Assessment of Interruption Costs in Electric Power Systems using the Weibull-Markov Mode
Doctoral thesis, 2003
Modern competitive electricity markets do not ask for power systems with the highest possible technical perfection, but for systems with the highest possible economic efficiency. Higher efficiency can only be reached when accurate and flexible analysis tools are used. In order to relate investment costs to the resulting levels of supply reliability, it is required to quantify supply reliability in a monetary way.This can be done by calculating the expected interruption costs.
Interruption costs evaluation, however, cannot be done correctly in all cases by methods which are based on the commonly used homogenous Markov model and is time consuming when using a Monte-Carlo simulation. It was the objective of this thesis to find a new way for calculating interruption costs which would combine the speed and precision of the analytic Markov method with the flexibility and correctness of the Monte Carlo simulation.
A new calculation method was found, based on a new stochastic model. This new model was called the "Weibull-Markov" model and is described in detail in this thesis. The new model and methods have been implemented in a computer program and the speed and accuracy of the calculation method was tested in various projects and by comparison with Monte-Carlo simulations.
It is shown in this thesis that disregarding the effects of the probability distribution of the interruption duration can lead to large errors, up to 40% and more, in the calculated expected interruption costs. An estimation of the possible error has been made for a large number of published customer interruption cost functions. The actual error in specific reliability calculations is hard to estimate. It is however clear that this error cannot be simply ignored.
The use of the new Weibull-Markov model and the reliability assessment methods do not significantly slow down the calculation speed, offer more flexibility in reliability worth assessment and produce more accurate results. They can be used in all areas of power system reliability assessment which have always been the exclusive domain of homogenous Markov modeling.
power system reliability
customer damage function