Electricity Supply Reliability: Evaluation of Improvement Solutions for Existing Electricity Networks

Abstract: Regulation of the electricity network business is continuously under
development in many countries. This is a reaction of an increasingly
electricity dependent society, which demands electricity supplies at acceptable
quality levels and at reasonable tariffs. Thus, electric network companies are
facing new requirements that change the conditions for exercising network
activities. Generally, incentives are given to the network companies to
maintain the present level of reliability in a cost-efficient way. In Norway,
however, incentives are given to the network companies to plan, operate and
maintain the networks in a socio-economically optimal way, taking into
account the supply-interruption cost to the customers. Therefore, in Norway,
electricity network companies strive to identify and implement the most cost-efficient
reliability improvement projects, i.e., the projects that yield the
greatest overall reduction in supply-interruption cost to the customers for the
invested money.
In this thesis, implementations of reliability improvement solutions on a test
system have been evaluated from a socio-economical point of view. For each
of the alternative solutions implemented on the test system, the average
annual supply-interruption cost to the customers supplied from the test
system has been estimated. Furthermore, the maximum annual capital cost
associated with the implementation of each solution has been estimated.
Then, a reliability improvement solution is considered justified socioeconomically
if the capital cost associated with its implementation is less than
the resulting reduction in the interruption cost to the customers.
The general conclusion from this thesis work is that the supply-interruption
cost to the customers supplied from a test system can be reduced significantly
by implementing reliability improvement solutions that are justified socioeconomically.
Even if the uncertainty of the input data is taken into account,
it is obvious from the results that the interruption cost to the test system
customers can be reduced to at least half the initial value.