[HN Gopher] NREL Open-Source Modeling Approach Simulates Low-Ine...
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NREL Open-Source Modeling Approach Simulates Low-Inertia Power
Systems
Author : rbanffy
Score : 38 points
Date : 2021-07-26 18:41 UTC (4 hours ago)
(HTM) web link (www.nrel.gov)
(TXT) w3m dump (www.nrel.gov)
| bob1029 wrote:
| How far can we push our power grids into the "no intertia" realm
| until things start to fall apart catastrophically? Is that what
| this is all about?
|
| If we ignored all of the other factors, wouldn't we ideally have
| as much inertia (damping) as we can spare for the grid?
|
| What would stop us from arbitrarily adding super-heavy motor-
| generators to the grid _but without the gas turbine part_? You
| don 't need a prime power source to actually add old-school
| inertia to the grid...
| bloudermilk wrote:
| What you're describing is effectively a utility-scale flywheel,
| which at least one company is trying.
|
| https://www.revterra.io/
| barney54 wrote:
| It sounds likes you are describing synchronous condensers:
| https://en.wikipedia.org/wiki/Synchronous_condenser
| bob1029 wrote:
| Yes! Thank you. I had no idea they were called this. It was
| difficult to believe that something like this didnt already
| exist.
| ZeroGravitas wrote:
| I believe the idea is to shift to synthetic inertia, which like
| synthetic diamonds, can actually be better than the real thing,
| but people get weirdly sentimential about the flaws in the one
| they are used to.
| bob1029 wrote:
| Are we claiming there are zero downsides to synthetic inertia
| when compared with its real counterparts?
| toomuchtodo wrote:
| That appears to be the case in Australia's NEM grid, where
| utility scale batteries are able to meet synthetic inertia
| needs [1] (as well as preliminary trials of grid forming
| inverters in Chile, which NREL took part in [2] [3]).
|
| [1] https://www.energy-storage.news/news/australian-
| transmission... (Australian transmission operator's
| commercial arm to tender for 300MW unsubsidised battery
| project)
|
| [2] https://www.nrel.gov/news/features/2020/renewables-
| rescue-st... (Renewables Rescue Stability as the Grid Loses
| Spin)
|
| [3] https://www.nrel.gov/docs/fy19osti/73207.pdf (NREL:
| Highly Accurate Method for Real-Time Active Power Reserve
| Estimation for Utility-Scale Photovoltaic Power Plants)
| rbanffy wrote:
| I'd assume the extra complexity would be a huge downside.
| If the control logic of the synthetic inertia can be
| disabled, it won't work.
|
| A heavy rotating mass will continue spinning no matter what
| until mechanical losses (or external forces) stop it.
| guerby wrote:
| Inertia is always pictured as a "good thing", my (very limited
| and probably wrong) understanding is that when production drops
| abruptly because of a failure inertia of rotation based
| generators serves as a temporary battery to cover for the
| imbalance.
|
| But what happens when demand drops abruptly in an inertia heavy
| grid?
|
| Eg if some evil AI turn off plenty of IoT controlled electrical
| appliance countrywide at exactly the same time.
|
| https://www.nrel.gov/news/program/2020/inertia-and-the-power...
| brandmeyer wrote:
| Primary frequency reserve kicks in to automatically throttle
| back dynamic sources. Typical throttle rate is 100% throttle
| response per 5% frequency deviation. Inertia (both real and
| virtual) just slows down the system response enough that PFR
| will be effective. Just about every steam plant, combined-cycle
| plant, and gas-turbine plant participates in PFR. There have
| been proposals for inverter-connected systems to participate as
| well, but I don't know how common it is in practice.
|
| Once upon a time the rated load-step response for a sub-grid in
| the US was a step-off transient of a nuclear power site going
| off-line.
| guerby wrote:
| Thanks for your reply.
|
| Is the Hornsdale Power Reserve "participating" in this
| mechanism?
|
| https://en.wikipedia.org/wiki/Hornsdale_Power_Reserve
|
| Since it's a Lithium battery I assume it's "inverter-
| connected".
| kdheepak wrote:
| Hi everyone, I'm a researcher at NREL and I've contributed to
| this effort. I'm happy to answer any questions. I'll also let the
| other researchers know that they can chime in here.
| 7thaccount wrote:
| Small world. I've looked through these libraries before and
| have chatted with NREL staff at conferences (didn't expect to
| talk on HN though). I've enjoyed some of the more recent papers
| on inertia and frequency response as well and will have to look
| into this study in more detail.
|
| I tend to stick more to Python + Numpy and ScyPy, but do check
| in on Julia from time to time. I'm still questioning whether
| the sparse matrix routines have matured enough in Julia
| (necessary for the truly large systems). On the optimization
| side, has all of NREL switched to Julia + JuMP, or is the
| native Python API for GUROBI used and Julia for the network
| pieces?
| kdheepak wrote:
| I was surprised to see this on HN too.
|
| Definitely not all of NREL has switched to Julia + JuMP. From
| what I can tell, Python, MATLAB etc still are quite prominent
| across the laboratory. And, NREL is a large organization and
| we are a small team; we don't have much insight into what
| tools developers decide to choose and why. If anything, it is
| possible that we've set the precedent that Julia + JuMP _can_
| be used for this sort of work.
| 7thaccount wrote:
| Ah, yeah I think that makes more sense.
|
| I know Matlab is a good R&D tool (like Mathematica), but it
| is a little painful for the end user and far too expensive
| for a lot of industrial users who don't work at a company
| already entrenched with the ecosystem. I don't want to pay
| $5k for a database toolbox if you know what I mean. If the
| code is only for a study though...it probably doesn't
| matter a whole lot.
|
| Python seems like a good lingua franca and Julia isn't far
| behind overall. What makes me excited about Julia is that
| (at least in theory) I can write some blazing fast code
| without being a systems level programmer and also get the
| ability to look at the assembly output (just all around
| cool) and write macros (a la lisp). I doubt I'd ever use
| macros on serious code, but having the opportunity is a
| plus. It's a neat design.
|
| Best of luck in your future endeavors.
| jjoonathan wrote:
| Cool! I'm glad someone is looking into this -- figuring it out
| the hard way sounds... potentially quite destructive.
|
| Have you found any scenarios that seem likely to hit
| oscillation first?
| guerby wrote:
| Hi, is the paper "Transient Simulations With a Large
| Penetration of Converter-Interfaced Generation: Scientific
| Computing Challenges And Opportunities" available in PDF
| without paywall? https://doi.org/10.1109/MELE.2021.3070939
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