Hedging Strategy and Electricity Contract Engineering - IFOR
Hedging Strategy and Electricity Contract Engineering - IFOR
Hedging Strategy and Electricity Contract Engineering - IFOR
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¢<br />
4.3 Hydro storage plant 83<br />
I<br />
k<br />
L k<br />
¢<br />
V k<br />
¢<br />
Fig. 4.5: Illustration of a hydro storage plant in discrete time.<br />
x k<br />
¢<br />
dispatch strategy 9 <strong>and</strong> since the optimization later will boil down to a LP, the<br />
st<strong>and</strong>ard notation, namely x for the decision variables is introduced already<br />
here.<br />
The boundaries on x k is determined by the technical characteristics of the hydro<br />
storage plant, such as height of water column, dimension of water pipes,<br />
pumps, turbines etc. The maximum capacity of the turbines <strong>and</strong> pumps is denoted<br />
p max <strong>and</strong> p min respectively as expressed in (4.3), where we state that the<br />
dispatch must lie within the technical limitations in each period<br />
p min x k p max<br />
š kž (4.3)<br />
In reality p max <strong>and</strong> p min are actually functions of the water level <strong>and</strong> hence<br />
V . The water column <strong>and</strong> hence the velocity of the water stream hitting the<br />
turbine blades is dependent on the water level. This dependency is however<br />
negligible for a typical hydro storage plants in, for example, Switzerl<strong>and</strong>,<br />
where the water column down to the generators <strong>and</strong> the pumps normally is a<br />
few hundred meters, whereas the dam water level can differ with some tens of<br />
meters.<br />
9 See Chapter 6.4.5.1.
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