Umeå Energi has integrated Siemens PLCs with ABB AbilityTM System 800xA across its district heating plants to lower operator risk while minimizing running and maintenance costs.

The technology provides an improved and simplified single operator interface, that gives greater insights into the performance of district heating plants, and is now benefiting Umeå Energi after it standardized on ABB control technology. With fewer process screens leading to lower operator risk, the company has significantly improved monitoring and process control and operator effectiveness of its plants.
Control room
Because the district heating network had expanded over time, the Swedish energy provider found itself using a mix of control systems, human-machine-interfaces (HMIs) and programmable logic controllers (PLCs).

Umeå Energi’s ambition is for all its PLCs to be visible through the same HMI, so that the operator would have a familiar work environment, while minimizing risk, operating and maintenance costs. Having all information available in one single HMI gives the operators and maintenance staff new ways to proactively monitor processes more efficiently and maintain a high system and plant availability.

At the heart of its distributed control system are three independent ABB Ability™ System 800xA platforms, each managing sections of the two district heating plants covering Umeå. In addition, the company uses 21 Siemens S7-300 PLCs to control pumps in booster stations and sectioning chambers so that the correct pressure is maintained throughout the network. The PLCs were operated using two Siemens Simatic HMIs.

However, these HMIs were outdated, making PLC operation increasingly difficult. This led to higher maintenance costs and increased risk. Furthermore, with only basic integration with the Ability System 800xA, operators were forced to use different HMIs, each with its own look and feel, to manage different parts of the same plant.

While modernizing the Siemens HMIs would be the most obvious answer, it would not provide the single operator experience Umeå Energi desired. An alternative approach was sought that would integrate the 21 PLCs into ABB System 800xA, which would then act as the main HMI.

The fast track way of integrating PLCs is to use ABB OPC Connect; a tool that connects PLC objects and its signals simultaneously, such that up to 50 per cent of engineering time can be saved. This avoids the time-consuming manual integration of individual signals from each asset.

Umeå Energi took the opportunity to standardize on the function blocks used within its PLCs, thereby removing the many different object types created for the same asset, such as pumps or valves.

“We did a thorough work in standardizing our function block library. I think it is absolutely necessary if you are planning to do this kind of integration,” says Dirk Mottmann, IS and Process Manager at Umeå Energi. Now with function blocks optimized to match their application and fewer object types, integration into the System 800xA’s HMI would be highly cost efficient.

Umeå Energi now has one common HMI that spans the entire system and its processes, giving the operator a completely integrated plant and district heating network experience.

Furthermore, all production and distribution network process data are available in one common database. This enables Umeå Energi to conduct, for the first time, a larger investigation to see how different parts of the distribution network interact and how they could be optimized together.

The PLCs are optimized to work together, fine tuning the complete process, instead of only completing their individual task therefore creating a much more coherent process control of the PLCs.