Elkview Coal Corporation, an open-pit coal mine in B.C.'s Rocky Mountains, is not only "power smart" but an aggressive automation leader in North America's mining industry.One of five mines located on the East Kootenay coal field, Elkview draws a hefty 105 billion watts annually to produce some 3 million tons of mostly metallurgical coal.
Elkview has come a long way in controlling electricity since late 1992, when Teck Corporation purchased the mine. Plaguing power quality problems coming from the mine as well as its utility have since been identified and solved.Measuring power also helped identified inefficiency and waste. Elkview has already dropped its average power demand from almost 24 MVA down to about 20 MVA. And cut its overall energy bill by 10 percent, an annual reduction of almost 6 billion watts, with even greater savings expected later this year.
Elkview achieved better control of cleaner power through an integrated, system-wide approach to power measurement. The mine has just upgraded an earlier PC-based SCADA system from Victoria, BC's Power Measurement Ltd. (PML) to that vendor's new PEGASYS client/server Windows NT-networked software. This provides end-to-end, mine-wide integration of power measurement and control using a fully expandable desktop PC graphical energy analysis system.
The ability to integrate other systems is a crucial foundation to Elkview's long-term goal of creating one integrated information network. The company wants to bring all information, regardless of where it's generated whether from dispatch, electrical or PLC systems into an all-encompassing, mine-wide information system and distribute the data to everyone who needs it.
In effect, what began as an electrical monitoring and control project is quickly evolving into a centralized computer system that will soon distribute all mine-generated information to anyone connected to the company's local area network. Far from dreading new technology, Elkview's electrical department is eagerly embracing it. Elkview has emerged as an automation role model not only for other mines in the area, but also within Teck Corporation's 10 Canadian mining subsidiaries, a power quality and cost-cutting effort not overlooked by top management.
First Priority: Improve Incoming Power Quality
Back in 1993 Elkview's first priority was improving the quality of the power it received from its utility. This effort launched the mine's ongoing "power smart" automation program.
"We hesitated signing a contract with BC Hydro because our utility was creating severe power fluctuations and much instability in our internal electrical distribution system," says Bryce Short, electrical general foreman. "In its contract, BC Hydro wanted a voltage variance of plus/minus 9.8 percent. This was unacceptable."
Consistent voltage is critical to Elkview's drills and shovels at the mine pit and to its voltage-sensitive, coal cleaning process at the preparation plant.
"Under and over voltages can cause extensive damage to our equipment if we don't catch it in time," says Short. "That's why we needed to monitor our supply."
The plant's internal power distribution was quite stable with a powerful transformer running at below 30 percent load at a baseline of about 68,000 volts. "Yet, within seconds, we'd get massive jumps, spikes as high as 74,000 volts followed by drops down to 61,000, even 58,000 volts," recalls Short.
After each disturbance, Short and his electrical department complained to the utility. BC Hydro told them the utility's responsibility stopped at the gateway and Elkview had itself to blame for any power problems.
This early impasse was solved by Elkview clearly documenting the disturbances as proof positive that the utility, not the mine, created these power problems. On its main incoming power feed, the mine upgraded an older power meter, inherited from Westar, to the more advanced 3720 ACM power meter.
Instead of arguing about whose fault it was, Elkview printed out the waveform recordings after each disturbance and sent them to the utility as documented proof, "that power, for example, had fluctuated or dropped on a particular second of a certain day," says Filippo "Rocky" Roccamatisi, field electrical foreman.
At first, this surprised BC Hydro because none of the other five coal mines in the 100 miles-long East Elk Valley had the ability to track electricity as Elkview did or determine the cause of problems. Moreover, according to Short, "The utility was also amazed that we had better power measurement tools than they, themselves, had at the time."
Eventually, Elkview did sign the contract with BC Hydro after the utility promised to keep voltage variances within 3 percent. "That was acceptable to us," says Short.
Short and his electrical department realized that if the new power meter could be used to make their utility listen to them, then they could certainly use that same tool internally to lower demand costs as well as solve their own in-house power quality problems.
To that end, in late 1993, Elkview began upgrading the metering of its internal power distribution system to 3720 ACMs, beginning with the main substation's four secondary feeders and slowly expanding to include switch houses. Elkview also installed an earlier PML DOS-based supervisory control and data acquisition system called M-SCADA. The meters communicated with the M-SCADA system's PC master display station via dial-up modems.
Elkview's 3720 ACMs measure mainly incoming power and various electrical status information. "For example, who pushed a button at what time to trip a breaker or when a fault occurred in the distribution system," says Roccamatisi.
Electrical Audit Identifies Wasted Power
Having resolved its external power quality problems, Elkview's next priority was to trim demand. This money-saving effort developed into an ongoing efforts to measure power everywhere, including continuous internal audits.
But throughout 1993, Elkview's continuing high power consumption troubled Short, Roccamatisi and Don McCarty (power distribution and communications foreman) all BC Hydro veterans who understood demand side management. "That prompted us to measure where all the electricity was going," says Short. "We had to identify excessive loading, where power factor correction was needed ... let's face it, if you can't measure it, you can't change it."
Therefore, in early 1994, Elkview decided to conduct an energy audit of the entire mine. Given the monumental effort of inventorying everything electrical, Elkview turned to BC Hydro for help in staffing the audit task force.
Since a substation may feed 15 different buildings and any amount of machinery, Elkview and BC Hydro personnel had to measure all power consuming areas in Elkview's entire electrical system, right down to individual pieces of equipment.
For example, electricity from BC Hydro, on whom Elkview depends for all its power, is fed at 69 kV into the mine's main valley substation. There, power is stepped down for distribution throughout the company over four secondary feeders.
One electrical distribution network feeds power, at 69 kV, a mile higher up the mountain to the mine site coal extracting operations. There, 13 substations step down the incoming 69 kV electricity to 6.9 kV to power huge coal excavation shovels and drills, each having its own portable switch gear. Four drills drive 15-inch holes, 55 feet deep into the mountain into which are inserted explosives to blast loose the rock.
Seven gigantic shovels (with bucket capacities from 15 to 54 cubic yards and loading up to 80 tons each pass) fill a fleet of 24 production trucks making 1,200 trips each day. These trucks haul the raw coal on their 13 feet-high tires to a network of conveyor belts. The conveyors move the mixture first for storage in the raw coal silos, then to the preparation plant, 1 1/2 miles down in the valley.
The preparation plant is fed by the three other electrical distribution networks at 13.8 to 41.6 kV. At the plant, the raw coal is washed, separated by grade and dried (via a 7,500 hp exhaust fan) in North America's largest metallurgical coal drying system.
Thereafter, the coal is moved via another conveyor belt and loaded into clean coal silos to await the weekly train to the coast.
Elkview's power audit task force used a 3720 ACM power meter to measure each major component of this extensive electrical system. The task force checked everything, from measuring current on motors down to counting every light fixture. The data was collected and analyzed by the earlier M-SCADA's central PC.
The electrical department now had a model of the electrical usage for a normal, full-run production day. "We compared this to our energy consumption model for the year and found that it matched almost identically to our power bills," says Short.
But the audit did identify where much of the power was wasted: too many lighting outlets operating continuously and drawing too much energy, overloaded motors, and systems not functioning as designed. For example, the greatest waste was found in big energy consumers such as compressed air and water systems, with pumps not running at maximum efficiency.
Elkview's ability to measure consumption enabled the mine to correct these problems. "At the mine site, for example, all shop lighting is now controlled by PLC systems," says McCarty. "The 1000 watt street lights, in the mine pit area, were replaced by more efficient 250 watt lights. And we turned off the power to 10 unoccupied buildings. Bottom line, we became power smart."
The electrical department then separated power costs between the different feeder areas and billed internally on that basis. "We tracked loads every week, informing department managers of the weekly peak demand and, if the peak rose higher this week than last, tried to identify which equipment in a particular area caused the load," adds Short.
The power audit also identified the type of power factor correction needed. Overall, the audit helped Elkview cut its annual average electricity consumption by 10 per cent.
Internal Phase Unbalance and Harmonic Problems
Elkview now had to focus on its next priority: improving its own internal power quality problems.
An incident occurred in the preparation plant in which a phase unbalance protection device on a transformer tripped causing a power outage. This resulted in the conveyor system accidentally dumping tons of coal into the plant. An electrician had disconnected a 1967-vintage meter thinking that the old originally-installed meters caused too many nuisance trips.
"This forced us to install PML's 3720 meters in that area a little earlier than planned," chuckles Short. Later, however, electricians found that the transformer that did trip had a phase unbalance as high as 60 percent. Today, the preparation plant's electrical distribution points are fully metered, initially tied into the earlier SCADA system and now PML's new PEGASYS network.
Another 16 3720 meters are scheduled to be installed in the plant this year and in 1997 to cover all 4,160 Volt motors.
"We may extend monitoring at the plant down to motors of only 200 HP, depending on how mission critical they are," says Short.
Another incident, this time a disturbance from an especially bad BC Hydro voltage swing, a year ago, blew up the main incoming substation's capacitor bank. Power dropped extremely low followed immediately by a very high spike. "That cost us $40,000 just to bring the capacitor bank back on-line," says Short.
Internally-generated harmonics (which also blew up the capacitor bank several times in the past) are watched closely. All of Elkview's heavy mine site excavation equipment contain solid-state electronics and are driven by SCR-controlled DC motors, thus pushing harmonics into the company's electrical system.
The capacitor bank problem was solved by redesigning it and installing a 3720 ACM for power factor correction monitoring. "Our 3720 ACM power meters will show us these harmonic problems, by selectively triggering on individual harmonics, particularly the 5th and 7th that we watch closely," says Short. "By activating the setpoint to the 5th harmonic, the 3720 ACM will shut off the capacitor bank if the 5th harmonic starts climbing."
At the mine pit, each equipment's portable switch gear has a 3720 ACM meter connected to the new PEGASYS network. "We can now determine not only the area, but also pinpoint which specific drill or shovel is generating the harmonics," says Short. Being able to measure and determine their source has identified the harmonics problem for Elkview.
"The 3720 ACM power meter is so powerful, packed with so many features that it can record events we wouldn't even think of monitoring," says Short. "On one occasion we didn't have the background to interpret what the meter was showing us."
Short is referring to a problem that occurred with one of the big 54-cubic-yard-bucket P&H 4100 shovels. The shovel's on-board power factor correction kept tripping off as phases became unbalanced, for which Elkview's electrical personnel couldn't find the cause.
So they removed the phase unbalance protection and, two days later, the shovel experienced major problems. The cause of this difficulty was ultimately diagnosed as an arcing bus bar which had not been properly connected by the manufacturer. "We had more than enough information but didn't understand it because we'd never faced this type of problem before," says Short. "We learned the hard way to listen to our meters."
System Upgrade
Short, McCarty and Roccamatisi were thrilled to upgrade their earlier SCADA system to PEGASYS which gives them many of the features found on large, expensive, mainframe-based energy management and distribution control systems.
"The system's open-ended, modular design totally changed the way we work," says Short. Running under the easy-to-use Windows NT operating system, the system brought the flexibility of object-oriented computer technology to dramatically extend Elkview's instrumentation capabilities.
"It has not only reduced our operating costs, but greatly improved productivity by making our work much easier and the electrical distribution system much clearer," says Short. "We now see everything as graphical representations. This makes it easier for our users to understand the power flow and what's happening in the electrical system."
The software's Dynamic Data Exchange (DDE) capabilities enables them to bring power information, accumulated in their office Pentium/100 PC server, over the NT network, into Excel spreadsheets to create their daily, week-to-date and monthly power reports. "Now we just pull it over, the numbers come up, the form is made and you're done," says Roccamatisi. Short, McCarty and Roccamatisi have also created Excel worksheets, based on these reports by area, that any user on the local area network can access.
In the mine pit, some 18 portable switchgear lineups (each feeding excavation equipment such as a drill or shovel) are now monitored by a PML 3720, communicating with PEGASYS via Motorola DARCOM radio modems. In case of a fault, a 3720 will trip the breaker. Immediately, it gives electrical personnel a record in their offices showing exactly why the breaker tripped, thus enabling them to diagnose the problem much faster than before. "The min/max values note any changes by area showing us if we're experiencing voltage swings that are causing us problems," says Short.
PEGASYS also helped Elkview electricians change mine site distribution locations, when they had low voltage problems, in effect assisting them to redesign in-pit power lines without having to bring in outside consultants. "It actually works much better than an in-house consultant, continuously analyzing the power system," adds McCarty.
Foundation for a Mine-Wide Information System ...
Although now fully electrically monitored, the coal preparation plant, built in 1967, still contains original equipment. However, this year the plant's huge dryer and conveyor system will begin to be extensively automated with control devices installed. "When it's done we'll really control the preparation plant power and shed loads," says Roccamatisi. "And the 10 percent energy savings we've achieved thus far at Elkview will seem minor compared to what we'll achieve at the preparation plant alone."
Upgrading this equipment is the only delay in Elkview's vision power automating the plant, and eventually all of Elkview's operations. The open architecture of PEGASYS gives them the means to exchange the control data from PLCs, at the mine and preparation plant, with that of the electrical monitoring and control meters.
"In other words, instead of PLCs and electrical control running as separate entities, we'll be able to unite them into one integrated system," explains Short.
Elkview's electricians want to control all energy-consuming equipment as much as possible. Short sees this tight control as only coming from a PLC system. "One of the biggest benefits we've had seen from the system is its ability to exchange information with other devices to give us both an automated control and extensive monitoring system," says Short. "Everything we do manually now we'll automate by the middle of next year."
"Currently, our accounting people break down our weekly power report into mine and plant areas for monthly distribution of operating costs," he says. "We want anyone with a need to know (not only electrical personnel) to be able to access the information."
Power Smart's "Industrial Facility of the Year"
The electrical department's automation efforts have caught everyone's attention, from management at Elkview and Teck Corporation to other nearby mines, some of which have begun to follow Elkview's lead.
Elkview's relationship with its utility has also evolved. Unlike earlier days, when BC Hydro and the mine worked against each other, arguing about who created power problems, they now work closely together to improve power quality.
BC Hydro, which now knows Elkview's operation schedule, even plans power outages on its 500 kV line on Thursdays and Fridays, when the preparation plant is not working, to prevent any power problems from affecting the mine. Overall, BC Hydro has been very understanding and supportive of Elkview's efforts to improve power quality.
"I wouldn't say our utility's power problems have entirely disappeared," says Short. "But we've come a long way from when the utility would never inform us of any power problems they were experiencing."
Now, BC Hydro calls or faxes to warn Elkview when taking power lines out of service, or any event that will affect the mine's power supply. "We still call them, though, whenever their 69 kV input to the mine is dropping low because, with PEGASYS, we're always tracking their power and ours," says Short.
Besides tracking disturbances, Elkview also watches its power bills and wants to reconcile its monthly energy usage by comparing the utility's measurements against its own meter. "We've asked BC Hydro to let us connect a 3720 ACM onto their CTs in their substation, located 2 miles from our own main incoming,' says Short.
According to Short, a world of "power smart" communications has opened up between Elkview, the utility, and the mine's own employees. "Two years ago, we'd discuss power with our own people and they wouldn't even know what we were talking about," he says. "Today, I bet anyone in management could tell you how much power their department is drawing and be knowledgeable about power costs and quality."
Short says that it's been exciting to watch Elkview's power automation progress from its early days to where the mine is now and where it will be by 1997. Much has been accomplished in three years. And Short admits that much work still needs to be done.
Short credits PML's instrumentation for two 1995 awards won by Elkview: the Canadian Institute of Energy's (CIE) applied energy innovation award, and BC Hydro's "Power Smart" excellence award, which singled out the mine as the "industrial facility of the year."
Today, Elkview is well positioned with the most technologically advanced foundation on which to build its mine-wide information system to meet specific needs of a variety of users, anywhere in the company.
Ralf Edler is with Telecomputer Communications located in Victoria, B.C.