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Procedings
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e n e r g y + p r o c e e d i n g s 35 homeostatic utility
control
in 1978, fred c. schweppe [2] wrote about different levels of
control
of electricity
systems
and the devel- opment of customer oriented markets. the concept was called “homeostatic utility
control
”. in the future, central grid
control
would not suffice any- more, and different market players would buy and sell power on markets. his vision also included customer generation, weather dependent production, growth of ict, modelling as a basis for
control
systems
, and the separation of market transactions and the physical flow of electricity. homeostatic utility
control
requires three distinct functional developments for its successful implemen- tation: 1. a short-term mechanism to balance the supply and demand; 2. an
energy
marketplace; 3. a communication system. the first is a short-term mechanism which can oper- ate to balance supply and demand in a time frame less than five to 10 minutes. within current utility generation
systems
this function is generally fulfilled by governor and agc action in central power plants which cause supply to follow demand. an alterna- tive approach causes demand to follow supply and is based on a frequency adaptive power
energy
rescheduler (faper). a faper is a frequency- responsive switching device which will
control
significant
energy
(as opposed to power) consuming loads. an example or such a load would be an electric heating system. the basic principle of the faper is rescheduling uses of electricity in which the demand is for an average rather than an instantaneous condi- tion. the faper will turn the device off and back on as a function of the utility’s ability to provide
energy
. the second concept required is that of a mechanism by which consumers can pay a price for electricity which reflects, over time, the true current cost of the
energy
which they are receiving. this
energy
market- place contains three classes of actors: first, the cus- tomer who purchases power from the marketplace or sells excess generation to it, second, the utility gen- eration which is a supplier of electricity to the mar- ketplace, and, third the utility marketing system which acts as a broker for the electricity. the third concept is the requirement for a device or set of devices which can provide the communication and recording functions critical to the operation of a system with high variability in the critical variables such as cost and price. the marketing interface to customer (mic) capable of maintaining and billing against variable spot prices as well as acting to credit a consumer with significant ‘storage’ through fapers installed in his system. a mic varies in complexity as a function of application and expected
energy
usage from large
systems
for the industry to relative sim- pler
systems
which could be installed in an individual residence. in power system ‘2000’ [3] fred c. schweppe men- tions another solution for grid balancing with large amounts of distributed generation: different
control
levels. with this concept, operation and
control
of the grid is done by a central tso and different local operators together and by using computer technol- ogy and data-network communication. the long-term management is done by people, while computers are used for short-term operation decisions. information standards and user friendly interfaces are required for effective cooperation between local and central opera- tors and between humans and computers. in power system ‘2000’ [3], large-scale
energy
storing
systems
are named as a solution to large differences between production and demand. nowadays, how- ever, large-scale
energy
storage for electricity
systems
is not widely used. spinning generators provide some
energy
storage, which automatically balances the grid on the very short term. many other possible types of storage can be named. large facilities are under construction. in the future, storage could be an effi-
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