generator motoring 100%

[odlanor]

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.

 

[DTR2011]

Do you have a question?

 

[odlanor]

No. This is an information.
I never found any protection book with a motorization table above 50% and hydroturbine above 2%.

 

[rasevskii]

So what is the point of your posting?

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

 

[odlanor]

That was original 32R setting.
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.

 

[odlanor]

That was original 32R setting. but

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

 

[DTR2011]

Hope things were not damaged during the 16 second "test" @ 130MW

 

[rasevskii]

Sounds like a bad design. If you allow the unit to absorb 130MW and it is rated at 80MW possibly you are wrecking something. I would question the reading of 130MW in any case. Is that from built in instrumentation or some test recording?

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

 

[odlanor]

rasevskii ,
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?

 

[odlanor]

smallgreek,
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.

 

[rasevskii]

@odlanor:

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

 

[odlanor]

rasevskii

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!

 

[rmw]

I am assuming that your generator is always connected to the turbine which then becomes an impeller when the generator is motoring. Just like any pump running out on its curve, the more it pumps the more power it draws, so 130 MW sounds reasonable to me.

rmw

 

[mgtrp]

If you're worried about synchronising, try setting a two-stage 32R system - one more sensitive, with a long time delay or a "AND" with some other parameter, and one at a much lower sensitivity with a shorter time delay or no "AND".

 

[rasevskii]

OK on all that.

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

 

[odlanor]

rmw,
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.

 

[rasevskii]

@odlanor:

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

 

[odlanor]

rasevskii,
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.

 

[rasevskii]

@odlanor:

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

 

[odlanor]

rasevskii,

Do you mean -5% and 10 seconds WITH low load order ?
because -5% and 10 seconds is my backup setting.