Surge is a harmful fault of induced draft fan in power station while the lack of fault data restricts the identification and prevention of surge. The overall model of induced draft fan as well as its upstream and downstream duct and equipment is established based on simulation software Apros

and the surge simulation test is carried out after verifying the accuracy of the model. Precursory characteristics of induced draft fan surge are analyzed according to the test results. The simulation test results show that

greater flue resistance leads to shorter surge period. When the resistance occurs upstream of the induced draft fan

the space from the resistance area to the end of the duct on one side will store and release mass alternately during surge

while the storage mass in areas upstream of the resistance area is basically unchanged. The change of flow parameters at different positions of the duct can be used as precursor features to identify surge. When the downstream resistance of the induced draft fan increases

the surge occurs in the space from the back of the dust collector to the end of the duct on one side. The identification of surge depends on the monitoring of the flow parameters at each position in this area. The flow on both sides can compensate each other

and excessive resistance of public duct will cause surge of fans on both sides.