Enhanced outage models for reliability calculations of electric power systems

In the past outage models used for reliability analyses of electric power systems have been a compromise regarding model accuracy due to poor statistical input data and limited computer power. The input data was mainly derived from special investigations of incident behaviour of small parts of German networks /e.g. Bitter et. al./. Since 1994 the new, enhanced German VDEW statistics of incidents /Bose et. al., Fass et. al./, which covers reliability aspects to a high degree of detail, collects incident data for networks with nominal voltages U(n)greater than or equal to 110kV all over Germany. Based on this solid database enhanced outage models are proposed, which are able to simulate outages more closely to reality. In detail twelve different outage models like active component failures, independent outages due to accidental tripping of switches, simultaneous outages of several components due to common-mode failures, multiple outages due to multiple earth faults on different components, dependent outages of several components due to malfunction or unnecessary operation of protection devices or malfunction of circuit breakers and dependent outages during maintenance of network components are taken into account and fed with data by the VDEW statistics of incidents. Due to their time dependency the enhanced outage models are applied to a reliability calculation program for electrical power systems using a time-sequential Monte-Carlo simulation approach /Backes et. al/. The paper presents the proposed outage models as well as their dependencies in detail. A example calculation of an existing 110-kV-network shows the advantages of using the enhanced outage models which lead to calculation results closer to reality.