Sempra subsidiary PXiSE Energy Solutions plans to create a federation of microgrids to boost renewable energy in remote Australia towns under a new agreement with utility Horizon Energy.
Many of the isolated towns now have mini-grids or microgrids, each about 1 MW in size, that burn up to 95 percent diesel, said Patrick Lee, president of PXiSE Energy Solutions.
Efforts to boost the amount of renewables in remote areas generally only yields about 30 percent of the energy the region needs, he said.
“That’s a limitation around the world. In Hawaii and other places, when you get to 30 percent renewables, you have curtailments, or people have power quality issues,” he said. In some cases, like Hawaii, utilities have called for moratoriums on additional solar.
However, with its distributed energy resource management (DERM) system, the company says it can bust through that barrier and boost the percentage of renewables to 50 percent and above. The company’s DERM system networks various distributed energy resources together, with the ability to adjust to grid challenges very quickly.
Why a federation of microgrids
“We can create a federation of microgrid systems that can respond to fast changes and go beyond 50 percent renewables,” Lee said.
In some of the towns, as homes are built closer together, the company plans to operate the resources initially as individual microgrids, and over time, operate them as a federation of microgrids, which means the company could network the microgrids together and exchange energy among them.
Lee compared this process to managing highway lanes on a freeway. “Initially we control cars on three different freeways, but eventually connect them as opposed to having three separate controls. Our system looks at the many distributed resources you can control and influence, and over time, ties them together.”
PXiSE’s Active Control Technology (ACT) is at the heart of this breakthrough. It’s able to expand the percentage of renewables because of the data transparency and quickness it provides, Lee said.
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Balancing small grids in remote areas requires quick response to challenges or changes in the system. The company says its ACT runs 23,000 percent faster than most existing grid control systems. As a result, the ACT platform can address challenges as they occur in real time, Lee said.
For example, if a town has many solar roofs, and a cloud comes by and shades the solar panels, the solar power output drops quickly. “That happens in seconds, and you have a ripple effect quickly. You need the system to respond quickly and manage the supply and demand drop,” Lee explained.
In addition, it’s important to manage the power quality because voltage can change quickly.
In a traditional system, it takes minutes to adjust the power output of fossil fuel or natural gas generators in order to make up for the loss of solar. That’s what causes the grid problems experienced in high-solar regions — Hawaii and California, for example.
But PXiSE’s data system allows for what Lee calls “x-ray visibility.”
“The high resolution and high speed allow us to have fast control and response. If I can see it quickly I can also control something very fast. In the time it takes you to blink your eye, the systems can make 30 adjustments,” he said.
The company plans on first networking the remote microgrids together and then adding distributed energy resources so that its system is controlling up to 50,000 resources — solar, electric vehicle charging, storage and others.
Adding distributed resources increases the complexity of the project.
A simple microgrid generally includes solar, a battery and one inverter, Lee said. But adding multiple inverters, solar, and other resources can be a challenge. That’s a complex microgrid, what the company specializes in managing.
No spinning generation
PXiSE uses its control system to operate a grid that doesn’t include fossil fuels or a spinning generator — resources that slow down if energy supplies on the grid are limited.
“Spinning generators tend to slow down if there’s not enough supplies on a grid. Then frequency drops, creating problems. Avoiding slow-moving spinning generators helps the company’s system operate more quickly, he explained.
“We can operate a grid with no spinning generation. This enables us to operate a grid with more renewables and no fossil fuels,” he said.
The system can dispatch the renewables first and avoid curtailing them as most high-penetration renewable grids must. In addition, distributed resources — not slow-moving, big fossil-fuel plants — can be used to balance the high and low supplies.
Peer-to-peer trading eventually
Eventually, the hope is that small solar producers in Horizon’s territory can sell their excess solar locally through peer-to-peer energy trading.
“Smart inverters allow them to participate. You would sign up and say, ‘I want to participate tomorrow if the price is a certain amount,'” Lee said. The company would forecast these and other DERs’ potential contribution to the grid and monitor their participation in real time.
Horizon would have to manage a centralized market before it could experiment with peer-to-peer trading, he noted. “Once they learn enough and can operate the grid reliably, they can experiment with peer to peer trading.”
All of this is possible because of PXiSE’s system that acts like a “brain,” said Lee.
“I call it the brain of the power grid, a modern operating system for the grid. It’s automated, there’s less human intervention and it’s faster.”
And that yields improved reliability, increased efficiency and high percentages of renewable energy — just what the solar-saturated grids of today need, he said.
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