Large-scale heating furnaces in the refining, chemical, tire, glass and other industries use AC power-regulating circuits. These AC power-regulating circuits have impact loads, which have large capacity and strong non-linearity. Waves and impact current components can cause problems such as transformer overheating and system relay malfunction. However, there are few researches on the AC power-regulating circuit with impact load. In this paper, the AC power-regulating circuit with impact load is analyzed for its current periodicity, in order to overcome the difficulty of accurately tracking and controlling the APF output when the load is sudden. The problem of current, the introduction of PI-repetitive control control method, the establishment of a new APF model to mitigate intermittent impact current and harmonic control, can not only carry out harmonic control and reactive power compensation, but also has active smoothing function. Through experiments, aiming at the actual situation of a refinery in Shandong, the simulation circuit of the AC power-regulating circuit with impact load is built. The verification model effectively reduces the DC bias current, and the current distortion rate is small, stable and reliable.

impact load,power regulating circuit,repeated control,APF,active smoothing