Developing of compilation of interruption statistics in Finland to meet various new requirements

In Finland the Energy Market Authority has decided to renew the interruption indices collected from distribution network companies. The background of the renovation is the regulation of the network business, which remained as natural monopoly when the electricity market was deregulated. Formerly, the Energy Market Authority has been collecting two interruption indices, namely T-SAIFI; the average number of interruptions and T-SAIDI; the average duration of interruptions, which have been used also for regulation purposes. When assessing the reasonableness of the pricing, the Energy Market Authority has taken into account also the efficiency of the network companies. The efficiency has been calculated with DEA-model, in which power quality in the form of interruption time is one of the input parameters. Although for the next regulation period 2005–2007 DEA-score is not used, but background data for the future is collected and DEA-scores will be considered in the following regulation periods. With a few years experience on the regulation model, it was seen that it did not treat the network companies equitably. For example, in the use of interruption indices, it was formerly practically assumed that all secondary substations within a utility have same amount of equal customers. Now, to fix this inequitableness, the Energy Market Authority has decided to collect eight new indices (in addition to the old ones) including number and duration of unexpected and planned interruptions (weighted with the annual energy of affected secondary substations), number of high-speed and delayed auto-reclosings (weighted also with the annual energy of affected secondary substations) and annual number of unexpected interruptions in low voltage and medium voltage network.