Multimodeling Control via System Balancing

A new approach in multimodeling strategy is proposed. Multimodel strategies in which control agents use different simplified models of the same system are being developed using balancing transformation and the corresponding order reduction concepts. Traditionally, the multimodeling concept was studied using the ideas of multitime scales (singular perturbations) and weak subsystem coupling. For all reduced-order models obtained, a Linear Quadratic Gaussian (LQG) control problem was solved. Different order reduction techniques were compared based on the values of the optimized criteria for the closed-loop case where the full-order balanced model utilizes regulators calculated to be the optimal for various reduced-order models. The results obtained were demonstrated on a real-world example: a multiarea power system consisting of two identical areas, that is, two identical power plants

ICT Technologies in Optimization of Machines Movement at Open-Pit Coal Mine

Auxiliary machinery is used at the open-pit coal mine (machines: bulldozers, trench excavators, pipe-laying machines, ...) for performance of auxiliary work (excavation, construction of route, ....) in order to provide an uninterrupted operation of the basic machinery for excavation of waste rock and coal. Machines are moving from one area of the open-pit to another. Movement of machines along the open-pit is limited space-wise by conveyor belts serving for conveyance of waste rocks and coal, including other natural obstructions (steep slopes, mud, water). These obstructions affect the open-pit machines' length of trajectory, duration of movement and consumption of fuel. Observing the said problem, a model for optimizing the "movement" of open-pit auxiliary machinery has been developed and applied with ICT, namely GPS/GPRS and appropriate software solution, as presented herein. Model determines the "shortest" path of the machine to the job which can result in significant fuel savings and reducing failures of machines

The system order reduction via balancing in view of the method of singular perturbation

U radu je predstavljeno nekoliko tehnika za redukciju reda sistema, poznatih iz literature, koje su sve zasnovane na uravnoteženju sistema uz primenu metode singularnih perturbacija. Ove tehnike imaju istu robusnost tačnosti izračunatu u skladu sa H∞ normom sistema redukovanog reda kao i dve tehnike poznate pod nazivom direktno odsecanje i metod balansirane rezidualizacije. Modifikacija ovih tehnika zadržava tačnu vrednost pojačanja jednosmernog signala kakva je kod originalnog sistema i daje aproksimaciju od veoma dobre do odlične tačnosti na nižim i srednjim učestanostima. Efikasnost prikazanih tehnika za redukciju reda modela data je na realnom primeru.This paper presents several techniques for system order reduction, known from literature, all of them based on system balancing by employing the method of singular perturbation. These techniques have the same robustness accuracy evaluated with respect to the H∞ norm of the reducedorder system like two techniques known as the direct truncation and the balancing residualization method. A modification of these techniques preserves the exact DC gain as the original system, and produces from very good to excellent accuracy at low and medium frequencies. To illustrate the efficiency of the order-reduction techniques here presented, a real simulation example is given

The influence of magnetic field shape on dielectric characteristics of vacuum switches

Cilj ovog rada je ispitivanje uticaja oblika magnetnog polja u međukontaktnom prostoru u smislu degradacije kontakata tokom sklopnih operacija isklopa pod opterećenjem. U tom smislu statistički su analizirani rezultati merenja naizmeničnog probojnog napona i impulsnog probojnog napona. Eksperimenti su sprovedeni na komercijalnim prekidačima sa CuCr kontaktima. Parametri u eksperimentu bili su vrednost napona prilikom prekidanja struje i međukontaktno rastojanje. Ustanovljeno je da prekidači sa radijalnim magnetnim poljem u međukontaktnom prostoru trpe manje ireverzibilne promene tokom prekidanja nominalne struje i nominalne struje kratkog spoja.The aim of this paper is to examine the influence of the magnetic field shape in the inter-contact space in the context of contact degradation during the switching operation of circuit-breaking with current. The results of measuring the AC breakdown voltage and pulse breakdown voltage are statistically analyzed for that purpose. The experiments are carried out on the commercial switching elements with CuCr contact. The experiment parameters are the current breaking voltage value and inter-electrode distance. Results showed that switches with radial magnetic field suffer less irreversible changes during the breaking operation such as circuit-breaking with nominal current and circuit-breaking with short-circuit current

Linear control of nearly singularly perturbed hydropower plants

In this paper we consider a special class of linear control systems represented by the standard singularly perturbed system matrix and with the control input matrix having three different nonstandard forms. Many real systems (such as hydropower plants, systems with only few actuators) possess the control structure studied in this paper. The obtained results are quite simplified (comparing to the standard singularly perturbed control systems), and in one case the optimal solution of the algebraic Riccati equation is completely determined in terms of the reduced-order algebraic Lyapunov equations. The proposed method is successfully applied to the reduced-order design of optimal controllers for the real hydropower plant of the Serbian power system

Suboptimal design of hydroturbine governors

A state space method for the design of turbine governors in hydro power plants with Kaplan turbines is presented. The design is based on the suboptimal regulator problem solved by the use of projective controls. A design procedure that permits the design of multivariable static and low-order dynamic hydroturbine governors is proposed. It provides an organized way of choosing the governor structure and the tuning of its parameters. A case study is presented to illustrate the proposed design method and to demonstrate the extensive applicability of the suboptimal solution and its merits as compared to conventional governors

Recursive approach to Nash games of Quasi singularly perturbed linear systems

In this paper we derive an algorithm for solving the linear-quadratic differential Nash game problem of singularly perturbed systems. It is known that the general steady state solution to the above problem is given in terms of the ill-conditioned coupled algebraic Riccati equations. We show that for a special class, so-called quasi singularly perturbed systems, the positive definite stabilizing solutions of the coupled Nash algebraic Riccati equations can be obtained in terms of reduced-order well-conditioned algebraic equations corresponding to slow and fast variables

Exact decoupling of non-classically damped matrix second-order linear mechanical systems

Matrix second-order damped linear dynamic systems are frequently encountered in mechanical, structural, civil, aerospace engineering, and related fields. This class of systems is also obtained by approximating dynamics of systems described by partial differential equations (distributed parameter systems). There are many papers in the engineering literature on analysis and control of matrix second-order linear damped systems. They provide either approximate (simplified) analytical results or accurate numerical results (usually computationally involved). In this paper, we show how to decouple exactly a matrix second-order linear system into scalar second-order subsystems and study exactly the corresponding system dynamics at the subsystem level using simple analytical tools. Conditions are established under which the presented procedure is applicable. An example is included to demonstrate the efficiency of the proposed technique

The method for mathematical model reduction of the process control systems

Matematičko modelovanje realnih fizičkih sistema sa dovoljnom tačnošću ali i jednostavnošću za razne primene predmet je proučavanja dugi niz godina. Posebno su od interesa pojednostavljeni matematički modeli za dinamičke analize i sinteze upravljačkih algoritama. U radu će biti prikazano nekoliko poznatih tehnika za snižavanje reda sistema, koje su zasnovane na balansiranju sistema uz primenu metode singularnih perturbacija. Ove tehnike imaju istu tačnost i robusnost procenjenu prema H∞ normi sistema sniženog reda kao i metoda direktnog odsecanja i metoda balansiranja rezidualizovanog modela sistema. Prikazana je i modifikacija tehnike koja obezbeđuje tačnu vrednost pojačanja konstantnog ulaza kao kod originalnog modela sistema. Testirane tehnike daju odličnu tačnost na nižim i srednjim učestanostima. Za ilustraciju efikasnosti prikazanih metoda za snižavanje reda sistema izabrani su realni primeri iz procesne i vazduhoplovne industrije.The mathematical modeling of real world systems has been treated from different viewpoint. Usually, two opposite demands have to be fulfilled: the model must be accurate but simple for dynamic analysis and control synthesis. This paper presents several techniques for system order reduction, all of them based on system balancing by employing the method of singular perturbation. These techniques have the same robustness accuracy evaluated with respect to the H∞ norm of the reduced-order system as the two techniques known as the direct truncation and balancing residualization methods. A modification of techniques is described that preserves the exact DC gain as the original system, and produce very good to excellent accuracy at low and medium frequencies. To illustrate the efficiency of the order reduction techniques here presented, a real simulation examples from process and airspace industry are presented

Optimal SIR-based power updates in wireless CDMA communication systems

In this paper we present two new control algorithms that potentially can be used as efficient techniques for power updates in wireless CDMA communication networks. The algorithms are obtained by optimizing the signal-to-interference error. The control laws are distributed, respectively linear and bilinear, and require either estimation of the channel interference (or a quantity inversely proportional to the signal interference) or the development of efficient numerical algorithms for solving the set of algebraic equations obtained. In addition, ideas of how to accelerate the convergence of a Nash game power control algorithm are presented