a turbofan blade structure (2) having a transmission shaft (21) perpendicular to a direction of environment airflow, the turbofan blade structure (2) being driven by the environment airflow to rotate with the transmission shaft (21) as a rotation center;

a speed control mechanism (22), one end of the speed control mechanism (22) being connected to the transmission shaft (21) and the other end driven by the transmission shaft (21) and outputting torque;

a generator (3), a rotor drive shaft of the generator being connected to the speed control mechanism (22), and driven by an output torque of the speed control mechanism to generate power;

an indicator (6) including a switch that is connected between the generator (3) and a cable (10) to connect and disconnect a power output path between the generator and the cable;

wherein the generator (3) comprises an excitation device automatic control system connected between a main generator stator coil and an excitation rotor controlling a self-excited constant voltage, regulating an excitation current of a rectifier bridge connected to the excitation rotor according to a deviation value of an output voltage of the main generator stator coil and keeping the output voltage of the self-excited constant voltage generator stable.