Originally Posted by
megan
certifs, from todays reports
I assume you are talking about the article in the Australian. More to say on that further on.
Originally Posted by
megan
it seems the zombie argument might, in fact, be fact. It is being reported that the software control systems for the wind farms had been set at too conservative a level in their ability to handle faults. They don't specify the faults which occurred, making mention only of lightning strikes, so wind as I mentioned may, or may not, have have been one of the faults.
No. It really, really wasnt.
There are things which are plausible and things which aren't.
There are a number of systems on a windturbine that you might loosely call protection. Some for mechanical reasons (eg overspeed, oil temperature etc) and some for electrical problems (eg over current, phase unbalance, earth fault etc). The only fact we know is from the AEMO report which shows that the generators stopped working _after_ the lines stopped working.
For it to be a wind/speed related shut down it must be argued that the turbines shut down (remember there are 10's of them, each individually speed monitored) all coincidentally at the same time, coincidentally a second or two after the lines failed (in whatever way they failed). And that happened twice. At different geographic locations.
OR we could assume it was an electrical protection operation in response to the line fault (ultimately by one or two circuit breakers disconnecting the whole farm at once from the grid). In which case, effect does follow cause, the outcome is what could be expected. And because the are a number of different ways, with different settings, that the electrical protection could operate, that would explain the "we don't know the reason" that is being touted around in the media.
Originally Posted by
megan
The interconnector dropped out due to its inability to handle the load after the wind farm dropped out. The wind farm has now had control systems set to a more realistic level of fault toleration, and operator is now wondering about about liability claims as a result of its too conservative an approach with regard to faults.
If this is based on the Australian article (otherwise what article was it from?) I will note a couple of things. Their un-named "industry expert" is the one who is talking about liability. I doubt any of the windfarm participants really care too much, there will be some juggling of blame and maybe someone will pay something. This is just cost of doing business. Refer to gerry111's comments on the SRAS. Those people _do_ have something to worry about. Weirdly, no one want to talk about paying millions (yes $50 million over the last few years for all of the NEM, I believe) for a service which wasn't provided.
Anyway, the expert seems to be talking about ride through ability that most power stations should have (I am not sure all power stations do in fact have these performance standards because some older stations had some of the standards waived, at least early on in the transition to the market, but all the new wind farms would/should). There was an interesting report done after a fail to ride through by the now extinct Northern Power Station in 2005. They got fined, some 100's thousands dollars from memory. You should be able to find it on AEMO website.
Anyway back to the Australians expert. He talks about riding through 50 faults in 2 minutes. I am unfamiliar with what part of the National Electricity Code he got that from. There are a number of ride through parameters (how low the voltage can go, for how long etc) in the code. The relevant ride through for windfarms with 100% voltage loss is 430 milliseconds. This seems to line up fairly well with factual data from the AEMO report.
You'll also note from the last couple of paragraphs tucked away at the end of the Australian article, both the AGL chief and an un-named spokesman have fairly carefully worded their responses to indicate they have "read the report" ie they aint sayin' what they have done (if anything) and are pointing the finger at the grid protection settings (which was my first suspicion last week, though I don't hold that view as strongly now, in view of the extent of damage to the transmission system).
Originally Posted by
megan
The towers apparently came down after the wind farm isolation.
Yes, some of them did. Do you think that mean that the ones that came down before the windfarms tripped had no effect?
Certifs