Synchronize Generators To Utility 4

[SyncCheck]

Hello all,

I need to synchronize 4 CAT C9 generators to a bus and then synchronize the bus to utility.

I am useing a Woodward SPMD synchronizer & load sharing module on each generator.

Now here is the part that I am haveing problems with
how do I synchronize the bus to utility?

I was thinking of useing an SPMD on the utility side and use the speed output from the utility SPMD and parallel it to all to the load share modules on each generator and then the generators would actively sync to utility.

Any ideas?

The transfer would be fast because all what I need to do is a bumpless transfer from generators to utility,(kind of like a closed transition transfer switch)

If you need any more info let me know.

Thanks for all the help

 

[SyncCheck]

burnt2x,

I always design simple to operate systems thats why I will disagree with everyone that thinks otherwise.In my eyes it takes a complex design to achieve a simple operation while every one wants to take the short cut and design the control system to be simple but not the operation.At the end of the day I do not want a hospital maintenance person trying to synchronize a MW of power to the
utility,automating the process is complex but in turn this will simplify everything.

If their is a hole in the ground you can put up a sign that says "danger hole in the ground" and not have to do any work or you can just fill the hole and prevent some one from ever falling in the hole.I fill the hole...

catserveng:

Yes the PLC will sence a recloser,voltage,frequency or overload condishion and synchronize and transfer,it works both ways.The system is completely autonomous and needs no one to be their.

davidbeach:

First the DAY TANKS are required to have a MIN 4 hour run time,I have sized mine for 24HR run time and also have underground UL–142 extended run main fuel tanks for 72HR run time with double redundant fuel pumps.

So no this is not code violation and certainly not engineering malpractice.

Thank you all for your comments

 

[nawao]

SyncCheck,
You say:
“I am in the design stage right now and looking at what would be the best way to achieve this...
I am still looking at different controllers to do the job easier and use less of the PLC for control.
I always design simple to operate systems that’s why I will disagree with everyone that thinks otherwise.”
The generators will work as a isoch group when carrying the hospital load.
To parallel to the grid before transferring the load the generators must be on droop mode.
Which kind of “simple logic” will allow you to do it automatically?
As catserveng says: “trying to do it for a hospital could be a rough road for lots of people, you included.”

 

[ScottyUK]

nawao,

In the utility world our machines ran up in speed control to synchronise to the grid, with the speed reference following a defined acceleration profile. Isochronous mode is just a specific case of speed control with a fixed reference. Units transferred into either load control or went to base load using a fairly simple bumpless transfer between control loops. Obviously there are other factors like loading rate limiters to consider, but it's not especially complex or unusual. We also had the capability to run as a true isoch generator under black start, but we effectively would be 'the utility' and others would sync to us so it's a slightly different situtation to what you are considering. The change from isoch to droop or load control isn't in principle any different to a regular sync, other than the machine is carrying more load than normal at the time it moves from one control mode to another.

Are you developing your own control scheme within the PLC, or are you using one of the packaged governor and AVR systems?


----------------------------------

If we learn from our mistakes I'm getting a great education!

 

[slavag]

Hi.
SyncCheck , for my opinion, you are right.
I was worked in the few big hospitals, and this is a normal practic, silent back to grid with generator bus.
In the generator control cubicle installed some switch:
1. make before break - 2. break before make.
Normal mode is 2, after operation on the generator bus and back normal voltage to grid inffeed: opeartional personal move this switch to position 1 , connected to grid, disconnect generator bus and back switch to position 2.
All provideed with PLC.
Of course generator connected to load only after some load shedding operation.

Once per month, personnal check generators, move switch to 1, connected to gris and tested whole system.

Best Regards.
Slava

 

[niallnz]

Hi SyncCheck

If you are using the new digital SPM-D11/LSR, get another one and use it to control the utility tie breaker. This model of SPM has all the functionality to synchronise a group of generator to teh bus and then soft unload the generators.

 

[SyncCheck]

Thanks nawao, ScottyUK, slavag & niallnz,

Has anyone worked with Woodward SPMD11 & SPMD21?

It looks like I will be useing these controllers,I looked at the manual in it is not helpful at all...

Dose anyone know how the SPMD21 works as far as going to Utility and going to generator? I dont see any thing in the manual to do that and their are no inputs to command the SPMD21 to switch just an enable,my best guess is when ether source is energized the SPMD21 will auto sync and close the breaker.Am I right?

Thank you for all the replies

 

[plantpro]

Interesting reading! It appears that everyone here is discussing newer type equipment with some type of elertronic control be it woodward or basler or whatever. I manage/operate @ 120MWs of CIICE engines the newest of which was installed between 1948 and 1981. None of these machines are equiped with auto/electronic anything. Syncing back to the grid is a standard pratice, done frequently by our operators. Perhaps I misunderstand the OP's problem? Are not your units equipped with speed control? We also have @50MWs of new machines (Cat 3500 and 3600 series) some of which do not have a manual speed control. Those installed in the last year have been equipped with a mop to control speed.

 

[genhead]

I'm not sure what's available in the US, but in other parts of the world there are several manufacturers of "Integrated" controllers which automatically look after the entire sequence of start/synchronising/load-sharing/protection of generators. They are all capable of synchronising a group of generators to the utility, sometimes with the addition of a "mains module". They are all relatively simple to use, and can be retro-fitted to existing systems fairly easily.
They all do pretty much the same thing, but quality varies considerably between different manufacturers.
Examples are Comap (Inteligen/Intelisys), Deif (AGC), Heinzemann (Sitec), Deep Sea Electronics, Wexler (Gencon). There are others.

 

[xxjohnh]

You need to consider the voltage regulators as well as the governors. But for sure contact the utlity and see what their requirements are. It is a good way to test generators by synchronising instead of load banks but few places allow it. After the LA earthquake it was found many hospital systems did not work the way they were supposed.