paulmac_ie
I spent a week in bed in excruciating pain, throwing up blood regularly. The doctor visited a couple of times, I'm not sure what he told my mother, but it was a week before he agreed I should go to hospital.
At that stage I was severely anemic and had peritonitis. I ended up in surgery to have a third of my stomach and some of my small intestine removed. A couple of weeks in intensive care and another few weeks in the children's ward before I was strong enough to go home.
When I left, I was told that I shouldn't eat acidic or spicy foods, and that I had an ulcer because of stress. I was 10, and I can tell you, while we didn't have a whole lot, I was far from being stressed.
Nearly 40 years later that surgery still impacts on my life. I still have some digestion issues, but knowing that Warren's & Marshall's work has prevented others from repeating my experiences has been some comfort.
Good on your doctor for trying something experimental which had such a great outcome.
Large thermal plants provide inertia that renewables simply can't provide. A lot of the work around incorporating renewables into grids is around the provision of synthetic inertia and how to manage sudden drops in supply.
Battery storage is one solution. Better demand response solutions backed by energy markets that incentivise the participation of large numbers of energy users is another.
Grids that have a high level of interconnection with other grids also reduces the impact of inconsistent supply, but not every grid has enough inter-connections for that to be a viable full solution. (See ERCOT in Texas, AEMO in Australia, Eirgrid in Ireland for examples)
Here in Ireland, we frequently run the grid up to 80% renewables, but the grid operator only does that because they have the mechanisms in places to handle sudden drops in supply.
My favourite part of my job is naming internal tools and applications after characters and quotes... it helps that the owner of the company is a huge Ted fan.
Scrap Saturday was arguably a watershed in Irish culture. It was broadcast on the national broadcaster (RTE) that even today is criticised for being too close to the government. By making fun of powerful figures, it opened peoples eyes to how ridiculous and corrupt Irish politics could be.
Ironically, Fr. Ted was commissioned and broadcast on Channel 4 on UK TV. At the time, the talk was about how RTE refused to commission the series because they didn't want to mock the Church, although this has been refuted by the writers.
Over the course of two series, Dermot Morgan mocked both the political and religious establishment and brought both closer to the common person. Whether this reflected the changes that were happening in modern Ireland, or lead the way can be debated. But we're certainly poorer for his loss.
if [ "$color_prompt" = yes ]; then
PS1='\[\033[0;32m\]\[\033[0m\033[0;32m\]\u\
[\033[0;36m\] @ \[\033[0;36m\]\h \w\
[\033[0;32m\]$(__git_ps1)\n\[\033[0;32m\]└─\
[\033[0m\033[0;32m\] \$\[\033[0m\033[0;32m\]
AWS:${AWS_PROFILE} ▶\[\033[0m\] '
else
PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
fiAs for how we control them so quickly, it's usually via a direct connection to a breaker of some description, or where there's a SCADA system that can trip out the loads in the required time frames. Before the site can participate in these services, we perform extensive testing to ensure they meet the required time constraints.
Our system monitors the grid voltage and current at 8 kHz, and we down sample that to 50 Hz (average grid frequency). We can detect a frequency event across 3 phases within 60 milliseconds. (We check all three phases for multiple cycles to reduce any false positives.)
When we trip out the loads, production stops. We'll notify the client why their loads have been turned off, but the SMS message will usually arrive a few seconds after the trip.
The clients that participate in these services get paid quite well to make their loads available and they're aware of the process. They agree to turn off demand without notice when there's a frequency event.
It's not suitable for every site. We work quite a lot with pharma companies for "regular" demand response, but very few can do FFR. Shutting down a pharma plant with no notice can cost a lot of money in wasted product and down time as they clear the wasted product off the production lines.
In cases like this, our systems would detect the frequency deviation, and shut off loads within 100 milliseonds to reduce the demand on the grid. This helps in cases where demand is greater than supply.
The entire system is automated - the required time frames are so quick that you don't have time for humans to be involved. By the time we're aware that an event has occurred, we've already reduced demand on the grid.
Handling high frequency events where supply is greater than demand is tricker. Sites that have long running generation can be instructed to shut down their generation, but large-scale batteries are probably the best solution in these cases. They can be switched quickly to start charging (if they have spare capacity).
As you've identified, one potential issue is that you can end up over-responding to the event and move from a low frequency event to a high frequency event.
The way we do in in Ireland is that our response is proportional to the frequency nadir. Not everything is tripped off at the same time.
As other posters have noted, the actual frequency deviations that occurred are not that big. 49.7 Hz is not that low compared to normal grid frequency. In fact, some of our systems wouldn't even activate at this level. They would see it, but wouldn't trip off any loads.