Automation turns power into a manageable asset

Using automation to monitor plant electrical infrastructure allows end users to view utilities – especially electricity – as assets to be optimized. That means they can be leveraged to add real dollars to the bottom line.

“Electrical infrastructure is an asset; it should be managed as such. A lot of times, it’s ignored,” said Chuck Miller, solution design manager at Johnson Controls. “Some companies have asset management programs, but are running their businesses on 50-year-old electrical infrastructure.”

Miller said it’s not just about blowing fuses. There are safety risks associated with power line management or switchgear in older systems. “If the electrical infrastructure within a plant is aged, it doesn’t get the updates that traditional assets get. It’s not modernized,” he said.

To reduce the money spent on energy, plants must either buy it cheaper or use less of it. Either of these solutions requires information on how much energy is used, how much is required and which systems in the plant need the most.

Michael D. Longman, vice president of power chain management at Eaton said information management is the glue in the network of meters, gateways and software “to aggregate that information to be able to give you a window into the system.”

“One of the most overlooked values of an automation system when dealing with electrical infrastructure and utility distribution within a facility is information,” said Miller. “You don’t know anything unless it comes back to your automation system, which could be a manufacturing automation system, distributed control system, building automation system or it could be a system that ties those things together.”

Knowing electrical power trends and characteristics allows users to negotiate the best rates with the utility by providing usage history, load profiles, demand, power quality and power factor. This information is also powerful when addressing disputes with the utility.

“Electrical energy is probably the last – probably the only – unverified invoice that a customer pays,” said Dave Loucks, power chain management solution manager at Eaton. “There’s a utility meter on the wall. They tell you you’ve used this much power and you pay the bill. If you or I were supposed to ship something by UPS, and we didn’t send it, when we demanded payment, obviously they wouldn’t pay because they would verify with the UPS logs that it was never delivered. Who does that with electricity?”

For industries with co-generation capabilities, the economics of power generation vs. power purchase is a typical automation integration example. “Earlier systems rarely merged databases available from the metering, production or protection departments to determine if internal generation was cost effective. The systems to do so were expensive and proprietary,” said John Popiak, staff automation specialist at ABB. “Integration of inexpensive server/HMI, open industry protocols and inexpensive multifunction 'intelligent electronic devices’ allows data to be collected and analyzed instantaneously, enabling the plant engineer to effectively run the plant infrastructure from internally-generated power or purchased electricity.

PLCs operate simple automatic controls in electrical distribution equipment – for example, auto-throw-over schemes to select available source power. Automation now extends to far more complex applications.

In the last decade, microprocessor-controlled protection, automation and communications devices have simplified power system automation and management. In addition to enhanced features, these devices make power management systems more reliable and economical.

“With the increased reliability and capability of specially ruggedized computers, programmable automation controllers, communications and networking devices, it is natural to marry the electrical protection and control subsystems to the plant I&C systems to optimally control the entire plant,” said Saurabh Shah, branch manager of engineering services at Schweitzer Engineering Laboratories, Inc., Pullman, WA. He said power management systems let end users treat the plant’s electrical power infrastructure as an asset.

Common Ethernet networking accessories such as routers, switches and Web servers are shared by both power and automation systems. Ethernet and Web servers embedded in switchgear, switchboards, panelboards and motor control centers allow access to energy usage and operational data. “All your copiers connect to your network – why not a $50,000 piece of electrical equipment?” said Robert Kennedy, director of product management at Square D Engineering Services, Schneider Electric.

Microprocessors allow various devices to serve as I/O extensions. For example, a protection relay may use the digital and analog I/O to transmit the data via the embedded communication port back to the SCADA host device. Previously, load shedding applications were difficult to justify due to the infrastructure required. “Today, the logic, metering, I/O and protocol capabilities in even the most basic relays coupled with an inexpensive communication infrastructure enable an automation system to be deployed to decrease operating costs,” said Popiak.

“For example, many relays, revenue meters, protective relays, generator governors have Modbus or Modbus TCP/IP Ethernet as a common communication protocol allowing for the rapid integration,” Popiak added. “Utilizing a relay’s sequence of event, power quality capture, waveform capture, internal logic and metering capabilities, several discrete components can be eliminated in a system. The relay can also be attached to a system host through an Ethernet infrastructure to serve the information to one or more host devices. The implementation costs are reduced and the mean-time-between-failure ratings of such a system are improved dramatically.”

According to Shah, major functionality of an automated power management and control system includes:

• Flexible, high-speed load shedding – Prevents frequency-based blackouts by shedding non-critical load within a few milliseconds of lost generation or utility ties. The system continually calculates the amount of load necessary to shed for every possible supply loss. Loads are prioritized and only shed when necessary to satisfy the contingency.
• Islanding detection and intelligent system separation – Detects dangerous power conditions, and islands the plant’s power system to avoid blackouts. Detects separation using synchro-phasor state information, 4-millisecond detection of remote and local breaker openings and supervised protection elements. Performs separation using distributed logic in devices and preserve the stability of each island using intelligent load shedding.
• Generation and frequency control – Automatically controls generators for optimal dispatch. Controls systems for either maximum system stability under islanded operation or optimal economic benefit.
• Voltage and MVAR control – Mitigates many forms of voltage-induced blackouts using voltage and MVAR control. Controls all voltage and MVAR-controlling components in the plant’s power system. Manages load tap-changers, generator-field exciters, large synchronous-motor exciters, STATCOMs, static-VAR compensators and capacitor banks to maintain system inter-tie and bus voltage set points. Controls active components to conditions that provide optimal disturbance rejection.

Kennedy said load preservation schemes for ensuring power to critical loads involve a combination of automatic controls to switch to backup power while simultaneously stopping power to non-essential loads in order to protect generation capacity and preserve power to essential loads. “In order to meet utility curtailment rate agreement peak demand limits, non-essential loads are automatically disconnected until the target limit is reached. Alternatively, backup generation is brought online automatically to reduce peak demand seen by the utility – without shutting loads,” he said.

Because electrical power is an asset that can be managed, it can also be optimized, but it takes automation to do it. “Once you know where your energy is going, then you move into the economizing phase,” Miller said.

Viewing the process in terms of cost-per-product, users must take into consideration the unit cost of energy per unit produced – whether that unit is measured in gallons, pounds or items. Miller said the objective from an OEE perspective is to drive that cost-per-product down as low as possible, because then you’re as competitive as you can possibly be.

“If those control systems are controlling utilities, that’s the way you can drive energy costs out of your operation. And those costs drop right to the bottom line. That’s the important thing that people need to realize,” Miller said.

Automation helps enterprises achieve a competitive advantage through proactive management of the power system as a strategic, integrated asset throughout its life cycle. According to Longman, power automation benefits include reliability, operating cost efficiencies and enhanced safety.

“The level of reliability you need differs depending on the application,” Longman said. “It even depends on what kind of plant or facility you’re talking about. It’s not a 'one-size-fits-all’ kind of answer, which is why it’s not a shrink-wrapped, here-it-is (solution). You can engineer in overall system-wide reliability, but you can’t engineer in 99.9999% reliability without having some kind of monitoring with some service connected to it.”

Automation isn’t free. When it comes to business decisions for putting in automation systems, money is always an issue.

“A lot of companies won’t make that leap, because, traditionally you had to run hard wires to get meters back to the automation system,” Miller said. “That was a considerable effort. But now, with wireless technology, the available products are taking advantage of it. Wireless technology is now coming of age. It’s been available for about the last six or seven years. But now it’s robust.”

“If I wanted to get one point across, it’s this: the windows are there; open the shades,” Miller said. “You have to take advantage of the automation infrastructure as a window into the process environment. Use it to see everything you can see, which is the spend on utilities within your process. Once you have that information, then you can start to have impact.”