Mark VI Droop geovernor response

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GE Mark VI controllers have among others the logic for governor droop speed control. This is the operation mode other than isochronous (island) or temperature control (base load). On our site droop is set at 4%. This means that GT will change 100% its load upon a grid frequency change of 4%. Can you tell me which are the Mark VI controllers parameters with that settings of droop governor? Is there a possibility to make the droop response more insensitive to grid frequency changes?
 
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How the droop % is set in Mark VI

There is no specific control constant in mark VI in which you feed 4%. There is a droop correction factor which helps fix the droop percentage.
The droop is in effect controlled by the FSRN block. In the FSR block you will see that the FSRN is calculated as follows

FSRN = (TNR - TNH )*FSKRn2 + FSKRN1

where TNR - is the speed reference
TNH - is the actual speed of the machine
FSKRN1 - the full speed no load FSR of the machine
FSKRN2 - the droop correction factor of the machine

The calculation below shows how the FSKRN2 is calculated. Note - this is a sample calculation only ,i am taking some typical values here , and it may not be what is present at your site.

Let us assume that the droop percentage needed to be set is 4 % . This means that at full load of the machine the difference between the TNR and the TNH needs to be 4%. so in the above equation we can fix
TNR - TNH = 4

The FSNL FSR is already known from chara graphs of the machine or by a field test at site. let us say that it is 20%.

The maximum base load FSR value is also calculated from graphs in accordance to the site conditions and in later stages from the base load test of the machine. Let us say that this is 75% . There is usually some amount of changes to this constant during the comissioning.

so from the above it can be seen that at base load conditions

75 = 4*FSRKN2 + 20

FSRKN2 = 13.75%

There is usually some amount of changes to this constant during the comissioning to reflect the field conditions.


"Is there a possibility to make the droop response more insensitive to grid frequency changes?"

In what mode are you running the machine in droop or in preselect control? . By insensitive do you mean lesser load changes ?? by reducing the droop percentage you can make this possible but it is not recommended. There is always the preselect mode which will keep the machine loading constant during the grid frequency changes.Please give us more information on how the machine is operated so that we can help you more.
 
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