A computer-implemented method for frequency domain-based determination of currents for injection into a power network, the method comprising: compiling Thévenin parameter data structures for each of a Thévenin voltage, resistance and inductance, wherein each data structure has values for each of one or more lines at each of a predetermined set of frequencies, the values having been obtained at a point of common coupling to a power network having the one or more lines; compiling an offset data structure including offset values, each of which is to be applied to a corresponding value of the Thévenin voltage data structure to output an offset Thévenin voltage data structure, wherein the offset values are calculated to satisfy physical constraints associated with the power network; compiling the offset Thévenin voltage data structure; compiling a point of common coupling optimal power data structure including values having been determined based on a specific amount of total power at the point of common coupling and the minimum achievable line losses that are based on the offset Thévenin voltage data structure or a derivative thereof; using the point of common coupling power data structure and the offset Thévenin voltage data structure to calculate current components for each line and for each of the predetermined set of frequencies for determining current for injection into or extraction from corresponding lines at the point of common coupling so as to inject or extract a specific total amount of power in a manner that reduces total electrical transmission losses of the power network; and, controlling injecting or extracting, at the point of common coupling, currents associated with the current components to reduce total electrical transmission losses of the power network. compiling Thévenin parameter data structures for each of a Thévenin voltage, resistance and inductance, wherein each data structure has values for each of one or more lines at each of a predetermined set of frequencies, the values having been obtained at a point of common coupling to a power network having the one or more lines; compiling an offset data structure including offset values, each of which is to be applied to a corresponding value of the Thévenin voltage data structure to output an offset Thévenin voltage data structure, wherein the offset values are calculated to satisfy physical constraints associated with the power network; compiling the offset Thévenin voltage data structure; compiling a point of common coupling optimal power data structure including values having been determined based on a specific amount of total power at the point of common coupling and the minimum achievable line losses that are based on the offset Thévenin voltage data structure or a derivative thereof; using the point of common coupling power data structure and the offset Thévenin voltage data structure to calculate current components for each line and for each of the predetermined set of frequencies for determining current for injection into or extraction from corresponding lines at the point of common coupling so as to inject or extract a specific total amount of power in a manner that reduces total electrical transmission losses of the power network; and, controlling injecting or extracting, at the point of common coupling, currents associated with the current components to reduce total electrical transmission losses of the power network.