  Keeping the electricity production in balance with the actual demand is
becoming a difficult and expensive task in spite of an involvement of
experienced human operators. This is due to the increasing complexity of the
electric power grid system with the intermittent renewable production as one of
the contributors. A beforehand information about an occurring imbalance can
help the transmission system operator to adjust the production plans, and thus
ensure a high security of supply by reducing the use of costly balancing
reserves, and consequently reduce undesirable fluctuations of the 50 Hz power
system frequency. In this paper, we introduce the relatively new problem of an
intra-hour imbalance forecasting for the transmission system operator (TSO). We
focus on the use case of the Norwegian TSO, Statnett. We present a
complementary imbalance forecasting tool that is able to support the TSO in
determining the trend of future imbalances, and show the potential to
proactively alleviate imbalances with a higher accuracy compared to the
contemporary solution.
