Outage Models of System Components

This chapter systematically discusses the outage models of system components. Generally, component outages can be divided into two categories: independent and dependent. The independent outage modes of power system components are categorized as follows: forced outage (repairable forced failure and nonrepairable forced failure), planned outage, semiforced outage, partial failure mode and multiple failure mode. Nonrepairable forced failure includes aging failure and chance failure. The aging failure mode of components should be incorporated in risk evaluation when components approach the end of their lives. Dependent outages can be classified as: common-cause outage, component-group outage, station-originated outage, cascading outage and environment-dependent failure. The common characteristic of all the dependent outage modes is that an outage state includes outages of more than one component. Dependent outages generally produce much more severe consequences than independent outages.