Control issues at Cardiff Bay Barrage24 July 2009
Operation of the Cardiff Bay barrage is now easier following an ABB upgrade of its six-year-old Alfa Laval, SattControl system
A major engineering project that cost around £220M (US$336M) and took five years to build, the Cardiff Bay barrage is designed to regulate the level of a 200ha lake - Cardiff Bay - by isolating it from the sea.
Five large sluice gates regulate the level of the bay, prevent high tides entering and allow the two rivers to flow out of the bay to the estuary.
The barrage has three locks, one 40me long and 10.5m wide, and two 40m long and 8m wide, which allow 24 hour access to and from the bay, a great improvement on the previously tide dependent bay. Three bascule bridges carry the road across the locks and are raised to allow boats to enter and leave.
ABB’s association with the barrage goes back to 2001 when it upgraded the original control system shortly after the facility was completed. This involved the replacement of the serial communications with an Ethernet system linking 14 PLCs to increase the speed of response.
Steve Rees, of the Satt product lines, now supported by ABB, says: "We first provided a Satt control system for operation of the barrages and locks and recently we have been evolving and expanding the system to the latest 800xA control system to keep it modern. We have also connected the ABB system to existing control equipment provided by other suppliers to give a more integrated and sophisticated control and to improve ease of use by the operators of the locks and barrages."
There was also a need to establish a telemetry link so the operators could send information on tidal conditions to the Environment Agency. Salinity monitoring was also required to provide a better way of capturing river flow data.
The Satt OCS (Open Control System) comprises everything from products to total solutions depending on the customer’s requests. Satt OCS products and systems cover automation solutions like Distributed Control Systems (DCS), PLC, Scada, I/O systems and programming tools. Satt OCS provides a good foundation to migrate a control system to the latest ABB automation technology.
Installed on a server in the main control room, the system also has a back up at a remote station. This redundancy allows a switch over of control in the event of a failure of the main server, with a seamless handover that has been developed to go unnoticed by the operators.
The 800xA gathers data including event histories, alarms and trends and provides a Graphical User Interface that allows the operators to control the sluices, locks and bridges. Data on the level of the bay is very important to the civil engineers managing the many building projects in progress in the area. It also allows easy control of auxiliary circuits such as outside lights.
The addition of the 800xA system to the SattControl system was part of a process to develop the control of the barrage as its operational needs changed. Roger Thorney, operational manager for the Cardiff Bay barrage, says: “We were looking for a company that could not just upgrade the control system but one that would become involved in a process of improvement, with a regular review of our needs. We wanted a company that could make recommendations and give us the options, allowing us to cut our cloth to suit.”
ABB now conducts an annual control audit to determine the current needs of the barrage. The latest audit identified the need for a better Human Machine Interface that would allow better monitoring of the barrage and also allow more detailed data to be gathered.
|Barrage of information|
The Cardiff Bay Barrage was conceived to perform two functions: to create a permanent fresh water lagoon to promote the regeneration of the area, and to provide a flood relief structure from both rising sea levels and control of water levels in the Rivers Taff and Ely. Complex studies by maritime engineers and dam specialists commenced in 1987 and Royal Assent for construction was granted in 1993.