Advantages and difficulties with the application of methods of probabilistic safety assessment to the power systems reliability

The probabilistic safety assessment is a standardized and widely accepted method for assessing and improving the reliability and safety of complex technologies, which is particularly true for the nuclear and the aerospace industry. The number of its applications to reliability of power systems is increasing. The objective of the paper is to collect and present the advantages and difficulties with the application of methods of probabilistic safety assessment to power systems reliability. The methods which apply the features of fault tree analysis to reliability analysis of power systems are presented and compared.The results are discussed and evaluated. The main advantages are connected with the facts that the methods are relative simple, the models are mostly available and that the data is intensively collected, evaluated and can serve as an excellent support for the quantitative part of the analyses. The difficulties are connected with different nature of components interaction within the power system compared to the safety systems in a nuclear power plant and with the large complexity of the power system, which distinguishes the term reliability into its static and dynamic parts known as adequacy and security. The results show large impact of common cause failures. The lack of data for the evaluations in the field of common cause failures of power systems increases significantly the uncertainty of the results. The uncertainty of the results may be reduced by improved data collection and analysis similarly as it is done in the nuclear safety.

► Relation between power system reliability and nuclear power plant safety.
► Common cause failures of switchyards.
► New power system importance factor: network risk increase factor, network risk decrease factor.
► High uncertainty can be reduced by improvement of data base.