Hi ALL ,Hello Controls guy 25
Following is submitted:
1. Did you ever try to compare both Load sharing module behaviour..
"May i know how can i do it separately for individual generators. we don't have a testing facility onboard as of now."
By using Load sharing module ( which OEM is it?) make some tests on reactive load bank ..see if KVAr COMPENSATION is done by Generator excitation ( field current )...
Dont know what kind of load is mostly present in your ship...there can be some devices that demanding Kvars..
Can you specificy facility load consumers..
If you have necessary materials you can perform some test separately I mean for 2 generators ( doing same tests ) like factory test ...you surely understood whta i mean..
2. Both AVRs should have same caracteristics/settings as you mentionned.
"Yes sir, as per my knowledge both the settings are same quadrature droop set to 2% and AVR is set for quadrature droop setting not the cross current compensation. (2 AVR's are not communicating to each other)"
Can you ( are you able to check capability curves and carcteristics of both generator )by performing tests as rules and regulations (OEM recommandations, )
3. Does the reactance value or the resistance value of the rotor/ stator can vary overtime which can lead to unequal sharing of KVARs? if yes is there any reference book wherein i can read about the same.
You may check if you can make some transients test and see if caracteristics on both ge,nerators are matching or not its a good idea!
That can be a reason but for me it is relatively minima to give KVAR sharing unbalanced
You right but we still do not know what is gap in KVAR SHARING MODE in this ship...
Sir, i did a small MATLAB simulation in which i came across that, if the Xd, Xd', Xd" and Xq, Xq', Xq" are varied for a similar rating machine then the reactive power sharing is unequal. (although not much but it is unequal) i don't know the how the reactances vary with time- (i am looking for some reference material wherein i can go in-depth on this topic)"
Will check if i can add here a reference for such tests in matlab..
4. I guess that these generator criterias that you mentioned are more subject during transients mode/operations
"but this is happening during steady state as well"
Okay can you give us again Kvar sharing values( both generators )and field excitation values on this topic..
5. Can you tell us how you operate those units in the ships..( isochronous/droop mode used)
"we operate in a droop mode- The no-load voltage of the incoming generator is made equal to the no-load voltage of the running generator using voltage trimmer in switchboard. Post matching the no-load voltages- the units are synchronised' . once both the units are synchronised we see the KVAR sharing- if it is deviating at steady state then we again alter the trimmer to ensure good KVAR sharing. "
How frequency is maintained on this ship?
6. Also did you have a read on cross current compensation /droop KVAR compensation?
"yes- after your suggestion' Good
7. My advice is to get the kvar droop compensation /cross current compensation ok...
"do you intend to say that i need to tune the AVR?" (if yes then why it is required when it is already tuned initially as per OEM recommendation- this is my specific question- i could make out that AVR need tuning but WHY? what factors do change overtime?)
Maybe capability curves registred on AVR (if existing ) is not matching load consumers in this ship needs no more ...
I mean generator capability (mostly recative power capability need to be confirmed for both)
8. Also what is OEM of the Load sharing module ( woordwad ? or other brand)...
"The governor is woodward and the AVR is COSIMAT N8+."okay what about load sharing module (PMS ) brand ?
9. A good thing would be to get some datas capture during the mode that you described ..so we can have better overview on the plant behavior then we will be a better support from here..
"i will get back to you on this but for now i have a grab which shows;
Gen-1 380V 258KW 583Amps 50Hz 0.67PF
Gen-2 380V 275KW 520Amps 50Hz 0.77PF
Both generators are running in parallel mode (with APMS- semi Control mode)"
Thank you sir,
Regards
@Shagun Tandon here some answers( written in red ) on the questions that you posted ( see your last post18)
This is what i can add for the moment, as we still do not know how APMS is operating in KVAR sharing mode ...
Also we need KVAR /field excitation values for both generators during that event..
Thank you
regards,
James