-
PLC in the Ice Storage Central
Air-conditioning
System of Control
1 Introduction
Ice
storage
air-conditioning
is
the
Central
V
alley
will
be
redundant
power
grid
electricity
at
night
to
form
ice
cold
storage,
electricity
consumption
peak
during
the
day
when
the
ice
will
melt
to
provide
air-
conditioning
services.
As
in
most
parts
of
China's electricity at
night
is
much
lower
than during the
day
,
using
ice
cold storage
central air conditioning
can significantly reduce the user's operating
costs.
Ice
storage
central
air-conditioning
system
configuration
of
equipment
than
conventional
air-
conditioning
system
to
increase
the
number
and
require
a
higher
degree
of
automation,
but
it
automatically
to
meet
the
requirements
of
the
air-conditioned
buildings throughout the day
under
the conditions of the day will
be
with all the energy
spent, the largest At least to save operating
costs.
2 Control system.
Control
system
from
the
next
crew
(the
scene
control
workstations)
and
PC
(central
management
workstations),
with
the
crew
using
programmable
logic
controller
(PLC) and
touch screen, PC
using
industrial-grade computers and
printers,
system
configuration
necessary
if
the
annex
Communications
equipment
interface
cards,
modems,
etc.,
to
achieve
the
parameters
of
the
storage
system
and
automatic
intelligent run.
The
crew
at
the
scene
and
touch-screen
system
can
control
parameter
settings
and
data.
PC
remote
management
and
printing,
which
includes
the
crew
and
all
the
features touch screen. Following the
system as a whole crew of
the
industrial PLC as
the
core,
the
automated
control.
Control
equipment
and
devices
include:
detection
sensor components, electrical valves,
converter, and so on.
1
2.1 Under the machine
system (Regional workstations)
2.1.1 TP21 touch-screen
TP27
used
as
a
color
touch-screen
operation
panel,
completely
replace
the
conventional
switch
button,
light,
and
other
devices
to
control
more
interviews
counters
clean.
And,
TP27
touch
screen
can
be
realized
at
the
scene
state,
system
settings,
the
model
chosen,
the
set
of
parameters,
fault
recording,
load
records,
time
period,
real-time
data,
load
curve
and
reporting
statistics,
and
other
functions,
the
Chinese user interface
intuitive and friendly
.
2.1.2 SIEMENS PLC
SIMATIC S7-300 series
PLC applied to all walks of life and various
occasions in
the detection, monitoring
and control of automation, its power to both the
independent
operation of, or connected
to a network able to achieve complex control.
The
photoelectric
products
with
isolation,
high
electromagnetic
compatibility;
have
high
industrial
applicability,
allowing
the
ambient
temperature
of
60
℃
;
has
strong
anti-jamming
and
anti-vibration
and
impact
resistance,
so
in
a
harsh
working
environment has been widely
Applications.
I also mean freedom of communication
S7-300 type PLC' s a very unique feature,
which allows S7-300-PLC can deal openly
with any other communications equipment,
communications
controller,
or
PLC
S7-300
type
can
be
defined
by
the
user's
own
Communications
protocol
(of
the
agreement
ASCII),
the
baud
rate
to
1.5
Mbit
/
s
(adjustable).
So
that
can
greatly
increase
the
scope
of
communications
so
that
the
control
system configuration
more
flexible and convenient. Of any kind
with a
serial
interface
peripherals, such as: printers or bar code
readers, Drives, a modem (Modem),
the
top
PC-connected,
and
so
can
be
used.
Users
can
program
to
develop
communication
protocols, the exchange of data (for example:
ASCII character code),
RS232
interfaces
with the
equipment can also be
used PC / PPI
cable
linking the free
communication communications.
2
When
the
PC
offline,
under
the
control
of
the
next
crew,
the
whole
system
can
operate normally.
2.2 Computer System
(central management workstations)
2.2.1 PC
PC
that
is
by
control
centre,
mainly
by
the
PC
and
laser
printer
components,
using
SIMA
TIC
WINCC
software
platform,
the
all-Chinese
interface,
friendly
man-machine dialogue. Managers and
operators can be observed through a PC, shown
in
the
various
kinds of
information
to
understand the present and past
the
ice-storage
operation
of
the
automatic
control
system
and
all
the
parameters,
and
through
the
mouse to print equipment management and
implementation tasks.
2.2.2
WINCC software platform
WINC
C
software
in
the
field
of
automation
can
be
used
for
all
the
operators’
control
and
monitoring
tasks.
Can
be
controlled
in
the
process
of
the
events
clearly
show, and shows the current status
and order
records, the
recorded data can show all
or
select
summary
form,
or
may
be
required
for
editing,
printing
and
output
statements and trends .
WINCC able to control
the
critical situation
in
the
early
stages of
the report,
and
the signal can be displayed on the
screen, can also
use sound
to be
felt. It supported
by online
help and
operational
guidelines to eliminate
failure. WINCC a workstation
can be devoted to the process control
to the process so that
important
information
not
is
shielded.
Software-assisted
operation
strategy
ensures
that
the
process
was
not
illegal
to visit and to provide for non-industrial
environment in the wrong operation.
WINCC is MICRSOFT WINDOWS98 or
WINDOWS NT4.0 operating system,
running
on
a
PC
object-
oriented
class
32-bit
applications,
OLE
through
the
window
and
ODBC
standard
mechanism,
as
an
ideal
partner
to
enter
the
communications
world
WINDOWS,
it
can
be
easily
WINCC
To
integrate
a
company-wide
data
processing system.
3
3 The control
of ice storage system
3.1 control
objectives, scope and mainly controlled equipment
Storage
control
system
control
Objective:
To
host
the
refrigeration,
ice
storage
devices, plate heat
exchanger, and the system pumps, cooling
towers, pipeline control
valve
system
to
control
and
adjust
ice
storage
system
of
the
status
of
the
operation
mode, in the most economical
Circumstances to the terminal to provide a stable
water
temperature.
At
the
same
time,
improve
the
level
of
automation
and
improve
the
management efficiency and reduce
management labor intensity
.
Control of the entire
ice
storage systems,
including the
parameters of state, state
and
control
equipment,
the
main
control
equipment
are:
the
status
of
host
duplex,
electrical
valves,
cooling
towers,
cooling
pumps,
ice
storage
devices,
the
primary
glycol pump, plate
heat exchanger, and Sub-glycol pumps.
3.2 control
Control
features
include
the
entire
ice
storage
system
stability
,
economic
operation with the
features.
3.2.1 Condition
conversion feature
According
to
the
season
and
operation
of
machinery
,
automatic
control
system
with the following
conditions conversion features:
a)
duplex
host status at the same
time cooling
ice-making
mode; b) duplex
host
the status of a separate
ice-making
mode; c) host and
the cooling
mode of
ice
storage
devices; d) the ice-melting
separate cooling mode; e) alone for the host Cold
mode.
3.2.2 The status of
Commitment, display and fault alarm functions
Control
system
according
to
the
schedule
in
chronological
order,
with
load
forecasting
software,
host
and
external
control
refrigeratio
n
equipment
and
the
number of start and stop all
surveillance equipment, working conditions and
operating
parameters,
such
as:
-
refrigeration
host
Commitment,
status
and
fault
alarm
-
host
refrigeration
Operating
parameters
-
host
of
dry
cooling
protection
-
host
for
4
refrigeration/return water temperature,
pressure, telemetry and display; - chilled water
pumps start and stop, status and
fault alarm -
glycol pump
start and stop, status and
fault
alarm
-
cooling
Pump
Commitment,
status
and
fault
alarm-the
pressure
of
the
bypass
with
significant
pressure
measurement
Show-
the
cooling
tower
fan
Commitment, status and
fault alarm;
For cooling tower/backwater temperature
control and display - for / return water
temperature, pressure remote control
and display - the
import and export
side of plate
heat exchanger
temperature control and display -
into
the
ice
storage devices,
export
control
and
temperature
telemetry
Show
-
chilled
water
flow
control
and
display
backwater - electric
valve switch, regulating
valve and-control and display - outdoor
temperature
and
humidity
control
and
display
telemetry
-
ice
storage
and
display
of
measurement - the end of cooling load
control.
3.2.3 Data
recording and printing
Control system
on some points need to monitor the trend recorded
throughout the
year;
the
entire
control
system
can
be
in
the
load
(including
the
biggest
daily
total
load
and
full-load)
and
equipment
uptime
tables
and
charts
to
record
for
users.
All
monitoring points and the calculation
of the data can be automatically print
regularly
.
3.2.4
Manual / automatic conversion feature
Control
system
configuration
flexibility
of
manual
/
automatic
conversion
features.
3.2.5
Optimized control
According to
outdoor
temperature, weather,
the
weather
trend,
history and other
data automatically host the ice-melting
or priority
. Meet the load in the end,
under the
premise of daily End of cold
storage, to run as little as possible hosts. Give
full play to
advantages of ice cold
storage system, saving operating costs.
3.2.6 Features automatic
operation
From
the
host
computer
system
can
work,
according
to
a
timetable
for
the
5
automatic
ice-making
and
control
system
operation,
the
status
of
conversion,
the
system
for automatic
fault diagnosis, and remote alarm.
Touch-screen display system
running,
processes, the parameters of nodes, running
records, police records.
3.2.7 Holidays set features
According
to
the
timetable
system
can
be
run
automatically
,
but
also
can
be
pre-set
holidays,
ice
control
certificates
and
certificates
of
ice
time,
the
system
does
not
need
the
holiday
season,
when
the
supply
of
places
to
stop
air-conditioning
cooling.
3.2. 8
Under the crew operating functions
The crew operating functions are as
follows:
a)
man-
machine
dialogue.
The
operator
through
the
touch
panel
can
be
interactive,
user
interface
completely
in
the
culture,
with
tips,
help,
and
the
set
of
parameters,
key
settings,
fault
enquiries,
history
,
and
other
functions.
b)
System
settings.
Including
the
operation
of
password
settings,
running
set
up,
run
the
timetable
set
records
overflow
with
automatic
/
manual
/
test
selection,
holiday
settings,
the
system
set
of
parameters
(including
the
node
temperature,
pressure,
the
flow
of
the
medium,
the
reservoir
of
ice,
ice-making
Rate,
the
ice-melting
rate,
the
valve
open,
end
load,
and
so
on.) .c)
Record
of
failure,
running
records,
historical
records.
3.3
Remote Control
Control
system
through
telephone
lines
or
broadband,
connections
with
the
expert
system,
the
system
operational
control,
parameter
changes,
such
as
data
collection,
the
system
continuously
improved
and
upgraded
version
of
the
software,
allows users to
get better service. Remote Control is aimed at
users through the PSTN
(public
switched
network
transmission)
of
frozen
remote
monitoring
station
at
different
places.
At
the
same
time
can
achieve
long-range
adjustment,
remote
monitoring and timely maintenance, and
other online, thus greatly reduce the intensity
6