Modelling of power system components for reliability analysis

The components of the power system can be divided in smaller units, subcomponents. The components can also be divided to passive and active units and they can be modelled both physically and operationally. In the operational models all the possible operational states of the components are taken into account and the most probable transfer routes between these states are considered. In the physical model all the connections between subcomponents are studied. These two models can be combined in order to form a fault tree that shows how the component can cause a failure in the transmission network. The aim of the paper is to present a simple component model. With the model it is possible to assess the probabilistic effects of different subcomponent failures to the system reliability.