Wyniki wyszukiwania - BazTech

1

Design of robust multi-loop PI controller for improved disturbance rejection with constraint on minimum singular value

Arun Pathiran, Muniraj Rathinam, Boselin Prabhu S.R., Jarin T., Willjuice Iruthayarajan M.

Archives of Control Sciences

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2023

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Vol. 33, No. 4

839--859

EN

Disturbance rejection performance optimization with constraints on robustness for a multivariable process is commonly encountered in industrial control applications. This paper presents the tuning of a multi-loop Proportional Integral (PI) controller method to enhance the performance of load disturbance rejection using evolutionary optimization. The proposed design methodology is formulated to minimize the load disturbance rejection response and the input control energy under the constraints of robust stability. The minimum singular value of multiplicative uncertainty is considered a multi-loop system robust stability indicator. Optimization is performed to achieve the same, or higher level than the most-explored Direct Synthesis (DS) based multi-loop PI controller, which is derived from a conventional criterion. Simulation analysis clearly proved that the proposed multi-loop PI controller tuning method gives better disturbance rejection, and either, the same or a higher level of robust stability when compared to the DS-based multi-loop PI controller.

2

A decentralized control strategy to bring back frequency and share reactive power in isolated microgrids with virtual power plant

Khanjanzadeh Amir, Soleymani Soodabeh, Mozafari Babak

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 1

art. no. e136190

EN

In this paper, a novel Power-Frequency Droop Control (PFDC) is introduced to perfectly bring back the system frequency and share the reactive power in isolated microgrid with virtual power plant (VPP). The frequency-based power delivery must be essentially implemented in VPP which can operate as a conventional synchronous generator. It has been attained by enhancing the power processing unit of each VPP to operate as an active generator. The inverter coupling impedance which has been assigned by the virtual impedance technique has reduced the affected power coupling resulting from line resistance. The reference has been subsequently adjusted to compensate the frequency deviation caused by load variation and retrieve the VPP frequency to its nominal value. In addition, the line voltage drop has compensated the voltage drop and load sharing error to obliterate the reactive power sharing imprecision resulting from the voltage deviation. The voltage feedback confirms the correct voltage after compensating the voltage drop. As an illustration, conventional PFDC after a load change cannot restore the system frequency which is deviated from 50 Hz and rested in 49.9 Hz while, proposed PFDC strategy fades away the frequency deviation via compensating the variation of the frequency reference. Likewise, the frequency restoration factor ( γ) has an effective role in retrieving the system frequency, i.e., the restoration rate of the system frequency is in proportion with γ. As a whole, the simulation results have pointed to the high performance of proposed strategy in an isolated microgrid.

3

Decentralized controller for software interconnected system subject to malicious attacks

Kishore Pushkar, Barisal Swadhin Kumar, Mohapatra Durga Prasad

Annals of Computer Science and Information Systems

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2021

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Vol. 26

211--218

EN

This paper examines the decentralized controller for a software interconnected system subject to malicious attack. The security of software interconnected system (SIS) subject to malicious attacks is discussed using Event-Triggered Mechanism (ETM). We design a novel ETM with decentralized feedback for managing resources and keeping system stable during attacks. We use Numenta-Hierarchical Temporal Memory (N-HTM) for monitoring the ETM values. Numerical simulation of service provider system is considered for illustrating our model's effectiveness. Experiments reveal that our model stabilizes system after an average of 2s from the launch of last attack. Average consumption of the resources is reduced by 70%.

4

Decentralized PID control by using GA optimization applied to a quadrotor

Hasseni S. E. I., Abdou L.

Journal of Automation Mobile Robotics and Intelligent Systems

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2018

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Vol. 12, No. 2

33--44

EN

Quadrotors represent an effective class of aerial robots because of their abilities to work in small areas. We suggested in this research paper to develop an algorithm to control a quadrotor, which is a nonlinear MIMO system and strongly coupled, by a linear control technique (PID), while the parameters are tuned by the Genetic Algorithm (GA). The suggested technique allows a decentralized control by decoupling the linked interactions to effect angles on both altitude and translation position. Moreover, the using a meta-heuristic technique enables a certain ability of the system controllers design without being limited by working on just the small angles and stabilizing just the full actuated subsystem. The simulations were implemented in MATLAB/Simulink tool to evaluate the control technique in terms of dynamic performance and stability. Although the controllers design (PID) is simple, it shows the effect of the proposed technique in terms of tracking errors and stability, even with large angles, subsequently, high velocity response and high dynamic performances with practically acceptable rotors speed.

5

A computational scheme for decentralized time-optimal resource allocation in a sequence of projects of activities under constrained resource

Stankiewicz A.

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes

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2016

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Vol. 5, No 3

83--94

EN

We consider a sequence of projects of independent activities; each project composed of activities available for realization at the same time. It is assumed that the activities are continuous dynamical systems whose dynamics depend continuously on the allotted amounts of the resource, and the initial and terminal states are fixed. The problem is to allocate a renewable, continuously divisible resource (e.g., power, fuel flow, money per time unit, approximate manpower) to the activities in order to minimize the performance time of the sequence of projects under the assumption that the allowable level of the total usage of the resource is constant. Although the solution to this problem is known in the literature, nevertheless there is a lack of effective computational algorithms for the time-optimal resource allocation, especially in the case of really large projects. In this paper a decentralized two-level control scheme using the time-decomposition is proposed to find the time-optimal resource allocation in a sequence of projects. The price mechanism is applied to coordinate the lower level tasks of the optimal resource allocation in the successive time intervals determined by the moments at which the successive projects are available for realization. Necessary and sufficient conditions to ensure the determination of the optimal resource allocation according to the method proposed are stated. The problems connected with the numerical realization of the scheme are discussed and the resulting computer algorithm is outlined.

6

Input-output pairing criterion applied in the genetic algorithm for unstable linear systems

Baban P. Q., Rahimabadi I. N.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2016

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Vol. 64, nr 4

873--876

EN

In this paper, a new approach towards input-output pairing for an unstable system has been proposed. First, it is demonstrated that the previous method of input-output pairing for unstable plants cannot find appropriate pairs as it only checks necessary conditions for stability and integrity. Then, a new approach using relative error matrix and genetic algorithm for finding appropriate pairs in unstable systems is proposed. As it is shown, this approach takes into consideration both static and dynamic information of plant in measuring interaction. Finally, the accuracy of proposed method is demonstrated by an example and closed loop simulation.

7

Nash equilibrium design and price-based coordination in hierarchical systems

Karpowicz M. P.

International Journal of Applied Mathematics and Computer Science

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2012

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Vol. 22, no. 4

951-969

EN

This paper deals with the problem of designing Nash equilibrium points in noncooperative games in which agents anticipate values of Lagrange multipliers coordinating their payoff functions. The addressed model of agents' interactions, referred to as the price-anticipation game, is studied within the framework of coordination and mechanism design theory for hierarchical systems. Sufficient conditions are formulated for Nash implementation of a regular and isolated solution to a coordination problem. An equilibrium design procedure is proposed and applied as an analytic tool in a study of mechanism design games. In the setting considered the well-known fact is demonstrated that gains from reaching a desired solution to a coordination problem in a Nash equilibrium point need not balance the overall costs of its implementation. However, it is also demonstrated how these costs can be distributed among the agents and related to the particular organization of interactions in the system. Finally, application of the developed framework in the field of Internet traffic engineering is presented.

8

Pairwise control principle in large-scale systems

Filasova A., Krokavec D.

Archives of Control Sciences

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2011

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Vol. 21, no. 3

227-242

EN

The purpose of the paper is present an algorithm of partially decentralized control design for one type of large-scale linear dynamical system. The pairwise autonomous principle is preferred where design conditions are derived in the bounded real lemma form, and global system stability is reproven to formulate potential application principle in fault tolerant control. The validity of the proposed method is demonstrated by the numerical example.

9

Robust output feedback Model Predictive Control design

Vesely V., Rosinova D.

Archives of Control Sciences

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2010

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Vol. 20, no. 3

303-316

EN

The paper addresses the problem of designing a robust output/state model predictive control for linear polytopic systems without constraints. The new robust BMI stability condition for given predictive and control horizon is derived which guarantees the parameter dependent quadratic stability and guaranteed cost.The proposed condition is appropriate for centralized and decentralized control design, as illustrated on example.

10

A matrix inequality based design method for consensus problems in multi-agent systems

Zhai G., Okuno S., Imae J., Kobayashi T.

International Journal of Applied Mathematics and Computer Science

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2009

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Vol. 19, no 4

639-646

EN

In this paper, we study a consensus problem in multi-agent systems, where the entire system is decentralized in the sense that each agent can only obtain information (states or outputs) from its neighbor agents. The existing design methods found in the literature are mostly based on a graph Laplacian of the graph which describes the interconnection structure among the agents, and such methods cannot deal with complicated control specification. For this purpose, we propose to reduce the consensus problem at hand to the solving of a strict matrix inequality with respect to a Lyapunov matrix and a controller gain matrix, and we propose two algorithms for solving the matrix inequality. It turns out that this method includes the existing Laplacian based method as a special case and can deal with various additional control requirements such as the convergence rate and actuator constraints.

11

Sterowanie rozproszone systemem zasilania bezprzerwowego

Strzelecki R., Wojciechowski D., Rutkowski M.

Przegląd Elektrotechniczny

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2007

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R. 83, nr 12

33-36

PL

W referacie przedstawiono propozycję jednofazowego systemu zasilania bezprzerwowego (UPS) zbudowanego w oparciu o pracujące równolegle moduły przekształtników DC-AC-DC-AC z separacją galwaniczną. Opisano opracowany i zastosowany w układzie system komunikacji pomiędzy modułami oparty na warstwie fizycznej CAN, obsługujący sterowanie rozproszone typu master-slave pozwalające na uzyskanie wysokiej dyspozycyjności systemu UPS. Układy sterowania poszczególnymi modułami zaprojektowano tak, aby zapewniały wysoką jakość napięcia wyjściowego przy obciążeniu odbiorami zarówno liniowymi jak i nieliniowymi. Przedstawiono wybrane wyniki badań symulacyjnych i laboratoryjnych układu z modułami o mocy 5kVA.

EN

The paper presents the single phase uninterruptible power supply (UPS) system with galvanic separated DC-AC-DC-AC converters operating in parallel. The CAN physical layer based system of communication between converters has been developed and applied, which allow to utilize a decentralized master-slave control providing high availability factor of the whole UPS system. The control system of particular converters has been developed to ensure a high quality of the output voltage for both linear and nonlinear load. The selected simulations and experimental results obtained for 5kVA prototype modules are presented.

12

Decentralized structural control approach for Petri nets

Aybar A.

Control and Cybernetics

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2007

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Vol. 36, no 1

143-159

EN

The structural controller, described by adding the control places to the Petri nets, is introduced in this work to lead the Petri net to the desired marking vectors. An algorithm (Algorithm I) is developed to determine the control places for the given Petri net. The connections and the initial marking of each control place are determined in this algorithm. Moreover, a decentralized structural control approach, based on overlapping decompositions, is introduced in this work. In this decentralized approach, all disjoint Petri subnets, which are obtained by using overlapping decompositions, are determined. The control places for each Petri subnet are determined by using the given algorithm. Then, the control places for the orginal Petri net are obtained by the control places of each PSN by another algorithm (Algorithm II) and these places are added to the orginal Petri net. Therefore, a decentralized structural controller which guarantees to lead the Petri net to the desired marking vectors is obtained.

13

Hierarchical control in a large scale stochastic system with nonclassical information structure

Duda Z., Brandys W.

Archives of Control Sciences

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2003

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Vol. 13, no. 4

493-504

EN

In the paper a synthesis of a control law for a large scale stochastic system is presented. The system composed of coupled linear subsystems and quadratic performance index which should be minimized, is considered. The problem is solved in a two-level hierarchical control structure wtih a coordinator on an upper level and local controllers on a lower level. An algorithm, in which it is possible to partially decompose calculations and to realize decentralized control, is proposed. a simple example is presented.

14

An approach to decentralized adaptive control

Perutka K., Bobal V.

Archives of Control Sciences

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2003

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Vol. 13, no. 1

33-46

EN

The paper presents a way of control of decentralized two inputs two outputs (TITO) systems. The base of the approach is usage of the set of one-dimensional self-tuning controllers wiyh reduced orders, being tuned simultaneously, in contrast to methods using relays in feedback. A method of the recursive least squares with directional forgetting factor applied to the continuous-time system is used as the identification algorithm for the self-tuning controllers. Itobtains data using the differential filters. verification was done in MATLAB-SIMULINK on the systems with "P" and "V" structures. two methods of tuning the controllers were used: the suboptimal linear quadratic method, and the dynamics inversion method. This approach give good results, and enables to use arbitary method of tuning the controllers, in particular, to apply the approaches of control of SISO systems, which are quite common for the multi-variable systems.

15

Fuzzy adaptive-predictive decentralized control of discrete time interconnected systems

Tzafestas S., Kyriannakis E., Apostolikas G.

Systems Science

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2002

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Vol. 28, nr 1

5-24

EN

Proposes an approach for the design of discrete-time decentralized control systems with m-step delay sharing information pattern, employing model-based predictive control (MBPC) combined with fuzzy prediction for the interconnections among the subsystems. A state space model is used at each control station to predict the corresponding subsystem output over a long-range time period. The interaction trajectories are considered to be non-linear functions of the states of the subsystems. For all cases the interconnections and the necessary predictions for them are estimated by an appropriate adaptive fuzzy identifier based on the generation of linguistic IF-THEN rules and the on-line construction of a common fuzzy rule base. Representative computer simulation results are provided and compared for nontrivial example systems.

16

Decentralized Variable Structure Tracking for Systems With Time-Domain Dominance

Balluchi A., Bicchi A.

International Journal of Applied Mathematics and Computer Science

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1999

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Vol. 9, no 2

265-291

EN

In this paper, we consider the design of tracking controllers for linear MIMO systems described by an input-output model. The presence of known 'weak' interactions among SISO or MIMO subsystems may allow the designer to achieve objectives by using independent controllers of lower complexity than are necessary in general (control decentralization problem). Sufficient conditions for asymptotic tracking employing decentralized variable structure techniques are derived. The condition is shown to be closely related to (and in a sense, a time-domain counterpart of) dominance criteria used in frequency-domain techniques, as they have developed out of Rosenbrock's original diagonal dominance concept. The synthesis of a decentralized variable-structure controller for asymptotic tracking is illustrated for systems obeying some conditions on their nominal relative degrees.