@ControlsGuy25
The relay setting and coordination is as per commissioning ( year1992). For electrical study , I'll get back to you, once I get hold of such document.
Plant SLD is attached. Generator AVR get's supply from shaft mounted PMG. No other excitation transformer is there.

Apart from AVR, no field boosting/flashing option is there.

Regards
Mohit

@Mohit.Sharama
Thank you for this answer and clarifications.

So you got a self excited Generator with PMG .
Can we got a pic /schematic of the mentionned excitation system...for me even with PMG i use to see a separate excitation transformer for Boosting /field flashing durin event which need Voltage raise up /build up quickly...

Please have a read on how Voltage build up is done with self excited generator on that screenshot:




https://www.powerplantandcalculations.com/2020/05/pmg-excitation-avr-power-generation.html

How does the self excited DC generator build up its output voltage?
Due to flow of small current in the coil, an increase in magnetic field occurs. As a result, voltage output increases, in turn, increases the field current. This process continues as long as the electromotive force in the armature is more than the voltage drop in the field winding.

What is self excitation in generator?


A self-excited DC generator is the one whose field winding is excited by the current from the output of the generator itself. Depending upon the connection of field winding with the armature, the self-excited DC generators are of three types − Series Generator. Shunt Generator. Compound Generator.

Maybe ( thats just a guess ) that Protection on Overfluxing operated then AVR could not build up the nominal voltage


Do you confirm that you got such arrangement on these Generators?

Regards,
James

 

Do you know about GT speed parameters during that event...I mean you need to know if GT speed as sufficient for DC generator armature self excited to build up the voltage.
Thats one point to look at ...

 

@Mohit.Sharama
Thank you for this answer and clarifications.

So you got a self excited Generator with PMG .
Can we got a pic /schematic of the mentionned excitation system...for me even with PMG i use to see a separate excitation transformer for Boosting /field flashing durin event which need Voltage raise up /build up quickly...

Please have a read on how Voltage build up is done with self excited generator on that screenshot:

View attachment 2314


https://www.powerplantandcalculations.com/2020/05/pmg-excitation-avr-power-generation.html

How does the self excited DC generator build up its output voltage?
Due to flow of small current in the coil, an increase in magnetic field occurs. As a result, voltage output increases, in turn, increases the field current. This process continues as long as the electromotive force in the armature is more than the voltage drop in the field winding.

What is self excitation in generator?


A self-excited DC generator is the one whose field winding is excited by the current from the output of the generator itself. Depending upon the connection of field winding with the armature, the self-excited DC generators are of three types − Series Generator. Shunt Generator. Compound Generator.

Maybe ( thats just a guess ) that Protection on Overfluxing operated then AVR could not build up the nominal voltage


Do you confirm that you got such arrangement on these Generators?

Regards,
James

@ControlsGuy25

Thanks James for the input. PMG produces fixed field (due to fix strength of magnetic poles) and output is dependent on generator shaft speed. Rest of the work is being done by AVR - both in steady operation and transient case.
For the overfluxing operation, we are just waiting for ABB's analysis on the data.

 

Do you know about GT speed parameters during that event...I mean you need to know if GT speed as sufficient for DC generator armature self excited to build up the voltage.
Thats one point to look at ...

Thanks, we also had thought of that and looked at turbine speed curve, it actually over speeded momentarily (may be due to loss of active load owing to fault feed). but overall speed was maintained at rated till generator trip.

 

Mohit....
Now can you identify for me the Current and Voltage channels for the following locations:
Q19) VCB-52G.
Q20) VCB-52S (if available).
Q21) Downstream side of Excitation Transformer.
Regards

 

@ControlsGuy25

Thanks James for the input. PMG produces fixed field (due to fix strength of magnetic poles) and output is dependent on generator shaft speed. Rest of the work is being done by AVR - both in steady operation and transient case.
For the overfluxing operation, we are just waiting for ABB's analysis on the data.

@Mohit.Sharama thank you for this reply.

I have seen a ABB 6080 excitation system with Unitrol.

Looks like there is excitation transformer..

Can you share schematic on that PMG with exciter/excitation I am bit confused to get the overall picture at your site for better support.

Regards,
James

 

Also I have see that ABB sell kind of Unitrol simulateur module système..
It can be a good thing for you to study behavior of the units during transient modes like 3 phases short circuit..

 

Mohit...
At the beginning of this project you presented a chart that tabled 2 Variables over time:
a) Current Magnitude Vector.
b) Current Vector Angle.

The variables shown are exactly what is needed to find the "single key" to the question "Was it a 3-phase fault or not?" Unfortunately, the single-phase table is insufficient !

Mohit... can you undertake the assignment to produce a table listing the two variables for all 3-phases?

Regards, Phil Corso
[email protected]

 

Mohit...
I apologize for suggesting something that "turned you off"!
I reasoned that you probably had the data in EXCEL, thus relatively easy to get.
On the other hand, I had to extract a large amount of numbers from very hard to read printed charts, to solve the problem using Symmetric-Component-Analysis!
Sincerely, Phil Corso

 

Thanks, we also had thought of that and looked at turbine speed curve, it actually over speeded momentarily (may be due to loss of active load owing to fault feed). but overall speed was maintained at rated till generator trip.

Good day Mr Sharama,

Can you give a quick update on the issue you ve been facing...

We can support in case this issue is still pending /not solved..

Regards,
Controlsguy25

 

Mohit Sharma.
Just a note. Although the slight speed change was something new, you have not revealed any progress by ABB.
However, if I had the information requested, I might be able to prove incident's result was inevitable!
Stay Well,
Phil Corso

 

Looks like original poster did not come here for an update on this issue,

So We can consider that this thread is close

A message for all posters here , please do not leave us without feedback /update on the issues you ve been facing...

 

Mohit:
Your topic is still of interest. Since, you were not able to provide additional info, I ask a favor...
Please repeat the Disturbance Chart, but with an increase in clarity so that when expanded the data is legible enough for me to read !
On the other hand, acknowledge that your Employer-Employee obligation requires that you drop the subject !
Thank you,
Phil Corso ([email protected])

 

Mohit...
In a few days I will submit my opinion of what caused the ABB Unitrol-6080 failure, unless you advise otherwise ?
Stay Well, Regards, Phil Corso !

 

@PhilCorso ,

It looks like original poster is no more in the game... At least on this thread..

Regards,
@ControlsGuy25