Comparison of interruption statistics and their use in network business regulation in Nordic countries

Norway, Finland and Sweden have been in the leading edge in the deregulation of the power market. In Norway the deregulation process started in 1991, in Finland in 1995 and in Sweden in 1996, respectively. Electricity distribution has remained as natural monopoly in deregulated power market, which means supervision of distribution companies by the national market authority. Quality of supply is part of the regulation models and in the first phase the quality of supply has often been depicted with interruption time. This has led to a need for more versatile and reliable interruption statistics and in the future even more detailed supply quality data (e.g. voltage quality) will be used for regulation purposes.