Billster,Trying to keep speed changes at the turbine to a...

Billster,

Trying to keep speed changes at the turbine to a minimum.

The issue is not so much the thermal mechanical (and to an extent thermodynamic (shudder)) inertia, it is the effect of the stresses on the turbine bearings particularly and the blades (to a lesser extent).

The changes in speed and load transfer from the rotating mass to the case are ok according to the electrical engineer but make the mechanical guys grumpy. (That's a technical explanation)

The comment about the steam turbine (compared to a hydro) is that in a hydro the incompressibility of the water improves the apparent inertia of the turbine.

In the sequence you have below, the difference between my suggesting a diesel in as a compensator (partially loaded) is the diesel can cope with very small time scale (intra-second) variations in load while the control system (as you note) deals with larger variations in load over longer time frames.

I am not sure (precisely) how the thermal transfer regulation would (practically) work in this (HR) case. The NZ systems are all grid connected, and the inertia of the overall grid minimises the impact of any one unit or load variation. That, of course, is not the case here.

1fellowes