The invention relates to a pretreatment unit capable of automatically generating power to control target loads, which comprises a signal quality test loop (I), a high-low limit monitoring alarm loop (II), a deviation calculating and monitoring loop (III), a signal holding and receiving loop (VI), a signal abnormality comprehensive alarm loop (V) and a signal holding and receiving loop (VI). The pretreatment unit can provide alarm, effectively prevent AGC signal abnormality from impacting the normal operation of the unit set and prevent small fluctuation of AGC signals from causing frequent changes of unit set loads, fuel, water supply, air temperature and the like so as to have favorable function on the stable operation of the unit set and have the advantages of safety and obvious economic benefit.