Control & Automation

INTEGRATED CONTROL AND SAFETY THE NAME OF THE GAME FOR SCOTTISH & SOUTHERN ENERGY

Phil Black - PII Editor 20/04/2010

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Fully integrated control and safety system

When Scottish & Southern Energy (SSE) sought a fully integrated control and safety system for one of their gas storage facilities, they turned to the expertise offered by Siemens and Cordell ASR Technology Ltd. (CASR) to deliver against some key project objectives. As a result of a new control and safety system installation, the utility now has the ability to efficiently monitor and control a key storage facility, which has also seen the seamless integration of a safety system.

Siemens and CASR became involved on the project when as part of development at the new site in Aldbrough, SSE needed a control system to enable site operation and management, as well as provide proven high availability and reliability factors for the day-to-day operation of the gas storage facility.

The utility stores gas in underground caverns prior to distribution to the UK network and the new system provides for full control of both gas import and export into and out of the storage facility. As such the solution had to incorporate both a process control system for the management of the site, as well as integral emergency shutdown and fire and gas systems which are essential safety requirements when dealing with such substances.

The overall solution was based on a fully integrated Siemens PCS7 platform and system integrators, CASR recommended this as it enables the use of common hardware across both the distributed control system, as well as the emergency shutdown system. Underpinning all the systems is fully redundant technologies for controllers, power supplies and networks, ensuring that high availability is maintained at all times. In addition to the DCS and ESD systems, there was a requirement to seamlessly integrate CCTV into the main control system operator screens, and, this additional need has been incorporated without any issues.

The overall plant is controlled and monitored by a high availability dual processor process control system using the Siemens S7-400H hardware platform and PCS7 software.
The facility and the control systems allows total control and monitoring of all activities of the gas storage plant; provides interfaces for the operators and engineers; CASR developed an intelligent import & export campaign management system providing complete autonomous control of the facility allowing it to react quickly to any commercial demands; accurately records and logs all parameters and events at the site, and enables data acquisition and control functions for the gas compressor systems. (also based on Siemens S7 PLCs)

When dealing with operations such as gas storage, safety system performance is a critical element of any overall control system.
With the biggest risk the potential escape and subsequent ignition of natural gas, it was necessary for a Fire and Gas system to be provided to alert for the earliest warning of fire or gas accumulation. The system in place now continuously monitors the storage facility for any detected fire or gas accumulation and initiates safe isolation, shutdown and protection of the appropriate equipment in accordance with the designated Emergency Shut Down procedures.

The ESD system has been designed using a fail-safe dual processor configuration based on the Siemens S7-400F/H hardware platform using Siemens Safety Matrix software. The Emergency Shut Down system communicates into the process control system for alarm annunciation via an industrial Ethernet network. The ESD system has been engineered to meet the requirements of IEC 61508/61511 and the Fire and Gas system incorporates a dedicated addressable fire panel certified to EN54 .

The new control and safety system is now up and running at Aldbrough and is providing SSE with effective and efficient day-to-day control of the storage facility, backed by an integrated safety system that provides peace of mind for site management.