Back Synchronization
Back Synchronization
(OP)
Dears,
i am having a project with back synchronization with utility.
when utility returns we should get sensing from PTs before and after utility incoming breaker (6.6 KV) synchronize the genset with the sensed utility voltage then send the breaker (6.6 KV) closing comand.
now my problem is that the utility incoming cell in the Switch gear doesnot include the PTs for sensing before the 6.6 KV breaker! only after it.
so cutomer want us to get the sensing from the primary of the utility transformer (33/6.6) where there are PTs there, the power transformer is Dny11.
my question: is there is any device that can compensate the phase shift between the transformer primary and secondry voltage so that we can synchronize based on that sensing.
Marwa
i am having a project with back synchronization with utility.
when utility returns we should get sensing from PTs before and after utility incoming breaker (6.6 KV) synchronize the genset with the sensed utility voltage then send the breaker (6.6 KV) closing comand.
now my problem is that the utility incoming cell in the Switch gear doesnot include the PTs for sensing before the 6.6 KV breaker! only after it.
so cutomer want us to get the sensing from the primary of the utility transformer (33/6.6) where there are PTs there, the power transformer is Dny11.
my question: is there is any device that can compensate the phase shift between the transformer primary and secondry voltage so that we can synchronize based on that sensing.
Marwa
M.Khamis





RE: Back Synchronization
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If we learn from our mistakes I'm getting a great education!
RE: Back Synchronization
You can compensate for any phase angle or voltage differences in most synchronizers these days.
RE: Back Synchronization
RE: Back Synchronization
thanks a lot for your replies
Scotty: iam checking for teh interposing transformer solution , would that to be additional to the sensing PT(i.e in series to it)?
M.Khamis
RE: Back Synchronization
But don't disregard the comments from the other guys - most modern relays can internally correct the vector shift.
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If we learn from our mistakes I'm getting a great education!
RE: Back Synchronization
as an update on the above
the module that i am using for synch is Deepsea 7560 and by contacting the vendor i had found that it doesnot include vector compensation function , so i will be upgrading to a newer version DSE8660
by comminucating with othe rvendors , i had also found that woodward easygen3400/3500 have the vector compensation function while easygen3200 doesnot
Also dief AGC 3 do have the vector compensation function
i believe that will solve the transformers phase shift issue, thanks a lot for your help
but still not sure how to solve the tap changing issue
the utility transformer is 33/6.93KV – 20MVA – Tap Transformer – DYN11.
with Automatic tapchanger
do you think you can help
Marwa
M.Khamis
RE: Back Synchronization
"but still not sure how to solve the tap changing issue the utility transformer is 33/6.93KV – 20MVA – Tap Transformer – DYN11.with Automatic tapchangerdo you think you can help"
How about helping us out and telling us what you perceive the issue to be.
RE: Back Synchronization
M.Khamis
RE: Back Synchronization
If sensing on the HV side of the breaker and synchronising on the LV side then the voltage matching will only be correct for one tapchanger position, probably at the neutral position. The further away from the neutral position the tapchanger is then the worse the synchronising conditions will be across the breaker. Depending on how unstable the grid voltage is, it may not be possible to put the OLTC to the neutral position and match up the machine terminal voltage.
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If we learn from our mistakes I'm getting a great education!
RE: Back Synchronization
I guess the question is, is the range of the tapchanger outside the range of the generator voltage.
So mkhamsi what is the range of the tap changer vs the upper and lower limits on the AVR?