Method for determining parameters of a primary component of an electrical energy supply grid, wherein the parameters specify electrical and/or physical properties of the primary component and in which method the following steps are carried out: - recording input-side current and voltage values at the input of the primary component; - recording output-side current and voltage values at the output of the primary component; and - determining the parameters on the basis of the input-side and the output-side current and voltage values and a model description that is specific to the primary component and mathematically describes a dependency of the output-side current and voltage values on the input-side current and voltage values using the parameters of the primary component; wherein - the following further steps are carried out: a) starting values of the parameters are used as input values for determining a set of derived values of the parameters, wherein the values of the parameters used as the starting values are those that specify electrical properties of the primary component in an unused state or in a used state; b) using the input-side and the output-side current and voltage values, a subset of derived values of the parameters, which are used by the model description to describe the dependency of the output-side current and voltage values on the input-side current and voltage values with high quality, is chosen from the set of derived values of the parameters; c) a new set of derived values of the parameters is determined using the subset of derived values of the parameters as input values; d) using the new set of derived values of the parameters, steps b) and c) are carried out until an abort criterion in respect of the quality of the determined derived values of the parameters has been met, characterized in that recombination and/or mutation of the respective input values is carried out using an optimization by means of an evolution strategy in order to determine the derived values of the parameters. - recording input-side current and voltage values at the input of the primary component; - recording output-side current and voltage values at the output of the primary component; and - determining the parameters on the basis of the input-side and the output-side current and voltage values and a model description that is specific to the primary component and mathematically describes a dependency of the output-side current and voltage values on the input-side current and voltage values using the parameters of the primary component; - the following further steps are carried out: a) starting values of the parameters are used as input values for determining a set of derived values of the parameters, wherein the values of the parameters used as the starting values are those that specify electrical properties of the primary component in an unused state or in a used state; b) using the input-side and the output-side current and voltage values, a subset of derived values of the parameters, which are used by the model description to describe the dependency of the output-side current and voltage values on the input-side current and voltage values with high quality, is chosen from the set of derived values of the parameters; c) a new set of derived values of the parameters is determined using the subset of derived values of the parameters as input values; d) using the new set of derived values of the parameters, steps b) and c) are carried out until an abort criterion in respect of the quality of the determined derived values of the parameters has been met, a) starting values of the parameters are used as input values for determining a set of derived values of the parameters, wherein the values of the parameters used as the starting values are those that specify electrical properties of the primary component in an unused state or in a used state; b) using the input-side and the output-side current and voltage values, a subset of derived values of the parameters, which are used by the model description to describe the dependency of the output-side current and voltage values on the input-side current and voltage values with high quality, is chosen from the set of derived values of the parameters; c) a new set of derived values of the parameters is determined using the subset of derived values of the parameters as input values; d) using the new set of derived values of the parameters, steps b) and c) are carried out until an abort criterion in respect of the quality of the determined derived values of the parameters has been met,