OT John T or any other electrical guru?

The thread on solar panels got me to wondering. I remember on the ship, the sparkys would have to twist a bunch of dials and synchronize a diesel generator before letting it take part of the load. Makes sense to me-if you're beating 2 60hz waves together you'd want them crest to crest for max constructive interference.

So here's the question. On wind farms, you can't really put a governor on the wind. And it seems like a costly endeavor to generate DC and convert it to AC in phase with the grid. The same goes for solar. So how do these alternative energy sources get the power from the generator to the grid?

Possibly they all make DC and convert? I know where mom lives in north eastern ks they want to run a high voltage DC transmission line. It will take power from western ks wind farms and move it to some eastern states. Plenty of controversy about that. Goggle Clean Line Energy.

The need to synchronize an alternator with the grid exists any time a generator is brought on line, whether it's a wind turbine or one of the generators at Hoover Dam. But it's not such a huge problem as you might think, since a three-phase AC alternator is also a synchronous motor. So as long as you have power from the grid, you can motorize the alternator to bring it up to speed; it will then be in sync with the grid.

As it turns out, there are both AC and DC wind turbine generators, check the link below.

BTW, the reason generators must be synchronized BEFORE they are brought on line is that they WILL be in sync AFTER they are connected to the grid. Connecting an unsynchronized generator to the grid is going to break something; it might rip the generator right out of its mounts.
Wind turbine design

It is too costly to produce a segmented commutator in the kilo or mega watt range, so that is why first a.c. then rectify to d.c. then electronically produce a 60 hz sine wave. I have a little Honda generator that does just that.Also it is probably easier & more precise to match the phases this way?

DC transmission lines pay off when the distance is over about 300 miles. Whether the power originates from wind turbines is irrelevant; it's the distance that matters.

(quoted from post at 00:43:27 05/12/14) The thread on solar panels got me to wondering. I remember on the ship, the sparkys would have to twist a bunch of dials and synchronize a diesel generator before letting it take part of the load. Makes sense to me-if you're beating 2 60hz waves together you'd want them crest to crest for max constructive interference.

So here's the question. On wind farms, you can't really put a governor on the wind. And it seems like a costly endeavor to generate DC and convert it to AC in phase with the grid. The same goes for solar. So how do these alternative energy sources get the power from the generator to the grid?

Click to expand...

With solar you will be using an electronic inverter to produce AC from the DC the solar panels + battery bank makes. Some inverters sense the commercial power and automatically sync with it.

remember you've got to get that power to ac just to use it in your house - and that's usually only supplemental to the grid power so it must be synchronized.

So - can't tell you exactly how it's done - but I'm sure it's pretty routine.

That is why wind turbines use induction motors as induction generators.
wind turbines can"t make power unless they are connected to live utility lines to provide reactive power.
A whole field full of dozens of 2.5MW wind turbines are difficult to connect to the grid. Protection and control "P&C" values for frequency, under voltage, over voltage and over current . Have to be "de-sensitized" , re calibrated to reduce trips . Problem is the turbines are not synced together and thier individual output varies with wind gusts. they will every now and again all either push a burst of power together. Or all hit a lull together.
One of the reasons why the utility would rather connect turbines to small 27 , 44, 115 KV lines. Instead of the main distribution backbone of 230 or 500KV lines.

variable pitch blades controlled by a governing device. to bring on line; device brought up to generator speed, device's output voltage is matched to system voltage, device's frequency is matched to system frequency. once obtained by indications on syn. metering then device is tied to system, brought to desired loading at which point governing, load and voltage regulation controls is placed to "auto" controls.

I remember learning way back that when electricity was invented, on fella wanted to run DC but that would have meant power plants would need to be every few miles, as the wire run couldn't be that long.

The other fella wanted AC and that is how it went, and was a good thing.

Now the big trunk lines seem to be DC.

What changed there?

Paul

John,

The devices monitor the incoming wave pattern and synchronize the output with it. They will not output unless they determine an incoming wave pattern to prevent power output during an outage.

Inverter driven processing that allows radical high voltage (million volt range) and thus changing AC into HVDC then re making it into secondary distribution AC with solid state computer controlled electronics with high power capability. Jim

(quoted from post at 08:17:14 05/12/14) variable pitch blades controlled by a governing device. to bring on line; device brought up to generator speed, device's output voltage is matched to system voltage, device's frequency is matched to system frequency. once obtained by indications on syn. metering then device is tied to system, brought to desired loading at which point governing, load and voltage regulation controls is placed to "auto" controls.

Click to expand...

Sure if paralleling syncronous prime power generators.
Induction generators on wind turbines around here.

i have no experience at all with wind turbines. my
experience was in hydro generators and that was a
few years ago. wind generation was in its infancy
and the readings i had available then was they were
synchronized similar to hydros. enjoyed your post
below and after consideration i can see where tying
those to a grid is different. thanks

You are referring to the dispute between Thomas Edison, whose system used DC, and Nikola Tesla/George Westinghouse, who used AC.

The physics have not changed. What has changed, as pointed out by Jim N., is the practicality of generating high voltage DC power in significant volume and then stepping it down to a safe voltage.

It is not exactly correct that AC is better for power transmission than DC. But it is very true that you need high voltages to efficiently transmit power. In the nineteenth century, the only practical way to step voltage up and down was to use transformers, and transformers require AC. But alternating current is subject to several types of losses that don't affect direct current. Power engineers have looked to DC transmission for a long time, but it wasn't until the 1970s when it started to come together: Rising fuel costs, greater demand (requiring longer transmission lines), and improved technology made DC transmission cost-effective for long transmission lines, particularly underwater cables. The equipment required to generate high voltage DC and convert it back to AC is much more expensive per kilowatt than transformers, so DC is only used when the cost savings from improved transmission line efficiency justifies the additional expense of DC.