Hi,

I'm new here. I'm doing some research for a company about gas turbine governors. I'm looking for a way to determine the governor's transfer function. can anyone help me with it? In addition I'm in need of sources about these titles:

- Synchronizing governors.
- Gas turbine governor standards.
- Gas turbine start Control.
- Gas turbine shut down control.

Thanks in advance.

 

GT Startup control,

The startup control includes fire, warm-up and acceleration, which decide the startup FSR (FSRSU) that varies between 0 to 100%. In order to ignite the combustion system and provide cross firing around the turbine’s combustors, startup FSR is stepped to the firing value normally 18% (Firing FSR) while the spark plugs are firing. After the flame is detected FSRSU is cut back to reduce level normally 14% (warm-up) FSR occurs only after the flame is detected.

In order to keep the air fuel ratio constant for a given speed, it is necessary to bias the FSRSU as a function of ambient temperature. So the firings FSR, warm-up FSR, acceleration FSR are compensated with respect to ambient temperature by compressor air flow temperature correction. On a cold day the ambient bias will increase the startup FSR levels and in a hot day it will reduce the startup FSR levels in order to keep constant air-fuel ratio. The acceleration control computes the acceleration reference (TNHAR) and a corresponding FSR to maintain the acceleration rate. During acceleration FSR raises at the rate of 0.051% /sec. The shaft acceleration is calculated by speed actual with respect to time (TNHA). Then the two signals are compared and the acceleration FSR is adjusted once the turbine reaches full speed the acceleration reference is set to constant value, which prevents the turbine from over speed during a load rejection.

 

GT Shutdown Control

The fired shut down may be initiated either by manually giving stop command or automatic shut down due to the following reasons.

1. Inlet air filter DP high

2. Vibration input group disabled

The following sequences are taking place after the shut down command:
1. The fuel is changed over from naphtha to HSD

2. Load is gradually reduced and generator breaker opens. Load reduced at rate of 5.0MW/min (FSR reduction at 10%/min)

3. The shut down (FSRSD) ramps down from existing FSR to FSRMIN (minimum FSR) at set rate of 1% / sec.

FSRMIN is generated from a four position linear interpolator given below.<pre>
SPEED FSR
Up to 85% 16.42%
85% to 82% 14.15%
82% to 40% 11.75%
40% to 5% 9.46%</pre>
For example FSR reduced from its existing value to 16.42% at the rate of 1%/sec and maintains at the same value till speed reaches 85%

1. If the speed reaches 20% and flame is ‘ON’ then the FSR reduced at the rate of 0.1%/sec.

2. If one burner is flamed out then the FSR is reduced at the rate of 1%/sec which leads to total flame failure.

 

The western electric coordinating council (WECC) in the United States has developed at least one generic model that I know of: URGS3T. You can find brief explanations of this model in PSCAD manuals, or PSS/E manuals or GE's PSLF software manuals. I've never been able to find a detailed explanation of the model, so if you do, please let me know. IEEE has several models, but they are usually geared towards steam and hydro governors.

These standard governor models are very generic and don't really give you a detailed picture of the operation of the machine. As such, the transfer functions shown within the model don't really tell you what physical components they are representing (valves, actuators, etc). But, some manufacturers are easy to work with, and while they won't give you their exact models, they will at least verify that the model you have created behave true to form. Mitsubishi is pretty open to work with, GE is not.

The other information you are looking for (start up and shut down control, etc) will be described in the manufacturer provided operator's manual(s).