power grid

21 Articles

The Regulatory Side Of Rolling Your Own Moderate Solar Farm

June 17, 2021 by 25 Comments

[Russell Graves] lives in Idaho and recently connected his solar installation to the grid, which meant adhering to regulatory requirements for both the National Electric Code (NEC) as well as complying with the local power company’s own regulations. His blog post is an interesting look at the whole regulatory process and experience, and is of interest to anyone curious about running their own solar farm, whether they have plans to connect it to the grid or not.

A circuit breaker that met NEC code, but not the power company’s requirements.

The power company has a very different set of priorities from the NEC, and part of [Russell]’s experience was in having to meet requirements that weren’t documented in the expected places, so study of the materials didn’t cut it. In particular, the power company needed the system to have disconnects with conductors that visually move out of position when disconnected. [Russell] was using NEC-compliant circuit breakers that met NEC code, but they didn’t meet the power company requirement for conductors that can be visually confirmed as being physically disconnected. Facing a deadline, [Russell] managed to finesse a compliant system that was approved, and everything got signed off just as winter hit.

How well does his solar farm work out? Sometimes the panels produce a lot of power, sometimes nearly nothing, but it has been up and running for all of winter and into spring. Over the winter, [Russell] pulled a total of 3.1 MWh from the grid, mainly because his home is heated with electric power. But once spring hit, he started pushing considerably more into the grid than he was pulling; on some days his setup produces around 95 kWh, of which about 70 kWh gets exported.

[Russell] didn’t go straight to setting up his own modest solar farm; we saw how he began by making his own ideal of a perfect off-grid office shed that ran on solar power, but it has certainly evolved since then and we’re delighted to see that he’s been documenting every bit of the journey.

What’s The Deal With Rolling Blackouts In California’s Power Grid?

August 31, 2020 by 148 Comments

A heat wave spreading across a large portion of the west coast of the United States is not surprising for this time of year, but the frequency and severity of these heat waves have been getting worse in recent years as the side effects from climate change become more obvious. In response to this, the grid operators in California have instituted limited rolling blackouts as electricity demand ramps up.

This isn’t California’s first run-in with elective blackouts, either. The electrical grid in California is particularly prone to issues like this, both from engineering issues and from other less obvious problems as well.

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Ask Hackaday: Is Our Power Grid Smart Enough To Know When There’s No Power?

June 23, 2020 by 63 Comments

Just to intensify the feeling of impending zombie apocalypse of the COVID-19 lockdown in the British countryside where I live, we had a power cut. It’s not an uncommon occurrence here at the end of a long rural power distribution network, and being prepared for a power outage is something I wrote about a few years ago. But this one was a bit larger than normal and took out much more than just our village. I feel very sorry for whichever farmer in another village managed to collide with an 11kV distribution pole.

What pops to mind for today’s article is the topic of outage monitoring. When plunged into darkness we all wonder if the power company knows about it. The most common reaction must be: “of course the power company knows the power is out, they’re the ones making it!”. But this can’t be the case as for decades, public service announcements have urge us to report power cuts right away.

In our very modern age, will the grid become smart enough to know when, and perhaps more importantly where, there are power cuts? Let’s check some background before throwing the question to you in the comments below.

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The Hornsdale Power Reserve And What It Means For Grid Battery Storage

December 16, 2019 by 130 Comments

Renewable energy has long been touted as a major requirement in the fight to stave off the world’s growing climate emergency. Governments have been slow to act, but prices continue to come down and the case for renewables grows stronger by the day.

However, renewables have always struggled around the issue of availability. Solar power only works when the sun is shining, and wind generators only when the wind is blowing. The obvious solution is to create some kind of large, grid-connected battery to store excess energy in off-peak periods, and use it to prop up the grid when renewable outputs are low. These days, that’s actually a viable idea, as South Australia proved in 2017.

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Anatomy Of A Power Outage: Explaining The August Outage Affecting 5% Of Britain

September 7, 2019 by 18 Comments

Without warning on an early August evening a significant proportion of the electricity grid in the UK went dark. It was still daylight so the disruption caused was not as large as it might have been, but it does highlight how we take a stable power grid for granted.

The story is a fascinating one of a 76-second chain of unexpected shutdown events in which individual systems reacted according to their programming, resulted in a partial grid load shedding — what we might refer to as a shutdown. [Mitch O’Neill] has provided an analysis of the official report which translates the timeline into easily accessible text.

It started with a lightning strike on a segment of the high-voltage National Grid, which triggered a transient surge and a consequent disconnect of about 500MW of small-scale generation such as solar farms. This in turn led to a large offshore wind farm deloading itself, and then a steam turbine at Little Barford power station. The grid responded by bringing emergency capacity online, presumably including the Dinorwig pumped-storage plant we visited back in 2017.

Perhaps the most interesting part followed is that the steam turbine was part of a combined cycle plant, processing the heat from a pair of gas turbine generators. As it came offline it caused the two gas turbines feeding it to experience high steam pressure, meaning that they too had to come offline. The grid had no further spare capacity at this point, and as its frequency dropped below a trigger point of 48.8 Hz an automatic deloading began, in effect a controlled shutdown of part of the grid to reduce load.

This is a hidden world that few outside the high-power generation and transmission industries will ever see, so it’s very much worth a read. It’s something we’ve touched on before with the South American grid shutdown back in June, and for entirely different reasons in 2018 when an international disagreement caused the entire European grid to slow down.

Header image: Little Barford combined-cycle power station against the sunset. Tony Foster, (CC BY-SA 2.0).

The South American Power Outage That Plunged 48 Million Into Blackout

July 22, 2019 by 44 Comments

A massive power outage in South America last month left most of Argentina, Uruguay, and Paraguay in the dark and may also have impacted small portions of Chile and Brazil. It’s estimated that 48 million people were affected and as of this writing there has still been no official explanation of how a blackout of this magnitude occurred.

While blackouts of some form or another are virtually guaranteed on any power grid, whether it’s from weather events, accidental damage to power lines and equipment, lightning, or equipment malfunctioning, every grid will eventually see small outages from time to time. The scope of this one, however, was much larger than it should have been, but isn’t completely out of the realm of possibility for systems that are this complex.

Initial reports on June 17th cite vague, nondescript possible causes but seem to focus on transmission lines connecting population centers with the hydroelectric power plant at Yacyretá Dam on the border of Argentina and Paraguay, as well as some ongoing issues with the power grid itself. Problems with the transmission line system caused this power generation facility to become separated from the rest of the grid, which seems to have cascaded to a massive power failure. One positive note was that the power was restored in less than a day, suggesting at least that the cause of the blackout was not physical damage to the grid. (Presumably major physical damage would take longer to repair.) Officials also downplayed the possibility of cyber attack, which is in line with the short length of time that the blackout lasted as well, although not completely out of the realm of possibility.

This incident is exceptionally interesting from a technical point-of-view as well. Once we rule out physical damage and cyber attack, what remains is a complete failure of the grid’s largely automatic protective system. This automation can be a force for good, where grid outages can be restored quickly in most cases, but it can also be a weakness when the automation is poorly understood, implemented, or maintained. A closer look at some protective devices and strategies is warranted, and will give us greater insight into this problem and grid issues in general. Join me after the break for a look at some of the grid equipment that is involved in this system.

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A Field Guide To Transmission Lines

June 11, 2019 by 120 Comments

The power grid is a complicated beast, regardless of where you live. Power plants have to send energy to all of their clients at a constant frequency and voltage (regardless of the demand at any one time), and to do that they need a wide array of equipment. From transformers and voltage regulators to line reactors and capacitors, breakers and fuses, and solid-state and specialized mechanical relays, almost every branch of engineering can be found in the power grid. Of course, we shouldn’t leave out the most obvious part of the grid: the wires that actually form the grid itself.

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