Has islanding of solar generation inverters on a utility line ever happened?
Has islanding of solar generation inverters on a utility line ever happened?
(OP)
When the solar PV generation industry talks to utilities about connecting projects the conversation sometimes seems to be about whether the internal protection of the inverters is adequate to detect faults or loss of supply on the utility grid even though the inverters are certified with advanced protection functions and anti-islanding algorithms. The concern is anti-islanding and that where multiple inverters are installed on a line they will fool each other or that a rotating generator will maintain what looks like the grid. Does anyone know if such an event has ever happened in the real world and if so for what duration? Apparently it's theoretically possible but I have heard it said it's tough to even simulate in a lab under controlled conditions to certify the inverter for AI functions.






RE: Has islanding of solar generation inverters on a utility line ever happened?
If one does not exist, it would be in the PV generation industry's interest to write one to which they have a fair chance of actually testing and certifying, and to get a utility trade association to buy off on it.
So, which dog is yours?
Mike Halloran
Pembroke Pines, FL, USA
RE: Has islanding of solar generation inverters on a utility line ever happened?
RE: Has islanding of solar generation inverters on a utility line ever happened?
RE: Has islanding of solar generation inverters on a utility line ever happened?
RE: Has islanding of solar generation inverters on a utility line ever happened?
A few years old, so other methods may exist. I find it interesting that an algorithm forcing a positive frequency bias can be canceled by another forcing a negative one. Definitely room for further standardization.
RE: Has islanding of solar generation inverters on a utility line ever happened?
RE: Has islanding of solar generation inverters on a utility line ever happened?
RE: Has islanding of solar generation inverters on a utility line ever happened?
RE: Has islanding of solar generation inverters on a utility line ever happened?
RE: Has islanding of solar generation inverters on a utility line ever happened?
The system was designed and run for 100 years with a centralized generation - radial distribution paradigm.
The historical goal of the utility is to deliver to all of its customers a 115.00 VAC 60Hz perfect sine wave on a 24/7/365 basis (or 220.00 VAC 50Hz, OR... but you get the idea).
When something breaks, we need to SAFELY deal with it, and get everyone back to the ideal ASAP.
Anything that makes this harder is bad.
Mixing in Distributed Generation through a plethora of solid-state inverters that add short-circuit energy, less-than-perfect sine waves and are worse-than-useless when the main source goes away qualifies as 'makes this harder'.
Adding a non-zero risk to restoration workers (no matter how small) makes this harder.
Having 15% of a feeder's generation vanish with resultant system voltage swing BECAUSE A CLOUD ROLLED OVER makes this harder.
Please do not be surprised when utility folk require robust precautions to interconnect!
RE: Has islanding of solar generation inverters on a utility line ever happened?
I never, never want to have to talk to the family of a dead worker to explain that 'the studies revealed that the risk was quite low.'
Do you?
RE: Has islanding of solar generation inverters on a utility line ever happened?
RE: Has islanding of solar generation inverters on a utility line ever happened?
The plant nor the utility relaying sensed islanding for a few minutes. (One operator claimed 20 minutes). The plant was in commissioning at about 20% load and operating on steam pressure control. The controls were not designed for islanding. It was only the second or third time the 30 MW generator had been synchronzied. When the feed pump VFD started hunting and making funny noises, the start up engineer aborted the run and asked the operator to trip the generator breaker. They were surprised when the plant and neighborhood went black. He was accused of opening the 60 kV breaker by mistake but its red light was still on.
Most of us would have bet that could never happen.
That was a couple decades ago. Since then improvements in rate of change of frequency relaying, multiple frequency settings plus utility-plant breaker communications make this scenario even more unlikely.
But with a solid state inverter locked onto 60 Hz.... I would not bet that islanding could not occur.
RE: Has islanding of solar generation inverters on a utility line ever happened?