Reliability analysis of distribution networks

Monitoring of failures and outages in the transmission and distribution of electrical energy is necessary for determination of the reliability of network components and the supply of electrical energy to consumers. Incorrect input data leads, of course, to false results even if the correct computing method is used. The paper deals with obtaining of reliability indices of distribution network analyzing data about failures and outages of electric power supply from several distribution areas from the Czech Republic and the Slovak Republic. Data sources produce heterogeneous domain data. It is necessary to store them in one common scheme to be able to analyze and query such data. Scheme comes from Distribution Network Grid Code. We proposed multi-dimensional data structure to storage of the data that enable effective querying. Data from particular companies are transformed. The transformation language has been developed for this reason. For evaluation of reliability it is necessary to have data on the number and range of the examined piece of equipment. Thus it is not only the case of data on e.g. the number of failures and the mean duration of a failure of the line of the given type and the given voltage level, but also the case of data on the total range of the observed piece of equipment, i.e. here on the total length of the line of the given type and the given voltage level. The result of analysis is the determination of the failure rate and mean failure duration for particular items of equipment or for group of equipments. With more detailed databases, other pieces of information may be found that are important for operators, such as the most frequent cause of failures, areas of the greatest amounts of undelivered energy, etc.