Further to David's comment; VARs c 1

[waross]

Further to David's comment;
VARs cause increased line current which causes increased I[sup]2[/sup]R losses.
If you send the VARs back to the source and cancel them there, you save some losses in the generator and avoid reduced KW capacity of the generator.
BUT
You haven't reduced transformer losses or line losses.
The examples that crshears and I shared were plants that were at one time local to the city served. As more remote generation became available the plants were mothballed. as the load grew, the plants were put back into service as synchronous condensers.
These old generators were at the load end of the transmission lines, not at the source end.
Generating the VARs locally served two purposes;
1. Reducing the line losses and at the same time reducing the line voltage drop.
2. With sufficient capacity, VARs could be sent back up the transmission line with the result of raising the voltage. The raised voltage allowed a greater line capacity before the OLTCs bottomed out.


Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[Fischstabchen]

Davidbeach,

My experience isn't just within the Texas Interconnect. What I have seen also comes from MISO. I know there are large synchronous condensers to help with transporting power from northern california to the south but elsewhere it isn't done like that. Even Bacon's comments about SVC's being more common falls some in line with what I have seen. I would suspect that they are being used less even in the west due to NERC standards forcing planning to address N-1 and N-1-1 contingencies. Losing a 200 MVAR block for something like voltage stability or transfer would in the least be interesting.

 

[crshears]

I haven't seen a synchronous motor driven clock for a long time. What I am seeing is crystal controlled digital clocks.
This was in the third world and our operators struggled with meter multipliers. There is no way we were going to make their job more complicated by counting cycles.

Third world vs. Ontario, Canada: yeah, there would be differences . . . I recall that the control room at what we nowadays call the IESO had a special time error display that operated in real time, and when the Eastern Interconnection agreed that the time error had exceeded the threshold value all participants would simultaneously bias their frequency in the direction required to eliminate the lioness's share of the error.

For what it's worth, we have two synchronous motor driven clocks at home, one in the kitchen and one in the basement.

Dirt simple third world way to monitor time error is to have either a satellite clock or an accurate crystal one next to a synchronous motor driven clock connected to the grid; when the time error [difference on the time shown between the two clocks] gets crazy big, however locally defined, just run the frequency a little high or a little low until the two clocks are more or less close, like within a few seconds.

Then again, in third world locations, nobody may care . . .

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[waross]

Then again, in third world locations, nobody may care . . .

You hit that right on, CR.
We ran in droop and no-one ever noticed, ever.
The operators trimmed the frequency, sort of, every 15 minutes, sort of.
We had one operator who was challenged by meter multipliers. One set had an odd-ball CT on the KW meter.
Most of the operators had no problem with using a different multiplier for one set.
One guy couldn't get it. He used the same multiplier for all sets.
You could look the log sheets and tell when he came on shift and when he left. The numbers in one column would take a jump by the ratio between the correct multiplier and the wrong multiplier. It was easy to see when he was on shift, and easier to do a mental adjustment to the numbers that to try to retrain the guy.
We knew what to expect, and if we tried to get him to change who knows what we would get.
We respected the possibility of unforeseen consequences and never mentioned anything to the guy.
This was the same plant where I found a wiring error in the synchro-scope circuit.
They had been sync'ing 30 degrees early since day one. The breaker may trip a couple of times before it held in.Once or twice a year they sheared a coupling key.
Some of the operators were pretty sharp, some where slower. The fast guys would throw the breaker at exactly 12 o-clock on the 'scope.
The slower guys would hesitate and as they hesitated, the sets would be coming closer to sync.
The slow guys had far fewer breaker trips than the fast guys.


--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[bacon4life]

Coincidently, I found out today that one of my neighboring utilities is looking into decommissioning a fossil plant and turning it into a dedicated synchronous condenser. This would be very similar to the situation waross described in the OP. There has also been talk of a new SVC in the region, so it will be interesting to see which project ends up going forward.

 

[davidbeach]

Someplace that starts with a “C”?

I’ll see your silver lining and raise you two black clouds. - Protection Operations