Прегледај по Аутор "Nedić, Novak "
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- СтавкаANALYSIS OF POSSIBILITIES FOR DISTURBANCE REJECTION IN THE DECOUPLED MULTIVARIABLE PROCESS(Faculty of Engineering Hunedoara, University Politehnica Timisoara, 2016) Prodanović, Saša; Nedić, NovakProper behavior of multivariable process isn't guaranteed only through the disabling influence of its mutual coupling (interaction), but also compensation of disturbance has very important role. Investigation of disturbance that can be rejected by previously decoupled 2×2 process has been presented in this paper. Considered flow tank, as a multivariable process, was controlled using PI controllers. The aim was to determine limit of disturbance intensity under whose influence system can operate correctly, and in that way additionally check validity of designed decoupler, i.e. chosen non-conventional control. General expression for periodic rising signal that can be introduced into process in order to present array of disturbances has been derived, too.Investigation was supported by simulations.
- СтавкаCOMPARISON OF TWO MATHEMATICAL MODELS FOR CONTROL SYSTEM OF LEVEL IN CONDENSER OF TURBINE IN THE THERMAL POWER PLANT(International ConferenceProcess Technology And Environmental Protection, 2011-12) Prodanović, Saša; Nedić, Novak; Filipović, VojislavThis paper shows large importance of adequate mathematical modeling of system. Control system of level in condenser of turbine in thermal power plant Gacko is taken into exploration. Here it was presented in two ways, as first-order system and second-order system. Their analysis and comparison were carried out after auto-tuning of PID (proportional-integral-derivative) controller using relay feedback test simulation. Obtained parameters of PID controller were applied into both variations of the system block diagram and its responses have been utilized for giving evaluation of researched models.
- СтавкаDECOUPLING CONTROL OF THE TITO SYSTEM SUPPORTED BY THE DOMINANT POLE PLACEMENT METHOD(University of Nis, Serbia, 2017) Nedić, Novak; Prodanović, Saša; Dubonjić, LjubišaAppropriate approach to the nature of systems is a significant precondition for its successful control. An always actual issue of its mutual coupling is considered in this paper. A multivariable system with two-inputs and two-outputs (TITO) is in the focus here. The dominant pole placement method is used in trying to tune the PID controllers that should support the decoupling control. The aim is to determine parameters of the PID controllers which, in combination with decoupler, can obtain a good dynamical behavior of the system. Therefore, this kind of the centralized analytically obtained controller is used for object control. Another goal is to simplify the tuning procedure of PID controllers and enlarge the possibility for introducing the given approach into practice. But the research results indicate that the proposed procedure leads to the usage of P controllers because they enable the best performances for the considered object. Also, it is noticed that some differences from the usual rules in selection of the dominant poles gives better results. The research is supported by simulations and, therefore, the proposed method effectiveness, regarding the system behavior quality, is presented on several examples.
- СтавкаDesign of PID Controllers for the System of a Pump Controlled Hydro-Motor(Faculty of Mechanical and Civil Engineering in Kraljevo, 2021) Dubonjić, Ljubiša; Prodanović, Saša; Nedić, Novak; Savković, MileThis paper presents design of a PID controller for the system of a pump-controlled motor with a long transmission line. By using possibilities offered by computers and software the graphical method is used in the design of PID controllers. The D–decomposition method including system performances, damping and settling time was applied. This type of controllers frequently satisfies practical needs because the feedback loop system is fast, and the static error is reduced to 0. The proposed method allows easy design of PID controllers in significant modifications of lengths of the transmission line. The system performances are included in a new manner without the need for calculation of Chebyshev functions for every change of the damping coefficient thanks to strong software support.
- СтавкаEnergy saving in the power plants using automatic control(2011) Nedić, Novak; Filipović, Vojislav; Prodanović, SašaThe constant striving to reduce energy consumption leads toward introduction of strategies, which can enable it. In this paper, the strategy which includes frequency regulators into control system of condensate level in condenser of turbine in thermal power plant Gacko is proposed. Properly tuned PID (proportional-integral-derivative) controllers are precondition for appropriate process control. Therefore, the mathematical model of this system is formed and simulations of auto-tuning of PID controllers, using ideal relay and saturation relay as nonlinearity, are carried out. Static load disturbance are considered too, because of its adverse effect both directly on the object, and in auto-tuning process, which causes errors in determining of PID regulator’s parameters. The justification of the introduction of frequency regulators has been confirmed by calculation of energy saving. Its feasibility was proved through simulation of the functioning of the entire control system of level in condenser, based on consideration of characteristic parameters of system response.
- СтавкаImproved Auto-tuning PID Controller of Level in Condenser of Turbine in Thermal Power Plant Using Saturation-relay Feedback(Faculty of Electronic Engineering; Faculty of Mechanical Engineering, University of Niš, 2010) Prodanović, Saša; Nedić, Novak; Filipović, VojislavProperly tuned controllers should ensure correct and unobstructed functioning of the system, i.e. process. Using ideal relay as nonlinearity in process of auto-tuning gives significant errors in estimates of the ultimate gain and ultimate period. In this paper mentioned lack is overcomed by introduction saturation relay, where control system of condensate level in condenser of turbine in thermal power plant Gacko is used as a model. Due to the constant striving to reduce energy consumption, above settings are implemented in the system for which is proposed strategy which provides energy savings, i.e. includes frequency regulators.
- СтавкаINFLUENCE OF ADDITIONAL Pa CONTROLLER TO THE SYSTEM RESPONSE WHEN THE SET POINT IS CHANGING(Mašinski fakultet Istočno Sarajevo, Univerzitet u Istočnom Sarajevu, 2020-11) Prodanović, Saša; Dubonjić, Ljubiša; Nedić, Novak; Radić, Nebojša; Prodanović, SašaOne of the numerous approaches for disturbance rejection is occasionally introducing additional Pa term in parallel to the existing controller. It is strongly important to check effects of its operation to the system's transient processes caused by instant changes of set point, because it is well known that too high values of P term can lead system into unstable state. Therefore, this paper deal with researching of maximum proportional gain that can be used for disturbance rejection if it appear in the transient process (dynamical area of system response). Investigation has been carried out using numeric simulations, on the some characteristic process examples, that were considered in the previous survey of mentioned additional Pa controller.
- СтавкаModified approach to distillation column control(Association of the Chemical Engineers of Serbia, 2017) Prodanović, Saša; Nedić, Novak; Filipović, Vojislav ; Dubonjić, LjubišaThis paper contains methodology research for forming the control algorithm for a distillation column, modeled as TITO (two-input two-output) process. Its modified form was obtained by connecting the two parts, and this combination hasn't been applied for such a industrial plant, until now. These parts include: a simplified decoupler which was first designed and decentralized PID controller obtained using D-decomposition method for such decoupled process. The decoupler was designed in order to make process become diagonal, and parameters of PID controllers are defined for the two SISO (single-input single-output) processes starting from relation between IE (integral error) criterion and integrator gain, taking into account desired response characteristics deriving from technological requirements of controlled plant. Their connecting provides centralized control. Analysis of the processes responses, obtained by the proposed algorithm and their comparison with the results from the literature, were performed after the completion of the simulations. The proposed approach to the centralized controller design, beside its simplicity of usage and flexibility in achieving diversity of process dynamic behavior, gives better response characteristics, in comparison with existing control algorithms for distillation column in the literature.
- СтавкаNON-CONVENTIONAL CONTROL OF LEVEL AND TEMPERATURE IN THE FLOW TANK(Faculty of Engineering Hunedoara, University Politehnica Timisoara, 2015) Prodanović, Saša; Nedić, NovakControl of multivariable processes is greatly hampered due to the presence of mutual coupling (interaction) between their inputs and outputs. Therefore, the analysis of the mutual coupling, i.e. the determination of its measure, is very important for determining further activities towards the achievement of a satisfactory behavior of the controlled object. Present paper contains synthesis of decoupler for flow tank as a multivariable process in order to achieve decentralized control of level and temperature as its outputs. Afterward, PI controllers were tuned, and the quality of this nonconventional control was confirmed through the considerations of system time responses. The research was supported by simulations, and the results represent one of approaches in forming the concept for control of multivariable processes.
- СтавкаON THE DIVERSITIES OF MULTIVARIABLE CONTROL SYSTEMS(Faculty of Mechanical Engineering, University of East Sarajevo, 2018-11) Prodanović, Saša; Nedić, Novak; Dubonjić, Ljubiša; Golubović, Dušan; Košarac, Aleksandar; Jeremić, DejanSuccessful system control can`t be achieved without taking into account system nature. Present paper contain overview of control strategies for various multivariable systems. Regarding the mathematical model, order of system and eventual presence of dead time have high influence on the choice of method, which can ensure appropriate design of decoupler and controller. All in order to ensure desired dynamical behaviour of system. Due to that, it is very important to recognize if controlled object is mechanical system or industrial process. Systems with two inputs and two outputs has been illustrated here. Consideration has been supported and presented by appropriate simulations from relevant investigations.
- СтавкаReduced Energy Cost through the Furnace Pressure Control in Power Plants(2012) Filipović, Vojislav ; Nedić, Novak ; Prodanović, SašaMaintaining pressure in the boiler’s furnace is one of the key requirements for proper combustion in steam boilers in thermal power plants. This paper proposes a control strategy that eliminates flap in the channel for the output gases. This is achieved by applying the frequency regulator for asynchronous motor speed control. Reference value for the frequency regulator is obtained through the PI controller. Special attention is given to tuning of PI controller. Well-tuned PI controller with the use of frequency regulator provides significant energy savings, because asynchronous motor for ventilator of steam boiler in thermal power plants has a large power. Modification of relay feedback experiment has supported λ-tuning of controller whose two types (faster and robust) were tuned. This modification consists in: a) Replacement of relay characteristic with saturation curve, b) Fourth-order process identification with first-order process plus dead time. The methodology is illustrated by simulations.
- СтавкаSome Considerations on Application of Relay Feedback Test to the Multivariable Systems(Faculty of Electronic Engineering-Niš; Faculty of Mechanical Engineering-Niš, 2018-11) Prodanović, Saša; Nedić, Novak; Dubonjić, LjubišaWide usage of relay feedback test for controller tuning naturally leads to numerous investigations for its improvement and extension of its application to the various objects and control strategies. Present paper contains testing possibilities for application relay feedback test to the already decoupled two input two output system. The aim is to protect system from influence of the interaction during procedure of tuning of PID controller or its shorter variants. Survey has been supported by simulations in order to prove efficiency of presented approach on the two examples of systems. The results confirm that relay feedback test can be applied simultaneously to the all loops of the previously decoupled multivariable system.
- СтавкаSome Considerations on the Decoupling Control of TITO Systems(Faculty of Electronic Engineering; Faculty of Mechanical Engineering, University of Niš, 2016) Nedić, Novak; Prodanović, Saša; Dubonjić, LjubišaProper understanding of the system nature is significant precondition for its successful control. Always actual issue about its mutual coupling was considered in this paper. Multivariable system with two-inputs and two-outputs (TITO) was in the focus here. Dominant pole placement method has been used in trying to tune PID controllers that should support decoupling control. The aim was to determine parameters of the PID controllers which, in combination with decoupler, can obtain good dynamical behavior of the system. Another goal was to simplify tuning procedure of PID controllers and enlarge possibility for introducing given approach into practice. But, research results indicate that proposed procedure leads to usage of P controllers, because they enable the best performances for the considered object. Research has been supported by simulations and therefore effectiveness of the proposed method, regarding quality of system behavior, was presented on the several examples.