paper presents a nonlinear multivariable fitting model to decompose th
e optimal policies obtained by dynamic programming of a unique aggrega
ted reservoir. The nonlinear functions are generated using radial basi
s functions (RBF) neural networks. In this method the potential energy
of all the reservoirs in the hydropower system is added to form one e
quivalent reservoir. The operating policy of the equivalent reservoir
is determined by stochastic dynamic programming, and finally the opera
ting rules of each reservoir are determined using RBF neural networks.
To improve the multivariable representation of the data, a series of
piecewise RBF neural networks is determined using clustering analysis.
A fuzzy clustering approach is used to determine the RBF's parameters
. This approach has the advantages of being fast and simple to impleme
nt with well-established convergence properties. It also has a good re
presentation of the covariance matrix, since all the data belong to al
l the classes at the same time with different membership grades. A com
parison with the back propagation learning and principal components te
chniques is also reported for Quebec's La Grande River installations.
As a result, the proposed approach gives satisfactory operating rules
compared with principal component analysis, and the CPU time is reduce
d by a factor of 15 to 20 compared with the back propagation technique
.