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The Almond Valley, Seafield and Esk Project (AVSEP)
was a PFI initiative by Stirling Water, a consortium consisting of
Thames Water, MJ Gleeson and Montgomery Watson.
New Control and Monitoring Systems
The project involved the design, supply and
installation of 34 PLC/ICA panels along with the associated process
control software, telemetry monitoring system (comprising one master
station, 19 outstations and 2 remote client access,) and two SCADA
(Supervisory Control and Data Acquisition) systems networked to
monitor 29 PLC controlled areas. The project timescale to complete,
meant that the above had to be implemented over a 15 month period.
PLC Control
The PLC Control systems on all of the sites have been based around
the Rockwell SLC 500 range of PLC's connected together on each site
(where appropriate) by a Rockwell DH+ communications network.
Each PLC is directly connected to a LOI (Local Operator Interface) via
a serial communications link to facilitate local control and
monitoring of each area of plant.
Telemetry System
A New Serck SCX telemetry system has been installed with the master
station and three outstations, located at Seafield and an outstation
at each of the Almond Valley WWTWs and Esk Valley SWWs. This
system is primarily for monitoring purposes, but does incorporate a
number of interactive control facilities, including the automatic
optimum drain down on the Esk Valley SWW storm tanks after a storm.
The system facilitates remote client access from EOSWA and Thames
Water 24hr monitoring station.
Each outstation receives its I/O via hardwired signals for high
priority alarms and is also connected to its PLC via a serial
communications link for other necessary alarms.
SCADA
System
The SCADA system installed at
Seafield WWTW to replace the original old Serck system is a
duty/standby system and is connected to a DH+ communications network
for monitoring of the site data. This is also interfaced via a
fibre optic communications link to another onsite SCADA system
dedicated to the sludge drying process which allows the main site
SCADA to incorporate the monitoring and control of the drying process
in addition to the rest of the Seafield site.
Power Management
Systems
PMS Control has been
incorporated on Seafield and Newbridge WWTW to ensure the backup power
generator comes on line after a site mains power failure. It
also effects control of the Combined Heat and Power (CHP) units, to
minimise the amount of power required to be taken from Scottish Power
under normal operating conditions. The CHP units use the gas
from the sludge digestion system, with natural gas available as a
backup. The PMS philosophy includes the sequential restarting of
the plant after power restoration to minimise surges on the electrical
system and controlling of the CHP and generator sets under TRIAD
conditions. |
