The appearance and increasing penetration of electricity produced by weather-dependent renewable energy sources (such as solar and wind energy) are a great challenge, in that the transmission system operator has to keep the transmission system and the power plants secure. One cannot avoid these technologies and the tasks they include since ”green” energy is an essential element of sustainable growth and also because according to Hungary’s Renewable Energy Utilization Action Plan, by 2020 Hungary plans to cover 14,6% of the whole consumption of electricity by renewable energy sources.
The most accurate estimation of the expected production of electricity produced by weather-dependent renewable energy sources is very important for the tasks of the transmission system operator, because the change in production caused by the changes of weather circumstances for which the transmission system operator needs to have more reserve capacity can be a problem. It is important for the transmission system operator to have adequate tools facing the following problems: the system load and production changing with a given gradient possibly generates a need for more reserve capacity (beside the already allocated reserves), and production units which are not controllable at all or controllable for only a limited extent also affect the transmission system operator’s position negatively.
Furthermore, the possibility of a sudden increase in the number of small, domestic scaled power plants – which don’t need any production license for connecting to the low voltage network and are typically photovoltaic electricity producers –, and the lack of obligation for continuous or quarter-hour measurement of produced energy can endanger the system stability both from the aspect of the available gradient and from the aspect of the available control reserve.