Probabilistic availability analysis of control and automation systems for active distribution networks

The future smart electricity grids will exhibit tight integration between control and automation systems and primary power system equipment. Optimal and safe operation of the power system will be completely dependent on well functioning information and communication (ICT) systems. Considering this, it is essential that the control and automation systems do not constitute the weak link in ensuring reliable power supply to society. At the same time, studies of reliability when considering complex interdependencies between integrated ICT systems becomes increasingly difficult to perform due to the large amount of integrated entities with varying characteristics involved. To manage this challenge there is a need for structured modeling and analysis methods that accommodate this characteristics and interdependencies. In other fields, the analysis of large interconnected systems is done using models that capture the systems and its context as well as its components and interactions. This paper addresses this issue by combining enterprise architecture methods that utilize these modeling concepts, with fault tree analysis and probabilistic relational models. This novel approach enables a holistic overview thanks to the use of formalized models. It also allows use of rigorous analysis thanks to the adaptation of the models to enable Fault Tree Analysis. The paper is concluded with an example of application of the analysis method on a proposed smart grid function in a distribution network.