Process and power/electrical controls merging into unified systems

Here are the benefits they can provide together.

By Jim Montague, executive editor, Control

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The ones and zeroes don't care what physics or events they represent. Pressure, temperature, flow, oil, gas, chemicals, water, ore, slurries, pulp or tapioca pudding—it's all the same to them. Likewise, mathematics, algorithms, software and microprocessors are equally willing to chew on whatever digital data comes their way—and now it's power and electrical control's turn to join the process automation party.

The separation between process control and power is one of the oldest organizational barriers on the plant floor. However, digital data is starting to flow more freely between them, and their convergence is allowing users to achieve many and varied gains, improve efficiency and reliability, and reduce costs at the same time.

"We're seeing demand for integration of electrical control and process control across the board among our clients from hydropower to large production plants, mostly due to greater awareness of the IEC 61850 standard," says Brian Harrison, president of Coast Automation Inc., a CSIA-member system integrator in Vancouver, B.C. "I think it began six or seven years ago, when users tried to settle on a common programming language based on the IEC 61131 standard, and then this commonality spread via the fieldbuses and Ethernet-based protocols. Of course, everyone is looking for efficiency and energy savings, and IEC 61850 lets them look at power use at the production level, add meters to their motors and drives, and monitor their consumption and efficiency on a combined SCADA package."

Debbie Colclazier, product marketing manager for DeltaV engineering tools at Emerson Process Management, confirms that power and process control systems are coming together. She recently returned to Emerson from working for eight years at a U.S. oil and gas refinery, and reports its staff could see benefits from combining power and process systems.

"We put in a large compressor with a variable-speed drive at the refinery where I worked," says Colclazier. "The compressor had its own substation, breaker control and PLC. The interface to the PLC from the DCS, combined with hardwired inputs, allowed operators to initiate sequences needed for starting or stopping the compressor. The interface consisted of a sequenced set of communications between the PLC and the DCS to open and close breakers as needed, as well as providing the status of the sequenced events to the operators. In the past, electronic devices used in substations had their own PLC-type controls that could interact with a main PLC to monitor and control those devices. The DCS controls and the electrical substation controls have remained primarily separate until now, with maybe only a few values being integrated via Modbus to the DCS."

Happier together—in Brazil

The benefits of combining and coordinating electrical and process controls and their related systems can be huge, and achieve unprecedented efficiencies and joint performance gains. For instance, at Petrobras' Presidente Getúlio Vargas (Repar) refinery just north of Araucária, Brazil, engineers report that integrated process and power systems from ABB have saved 30% in engineering costs, 14% in installation time and 20% in training costs, according to Leandro Monaco, global product manager for ABB's 800xA system and electrical integration (Figure 1).

Likewise, Vale S.A.'s huge iron ore mine in Carajás, Brazil, has been working with ABB to develop an integrated, remote asset management and predictive maintenance program for the mine's electrical systems, which would also improve its planned energy efficiency. "The ideal management of a plant isn't just increasing production, but is also relating that production to energy consumption," state Monaco and Jose Catarino, Vale's automation and electrical coordinator, who co-authored a whitepaper on the project. "Production depends on the electrical system always being on, but users don't want to know more than that they can always plug in and run their process, even though one electrical device failure can shut that production down. So power systems don't get much attention, most electrical maintenance has been mainly corrective, and this usually means hours of lost production."

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