Toshkent davlat texnika universiteti xalqaro ilmiy-texnik anjuman

МЕЖДУНАРОДНАЯ НАУЧНО-ТЕХНИЧЕСКАЯ КОНФЕРЕНЦИЯ 
АКТУАЛЬНЫЕ ПРОБЛЕМЫ ЦИФРОВИЗАЦИИ ЭЛЕКТРОМЕХАНИЧЕСКИХ И
ЭЛЕКТРОТЕХНОЛОГИЧЕСКИХ СИСТЕМ
142
asynchronous motor". However, along with this electric drive, in some cases for solving 
individual production tasks and energy saving, the system "thyristor voltage Converter – 
asynchronous motor" is used, which provides voltage regulation of the first harmonic of 
the voltage supplied to the stator. 
In operation are also electric drives based on asynchronous motors with a phase 
rotor, regulated by changing the additional resistances in the rotor circuits, the so – called 
rheostat control systems – "rheostat control device – asynchronous motor with a phase 
rotor". Especially many of these electric drives are part of lifting and transport 
mechanisms. 
Taking into account the above methods and control systems for asynchronous 
electric drives, it is possible to outline the following directions for reducing AD energy 
consumption. 
The first direction is associated with the reduction of losses in the electric drive 
when it performs specified technological operations according to specified tachograms 
and with a certain loading mode. These are electric drives that operate in start-and-stop 
modes (cranes, elevators, main drives of slabs and blanks, auxiliary positional 
mechanisms of rolling mills, etc.) or long-term modes with a slowly changing load 
(pumps, fans, compressors, conveyors, etc.). In such electric drives, due to the reduction 
of electric drive losses in steady-state and transient modes, significant energy savings can 
be achieved. In cinematically connected electric drives (roller rails, multi-motor bogie 
drives, etc.), a uniform division of loads between the motors also minimizes losses in 
them. 
The second direction is related to changing the technological process based on the 
transition to more advanced methods of regulating the electric drive and the parameters of 
this technological process. This reduces the energy consumption of the electric drive. As 
an example, electric drives of turbo mechanisms (pumps, fans, turbochargers), 
reciprocating pumps and compressors, conveyors, fuel — air ratio control systems, etc. 
can be used. In this case, as a rule, the effect is not limited to saving electricity in the 
electric drive, in many cases it is possible to save resources (water, solid and liquid fuels, 
etc.). 
Both of these directions are characterized by the fact that they reduce energy 
consumption in the electric drive: in the first case, due to reducing energy losses, in the 
second, due to the use of less energy-consuming process control on the part of the electric 
drive. 
We can also mention the third direction, which ensures the implementation of 
energy-saving technologies. It is known that there are a number of technological 
processes where an electric drive of relatively small power controls the flow of energy, 
the power of which is tens or hundreds of times greater than the power of the electric 
drive. Such objects include DC and AC arc steelmaking furnaces, vacuum arc furnaces, 
ore recovery furnaces, induction heating plants, etc. On them, electric drives with a 
capacity of several kilowatts can control a process that consumes tens or even hundreds of 
megawatts. It is obvious that the efficient use of such significant amounts of energy 
largely depends on the perfection of the electric drive, its speed and accuracy, the degree 
of automation of the process. This direction is not associated with a decrease in the 
energy flow through the electric drive, more often than not, the energy consumption of 
the electric drive even increases. Nevertheless, since this direction is associated with 
significant energy savings, let's consider it on the example of an arc steelmaking furnace. 
Let's formulate the ways of energy saving in an asynchronous electric drive.
In the first direction, the following ways can be used to reduce energy losses in an 
asynchronous electric drive. 

МЕЖДУНАРОДНАЯ НАУЧНО-ТЕХНИЧЕСКАЯ КОНФЕРЕНЦИЯ 
АКТУАЛЬНЫЕ ПРОБЛЕМЫ ЦИФРОВИЗАЦИИ ЭЛЕКТРОМЕХАНИЧЕСКИХ И
ЭЛЕКТРОТЕХНОЛОГИЧЕСКИХ СИСТЕМ
143
1. Reasonable choice of the installed motor power corresponding to the real needs 
of the controlled mechanism. This task is related to the fact that the load factor of many 
engines is 50% or less, which indicates either a low qualification of developers, or the 
imperfection of the used method for calculating the power of the electric drive. It is 
obvious that an engine of low power quickly fails due to overheating, and an engine with 
a large power reserve converts energy inefficiently, i.e. with high specific losses in the 
engine itself due to low efficiency and in the supply network due to a low power factor. 
Therefore, the first way is to improve the methods of selecting engine power and 
checking it for heating, as well as to improve the skills of developers, designers and 
maintenance personnel. In practice, there are cases when a failed motor is replaced by a 
suitable shaft height or diameter, and not by power. The existing methods of selecting 
engine power and testing it by heating can only be considered as a first approximation. It 
is necessary to develop more advanced methods based on accurate accounting of the 
operating modes of the electric drive, changes in its energy indicators, thermal processes 
in the engine, insulation conditions, etc. Of course, this implies extensive use of computer 
technology and special software. 
2. Transition to more economical engines, in which the rated values of efficiency 
and power factor are increased due to the increase in the mass of active materials (iron 
and copper), the use of more advanced materials and technologies. This path, despite the 
high cost of such engines, becomes obvious when we consider that according to Western 
European experts, the cost of electricity consumed annually by an average engine is 5 
times higher than its cost. During the service life of the engine, which is tens of years, 
energy savings will significantly exceed the capital costs of such an upgrade. As noted 
earlier, this path has not yet been properly recognized in domestic practice. 
3. Transition to a more energy-efficient electric drive system. Energy losses in 
transient modes change markedly when using rheostat control, TPN – AD and PPC – AD 
systems with minimal losses when using frequency-controlled electric drives. Therefore, 
within each of these systems, there are more or less successful options in terms of energy 
and technology. The task of the designer is a competent and fully justified choice of a 
specific technical solution. 
4. Use of special technical means that ensure the minimization of energy losses in 
the electric drive. Since a significant part of asynchronous electric drives operate under 
conditions of slowly changing loads (electric drives of turbo-mechanisms , conveyors, 
etc.), the deviation of the load of the electric drive from the nominal one worsens the 
energy performance of the electric drive. Currently, such means can include devices for 
regulating the voltage on the engine in accordance with the level of its load. As a rule, 
these are either special voltage regulators based on TPN that are switched on between the 
mains and the motor stator, or frequency converters that provide a so-called power-saving 
mode. In the first case, the TPN performs, in addition to the function of energy saving, no 
less important functions of controlling the start and brake modes, sometimes regulates the 
speed or torque, provides protection, diagnostics, i.e. increases the technical level of the 
drive as a whole. In the second case, the power saving mode is considered as an 
additional option of the frequency Converter and is available only in some manufactured 
types of converters. Given the versatility of their application, such devices are 
economically feasible for variable-load drives, even at a relatively high cost. 
5. Improvement of electric drive control algorithms in the TPN – AD and PPC – 
AD systems based on energy criteria for evaluating its quality, i.e. improvement of known 
solutions, development of effective technical solutions for their implementation and 
search for new solutions that are optimal in the energy sense. 

МЕЖДУНАРОДНАЯ НАУЧНО-ТЕХНИЧЕСКАЯ КОНФЕРЕНЦИЯ 
АКТУАЛЬНЫЕ ПРОБЛЕМЫ ЦИФРОВИЗАЦИИ ЭЛЕКТРОМЕХАНИЧЕСКИХ И
ЭЛЕКТРОТЕХНОЛОГИЧЕСКИХ СИСТЕМ
144
In the second direction of reducing energy consumption, it is crucial to switch 
from an unregulated electric drive to an regulated one and increase the level of 
automation by including a number of technological parameters (pressure, flow, 
temperature, etc.) in the control loop.
The third direction of reducing energy consumption is characterized by the 
improvement of the electric drive system in combination with automation of the 
technological process and the correct choice of the appropriate quality control of the 
electric drive from the existing ones or the development of new, better systems. 

Download 9,23 Mb.