When load reduced to a certain degree

compressor will produce dramatic surge phenomena.This will seriously damage the machine and lead to a serious consequence.The purpose of this paper is to simulate the surging phenomena and its control in rich gas compressor of fluid catalytic cracking unit.The surge will happen in a short time

and its operation step length is thousands of times different from catalytic cracking running time

so it will simulate in two different time scales.First

the compressor model applying in active control is established by using user unit model extension.In order to overcome the consumption in steady areas brought by active actuator

switching control scheme designed that compressor implements active control in surge region while compressor without active control in stable region only applying PID control can satisfy the technological requirements.Finally

the scheme is used in the dual time scales simulation.The whole process validates the effectiveness of the proposed scheme and proves that it can both solve the problem of compressor could not work in high performance area in the traditional anti-surge passive control and resolve the increasing of the energy consumption brought by active actuator.