Calculation of relay protection and automation failure risks

The paper is aimed to the development of the algorithm for the risk calculation for the primary circuit objects according to the installed secondary equipment. The algorithm is based on the introduced graph probabilistic model taking into account the network topology, equipment state conditions, responsibility of consumers and short-circuits probability. The IEEE 14 test scheme was used as input data for a primary network while the information about secondary circuit's security was obtained from previous authors papers. The results show that the algorithm could calculate the risk of relay protection outage. To predict possible influence of relay system reconstruction it is required to change the probability indices, thus, the decrement of the system risk will be an indicator of system improvement. By comparing the risk decrement in different investment strategies it is possible to define which one is the best. The algorithm may be used for a reasonable planning of the relay protection replacement priority.