generator motoring 100%
generator motoring 100%
(OP)
during the comissioning of a submerged generator and impellers , bubble turbine, was realized the generator motoring:
the motoring was in the range of -100% power, ie, a machine 80 MW, a received power of approximately reverse in the turbine-130MW.
the motoring was in the range of -100% power, ie, a machine 80 MW, a received power of approximately reverse in the turbine-130MW.






RE: generator motoring 100%
RE: generator motoring 100%
I never found any protection book with a motorization table above 50% and hydroturbine above 2%.
RE: generator motoring 100%
Set the reverse power protection at around the usual -5 to -10% of rated power and a delay of not more than 10 seconds. Was there something wrong with the governor? Forget the book.
rasevskii
RE: generator motoring 100%
Now is 5% in 1sec, in a new logic:
(32R) AND (position contact of closed emergency valve solenoid)
in accordance with Siemens manual(7UM62) and Cigré protection guide.
RE: generator motoring 100%
during motorization tests generator absorved -130MW from system in 16sec.
Now is 5% in 1sec, in a new logic:
(32R) AND (position contact of closed emergency valve solenoid)
in accordance with Siemens manual(7UM62) and Cigré protection guide
RE: generator motoring 100%
RE: generator motoring 100%
The emergency stop solenoid should trip the GCB directly without the 32R having to trip also.
I rather fear this is some office exercise. Were you yourself actually at the plant when this happened? Is someone reporting this to you from the site?
The OEM will have something to say. Possibly cancelling the guarantees...
Forget the book and don`t wreck the plant.
rasevskii
RE: generator motoring 100%
1- we use emergency stop solenoid to close wicketgate and stop turbine.
for motoring protection we are using (fast 32R) AND emergency stop solenoid in close position , to trip GCB
2- Have you seen any generator motoring for submerged generator and and turbine (kaplan or bubble) in some book?
RE: generator motoring 100%
in hydrogenerator motoring , generator do not damage.
- for low waterflow wil be cavitation in turbine
- for high waterflow will be damage in turbine due to axial pressure int the bearings.
RE: generator motoring 100%
You say "we will use" implying that the plant is not yet built or commissioned, in other words such a test was never actually done.
I would doubt that any OEM would allow such a test for 16 seconds to take place unless it is specifically called for in the purchase contract. And how do you arrive at 130MW reverse power in any case?
That is about a 62% overload.
Is this really a tube turbine (Rohrturbine in German)? I did not know that such large units of this type were ever built (30 to 40MW has been the usual maximum size).
No I have not seen anything in some book. My background is commissioning on site.
32R OR Emerg. Stop must trip the GCB, not AND.
rasevskii
RE: generator motoring 100%
You say "we will use" implying that the plant is not yet built ...
WE WILL USE refers to change of 32R protection;
THIS POwer plant is being commissioning now. This motoring generator test ocurred recently , there is no oficial report yet.
I would doubt that any OEM would allow such a test for 16 seconds to take place unless it is specifically called for in the purchase contract.
MECHanical engineer told could be up to 20sec time to close wicket-gate from normal load position up to closed position.
And how do you arrive at 130MW reverse power in any case?
That is about a 62% overload.
I DONT know.
Is this really a tube turbine (Rohrturbine in German)? I did not know that such large units of this type were ever built (30 to 40MW has been the usual maximum size).
YOU RIGHT THATS greatest in the world.
IT will be two power plant with 50 units of 80MW each one.
No I have not seen anything in some book. My background is commissioning on site.
THERE ARE 100 turbine -generator to be commissioned!
32R OR Emerg. Stop must trip the GCB, not AND.
NO! MUST be AND. Otherwise, an instantaneous 32R will operate erronously during synchronization!
RE: generator motoring 100%
rmw
RE: generator motoring 100%
RE: generator motoring 100%
Mgtrp has it right. The 32R might trip on sync erroneosly if the load pickup does not happen immediately. The usual solution was to add a longer time lag. I would think 1 second is too short. Also to set up the governor so that a small load is taken up immediately after the unit is synced to the net.
So where is this 50 x 80MW x2 project? I will check out on Water Power Magazine.
rasevskii
RE: generator motoring 100%
generator is always connected to the turbine BUT not operate as pump.
mgtrp, rasevskii
see annex for better explanation of 32R,
and Siemens Multifunctional Machine Protection 7UM62 V4.6 Manual
item 2.17.1-pag 145.
I do not know how to attach 4 images in this email!
rasevskii,
it is in Brasil, at Madeira River , an tributary of Amazon River.
RE: generator motoring 100%
It looks like some remapping of the 32R function may be desirable. In fact the SIPROTEC manual is available online as a PDF and I have had a look at it.
What is being attempted as I see it is to avoid a false operation of 32R tripping the unit CB if a stop order has not been given. This could of course happen just after synchronizing the unit if 32R was not blocked by not having a stop order at that moment.
In fact a small load pickup could be arranged by an aux contact on the GCB giving a load order into the governor automatically,with such a large number of turbines to manage this could be useful.
In fact a second backup 32R could be implemented with a longer time delay and higher reverse power setting. Possibly as an alarm only into the DCS system, with a second stage time delay giving a trip order to the GCB.
Yes I have located the project. Indeed the largest tube turbines built so far.
rasevskii
RE: generator motoring 100%
I did not understand the need for very low load order.
In reality, generators are 13.8kV-80MW and only two are in parallel.
There are 12 setup-transformer 500/13,8/13,8kV-340MVA.
In each 13,8kV busbar is connected two generators.
Yes, it was added second backup 32R with a longer time delay.
RE: generator motoring 100%
The idea of a low load order at the time of closing the GCB is to insure that the unit does not go into the motoring region after the GCB has closed. This would avoid an unforeseen 32R trip. It depends on the setting of your second 32R, in other words how narrow is the setting and how short the delay. Maybe -5% and 10 seconds would be suitable.
The turbine OEM has to specify what settings are acceptable.
rasevskii
RE: generator motoring 100%
Do you mean -5% and 10 seconds WITH low load order ?
because -5% and 10 seconds is my backup setting.
RE: generator motoring 100%
Yes. The 32R backup has to be enabled, as you have done, even with the load order. Suppose that, for some reason, the governor does not open the guide vanes(wicket gates) upon GCB closure, then the 32R signals (alarms) that situation. If the operator does nothing, the unit will trip safely on 32R backup.
In such a large station, with many units, if things go wrong all at once (line disturbance?) then you are protected against motoring.
Are you involved in the commissioning at site?
Another thing is, with such large low head low speed units, there must be a lot of turbulance at around no-load gate setting, which will make a short time setting of 32R more difficult.
What is the head in meters and the RPM of theses units?
rasevskii
RE: generator motoring 100%
32R: Thank you.
commissioning: NO
H/RPM: 15.2 m / 94.7 rpm
RE: generator motoring 100%
.... Suppose that, for some reason, the governor does not open the guide vanes(wicket gates) upon GCB closure, then the 32R signals (alarms)...
If guide vanes is closed, rotor is not running and GCB can not close. It assume to energize a generator stopped. You should trip GCB not alarm.
There is a Inadvertent Energization protection with instantaneous trip.
I did not understand the reasoning
RE: generator motoring 100%
rasevskii
RE: generator motoring 100%
RE: generator motoring 100%
Attached is a motorization table with hydroturbine 100%, extracted from GE instruction GEI-33891.