WIND ENERGY SYSTEMS - Cd3wd

Chapter 5—Electrical Network 5–53
Figure 28: Monitoring and control hierarchy.
may want to buy electricity from another utility for two or three years before this coal plant
is finished and then sell the surplus electricity for three or four years until the utility is able
to use all of its capacity.
There are also times when short term sales are economically wise. One utility may have
an economical coal plant that is not being used to capacity while an adjacent utility may be
forced to use more expensive gas turbines to meet its load. The first utility can sell electricity
to the second and the two utilities can split the cost differential so that both utilities (and
their customers) benefit from the transaction. Such transactions are routinely handled by the
large computers at the power pool operating center. Each utility provides information about
their desire to buy or sell, and the price, to this central computer, perhaps once an hour.
The computer then matches up the buyers and sellers, computes transmission line costs, and
sends the information back to the utility dispatch centers so the utility can operate its system
properly.
Wind Energy Systems by Dr. Gary L. Johnson November 21, 2001