Starting a power generating unit involves bringing a plant from a shutdown condition to synchronisation between the electrical generator and the transmission network. Optimising this process requires a balance which minimises start up energy costs and limits plant damage. Traditionally, the start up of a coal fired unit is performed manually by highly skilled operators. For RWE npower, however, an analysis of the start up methodology using the PI System from OSIsoft revealed variation in the company’s techniques. Having identified the reasons for the variations, RWE then standardised and optimised the procedures to ensure that best practices were achieved for every start up.
Ranked among the leading energy utilities in the UK, RWE npower supplies over six million customers with electricity and gas. PI infrastructure has afforded it more visibility into this process allowing better performance management. The applications and techniques developed by RWE npower with the PI system have given the company the agility and flexibility to meet the challenges of a deregulated market by determining best practices, improving processes, and optimising start up with minimum damage to expensive equipment.
The company first implemented the PI System in 1990, to build a new OIS (operational information system). Following this, RWE conducted a cost/benefit analysis that it says proved that the PI System was a strategic product with quantifiable return on investment for the business. Since then, OSIsoft products have been implemented as standard on all new projects and acquisitions.
The PI System has also been implemented at a number of CHP (combined heat and power) plants and will be used at the company’s renewable energy sites to collect and analyse data from wind turbines and hydro units. According to RWE, the PI System provides strategic integration of systems, standardisation of best practices and empowerment of people. “We were delighted to learn that OSIsoft had integrated its portal product within Microsoft’s architecture since we were already using SharePoint as our platform for knowledge management,” says manager of information, Paul Ireland.
Engineering for technology services
RWE describes added value applications as those the company has built internally using the OSIsoft PI System. The suite focuses on cost reduction, revenue enhancement, and process optimisation. “PI is a great tool for integrating disparate systems and bringing data together,” says Ireland. “But if you install a PI System and do nothing with it, it will just sit there and collect data. It is important that you have a strategy to develop and support those applications that will improve your business. The strategy we have adopted includes training and empowering employees and getting them involved in application development and use.”
Added value application focus
The introduction of new, more efficient, and lower cost power generating plants has driven the need to improve operations, forcing older, less efficient plants to operate closer to the demand margin. When operating close to the limit flexibility is the key. The strategy is to stop and start the plant during low/high price periods, to extend its viable life. This is why reducing the start up times and cost at the plant has become so important. RWE’s startANALYSIS application and other solutions provide critical analysis and optimisation of start up to ensure generating units are reliable and cost efficient.
Getting power to the grid on time
In the UK, the generating unit must be synchronised within a 10 minute window when delivering power to the grid. If late, the grid operator may not accept the power at all, regardless of the fuel and production costs already incurred by the plant. The goal is therefore to get power to the grid on time without causing damage to expensive plant components. Many older plants were not designed to run with this flexibility and must be pushed outside the original design intentions. Best practices must be defined to operate at these outer limits in a safe, reliable, and cost effective manner. Once best practice procedure is defined and agreed upon, the challenge is to ensure repeatability. Using PI, operators can focus attention on those improvements which deliver the greatest benefit and use tools intuitively to ease the overall burden.
Depending on the temperature of the boiler and turbine, start up times can vary from one hour to several. startANALYSIS provides RWE with the guidance to reduce variation in start up times and ensure the correct sequencing of activities.
“We have got a great tool to get our employees on board with best practices,” says Ireland. “It is all about getting the operator involved because that is the person who is going to optimise the process and save the plant money at the end of the day. With PI, employees can clearly see which practices are working and which ones are not, and take ownership of making the right choices. The dynamic nature of the colour changing displays is invaluable.”
Aside from enabling change and empowering people, operations can be clearly visualised at every phase and analysed against best practices. By adopting a culture of real-time performance management and giving employees the tools to take the right actions, RWE says it has reduced start up costs by approximately one third. Additional cost savings have also been realised by minimising damage and extending the life of equipment.
“Using technology like the PI System ensures our business remains competitive,” concludes Ireland. “We are able to continually assess the condition and performance of the plant, make changes to the way we operate, maintain equipment and quickly evaluate the impact and benefit of those changes. With PI, we have better information to aid our decision making. Being agile is critical when markets or legislation changes. New technology offers new opportunities; as systems are upgraded and new systems are introduced, integration remains our biggest exploitation opportunity.”
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