Name
Grigorash Oleg Vladimirovich
Scholastic degree
•
Academic rank
professor
Honorary rank
—
Organization, job position
Kuban State Agrarian University
Web site url
—
Articles count: 65
One of the important issues in the design of static
converters of electric power, i.e. rectifiers and
inverters, is to calculate the parameters of the output
and the input filters. Output filters are designed to
improve the quality of output voltage of inverters, and
input filters are created to reduce ripple of the input
voltage of the converter that occur when commuting
power semiconductor devices, and smoothing
fluctuations of the current consumed from the power
supply. The complexity of analytical description of
the harmonic composition of the output and the input
of the voltage rectifiers and inverters makes it
difficult to develop some accurate methods for
calculating the parameters of their filters. At the same
time, considering the discreteness of the number of
possible parameters of real elements of the filter, the
practical value of such techniques with a high analysis
accuracy of the harmonic components is negligible. In
this article, we suggest the technique of the simplified
calculation of output and input filters for passive LC
filters rectifiers and inverters. At the same time, the
practice of mathematical modeling and design of
transducers has shown that the calculations of the
filter parameters for rectifiers and inverters are not
significantly different from each other. Therefore, the
analytical expressions for calculation of the filter
parameters of rectifier used ripple coefficient, and if
necessary the calculation of the filters of the inverter,
instead of the pulse number in the formula can be
substituted with the value of the harmonic; in
addition, we have also taken into account the value of
the load power factor
Currently operating in autonomous systems of power
supply DC voltages power sources are secondary
sources for operation devices, protection and control
of generators, motors, stabilizers and inverters have
relatively low operational performance. The work
proposes to improve the weight and the size of power
supplies to apply a high frequency link in their
designs. We provide structural designs and the
peculiarities of operation of secondary power sources
with a high frequency link. This article discusses the
fundamental electrical circuits of pulse regulators,
converters based on resonant inverters and
transformers with rotating magnetic field. The use of
resonant inverters in power sources will significantly
improve their weight and overall dimensions. In
addition, the use of secondary sources of supply for
transformers with rotating magnetic field will
simplify their design and reduce the level of
electromagnetic interference generated by
semiconductor devices. The features of operation of
pulsed regulators and prospective structuralschematics
converters discussed in the article,
performed on resonant inverters and transformers
with rotating magnetic field, will increase the
effectiveness of pre-work on the development of
secondary power sources with improved operational
and technical characteristics for devices of operating,
control and protection
Modern universities do not have effective
techniques for evaluating the quality of education
of students and effectiveness of teachers' activity
that allows controlling and directing its activities.
We have proposed to perform the quality evaluation
of students preparation based on the results of
intermediate assessments, examinations, and test
results of the teachers, who held their classes. The
article provides analytical expressions for
calculating the quality of the current preparation of
students and the quality of education of graduates,
the effectiveness of teachers in core activities
(educational, methodical and scientific work). In
assessing the quality of education, we have
considered the learning outcomes, employment
potential, i.e. educational and labor activity. The
proposed techniques will increase the objectivity of
the assessment of the quality of graduates’
education in technical universities and the
effectiveness of teachers. This will allow us to
make changes in the organization of educational
process and the content of working programs of
training, educational and methodical and material
and technical support, to change the contents and
technologies of improvement of qualification of the
teaching staff that will contribute to increase
demand for graduates in the labor market
In agricultural production, the direction of introduction
of renewable energy for power consumers remote from
the external electrical network is relevant. Here,
prospects are revealed in front of the solar PV stations.
One of the main functional units of solar power is
inverters that convert the DC voltage of the solar
panels into alternating current. The article describes
the advantages and disadvantages of the main methods
of voltage regulation of the autonomous inverters of
solar photovoltaic power plants. We have proposed
new structural designs of autonomous voltage
inverters, described their advantages, features of
design and operation for voltage stabilization. We
suggest stand-alone inverters designed using high
frequency link, which will significantly improve mass
and dimensions parameters of the converter. Due to the
use of single-phase transformer with a rotating
magnetic field in stand-alone inverters, we improve the
efficiency of the converter and the reliability of the
work. Patents of the Russian Federation confirmed the
novelty of technical solutions of the considered
schemes of autonomous voltage inverters. Structural
schematics of the voltage regulators considered in the
article, as well as features of their work, will allow to
increase efficiency of preliminary works on
development of autonomous voltage inverters with
improved operational and technical characteristics for
solar photovoltaic power plants
The article reveals the basic principle of stabilizing
the DC voltage, providing automatic control of
electrical devices and electrical equipment, control
systems, control and protection, etc. There are
functional diagrams (operated and promising) of DC
voltage stabilization with a device included in the
input and output power circuits of the rectifier, and a
new structural solution to a functional circuit of the
rectifier made of two controllable power electronic
devices and transformer with midpoint. The article
lists peculiarities of the circuits of the voltage
regulators and their main advantages and
disadvantages. We have reviewed functional
diagrams of existing and new solutions of the
stabilizers and the characteristics of their work; it
will increase the effectiveness of pre-project works
on the development of stabilizers of the DC voltage
with improved performance characteristics. This
article might be useful for post-graduates and
research workers who are involved in the
development of DC voltage stabilizers
The main structural units of the University are
departments; the results of their work influence the
quality of knowledge, skills and competence of
graduates and the image of the University. The article
reveals the reasons of unproductive interaction of the
departments with divisions, providing educational
process; it also discusses suggestions that will improve
the performance of the main indicators of assessment
of the efficiency of activities of the University. It is
shown, that a systematic approach is the basis in the
organization of work of structural divisions of the
University, but it is difficult to implement, if managers
and supervisors do not have authority. To improve the
quality of graduates and their demand in the labor
market, it requires exempting the Department from
administrative work. These functions can be redirected
to the management, departments and services with
modern electronic information processing system. To
achieve high results in training in-demand graduates is
possible when the offices and the departments will
work as a team with the lecturers, in cooperation and
understanding
Today, the questions of accelerated development of
science are essential; it has become a real productive
force, the most powerful factor influencing the level
of scientific and technical progress. The most
important part of the research work is experimental
studies. The article reveals the methodology of
experimental research involving the content of
laboratory and industrial research, main stages, as
well as graphic presentation and the analysis of the
results of studies; as well as the methodology for the
general analysis of theoretical and experimental
studies, the sequence of introduction of the results of
the research and criteria for evaluating their
effectiveness. The main issues of the methodology of
experimental researches discussed in the article will
increase the effectiveness of scientific and research
work of scientific collectives of organizations and
companies
Perspectives of science in high schools were always
defined by prospects of development of scientific
teams. The author proposes to divide (depending on
the contents of research targets) unities of the
research process and the results of research teams
of the Department into three categories: a scientific
group, a scientific school and a leading scientific
school. Research teams are characterized by not
only quantitative and qualitative composition, but
the annual results. We reveal functional duties of
leaders of research teams and the head of the
Department for their effective management. One of
the main tasks of the Department is to create
conditions for the disclosure of scientific and
creative abilities of students. The article describes
general concepts and the content of scientific
researches, including the formulation of themes,
goals and objectives of the research, as well as the
basics of research methodologies required for
students in conducting the research work. The
structure of research groups of the Department, the
content of their work, the main functional
responsibilities of heads of scientific disciplines and
the head of the Department, basics of scientific
research methodology discussed in the article, will
increase the organization's effectiveness and the
efficiency of R & D Department
The article discusses the features of design and
operation in the different modes of functioning of
autonomous hybrid power plants based on renewable
and traditional energy sources. We have given a
structural scheme of such a plant. It is shown that the
algorithm of the system in the autumn-winter period
should be adjusted according to the monthly
monitoring; and standby generator of independent
source can be run at a deeper discharge of batteries. It
is known that the most expensive and the weakest link
in the solar PV plants is rechargeable battery. In
addition, the larger the number they have in the
system, the more complicated the fulfillment of all
conditions of proper operation is. We have proposed
to extend the lifetime of batteries through the use of
passive balancing, which allows to increase the
reliability of operation and reduce the cost. It is
shown that a real possibility of improving the
technical and economic performance of autonomous
hybrid power plants is their execution on the basis of
solar photovoltaic power plants. We have also
discussed the features of construction and operation
of hybrid power plants, which will increase the
efficiency of preliminary works on development of
high-performance structural circuit design of the
stations
The high speed of solar energy development in the
modern world allows us to assert that in the near
future it will become one of the main sources of
electricity. The authors describe a classification of
solar power plants, which can be of two types –
thermodynamic and photovoltaic, as well as the
features of design and operation of these plants. There
is a structural and schematic solution of autonomous
solar power stations and ones operating in parallel
with the external power grid. The features of their
design and operation, including the main advantages
and disadvantages were shown. It is shown that to
improve the reliability, including uninterrupted power
supply, a promising direction is the development of
combined systems which in addition to the solar
power plant may use wind power, gas or diesel
power, etc. In addition, such stations may provide
power from the external power supply. We have
given one of the variants of structural designs of
combined systems of energy and disclosed
recommendations for the design of energy-efficient
combined systems of power supply, made using
renewable and conventional sources of electricity.
The final version of the combined system of
electricity supply and the degree of participation of
traditional and renewable energy sources in electricity
production is determined on the basis of the analysis
of the energy balance and electromagnetic
compatibility of the main functional elements of the
system