Abstract: Using controlled reactor of transformer type with high leakage reactance as new automatic tracking compensation device of distribution system was studied in the paper,which could automatically adjust arc suppression coil.The device’s control adopted the scheme of dynamic compensation,which could monitor the capacitive current of power net in real time.In normal working,the device was far from the resonance point.When the fault of instantaneous single-phase grounding happened,the device could compensate(quickly.) The result of simulation showed that the automatic tracking compensation device hadsome advantages such as good linearity of voltage-current characteristic,quick response speed,good compensation effect,strong adaptability,good performance index,etc.