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Control System, SCADA and Network Modernisation Case Study

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The Nottingham District Heating Scheme is one of the UK’s most established city heat networks, supplying heat and hot water to domestic, commercial and public sector customers across Nottingham.
The scheme is linked to the Eastcroft Energy from Waste facility, where general waste is used to generate steam. Steam from the energy recovery process is transferred to the London Road Heat Station, where it is used to generate electricity and produce hot water for distribution through the district heating network.
As a critical city energy asset, the scheme operates continuously and supports thousands of customers. Reliability and resilience are therefore essential, particularly when carrying out upgrades to live control, SCADA and communications systems.

FAIRFIELDS’ long-term involvement and added value

FAIRFIELDS has maintained and supported the Nottingham District Heating Scheme’s control system and SCADA infrastructure for over 30 years. This has included ongoing planned preventative maintenance, 24/7 support, system monitoring, obsolescence management and technical advice to the client.
Through this long-term service role, FAIRFIELDS has developed a detailed understanding of the scheme, its operational requirements and its legacy control infrastructure. This has enabled FAIRFIELDS to identify risks before they become critical, advise the client where improvements can be made, and plan upgrades in a carefully structured manner.
Rather than being delivered as isolated projects, the works have formed part of a managed programme of progressive modernisation. Upgrades have been planned around the operational needs of the heat network, with intrusive activities undertaken during planned shutdown windows wherever required. This approach has helped minimise downtime while allowing the client to move from ageing legacy platforms to modern, supportable systems.

Control system upgrades

The original control system was based on Rockwell SLC PLCs, many of which had been in operation since the mid-1990s. Over time, these systems became harder to support and limited the ability to improve diagnostics, reporting and integration across the scheme.
FAIRFIELDS has progressively upgraded obsolete PLC hardware and associated control panels with modern Rockwell CompactLogix – and ControlLogix platforms. The control system upgrades have included:

  • Progressive replacement of obsolete Rockwell SLC PLCs.
  • Migration to modern CompactLogix and ControlLogix platforms.
  • Replacement and upgrade of outstation control panels.
  • Improved local control of outstations, pumps and ancillary plant.
  • Integration of variable speed drives to improve control and diagnostics.
  • Replacement of hardwired monitoring systems with PLC-based monitoring.
  • Planned migration of remaining legacy I/O during agreed shutdown windows.

By phasing the works carefully, FAIRFIELDS has enabled the client to modernise the control system while maintaining continuity of operation for the live district heating network.

The original SCADA system consisted of four separate operator PCs operating across separate legacy networks. This arrangement was difficult to maintain and restricted the client’s ability to manage the scheme through a single integrated operator interface.
FAIRFIELDS upgraded the SCADA system to a modern, virtualised and redundant server solution. The four separate SCADA systems were consolidated into a combined server and client architecture using FactoryTalk View SE, virtualised servers, and Thin Clients controlled and deployed via ThinManager software.
The SCADA upgrades have included:

  • Migration from four separate SCADA PCs to a centralised SCADA platform.
  • Deployment of a virtualised redundant server solution.
  • Use of ThinManager and Thin Client operator stations.
  • Improved operator interface with situational awareness graphics.
  • Improved alarm visibility, diagnostics and system navigation.
  • Replacement of legacy reporting with modern historian-based reporting.
  • Centralised user management and improved access control.
  • Full server and client refresh on updated software and Windows platforms.

The control room interface was also modernised. The previous arrangement of separate screens was replaced with an integrated multi-screen operator environment using a single keyboard and mouse. The physical HV mimic panel was replaced with a large TV displaying the SCADA-based mimic, improving visibility and allowing the mimic to be maintained as part of the SCADA system rather than as separate hardwired equipment.

Network upgrades

The original communications infrastructure relied on obsolete fieldbus and serial networks, including DH485, DH+ and other serial communications links. These legacy networks limited performance, diagnostics and future integration.
FAIRFIELDS upgraded the communications infrastructure to a modern Ethernet/IP-based OT network, supported by a dual redundant fibre backbone around the station. This provided the foundation for the wider control and SCADA upgrade programme.
The network upgrades have included:

  • Replacement of obsolete fieldbus networks, including DH485 and DH+, with modern Ethernet/IP communications.
  • Installation of a dual redundant fibre backbone network around the station.
  • Provision of resilient Ethernet connectivity to key plant areas.
  • Migration of PLC, SCADA, drive and outstation communications onto Ethernet.
  • Replacement of serial site links with Ethernet and secure 4G communications where appropriate.
  • Integration of modern Modbus TCP equipment.
  • Improved remote support capability.
  • Improved cyber security through firewall deployment and network lockdown.

The upgraded network now provides a scalable communications platform for current operations and future upgrades.

Outcome

Over more than 30 years of ongoing support, FAIRFIELDS has helped the client manage the risks associated with ageing control, SCADA and communications infrastructure on a critical city energy network.
The works have combined planned preventative maintenance, 24/7 support, system monitoring, obsolescence management and technical advice with carefully planned upgrade delivery.
By structuring the works around live operational requirements and planned shutdown windows, FAIRFIELDS has progressively modernised the scheme while minimising downtime. The result is a more resilient and maintainable control environment, with improved operator visibility, enhanced reporting, stronger cyber security and a clear route for the continued replacement of remaining obsolete equipment.