Catalin Petrescu

Switching Solution for Multiple-Models Control Systems

Systems with multiple models or multi-controller structure represent one of the successful solutions for the real-time control of the nonlinear or multi-regime processes. The use of these structures imposes solving some specific problems, like best algorithm selection or control algorithm switching. The paper proposes a method for switching the algorithms of the multiple-models structure, based on the principles of manual to automatic bumpless transfer. The applicability of the method is proved using a real-time structure with an RST control algorithm. In the end, its software implementation is also shown

A WSN Based Monitoring System for Oil and Gas Transportation through Pipelines

Abstract This article introduces some results obtained in monitoring of long pipelines employed in oil and gas transportation. A mobile unit for signals acquisition, processing, identification and diagnosis (MUSAPID), based on wireless sensors networks (WSN) technology was employed. The MUSAPID architecture was adapted to match the configuration of monitoring system, inspired by the national energy dispatcher. Thus, the system includes four hierarchical levels assigned to: the central dispatcher, the zonal dispatcher, the local dispatcher and the sensor nodes. The sensors are acquiring the flow and temperature of oil from the monitored pipeline. Sensors distribution along the pipeline is of in-line type. Nevertheless, a cross-link schema between sensor nodes is proposed, in order to increase the exploitation safety and to reduce false alarms sending. Two independent monitoring approaches based on comparison between values of sensors in pairs of successive nodes allow controlling the occurrence of rifts and leaks in the pipeline network. One of the approaches is unconventional and uses inter-correlation between the data acquired from two successive sensor nodes, as well as auto-correlation of temperature data. A simple logic to avoid sending false alarms was also implemented.

Control and Optimization for Steel Plant Preheating Installations

Abstract The paper presents the results of the research performed by the authors on control systems and optimization for the operating process of the heating installations from the blast furnace at a steel plant. This system was developed on two relevant levels interconnected in a hierarchical control structure. The acquisition and control level

Some Considerations About the Refinements and the Accuracy of PID-Controllers

Abstract In now-days, the PID controllers are still implemented in the industrial applications of automatic control. The purpose of this paper is to improve the PID standard algorithm evaluating the PID control output value by some numerical refined methods and by computational accuracy of the hardware support. The experimental results were obtained in simulation, using a second-order closed-loop system with a first order plant model with time delay.

Photovoltaic Generators -- Modeling and Control

The goal of this article is to introduce a solution for modeling and control of a photovoltaic power plant. Two issues are addressed in this aim. The first one is concerned with the mathematical model of a photovoltaic cell and to tracking of the maximum power point. The second problem deals with the boost converter: how to obtain a desired and stable output voltage even though the input represented by tension from photovoltaic panel is unstable, influenced by internal parameters as resistivity and affected by perturbations.

Control and optimization for a petrochemical reactor

The main objective of this work is the design and implementation a numerical control solution for the ethylene reactor, the key-installation in the petrochemical industry. We introduce some technological characteristics of this petrochemical process and the main aspects about the control system solution for the process plant. A robust control strategy for numerical control systems are proposed. Finally, we found an optimal operating point, considering that the process has a nonlinear multivariable structure. The results have been implemented on an assembly of pyrolysis reactors on the petrochemical platform from Pitesti, Romania.

New approach for the control and the determination of attractors for nonlinear systems

For the attractor determination, we propose in this paper a new approach based on the definition of a comparison system by special description of the linearized model of the process around an operating state which correspond to a diagonalization or if it is not possible to the description with a matrix on the arrow form, and the use of aggregation techniques. As an illustration, this approach is applied with success for the case of a third order non linear system.

Balancing Strategy for Ratio Control Structures

The article represents a performance solution of (re)balancing a parallel control structure and maintaining the ratio between two adjustment quantities. The solution is based on the structures introduced by Visioli [1]. Applicability is proved on a control structure of the ratio where using two groups of tanks, a situation that has been encountered in the chemical industry, pharmaceutical industry and food industry etc.

Artificial Neural Network Based Model of Photovoltaic Cell

This work concerns the modeling of a photovoltaic system and the prediction of the sensitivity of electrical parameters (current, power) of the six types of photovoltaic cells based on voltage applied between terminals using one of the best known artificial intelligence technique which is the Artificial Neural Networks. The results of the modeling and prediction have been well shown as a function of number of iterations and using different learning algorithms to obtain the best results.

Design consideration on algorithms and control structures for photovoltaic grids

The main issue of paper consist in proposing a few algorithms and control structures for PV grids which can increase predictability and flexibility degrees with respect to specific disturbances. The starting point of our model is the division of the PV grid in subgroups of optimal dimension and pairings that offer minimal variation between the quantity of energy needed and the one prognosticated. We propose several strategies of choosing the dimension of subgroups and an algorithm for optimization. The structures obtained in this way are tested in a scenario that assumes modifications of both the set point and also the existence of a global and local perturbation. All of the structures were implemented in multiple experimental Matlab-Simulink simulators.