This research is an extension of the authors' previous work in double aucti
ons aimed at developing bidding strategies for electric utilities which tra
de electricity competitively. The improvements detailed in this paper come
from using data structures which combine genetic programming and finite sta
te automata termed GP-Automata. The strategies developed by the method desc
ribed here are adaptive-reacting to input-whereas the previously developed
strategies were only suitable in the particular scenario for which they had
been designed. The strategies encoded in the GP-Automata are tested in an
auction simulator. The simulator pits them against other distribution compa
nies (distcos) and generation companies (gencos), buying and selling power
via double auctions implemented in regional commodity exchanges. The GP-Aut
omata are evolved with a genetic algorithm so that they possess certain cha
racteristics. In addition to designing successful bidding strategies (whose
usage would result in higher profits) the resulting strategies can also be
designed to imitate certain types of trading behaviors. The resulting stra
tegies can be implemented directly in online trading, or can be used as rea
listic competitors in an off-line trading simulator.