We are facing the problem of over speeding of 25MW GE steam turbine. Governing system is consisting of woodword 505 governor and SPC. Hydraulic system is Parker's servo. We have observed the slow response of servo system during islanding.

You are requested to suggest to make fast response of servo with check point.

Also suggest about null current of servo.

 

The post was fairly open ended, so I'll give my first reaction. Sounds like you need to increase your PID gain on your WW505. There is a basic tuning example on p 142 of the manual, have you started here first?

 

Dear Sir,
I have already increased P up to 180 and tried.

Regds,
DSRathore

 

Mr Rathore-

I'm trying to understand with limited information, was that a "yes" to using the tuning procedure? There are three gain terms you have control over, not just proportional, that is why I ask. Also more information about your exact setup would really be needed for any rational discussion. For example, is your scaling correct for your servo controller? Have you driven the servo with a 4-20mA signal and verified 0-100% operation? What does your speed feedback look like?

 

Dear Sir,

I am we have tried the complete tuning procedure as defined in manual.
Setup is as under:
Governor 505E
P gain - 180
I gain - 4.5
D gain - 0
Output - 4-20 mA
Scaling - 0-100%

SPC - 8200
Position demand - 4-20mA ( 0-100%)
SPC Gain - P-1.2, I- 0.08, D-0 )
Feedback - LVDT ( 3500 Hz, 7.0 V )

Servo - Parker
Actuator Currant - +/- 50mA
Null current - 4 mA


I am facing the problem to adjust null current of servo. If you have some procedure about null current adjustment of servo, pls explain to me.

Regds,
DSRathore