Simulations Invade Model-Predictive, Abnormal Situations on Way to Real-Time

Process Simulations Are Bursting Their Former Boundaries and Storming into Optimization, Model-Predictive Control, Abnormal Situations Management and Closing In on Real-Time Operations

By Jim Montague

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Reaching Out with OPC

To better understand simulation's recent data processing gains and migration into optimization, we must look at how it is improving communications with their real-world counterparts.

"In the past, we used a simulator that our customer used. It had a fancy HMI package for graphics and software objects, but the problem for a system integrator like us was that it required a whole extra application step that we had to design, program and test, and this meant a lot of added time and money," says Ryan Gerken, technical director at E-Technologies Group (www.etech-group.com), a system integrator in West Chester, Ohio, which serves process and batch application users in consumer goods and pharmaceutical manufacturing. "So when we began a re-control project to migrate this same user's old batch process system from Honeywell's TDC 3000 DCS to Rockwell Automation's ControlLogix, we also needed a simulator because this production system runs at 100% capacity to keep up with demand. In this case, simulation can help us reverse engineer and work out problems without having to take down critical production lines."

During its search, Gerken reports that E-Technologies ran across Mynah Technologies' (www.mynah.com) MiMiC software, which is built on Microsoft's .NET and uses OPC-based servers from the OPC Foundation (www.opcfoundation.org) to expose its simulation environment, which allows it to be controlled from another HMI. "Previously, a whole simulation would have to be programmed separately, but MiMiC doesn't have to do this because it uses OPC servers that can communicate directly into the simulation environment," explains Gerken. "This connection allows users to write automation to an equipment database for valves or pumps, and spits the MiMiC environment to the HMI and back. So, if you have an HMI with graphic displays for those valves and pumps, then your operations guys can click in individual devices, open and close them in the simulation via the OPC server, and then simulate and run unusual conditions or alarms."

Gerken adds that E-Technologies even develops its own software modules and tools and then uses MiMiC to import and export them as templates via XML. "We can extend the existing software with our tools and then just click to generate PLC code, HMI tags, historian tags and models," adds Gerken.     

Training Partner

While simulators are famous for training operators, the story doesn't end there. Once trained, users naturally and almost reflexively want to use these virtual tools to help improve and maintain their applications. This is drawing simulation into a host of new applications and closer to operations too.

For example, RWE npower's (www.rwenpower.com) two-unit, 1,000-megawatt Fawley Power Station provides electricity  to 1 million people in Hampshire, U.K., so this peaking plant must start up quickly and efficiently and synchronize to the grid to cost-effectively respond to seasonal spikes in demand. Consequently, the 40-year-old, oil-fired plant has used Emerson Process Management's (www.emersonprocess.com) Scenario simulator since January 2008 to mirror its actual Ovation expert control system, which monitors and controls the boiler, turbine and other critical plant processes and systems. The station's high-fidelity Scenario simulator has virtual controller technology, in which up to five virtual controllers reside in one PC, and this enables greater affordability and scalability with a reduced footprint. Fawley has 4100 simulated I/O points that exist in 12 Ovation virtual controllers (Figure 2).

Fawley reports that Scenario's training abilities are especially valuable for peaking plant operators because their work is based on fluctuating demands. In this environment, the simulator can train new operators while keeping current operators sharp and familiarizing them with new control strategies, even when the plant is not running. As a result, when extra megawatts are needed, the plant can synchronize to the grid more quickly and within the necessary parameters to avoid equipment damage.

"With the simulator, new operators can come up to the standards of more experienced operators much sooner than would be possible if they were interacting with the control system only when the unit was operating," explains David Marmot, RWE npower's electrical and instrumentation leader. "By training operators how to start the unit faster to meet peak demand, we have the opportunity to not only enhance the plant's operational performance, but our financial performance, too."

Likewise, because well-trained operators who are prepared to handle abnormal operating situations can reduce costly plant trips, Fawley also had 20 malfunctions, including critical ones, pre-programmed into the simulator to further train its operators how to respond to emergency situations. Scenario uses tie-back logic, algorithmic models and first-principle models to provide training and engineering simulations that can be tailored to meet each facility's operational needs.

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