Vasilis Chatziathanasiou

Intelligent system for identification and replacement of faulty sensor measurements in Thermal Power Plants (IPPAMAS: Part 1)

This paper describes a procedure of identifying sensor faults and reconstructing the erroneous measurements. Knowledge discovery in databases is successfully applied for deriving models that estimate the value of one variable based on correlated others. The estimated values can then be used instead of the recorded ones of a measuring instrument with false reading. The aim is to reassure the correctness of data entered to an optimization software application that was developed for the Thermal Power Plants of Western Macedonia, Greece. The architecture of the application follows the Multi-Agent System approach in order to cope with its complexity and distributed nature. The application was tested on a case study and proved to be efficient.

Electrothermal analysis of overhead power lines

In this work a complete coupled electrothermal analysis of overhead power lines is presented. The electromagnetic field problem is solved analytically for both the AAC and ACSR cases. The Joule losses thus computed are input to the thermal problem yielding the analytical expression of the thermal impedance. A subsequent novel dynamic thermal analysis of the almost periodic load variations during an extended time period allows the prediction of temperature fluctuations (value and delay) and the prevention of the line expansion and/or overheating.

A solution for the study and understanding of PID controllers

Today, in most automatic process control applications in industry are used PID controllers. It is very important for the students to understand how work these controllers and how important it is to make an optimal tuning of these controllers. This paper presents a solution which permits to study and understand PID controllers. This solution is a closed-loop speed control system in a centrifugal load application which permits air flow control by fans motor speed adjusts using a VFD. The PID controller is implemented in a PLC that control the VFD by CANOpen protocol.

Study about influence of power system operation and control of the piezoelectric actuators

Electronical power and control systems can decisively influence the performance of the piezoelectric engines and actuators. This paper presents the modeling of some ultrasonic motor and the role of some equipments that amplifies signals of variable frequency with the lower limit of 20 kHz and various wave forms, in order to obtain new performance in using the types of engines achieved in the Research Center EMAD from Stefan cel Mare University of Suceava and to identify new applications of the piezoelectric engines and actuators powered, controlled and monitored by the electronic systems achieved.

An Agent Based Prototype for Optimizing Power Plant Operation

Mobile networks in compared to wired networks have unique characteristics. In mobile networks, frequent network topology changes may bring about by node mobility, which are rare in wired networks. In contrast to the stable link capacity of wired networks, wireless link capacity continually varies because of the impacts from transmission power, receiver sensitivity, noise, fading and interference. Moreover, wireless mobile networks have a high error rate, power restrictions and bandwidth limitations.

Enhancing Agent Intelligence through Data Mining: A Power Plant Case Study

In this paper, the methodology for an intelligent assistant for power plants is presented. Multiagent systems technology and data mining techniques are combined to enhance the intelligence of the proposed application, mainly in two aspects: increase the reliability of input data (sensor validation and false measurement replacement) and generate new control monitoring rules. Various classification algorithms are compared. The performance of the application, as tested via simulation experiments, is discussed.

Utilizing data mining algorithms for identification and reconstruction of sensor faults: a Thermal Power Plant case study

This paper describes a procedure of identifying sensor faults and reconstructing the erroneous measurements. Data mining algorithms are successfully applied for deriving models that estimate the value of one variable based on correlated others. The estimated values can then be used instead of the recorded ones of a measuring instrument with false reading. The aim is to reassure the correctness of data entered to an optimization software application under development for the Thermal Power Plants of Western Macedonia, Greece.

Thermal impedance measurement of integrated inductors on bulk silicon substrate

Abstract The article presents the results of transient thermal measurements of a coil integrated in a silicon chip. Based on those measurements and using numerical procedures, thermal impedance, time constant distribution and structure functions were obtained. Next, using simple physical models of heat transfer phenomena, the 3 major time constants of the device under test were calculated, compared with measurement results and explained physically.

Investigation of boiling and pressure feedback on neutron noise

Abstract Boiling and pressure feedback effects on neutron noise in BWRs are investigated with a 1-D reactor model and compared with experimental measurements. It is concluded that the structure of neutron noise coherences at low frequencies can be explained by either pressure or/and boiling feedback.