- TITLE:
THE EFFECT OF DIFFERENT SKY TEMPERATURE MODELS ON THE ACCURACY IN THE ESTIMATION OF THE PERFORMANCE OF A PHOTOVOLTAIC MODULE
- AUTHOR(S):
Bojan Perović, Dardan Klimenta, Miroljub Jevtić, Miloš Milovanović
- ABSTRACT:
This paper considers the effect of different sky temperature models on the accuracy in the
estimation of the performance of an open-rack-mounted photovoltaic (PV) module. It is found that,
for the same ambient conditions, the temperatures of the PV module calculated using individual sky
temperature models deviate, on average, by about 4 °C from the measured one. Further, this causes
an error in the estimation of the power output of the PV module that can not be ignored when a
precise performance analysis is required. The effect of different sky temperature models is estimated
using a heat balance equation of the PV module, where the term related to long-wave radiation heat
exchange between the sky and the PV module’s upper surface is significantly affected by the sky
temperature. Based on comparisons between the calculated and measured temperatures of the PV
module considered, sky temperature models, providing the best results, are singled out. Furthermore,
it is pointed out which models have the largest deviations.
- PAGES:
78-
- DOWNLOAD:
THE EFFECT OF DIFFERENT SKY TEMPERATURE MODELS ON THE ACCURACY IN THE ESTIMATION OF THE PERFORMANCE OF A PHOTOVOLTAIC MODULE
- TITLE:
EXPERIMENTAL COMPARISON OF SEVERAL FLUX ESTIMATION TECHNIQUES IN INDUCTION MACHINES
- AUTHOR(S):
Marko Rosić, Miroslav Bjekić, Marko Šućurović, Vojislav Vujičić
- ABSTRACT:
In order to estimate AC machine torque with high accuracy, high quality machine flux estimation
should be done before. The paper analyzes several basic flux estimation techniques in induction
machines with their cons and pros. Four mostly used flux estimation methods are described
theoretically after which experimental results are presented. Experimental results of analyzed
estimation techniques are compared to the built-in estimation flux algorithm implemented DSP
MSK2812 setup within application based on field-oriented control (FOC). At the end of the paper,
proper discussion of experimental results and most important conclusions are drawn.
- PAGES:
72-
- DOWNLOAD:
EXPERIMENTAL COMPARISON OF SEVERAL FLUX ESTIMATION TECHNIQUES IN INDUCTION MACHINES
- TITLE:
MEASUREMENT UNCERTAINTY OF TEST STATION FOR MEASUREMENT OF ENERGY EFFICIENCY OF ELECTRICAL MACHINES
- AUTHOR(S):
Branko Koprivica, Marko Šućurović, Alenka Milovanović, Srđan Divac
- ABSTRACT:
The aim of this paper is to present the method for calculation of measurement uncertainty of test
station for measurement of energy efficiency of electrical machines. Energy efficiency has been
measured by direct method in accordance to international standard IEC 60034-2-1. Measurement
uncertainties of all electrical and mechanical quantities of influence have been used for calculation
of combined and extended measurement uncertainty. The paper contains the results of measurement
of energy efficiency of the induction motor, model of energy efficiency, results of calculation of
measurement uncertainty, as well as a discussion of all the results presented.
- PAGES:
69-
- DOWNLOAD:
MEASUREMENT UNCERTAINTY OF TEST STATION FOR MEASUREMENT OF ENERGY EFFICIENCY OF ELECTRICAL MACHINES
- TITLE:
ANALYSIS OF COMPRESSOR EQUIPMENT OPERATION OF INDUSTRIAL SYSTEM
- AUTHOR(S):
Maria Raykova, Ivaylo Cviyatkov
- ABSTRACT:
An analysis was made of the operation of the industrial system compressor equipment for the two
modes of operation with and without frequency controller. The effect achieved by the presence of a
frequency controller is determined.
- PAGES:
62-
- DOWNLOAD:
ANALYSIS OF COMPRESSOR EQUIPMENT OPERATION OF INDUSTRIAL SYSTEM
- TITLE:
THE CHARACTER OF THE TRANSFER PHENOMENON IN THE WORK PROCESSES OF THE HYDRAULIC DAMPER
- AUTHOR(S):
Ihor Nochnichenko, Oleg Jakhno, Ihor Liberatskyi
- ABSTRACT:
The article considers the nature of the transport phenomenon, which is usually considered at
three hierarchical levels: macroscopically, microscopic, and molecular. It is shown that the viscosity
transfer coefficient significantly affects the resistance of the hydraulic damper and depends on the
level of consideration of the medium, work processes and their rheological properties of the working
fluid. Technical visualization of the working processes of the movement of the working fluid through
the throttles and valves made it possible to study the hydrodynamic processes and establish the
conditions for the formation of foaming and cavitation, which leads to the appearance of a two-phase
flow of the working fluid.
- PAGES:
58-
- DOWNLOAD:
THE CHARACTER OF THE TRANSFER PHENOMENON IN THE WORK PROCESSES OF THE HYDRAULIC DAMPER
