Mario Vrazic

Measurement of Excitation Winding Temperature on Synchronous Generator in Rotation Using Infrared Thermography

A new measurement method for infrared (IR) surface temperature measurement of excitation winding in rotation is presented. The method is experimentally verified on a 400-kVA salient pole synchronous generator. This method uses an industrial IR thermometer which represents an alternative to expensive fast IR thermometers or cameras. The target application of this method is the determination of the dynamic limit in the P-Q diagram of a synchronous generator due to excitation winding overheating. The measurement error model which shows the way how to minimize measurement error has also been derived. The effect of the interpolar surface can be cancelled if the IR thermometer is positioned at a certain angle with respect to the machines main axis. Digital temperature sensors have been mounted on the rotor to measure the excitation winding surface temperature for comparison.

Bluetooth wireless communication and 1-wire digital temperature sensors in synchronous machine rotor temperature measurement

This paper addresses the usage of digital temperature sensors in rotor temperature measurement. A rotor temperature measurement system had to be developed because of the complete synchronous machine thermal analysis. Rotor temperatures are measured using multiple DS18B20 digital thermometers and sent via a wireless link to the host. The measurement system has been mounted on a 400 kVA synchronous generator and the temperature measurements in rotation are presented.

Design of an Axial Flux Permanent Magnet Synchronous Machine Using Analytical Method and Evolutionary Optimization

The design optimization of an axial flux permanent magnet synchronous machine with a coreless stator and double external rotor is accomplished by using evolutionary optimization with a genetic algorithm and an analytical evaluation of objective functions. On the basis of eight variable geometry parameters, five objective functions are optimized in order to determine the maximum volume torque density and weight torque density, the minimum volume and weight of permanent magnets per Newton-meter, and the minimum machine price per Newton-meter. Based on the geometric parameters for minimum machine price per Newton-meter, a prototype is built for the rated torque. Optimized and analytically evaluated machine characteristics are validated with a finite-element method (FEM) and the measurements of a prototype. Evolutionary optimization with the analytical evaluation of objective functions significantly shortens the computational time required for design optimization in comparison with the FEM.

Comparison of expected and measured values of luminance sensors in dual-axis photovoltaic positioning system

A dual-axis photovoltaic positioning system has a primary task of directing a PV module towards the optimal light source. The idea of positioning a loop requires proper information on the PV module direction in order to get more insolation, i.e. more energy. The assumption of a proper luminance sensor distribution and position is described in this paper. With this distribution every angle position is described by a unique combination of luminance sensor readings. This paper compares expected readings and measured readings of a real mechanical model.

Some problems of synchronous hydro-generator temperature measurement

During complex measurements on synchronous hydro-generator 35 MVA, among other measurements, temperature measurement of stator winding end was realized. The real aim of this temperature measurement was to determine influence of excitation winding on armature windings during different operation points. This paper describes the measurement procedure, measurement system and some problems that occurred during this measurement.

Study of a vehicle conversion from internal combustion engine to electric drive

A conversion of an internal combustion engine vehicle (ICE) to an electric drive vehicle (EV) was a project carried out at the Faculty of Electrical Engineering and Computing (FER). This project has lead to valuable conclusions about the ICE to EV conversion, its costs and benefits. The whole process of conversion will be presented in this article, including the applied regulations, total labor and components expenses. Finally, an analysis of the conversion cost-benefit ratio has been done, taking into account lower fuel prices, maintenance costs, battery life etc. The comparison was done between an EV and a diesel ICE vehicle.

Structure of physical model for research of traction parameters of electrical vehicle

This paper will present a laboratory model for research of traction parameters of electrical vehicle. Closely, this laboratory model is used for research of electrical drive. The detailed description of laboratory model and some recorded data will be presented.

Calculation of no-load saturation curve for wound field synchronous machines based on magnetic equivalent circuits and conformal mapping

This paper describes a method for calculation of the no-load saturation curve for wound field synchronous machines based on magnetic equivalent circuits and conformal mapping. The method uses conformal mapping to calculate reluctances of the magnetically active parts of the machine which are then used in magnetic equivalent circuit for the calculation of magnetic fluxes. Proposed method is applied to a salient, six-pole, 400 V, 50 Hz synchronous machine with double layered armature winding and obtained results are compared with finite element method.

Influence of mounting temperature probes on the excitation winding on its temperature field

Accurate and reliable information about the temperature of the synchronous generator excitation winding hot spot is necessary to determine the dynamic limit caused by excitation winding overheating in the PQ diagram. For good estimation of a position and the hot spot temperature it was decided to mount 19 temperature probes on one pole of the 6-pole, 400 kVA, 50 Hz synchronous generator. Due to a large number of the probes and because the probes should be glued with the metal epoxy it was assumed that mounting of the probes will disrupt the temperature field of the excitation winding. To get the answer to this question the excitation winding resistance was measured before and after mounting the probes, in a hot and a cold state. Temperature rise can be estimated if the resistance ratio in the hot and the cold state is known. The paper also addresses the analysis of the measurement accuracy.

Hibrid drive dimensioning using MATLAB software package

The paper analyses vehicle dynamics during operation (drive wheel load). Parameters for the vehicle model were calculated from the vehicle force equations. To validate the model, speed and torque measurements on the conventional car (Fiat Punto) were carried out as well as a comparison between the measured and the simulated values. The electric motor, inverter and batteries were dimensioned on the basis of the vehicle traction characteristics. Models of the internal combustion engine (ICE), gear box and electrical drive (a motor with an inverter and batteries) were made. A comparison of hybrid and conventional drives and fuel consumption were made.