Dear all


Can anyone help have more insights in regards to the Function of VPL Tracking and VPL Control of Limiters Function in GE Steam Turbine?

Regards

 

Dear Isulamu,

Can you tell us meaning of VPL ..is that stand for Vapor power limiter?

 

There should be SPL (for Steam power limiter ) and VPL ( Vapor power limiter) can you tell us the difference between those definition as vapour and steam looks same in French

 

Or maybe you talking about Valve position limit(er) for VPL ??

 

Dear ControlGuy25

Firstly, thanks you very much for your interest. Since I was specialized on GT only till now. I was interested to gain some insights in regards to steam turbine control. I was going through the flow_min gate (same like FSR in GT) and on of the inputs was the VPL which Valve Position Limiter I think which is combined in its calculation with CVR (Control valve reference). Unfortunately, the tcw I am exploring is offline hence I cannot check the real time data and unit behavior which should have made life much easier for me to understand the philosophy. All the above reasons led me to post this thread in hope of finding few answers in regards ST control.
Any docs which can be shared of the ST control philosophy would help a lot too.
Thanks in advance

 

Dear Isulamu,

Thank you for this prompt answer I appreciate it!

Would you find attached a document showing VPL functions and definitions for a nuclear plant in South Korea

Regards,
James

 

Valve Position Limiter

A. Its function limits the upper ( or lower depend on Control Mode or Tracking Mode) limit on how quickly a CV can be opened by CV demand. For example, if the Load is 500MW and Frequency is 50Hz, turbine load is 77%, if the sudden big drop of the line frequency occurs, GOV free operation is performed. For this purpose, it requires more demand for turbine load than 77% and if VPL is 82% and new turbine load demand is 85%, CV valve only open at the curve of 82% and not open more than that. So that turbine will not participate in system frequency stabilization should it be required to open the control valves.

B. Valve Position Limit (VPL) Control

1) VPL control is selected by click Control PB on HMI after the Generator Online. It can be deselected by click Track PB or Cancel PB on HMI. VPL Control and VPL Tracking are mutually exclusive

2) VPL Control will lead to control the Turbine Load tracking VPL by 5% (TPWR = VPL + 5%). When selected, frequency decreases will not open the CV and IV. If sudden frequency increases which would result a Turbine Load reduce more than 5% and CV and IV will be close more, the Turbine Load only reduce by the amount exceeding 5%. The TPWR Turbine Load will track any long-term frequency changes with the 5% offset.

C. Valve Position Limit (VPL) Tracking

1) VPL Tracking is selected by click Tracking PB on HMI if the Generator Online and no-Load Setback.

2) It can be deselected by click Control PB or Cancel PB on HMI. VPL Control and VPL Tracking are mutually exclusive.

3) VPL Tracking will lead to the VPL tracking the Turbine Load by 5% (VPL = TPWR+5%). When selected, sudden frequency decreases can only increase the Turbine Load maximum 5% and lead to limit open of CV. The VPL will track any long-term frequency changes with the 5% offset.

 

Dear Isulamu,

Can you tell us meaning of VPL ..is that stand for Vapor power limiter?

Yes, it's a vapor power limiter.