Governor and Load Limit Mode

Turbine Free Governor and Load Limit mode already explanation on http://idpowerstation.blogspot.com/2011/07/turbine-control-mode.html
, but now we add with the numbers actual on turbine speed droop calculation.
(Free Governor Mode while frequency inside dead band area, but while frequency already outside dead band area, the Governor start working)

On Governor Mode with turbine speed droop is 5% can we see the picture below (or visit http://idpowerstation.blogspot.com/2011/01/load-variation.html), with Turbine speed dead band from 99.4% (2982 RPM) to 100.6% (3018 RPM). It means the turbine control valves will not reacting if the turbine speed still inside the range of its dead band.

If turbine valve position on 72% as demanded, and the turbine speed (frequency grid) goes down to 99% (2970 RPM), the turbine control valves demand will be increase to 80% as calculated of turbine CV position (speed droop 5%).

It propose to maintain the turbine speed back to 3000 RPM (50Hz) so explanation of Speed Droop is frequency sensitive of turbine speed in any load changes.


Governor Mode (Governor Follower Load Regulator) is governor setter automatically follow the value a little bit lower than a load limit set value. If the bias is 10%, Governor set value is 10% lower that Load Limit set value.

Governor mode is influence with grid frequency. If the grid frequency drop, Governor set is automatically increase and limitation with Load Limit value as the bias that we setted (10%).

On Load Limit Mode the unit load is giving signal to LL set, this also representative with CV Flow Demand and usually Governor set to maximum 110%.

Flow demand signal is coming from frequency grid. If the frequency grid tend to increase, the Flow Demand will compensate to decrease. If CV Flow Demand is higher than Flow Demand, the signal Load Limiting will active and turbine control freeze to last demand.

The summary, Flow Demand depend on frequency grid and CV (control valve) Demand depend on Load set. If we want to change mode from LL to Gov, Follower Load Regulator should be activated to avoid the load spike. Follower Load regulator make Gov Mode equal to LL Mode.

This CV Flow Demand should be the same with CV (Control Valves) position as Turbine Master Demand Control.