In a control system for controlling a power generator based on a command value associated with a control parameter, a receiver receives the command signal, a detector detects the command value included in the received command signal, and a determiner determines whether a duration of the detected command value being invariant within a predetermined range exceeds a predetermined allowed duration. In the control system, a controller controls an output of the power-generator based on a predetermined default value within the predetermined range in place of the command value when it is determined that the duration of the detected command value being invariant within the predetermined range exceeds the predetermined allowed duration.