Snowy Hydro finds extra power with intelligent systems

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Snowy Hydro finds extra power with intelligent systems

Data boom gets more from existing generators.

Snowy Hydro has passed the halfway point of a $60 million upgrade of the control systems for eight major power stations.

The project is part of a broader $400 million modernisation of the Snowy Hydro scheme that is expected to be completed in 2017.

That covers broader mechanical and electrical works, as well as the step change in controls and protection systems technology.

Snowy Hydro's controls technology manager Darryl Eager told iTnews that work had begun at the Murray 1 power station in August. Murray 1 is located about 10 kilometres east of Khancoban in southern NSW.

Other remaining stations to be kitted out include Murray 2, Tumut 1 and Tumut 2.

Eager said the modernisation project is a bit "like a travelling circus".

"It turns up at a power station, works its way from one end to the other, and then moves on," he said.

The upgrade is performed one generator at a time.

Elements of the old control systems are gutted "because we've got to reuse the same locations" for new equipment, Eager said.

"We get in, totally strip the unit, get rid of all the old controls, cables and everything else we're not using, put the new panels in place, cable them up and then do our testing," he said.

The core control architecture consists of Rockwell Automation components, including Allen-Bradley ControlLogix programmable automation controllers, PanelView industrial computer displays and associated systems.

The control system is supported by a new fibre optic network inside each station. Snowy Hydro has an existing backhaul network of fibre optic cables and microwave links that connect its various assets.

Snowy Hydro is the custodian of the Snowy Mountains Scheme, built between 1949 and 1974. The Scheme produces hydro electricity and diverts water for irrigation.

More power

A key advantage of the new control system is it enables Snowy Hydro to wring more energy out of its power-generating assets, by providing better visibility of the stress that a particular piece of power generation equipment is under.

In the past, equipment ran with "a fairly large safety buffer" to prevent it ever being pushed to a point where it might fail.

"You'd take it to the worst possible condition," Eager said. "You'd think of all the worst possible cases, and that used to be the limit, because you were always covered no matter what happened.

"Now we've got a new control system, we can actually predict how the plant will perform on higher loads, and predict where the weak points are, and set the limit up based on what that weak point is."

Eager said that a busbar - an electrical conductor consisting of strips of metal that connect the generator to a transformer - might constitute a weak point in the system.

"You might run into some sort of limit that you can't put any more energy through that bus bar because it's going to get too hot," he said.

"That potentially becomes a weak point. We actually predict where that weak point will be, and allow the system to go just up to that limit without going over it."

Eager said that Snowy Hydro conducted a study called Water to Wire to determine potential weak points across the generation network.

"Then we came up with an algorithm — basically a model — for each of those components based on things like ambient temperature, voltage levels and a few other bits and pieces," he said.

Snowy Hydro's Tumut 3 power station — the largest it operates — is able to wring up to 35 megawatts of extra capacity per generator, due to the dynamic monitoring capabilities the new control system provides.

"At T3, nominally we can get 265 megawatts out of a [turbine] — that's what we can do safely no matter what's happening — but we can actually go from 265 megawatts up to 300 megawatts as long as we keep an eye on these weak points and don't put them under too much stress," Eager said.

"The control system gives us those 35 megawatts times six [generator] units of additional energy into the grid, purely based on being able to monitor and predict the performance of all those potential weak spots in the system."

Data boom

Granular visibility also extends to other parts of Snowy Hydro's plant infrastructure, courtesy of an upgrade to some of the sensors used to monitor equipment.

"We put in some additional sensors and upgraded others," Eager said.

"We might have [had] a level switch to say when something is full. We got rid of the switch and put in a transducer so we know how many percent it's full."

Other sensors in the environments could be reused in the new control architecture.

A number of intelligent systems are also being rolled out in conjunction with the control system.

The intelligent systems include Schweitzer and General Electric generator and motor protection systems; ABB and GE excitation systems, which monitor generator voltage quality; and Morgan Schaffer CALISTO transformer oil monitoring systems.

Between the new control system, upgraded sensors and associated intelligent systems being deployed, Eager is seeing the amount of data generated increasing by a factor of ten.

"There's 10 times more points of data coming out of the system compared to what we had originally," he said.

"It was all real time in the first place, it's just there's now more of it."

The data feeds into the control system to Snowy Hydro's SCADA system and ultimately to the Scheme's controller "who controls the entire hydro scheme".

It also goes into a data historian, a repository for historical plant data that is common to process control systems.

"That information becomes available to everyone in Snowy Hydro," Eager said.

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