Determining a value of a characteristic of an electric power grid

Abstract

A method of determining a first value of a characteristic of an electric power grid observed at a first location of the grid comprises: obtaining a plurality of second values, each second value being indicative of a relationship between a difference in measured voltage of the electric power grid at the first location before and after a respective power change and a difference in measured current of the electric power grid at the first location before and after the respective power change. Each power change causes an electric power flow in the grid with a respective different ratio of reactive to active power. The first value is determined from the second values. This may be by determining a third value indicative of an extremum of the relationship. The third value may be the maximum. The second values may indicate impedance. The first value may indicate impedance, short circuit current or short circuit level. [Figure 14]