Recent extreme weather has prompted fresh thinking on the subject of grid resiliency. Part of the solution lies with the proliferation of distributed energy and how it can be harnessed for that purpose. Juan de Bedout, Chief Technology Officer of GE’s Grid Solutions business, spoke to Decentralized Energy about his company’s approach.

As Chief Technology Officer, de Bedout is responsible for designing and producing world-class products to help create a more efficient and reliable grid system. Prior to this role, Juan served as the Technology Director for the Electrical Technologies & Systems organization at GE Global Research.
Juan de Bedout, Chief Technology Officer of GE’s Grid Solutions
The most visible, recent sign of how modern grids can be affected by extreme weather came with the devastation of Puerto Rico in September. A lot of temporary power operators were called into action, when the grid succumbed, and much of the country is still without power.

“Hurricane Maria took out infrastructure at such a scale that 95 per cent of the people were without power and even a month later 88 per cent of the island was without electricity. That’s the world we are heading into and we must think differently about how we architect the grid so that it doesn’t leave people for days, weeks and even months without electric power.”

Much thought is now being applied to how to use new and existing energy resources on the ground, and offset some, if not all, of the power issues that plague post-storm regions.

“What is exciting is the ability to control these resources in a more optimal way, to balance variable resources like solar photovoltaics with demand response and energy storage for example. It’s also about facilitating a more cost-effective deployment of those distributed energy resources (DER).”

GE has been perfecting its microgrid tech over the years, with one of its stand out performers being the Philadelphia Navy Yard. Bedout’s team have been applying what it has learned to prolonging the time a microgrid can operate after a storm event.

“We have developed building distribution automation coupled with fault detection, isolation and restoration. When you consider those two technologies you now can build a large distribution system. If a storm passes through, you can identify the healthy portions and the damaged parts of the circuit very quickly and use it to restore power.”

One US utility that benefited from this was NSTAR (now incorporated into Northeast Utilities), who enabled resilience for healthy portions of the grid post-large storms. The company could ship power through alternate lines and then have the ability to more fully serve the portions of the circuit that could be enabled to power.

“It’s technically difficult. When you start reconfiguring circuits there can be concern about voltage but a cool thing about this technology is it takes it into account.”

“NSTAR used our system to restore healthy portions of the circuit after a major eventsin less than an hour. Take Tropical storm Irene in 2011 – that system had 6,000 power interruptions and half of those were fixed in less than an hour. That’s what we’re looking for.”

The recent damaging storm that tore through Puerto Rico saw both GE and its partners attempt to facilitate the complete restoration of the grid. The work there is ongoing and more strategic thinking is now necessary. Puerto Rico lies in an area of the world, where such weather events are not rare, and with the impact of global warming, the ferocity and frequency involved is unlikely to diminish.

“Our energy consulting group (power systems consulting team inside GE’s grid business) is working with Puerto Rico and helping them to envision how their system architecture would work going forward.”

“Resiliency is a key topic. Making sure some substations are hardened for heavy winds and that you have the right presence of distributed resources so that you can form microgrids to restore portions of the circuit, at least critical power. They are in the initial stages in helping them think through long term plans.”

Why has the Puerto Rico case been so much about reactive and so little about proactive up to now? Part of the issue lies in how the grid is sited on the island.
 
“You really want to rearchitect the system – essentially Puerto Rico today has most of its generation on the south of the island and a lot of the load is on the north of the island and when the transmission is wiped out connecting those two you have a big problem so it’s about thinking about that policy differently.”

“There could be higher proportions of DER in the northern part of the island where most of that load is for example. This is where we build more resilience into the system but it’s a different architecture.”

“You may have to restring wire but providing substations that don’t require a lot of work to bring them back up; that’s meaningful.”

There is one contributor to the DER spectrum that’s particularly relevant to grid practitioners at the moment and it presents both a challenge and an opportunity, according to de Bedout.

“To me the most striking DER coming up is solar. Last year solar was the highest proportion of new installed resources with 23 per cent of new global installs. The forecasts from BNEF say that solar and wind will be 73 per cent of renewables investment in generation capacity between now and 2040- we re heading into a totally different world and what’s really interesting about that its going to be a resource that is as available.”

“It will be very dynamic and in order to absorb it we are going to leverage the transmission infrastructure much more heavily for big imbalances – you will see transmission grids where the power exchanges across TSOs will be much bigger and occur much more quickly than what they do today.”

Bedout points to a recent study (Eastern Renewable Generation Integration Study (ERGIS)) undertaken by the National Renewable Energy Laboratory (NREL). Researchers used high-performance computing capabilities and visualization tools to show the power grid of the Eastern United States—one of the largest power systems in the world—can accommodate upwards of 30% wind and solar/photovoltaic (PV) power.

“They looked at what the transmission grid was expected to look like by 2026, but they modelled it with 30 per cent renewable content. They further modelled where wind and solar are most likely to be deployed and looked at what would happen across the TSOs where there is excess energy in one region needing to be moved to a different region.”

“There are great videos in that study showing how that power dynamic moves from one TSO to another in a matter of hours- For example, Florida gets all of its load through gas turbines, then at sun rise solar generation comes on quickly, backing off that gas power and compensating in drawing power in some cases from Georgia. Later on they are solely reliant on solar before in the evenings, as sun sets, they have to bring on the gas turbines as they go through the excess electricity and are forced to take large amounts of power again from their neighbours.”

In short the exchange of power through TSOs across regions is going to be moving much more quickly and in a more impactful way, but the technology now exists to manage that dynamic transfer across regions.

“It’s going to be very exciting at grid energy management and market management level. You will to see transactions completed much faster. Today it’s done on an hour ahead basis but to make their scenario work the NREL had to accelerate that to a five-minute window – there will be much more grid collaboration across TSOs and it’ll be all a different world.”

De Bedout says control technology is essential in making the existing infrastructure work most effectively.

“If you think about our GE renewables business it’s a lot about helping renewables be much better citizens of the grid, having the ability to control the amount of power they put on the grid in a very determined way.”

“You can ask a wind farm to go from one power level to another at a certain ramp rate and in some ways in proportion of time to operation of the grid that’s an important feature to have.”

“You can have wind farms that support frequency and wind farms that provide black start functionality. Those are the types of features that our wind business is working on -taking in renewable energy forecasts and analysing how we commit and dispatch resources on grids.”

“We are moving to have platforms that can run faster in the future and can identify problems in operation of the grid much more quickly.”

Part of that picture of grid resilience can include the company’s gas-fired power generation fleet, and its responsiveness to grid problems, being able to start and stop and turn down in a much shorter timeframe.

“A great example is the hybrid gas turbine – a turbine that has been paired with energy storage so it can participate in the peaking market but can actually turn itself off when it’s not needed.”

“While still participating in that market it’s got the capacity coming from the battery. If energy is needed suddenly from that gas turbine that battery is a bridge to black start operations. You now have ability for gas turbines to provide reserve capacity but don’t need to be on providing fuel and sending out emissions unless absolutely needed,”

GE’s microgrid unit has the technology most suitable to assisting the new challenges associated with DER on the grid. Most usefully microgrids can be connected to the main grid in times of outage, and controller technology smooths the process.

“You can use this controller to get DERS to interact in a smart way with the main grid and get these DERs to behave like an aggregated power generation resource. Then add a whole microgrid to increase the amount if exporting to the power grid or decrease the amount of power taken from the grid. Also, you could ask it to go from one level of power exchange to another level of power change respecting the ramp rate. The intel and smarts are there to take a collection of resources and make them well-behaved. “

Finally, there is GE’s DERM (Distributed Energy Resource Management) software, which de Bedout explains, provides operators with tools suitable to bring together consumption information from smart meters with load forecasts and status updates from the grid.

“DERM is about controlling that collection of resources together, looking at the bigger footprint and looking across many distribution maps. We can view whether responsive loads, DER units, battery storage, small power generators can be brought together in supporting the bulk grid.”

The ultimate goal remains the same – lessening the impact of these storms to the greatest extent possible.