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Hedging Strategy and Electricity Contract Engineering - IFOR

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ìj<br />

Û 1 bë<br />

j Ý?Ü j 1Ü á?á@á<br />

ö<br />

ö<br />

õ<br />

ìj<br />

1Ü õ<br />

ìj<br />

0Ü j 1Ü<br />

ö<br />

á<br />

6.5 Analysis of optimal dispatch strategy 137<br />

ÜÑôkÜ<br />

where j denotes an index from the set of pumping thresholds<br />

r<br />

opposed to an index from the set of production thresholds Sëi iâ 1 .<br />

Sìj<br />

ö<br />

1 as jâ<br />

Using these expressions in (6.25) results in<br />

÷uø<br />

max<br />

ÙmÚ<br />

r ã<br />

÷ ý ÙˆÚ¥¤<br />

s á<br />

t á<br />

r<br />

iâ 1<br />

ë õ<br />

i<br />

aëi<br />

¦<br />

è<br />

õ<br />

ìj<br />

aëj<br />

E S (6.26)<br />

1 jâ<br />

r<br />

r<br />

iâ 1<br />

iâ 1<br />

ë õ<br />

i<br />

¦ bëi<br />

ë õ<br />

i<br />

õ<br />

ìj<br />

bë<br />

j<br />

Wú ¦<br />

1 jâ<br />

õ ë<br />

i<br />

0Ü i 1Ü<br />

1Ü<br />

Ü r<br />

á@á?á<br />

Ükô<br />

á@á?á<br />

jâ 1<br />

§ ¨ Again a is concave <strong>and</strong> monotone increasing in b as shown by Theorem 6.1<br />

<strong>and</strong> hence we can conclude<br />

Corollary 6.6<br />

In the solution of (6.26)<br />

(i) Wú If bë1 then ë1<br />

1 <strong>and</strong> õ ì<br />

1<br />

1 is optimal<br />

õ<br />

(ii) If Wú ¦ é bër ¦ bë ö<br />

then the problem is infeasible<br />

(iii) Else at most two adjacent production weights õ i 1 <strong>and</strong> ë<br />

i<br />

<strong>and</strong> at most<br />

ë õ ì<br />

two adjacent pumping weights ìj 1 <strong>and</strong> ìj<br />

will be non-zero.<br />

õ õ ì<br />

A proof is given in Appendix A on page 196. To actually derive the solution we<br />

however need to study the dual problem. Consider the dual to the productionpumping<br />

problem (6.26)

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