1. A method, comprising: receiving, at a controller, an alternating current signal; determining harmonic values that describe a fundamental frequency component of the alternating current signal and harmonic components of the alternating current signal; accessing, by the controller, control data that defines a relation of harmonic values to operational instructions, wherein each operational instruction, when supplied to an inverter, causes the inverter to perform an operation defined by the operational instruction; selecting, by the controller, an operational instruction from the operational instructions, the selected operational instruction based on the determined harmonic values and the control data; and providing, by the controller, the selected operational instruction to the inverter to cause the inverter to perform the operation defined by the selected operational instruction.