A network of sensors is associated with a power distribution network. Sensors are positioned at each connecting line in the vicinity of each node of the power distribution network. The sensors regularly report the following measured data to the central processing unit: a geographical position of each sensor, direction of the energy flow relative to the nearest node; and value of RMS current synchronously measured over the entire network and averaged over chosen averaging period. The central processing unit includes an arrangement for receiving the measured data and using this data for constructing and updating a graph and a state of the power distribution network.