We have 6 nos. oF FRAME 6GE Make gas turbines installed in our site.

please let me know:
1) what are the parameters to be considered for calculation of DROOP from CSP.

2) How to find the rate at which load is increasing with controller in Auto selection (preselect,base load) & fast loading condition.

3) calculation formula for calculating the droop.

Thanks in advance for reply & wishing u happy new year.

 

About the fastest way to approximate the droop setting of a GE-design heavy-duty gas turbine is to look at the difference between TNR (Turbine Speed Reference) and TNH (Turbine Speed - High Pressure Shaft) when the unit is at Base Load. Typical droop settings are 4% or 5%. Ambient conditions, compressor cleanliness, and turbine efficiency all affect the Base Load setting, but minimally. If the difference is approximately 3.87%, the droop is probably set for 4%. If the difference is 5.11%, the droop is probably set for 5%.

Presuming your units are single-shaft, generator drive units with Mk V Speedtronic turbine control systems:

1) You need to determine if the unit uses 'Constant Settable Droop-' or 'plain' Droop speed control. If the CSP uses a block called something like DWDROOPxx to generate a signal called TNRL (Turbine Speed Reference - Load-biased), then the units probably use Constant Settable Droop. For units with Constant Settable Droop, the Droop value is MW/%. This has all been covered in previous threads; use the very powerful search feature of control.com.

2) You need to examine the CSP to determine what signals drive the speed selection logic array logic, usually L83JDn, where "n" is a number, usually 0-7. L70R is the RAISE SPEED setpoint logic, and L70L is the LOWER SPEED setpoint logic. There are several logics/conditions for each. DO NOT TRUST the LONGNAME.DAT descriptions--unless you know them to be 100% correct. You must review the logic to determine which is the manual and which are the automatic loading/unloading. Ultimately, these drive TNKR1_n, the "n" corresponds to the "n" of the L83JDn array. They are usually expressed in terms of %TNR/min; sometimes %TNR/sec. The rate will be calculated by knowing the droop. Presuming a 5% droop and a rate of 0.3333%/min, it will take 15 minutes (5% / 0.3333%/min) to load the unit from no load to Base Load, or from Base Load to no load. Or, the unit loads/unloads at approximately 0.3333% of rated load per minute. (It is believed this was also covered briefly once before in control.com, also.... If so, it could be found using the search feature, also.)

3) Previously covered; use the search feature. If you have a particular question or difficulty, write back.

markvguy

 

<p>Dear Markvguy,

<p>There are total 7 frame six GE Gas turbines are connected in our grid and we were done a load through off test in one GT (Load 30MW), other GTs behavior is as shown below.
DWATT DVX DF SVLX SFL1 TNH_RPM<pre>
14:43:26.875 18.8 10.92 50.12 10.88 50.09 5175
14:43:26.906 19.9 10.92 50.12 10.88 50.05 5167
14:43:26.937 19.9 10.92 50.12 10.88 50.05 5167
14:43:26.968 22.0 10.92 50.04 10.88 50.04 5167
14:43:27.000 22.0 10.92 50.04 10.88 50.04 5167
14:43:27.031 23.9 10.92 50.04 10.88 49.98 5160
14:43:27.062 23.9 10.92 50.04 10.88 49.98 5160
14:43:27.093 24.8 10.91 49.97 10.88 49.97 5160
</pre>

<p>There are total 7 frame six GE Gas turbines are connected in our grid and we were done a load through off test in one GT (Load 30MW), other GTs behavior is as shown above.

<p<To increase 18.8 MW to 24.8 MW GT took 0.218 sec. My question is how we can calculate loading rate (MW/Sec) of the GT while doing load through off test.

<p>GT set points are:
<pre>
TNKR1_0 -- Startup Accel Rate <9 %/min>
TNKR1_1 -- Speed Setpoint Raise-Lower Rates <22 %/min>
TNKR1_2 -- Manual Loading Rate <4 %/min>
TNKR1_3 -- Manual Speed/Fast Load Rate <6 %/min>
TNKR1_4 -- Auto Load Rate <0.75 %/min>
TNKR1_5 -- Startup Accel Rate <8 %/min>
TNKR1_6 -- Startup Accel Rate <15 %/min>
TNKR1_7 -- Startup Accel Rate <18 %/min>
TNKR1_8 -- Speed Matching Rate <6 %/min>
TNKR1_9 -- Speed/Load Setpoint Rate #9 <0 %/min>
TNKR1_10 -- Speed/Load Setpoint Rate #10 <0 %/min>
TNKR1_11 -- Speed/Load Setpoint Rate #11 <0 %/min>
TNKR2 -- Breaker Opens Setpoint <100.3 %>
TNKR3 -- Setpoint High Speed Stop <107 %>
TNKR4 -- Setpoint Low Speed Stop <95 %>
TNKR5 -- Setpoint Start/Stop Low Speed Stop <0 %>
TNKR7 -- Setpoint Startup Preset <100.2 %>
FSKRN1 -- Full Speed No Load FSR Constant 18.3 %
FSKRN2 -- FSR Droop Correction Factor 18.266 %/%
</pre>
<p>Thanks in advance <

 

Absolutely too many unknown variables to be able to comment on this "question."

It is believed you are talking about a load rejection test, where the generator breaker is opened while the unit is loaded.

It's not clear what you are trying to prove or determine with the load rejection test--usually the purpose of a load rejection test is to prove that if a 'generator breaker open' event (NOT a turbine trip) occurs that the unit 1) will not trip on overspeed, and 2) will not flame out when reducing fuel to prevent overspeed, allowing the unit to be resynchronized without waiting for a coast-down and re-start.

Someone really needs to be at your site to understand the conditions of the test and what is trying to be proven or demonstrated or tested. 0.218 seconds is pretty fast to pickup an additional 33% or so of additional load. Do you want it to be faster or slower than less than one quarter of a second?

markvguy

 

Hello I also have similar question

Sometimes we have unstable country network grid frequency when Russia and Kazakhstan grid disconnected. our plant generators connected to this grid by transformer to get energy during one of our generators trip. generators droop is 4 and frequency changing effect to MW changing 25% of base load. we need change droop to 10 and increase frequency dead band. we use GE frame 9 and 6

Question

For turbines shipped since 1990 with Constant Settable Droop

changing droop settings DWKDG->DWKDG*2.5, FSKNG-> FSKNG/2.5 is enough to get droop 10
could you advice frequency dead band value for TNKEDB

For turbines with FSR based droop

changing droop settings FSKRN2->FSKRN2/2.5, TNKR1_0,,,,,TNKR1_12 multiply by 2.5 is enough to get droop 10, also TNKR3 should be changed to 100+7*2.5=117.5 and TNKR4 = 100-5*2.5=87.5

 

nice explained