizon. The found optimal control is applied and measurement of an actual state of object at the end of a step is carried out. The prediction horizon is shifted one step further, and this algorithm are repeated. Results. The results of modeling the automatic control system show that the MPC approach provides maintenance of carbon dioxide content when changing oxygen consumption and overshoot caused by introduction bulk does not exceed 0.6 % that meets the technological requirements of the process. Conclusions. A fuse of the MPC and the quadratic functional given the constraints on the input signals is proposed. The problems of control degree of carbon oxidation in the convector cavity include non-stationarity, so the use of classical control methods is difficult. The MPC approach minimizes the cost function that characterizes the quality of the process. The predicted behaviour of a dynamic system will usually differ from its actual motion. The obtained quadratic functional is optimized to find the optimal control of degree of CO oxidation to CO2.

Today in Ukraine and the world, the problem of energy saving and reducing the cost of smelted steel is state of art. Metallurgical enterprises are developing in conditions of fierce competition, the main reason is that Ukrainian products are extremely energy-intensive due to the depreciation of fixed assets and outdated technological processes. The basic oxygen furnace process is a process of producing steel from liquid cast iron with the addition of steel scrap to the converter and blowing oxygen from above through a water-cooling lance. Nowadays, the production of steel by BOF process is the most popular in the world and is becoming increasingly common. The main disadvantage of the basic oxygen furnace is the need to provide the initial amount of heat (in the form of liquid cast iron) and as a consequence - restrictions on the processing of scrap metal. Reducing the cost of basic oxygen furnace steel is achieved by increasing the share of scrap metal by increasing the degree of afterburning of CO to CO2 in the cavity of the converter, by optimal control of the parameters of the blast mode using model-predictive control. The principle of model-predictive control is based on a mathematical model of the plant. This approach minimizes the functional that characterizes the quality of the process. The linear-quadratic functional was chosen. A forecasting model is proposed taking into account the constraint on changing the position of the lance and the pneumatic oxygen supply valve. It was found that the change in the rate of decarburization of the metal depends on the distance of the lance to the level of the quiet bath and affects the degree of afterburning of CO to CO2. The decarburization process is non-stationary, described by a first-order inertial model, the transfer coefficient and time constant of which depends on the melting period and the duration of the purge. The mathematical model of the blast mode of oxygen-converter melting has been improved, taking into account the influence of the blast intensity on the decarburization process of the bath, which allowed to increase the accuracy and quality of blast control in terms of changing oxygen flow during purging. The simulation results of the automatic control system show that the model-predictive regulator provides the required level of carbon dioxide in the converter gases when the flow rate of oxygen for purge changes.

The oxygen converter is intended for production of steel from liquid cast iron and steel scrap at blowing by oxygen. Nowadays, Basic Oxygen Furnace process is the main method for steelmaking. The main disadvantage of the basic oxygen furnace is the limited ability to increase the part of scrap metal. The task of the proposed approach is to control of the blowing mode parameters to establish the optimal level of CO2 that will ensure a minimum specific cost of steel in the presence of restrictions and boundary conditions of basic oxygen furnace steelmaking process. A model predictive control taking into account the constraints on the input signals and the quadratic functional is proposed. The design of Model Predictive Control is based on mathematical model of an object. This approach minimizes the cost function that characterizes the quality of the process. The result of the automatic control system modeling shows that the Model Predictive Control approach provides retention of carbon dioxide level when oxygen consumption is changing. The obtained quadratic functional is optimized to find the optimal control of blowing parameters.

The fulfilment of the condition for the simultaneous achievement of the desired chemical composition and temperature of the metal is ensured by controlling the oxygen consumption and the position of the oxygen impeller lance. The method for solving Model Predictive Control with quadratic functionality in the presence of constraints is given. Implementation of the described solutions will contribute to increasing the proportion of scrap and reducing the melting period without changing of technological process.

This article examines the use of Building automation system to give comfortable conditions for users to provide improving energy efficiency. We found out the impact of the Internet of Things concept on BAS development, and how the use of modern wireless technologies, edge and cloud computing is determining the way of the following progress. Also, their advantages and disadvantages were considered. A separate section focuses on the state of BAS in Ukraine and the key factors that influence it

The main objective of this paper is to review of fault detection and isolation (FDI) methods and applications on various power plants. Due to the focus of the topic, on model and model-free FDI methods, technical details were kept in the references. We will overview the methods in terms of model-based, data driven and signal based methods further in the paper. Principles of three FDI methods are explained and characteristics of number of some popular techniques are described. It also summarizes data-driven methods and applications related to power generation plants. Parts of control system applications of FDI in TPPs with possible faults are shown in the Table I. Some popular techniques for the various faults in TPPs are discussed also.

Under conditions of intensification and maximization of production profitability, a problem of regulation, optimization and improvement of the structure of automatic control systems arises. To date, there are many topical problems associated with the practical implementation of the PID controller, e.g. unification of the PID controller structure, implementation of a differential component, integral saturation and nonimpact switching of parameters and operating modes. Influence of nonlinearities, noise, disturbances, functions, and peculiarities of the PID controller on dynamics of the automatic control system was studied. It was shown that for the maximum efficiency of implementation of the PID controller for controlling inertial objects with a transportation lag, a complex approach must be applied: limiting the rate of growth of the target disturbance and conditional integration to eliminate integral saturation; simultaneous application of an exponential filter of the measured value and a differentiator with a low-cut filter to minimize the effect of noise and interferences on the transient processes; tracing the current state of the system allows one to prevent an "impact" when changing the operating modes of the PID controller; introduction of the controller insensitivity zone will potentially provide a longer operation life of the actuator. Mathematical modeling of the system of automatic regulation of rarefaction in the boiler furnace was performed taking into account the proposed set of solutions. These recommendations enable implementation of a PID controller suitable for practical use taking into account stochasticity, nonlinearity, quasi-stationarity and limitations of the technological processes. Integrated assessment and consideration of these problems will contribute to improving efficiency and reliability of equipment, reducing energy consumption and time to reach the set goal in the process of automatic regulation without changing the structure of the control system.

The article presents a method of controling an energy efficient hot water supply system, a large amount of heat energy in which is supplied by the solar collector. The study proves importance of energy saving technologies and their use in everyday life and industry. The study presents a generalized structure of the system of hot water supply as a control object. The devised analytical model of dynamics of the system individual elements is based on the equations of heat balance. The model is reduced to a form suitable for use in computer modeling of the dynamics of technological processes. Numeric values of the parameters of the model transfer functions are calculated for the selected model of the solar collector. The resulting model of the control object for a single­circuit system serves as a basis for the comparative studies of various controller structures and control methods that provide the minimum readjustment and the fastest transition process. The comparison is based on classical PID­algorithms and the IMC­approach. The article describes synthesis of the IMC of the temperature of hot water in the point of its supply to users. It is found that the proposed approach to designing a control algorithm based on the object model allows the IMC provide better performance quality as compared to traditional algorithms. It is shown that the controller synthesis requires taking into account the work of the actuator, and the controller filter order directly affects the valve drive motion making it smooth. We have considered the prospects of the proposed approach and possible options for upgrading the system.

The prospects of controllers based on fuzzy logic for maintaining the temperature component of systems for climate control in buildings and the results of research in this area are discussed in the article. The main aim of the research is developing automatic controller of temperature microclimate condition on the basis of technology of fuzzy sets, providing minimal overshoot and the transition process in the task of stabilizing the temperature. Using this method can reduce the overshoot of controlled parameters of ventilation systems, reduce their identification time and increase the robustness of the controller in the presence of incomplete information about the object control compared to regular algorithms. Ways to optimize the control system for maintaining the set quality parameters are outlined. It is proposed to use the controller based on fuzzy logic for air conditioning systems, in which there are uncontrollable external disturbances and there is incomplete information about the object of control. Research results can be applied by expert designers of automatic control systems involved in automation, the stages of development and control algorithms during commissioning works to reduce system setup time.

Наведені результати розробки і дослідження регулятора на базі нечіткої логіки для підтримання оптимального температурного режиму в системах вентиляції повітря. Описано процедуру синтезу нечіткого регулятора температури повітря. Показані межі застосування запропонованого рішення та дані рекомендації щодо адаптації нечіткого регулятора до особливості динаміки в системах з відсутністю повної інформації про об’єкт керування.

The paper presents the research of the steam heating unit as the automation object. The heating unit is a complex engineering system with an increased exploitation risk, caused by using high-parameter water steam. The paper describes the synthesis procedure of the automatic control system from the problem statement and object study to a description of the simulation results. The list of the main system process variables with the factors that influence the process course in relation to the block diagram of the heating point was presented. The process features, which are typical for steam plants were indicated. The experimental transients, obtained during the commissioning by influencing on the main process variables on the part of related control bodies were given. The processed data are summarized in the form of mathematical models of individual heating unit sections and represented by transfer functions. Based on the data obtained, the structure of the automatic control system was proposed and settings of automatic controllers that ensure the preset quality parameters were calculated. The description of contour control algorithms and interaction of individual equipment items that increase the system efficiency was given.

The article describes the ways of improving quality of automatic control systems, using auto-tuning methods. The structure of control system with internal model control and automatic tuning is proposed

This article describes examples of industrial use of adaptive automatic control systems; an adaptive system for heat-power facilities is represented; simulation results of comparative modeling are described and analyzed.