Electric Companies slowly taking back control

[Tony Scott]

I have no reason to doubt this is the case where you live, however this is not a universal situation.


Not sure how this is pertinent to the discussion but we have three if you must know. They all operate just fine with my off-grid backup system if we have a grid outage.


Underground power grids are phenomenally expensive to build, install and especially expensive to maintain/repair. At least an order of magnitude more expensive than overhead power transmission.

I asked the freezer.question because that is why people are getting into solar. How can running wires underground be that expensive when thwy alreqdy have the personnel and equipment? Amd is that not what all thise rate increases are for, to maintain the grid. The grid is unreliable, even the U.S government sayes it is, and when you have thousands tied up in food it makes plenty of since. Like I said at the start of the thread. "Do solar because you want to not because of some payment scheme". They will cancel all thise contracts and in the end,.force you to send power to the grid for free. Always look at the long term plan, survival needs no math only will.

 

[Tony Scott]

Almost all distribution protection is either a 50 element ( instantaneous overcurrent ) or the 51 element which is (timed overcurrent) . The instantaneous is usually set high for faults that are near the sub and the 51 is set according to the available fault current . The end of line fault is determined using the source impedance and impedance of the distribution line . The pickup is usually set between 1/3 to 1/2 of the available fault current because of the uncertainty of the fault resistance . The time to trip is determined by the fault magnitude and the selected TCC ( time current curve ). The idea is to have device closest to the fault trip first but have upstream devices pickup and operate if the closest device does not operate .
Now back to Solar Infeed - With the Solar feeding the fault it makes the coordination more difficult because the settings need to work if the Solar contribution is there or not .
Too much contribution to a feeder and it doesn’t work . If we are dealing with solar farms into transmission lines the 21 element ( impedance relay ) is affected and the fault appears farther down the line to the relay than it really is .

They do have equipment for that problem and they have had 40yrs (President Carter started a solar program) to fix it. The electric grid has not been updated for 1/2 a century, where did all the money go? This is what Americans are saying.

 

[Ampster]

Underground power grids are phenomenally expensive to build, install and especially expensive to maintain/repair. At least an order of magnitude more expensive than overhead power transmission.

Are you referring to behind the meter systems or truly "under the ground systems"? I think many of us hobbiests can build behind the meter systems that can deliver power at less than $0.20 per kWhr depending on our loads and our engenuity.

 

[Ampster]

Almost all distribution protection is either a 50 element ( instantaneous overcurrent ) or the 51 element which is (timed overcurrent) .

I think I understand the concept you are trying to convey. Can you dumb it down a little so it is understandable?

 

[wattmatters]

The grid is unreliable, even the U.S government sayes it is

Despite what Americans might think, America is not the entire world.

How can running wires underground be that expensive when thwy alreqdy have the personnel and equipment?

Do some basic research on the costs of underground grid power networks.

Are you referring to behind the meter systems or truly "under the ground systems"? I think many of us hobbiests can build behind the meter systems that can deliver power at less than $0.20 per kWhr depending on our loads and our engenuity.

I'm talking about the HV power grid, not homes or even the local low voltage AC supply from local power poles to homes (which are often placed underground). Putting HV grid underground is a seriously expensive exercise.

 

[Austint]

I think I understand the concept you are trying to convey. Can you dumb it down a little so it is understandable?

Sure no problem, basically when all the fault current feeding a fault travels from one source all of the reclosers see the same current and the are they timed so that the closest device will trip the fault ( which will affect the fewest customers) if we have distributed generation of any type it trickier to have it coordinate correctly . The problem with that generation being Solar vs a small hydro plant for example is the contribution from the Solar is not consistent .
All of the small residential Solar pushing into a feeder really depend on the utility relaying for faults . As long as the majority of power flow is from the grid then it’s no problem, the distribution will trip for the fault and then all of the inverters fall on their face because they cannot support the distribution load and the frequency falls . Again this is only a problem with too much pv on a feeder . Our utility likes to stay below 15 percent.
Another challenge is the voltage regulation . With the distributed generation the voltage of the line is supported by the inverters . Now cloud comes over and we have voltage drop across the impedance of the distribution line to the customers. The regulators ,basically a mechanical transformer with 8 steps of boost and 8 steps of buck , must hurry and step and raise the voltage on the feeder to keep the correct voltage . A few seconds later the clouds are gone and the regulators must step back down . The end result is the regulators in the sub and in the distribution line are making up for the inconsistent pv generation . We see thousands of more steps on regulators that are on feeders with pv . It wears out an expensive piece of equipment quicker .

 

[Tony Scott]

Despite what Americans might think, America is not the entire world.

Do some basic research on the costs of underground grid power networks.

I'm talking about the HV power grid, not homes or even the local low voltage AC supply from local power poles to homes (which are often placed underground). Putting HV grid underground is a seriously expensive exercise.

Ohhh I was talking about the lines only???

 

[Hedges]

As long as the majority of power flow is from the grid then it’s no problem, the distribution will trip for the fault and then all of the inverters fall on their face because they cannot support the distribution load and the frequency falls . Again this is only a problem with too much pv on a feeder . Our utility likes to stay below 15 percent.

I could see where this is like the 120% rule. Utility has OCP on power feeding a section of the grid, but we stuff in more power. Distributed, not at far end.

Another challenge is the voltage regulation . With the distributed generation the voltage of the line is supported by the inverters . Now cloud comes over and we have voltage drop across the impedance of the distribution line to the customers. The regulators ,basically a mechanical transformer with 8 steps of boost and 8 steps of buck , must hurry and step and raise the voltage on the feeder to keep the correct voltage . A few seconds later the clouds are gone and the regulators must step back down . The end result is the regulators in the sub and in the distribution line are making up for the inconsistent pv generation . We see thousands of more steps on regulators that are on feeders with pv . It wears out an expensive piece of equipment quicker .

Possible easy fix: Volts-watts. So long as regulators are stepped up, UL-1741-SA inverters that do Volts-watts reduce their output.

Frequency-watts was great for an island grid when SMA invented it. Simulates a generator slowing down when loaded. I don't see how it is useful for a grid spanning several states.

 

[Austint]

I could see where this is like the 120% rule. Utility has OCP on power feeding a section of the grid, but we stuff in more power. Distributed, not at far end.

Thanks Hedges , that is a good way to explain it

 

[wattmatters]

Possible easy fix: Volts-watts.

This is standard in Australia.

 

[wattmatters]

Ohhh I was talking about the lines only

Obviously we've been talking about different things. Local lines are minor chump change and rarely the problem for grid scale outages. That's street level / residence level only.

 

[Tony Scott]

Welcome to California. And the USA.

Someone said of our ~ 50% tax burden that the Boston Tea Party was supposedly over a 1% (or was that 1 cent?) tax on tea.
"Have you no muskets? Is your power not dry?"
Of course, Washington had to pay off the cost of the revolutionary war, and found a tax on whiskey to be a convenient funding source.

Cue the next episode ...

Whiskey Rebellion - Wikipedia

en.wikipedia.org

1cent tax on Tea