How does the anti-surge device of turbine air compressor work?

When the output pressure of the turbine air compressor is certain and the flow decreases to a certain value, surge will occur. To prevent surge, keep the flow from entering the surge area. During the operation of the compressor, when the resistance of the pipeline system increases, the flow will decrease accordingly, and it is likely to decrease below the allowable value. The task of anti-surge system is to automatically open the air vent valve which is ventilated or the bypass valve which flows back to the inlet to increase the flow through the air compressor when the flow drops to a certain safety lower limit, prevent entering the surge area.
It takes the lower limit of flow safety as the specified value of regulator T. When the measured value of flow is higher than the specified value, the air release valve will be fully closed: when the measured value is lower than the specified value, the regulator will output signals to open the air release valve to increase the flow. Perfect anti-surge device should be controlled according to the two signals of air compressor outlet pressure and flow.