A control system for an electric power grid configured to supply electric power from a supply point to a plurality of user locations (150, 160), the system comprising: a plurality of sensors, wherein each sensor is located at a respective one of a plurality of distribution locations on the electric power grid at or between the supply point and at least one of the plurality of user locations, and wherein each sensor is configured to sense a component of the supplied electric power at the respective distribution location and to generate measurement data based on the sensed component of the power; a controller configured to generate an energy delivery parameter based on the measurement data received from the sensors; a component adjusting device configured to adjust a component of the electric power transmission and electric power grid within a controller target band in response to the energy delivery parameter; wherein the controller target band has first upper and lower limits for a first control mode and second upper and lower limits for a second control mode; characterised in that the controller is configured to select either the first or second modes based on the measurement data received from the sensors; the component of the supplied electric power is voltage and the controller target band is a controller target voltage band; the first control mode is a conservation voltage reduction and the controller target band first upper and lower limits define a first range of voltage at distribution locations; the controller target band second upper and lower limits define a second range of voltage at distribution locations; and the controller is configured to select either the first or second modes based on a determination of a system energy state using a comparison of measurement data, including report-by-exception data, received from the sensors against previously stored patterns of voltage changes, wherein the second control mode is high variation loading. a plurality of sensors, wherein each sensor is located at a respective one of a plurality of distribution locations on the electric power grid at or between the supply point and at least one of the plurality of user locations, and wherein each sensor is configured to sense a component of the supplied electric power at the respective distribution location and to generate measurement data based on the sensed component of the power; a controller configured to generate an energy delivery parameter based on the measurement data received from the sensors; a component adjusting device configured to adjust a component of the electric power transmission and electric power grid within a controller target band in response to the energy delivery parameter; wherein the controller target band has first upper and lower limits for a first control mode and second upper and lower limits for a second control mode; characterised in that the controller is configured to select either the first or second modes based on the measurement data received from the sensors; the component of the supplied electric power is voltage and the controller target band is a controller target voltage band; the first control mode is a conservation voltage reduction and the controller target band first upper and lower limits define a first range of voltage at distribution locations; the controller target band second upper and lower limits define a second range of voltage at distribution locations; and the controller is configured to select either the first or second modes based on a determination of a system energy state using a comparison of measurement data, including report-by-exception data, received from the sensors against previously stored patterns of voltage changes, wherein the second control mode is high variation loading.