Технические
науки/ 12. Автоматизированные системы
управления на производстве
Brylina О.
(Candidate
of technical sciences, associate professor),
Tsytovich L.
(Doctor of Technical Sciences, Professor)
Russia,
Chelyabinsk, National Research South Ural State University,
the Department of the electric drive and automation
of the industrial installation
ELECTRIC DRIVE OF
CENTRIFUGAL mechanisms WITH parallel CHANNELS of REGULATION ON THE BASIS
OF MULTIZON SWEEP
CONVERTER
Abstract:
The
article dwells on the principle of constructing
the control system for a group of parallel electric drives for water pumps on
the basis of multizone integrating sweep converter. The block diagram of the
system and the principle of operation are disclosed
Keywords: electric drives,
multizone integrating sweep converter, automatic diagnostic, reservation.
The majority of electric drives of
water-pumping stations of dwelling houses
and housing estate, of reverse
cycle of water supply of industrial enterprises, of systems of smoke
purification and of gas-collecting, of fire-fighting systems, of compressor installations and other centrifugal mechanisms are contained by parallel channels of regulation, some
of which work in "cold" reserve and are switched on as required in a hand-operated
condition. At the same time, the increased requirements in part of
transition time for a reserve are imposed upon a whole series of industrial
objects. It makes actual the solving problem of automatic diagnosing and
reservation of similar regulating systems [1, 2, 3].
The following example of
asynchronous electric drives of water supply system shows the principle of
self-diagnosing and automatic backup of regulation
channels with using the method of a multizone integrating sweep conversion
is considered.
The system (fig.
1) contains «n» number of actuating paths on the basis of a smoothing filter (F), frequency
converter (FC), asynchronous electric motor (М) and actuating mechanism (AM), for
example, water pump. The FC, М, AM
are provided
with a complex of selective protection.
The
output signals of them are integrated on the function «OR» by logic gate (L) [4].
The feed-back sensor (FBS) forms a signal
proportional to regulated coordinate, for example, water pressure in a
dictating point of the trunk pipeline (ТP).
Fig. 1. The
functional circuit of electric drives with parallel and automatically reservation of actuating paths
The control of actuating paths «1 … n» is made from
the multizone sweep converter (MSC) [5], which is made on the basis of adders S1, S2,
integrator In and group of odd number 
of relay elements
RE1 – REn (the condition 
is not compulsory,
as MSC can be made on the basis of an even number of relay elements 
[6] too). The
output signals of RE1 – REn are changed discretely in limits 
. The switching thresholds of relay elements RE1 – REn
satisfy condition 
< 
< ….. 
, where the index at «b» corresponds to a serial
number of RE in a fig. 1. The number of modulation zones of MSC is determined
by a relation 
. The RE1 – REn are supplied with a gating input, which is connected to
an exit of the block L The presence of a signal logical «1» on a gating input
of the RE forcedly switches last in a state 
, at which the FC of the appropriate actuating path is turned off.
The mode of auto-oscillations in МSC always appears in a path of the relay
element having a minimum value of switching thresholds. Others REs work in a
static position 
or 
, whose position is determined
by magnitude of the assigning signal and feed-back of a control system. Thus,
in the initial state the «actuating
path 1» realizes smooth regulation of the
output coordinate of a system, and the others work in a operation
«switch on / switch off», depending on a level of error signal on an input of
integrator. Besides that, a predetermined number of actuating paths function as the «hot» reserve.
If denied any of
the elements of power control of channel FС, М, AM, then the signal "1" appears at the
output of the block L and an
appropriate relay element of МSC is blocked in the state 
. The presence of the integrator makes
the MSC in the mode of an automatic scan of the efficient actuating path, which is turned on by
the switching of RE in a position 
. In the event of failure, for example, of the «actuating path 1» the auto-oscillations mode (smooth regulation)
is passed to the following relay element. The system behaves in a
similar manner in the event of failure of relay elements of the МSC [7]. And the sources of tests-signals and computer
handling of response system are not required for the diagnostics and the
switching of the reservation regulators, that is
characteristic for traditional ways of diagnosing and automatic reservation
of technological objects.
Necessary
condition of constructing the system is the implementation of blocks In, S2 and F on the
basis of passive elements with a sufficient reserve on operating parameters,
that allows to consider them practically «ideal» in respect to reliability of
elements.
The considered
structure was used at automation of electric drives of gran-pool in the
slag-melting workshop ОSC «Chelyabinsk
Tube Rolling Plant». The system contains four actuating path. One of them makes a modulating control of water level
in the accumulative reservoir, the second actuating path works in a operation «switch on / switch off», and the
rest are in the mode of «hot» reserve.
Literature
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