Abstract: A surge prevention control system for use with a dynamic compressor provides a multiple module controller for operating an anti-surge valve to bypass flow around the dynamic compressor. The multiple module controller includes a PID control module and a rate control module. The PID control module controls the anti-surge valve to control the operating point of the dynamic compressor about the surge control line. The rate control module uses the rate of approach of the operating point to the surge control line as its process variable. In the event of high rate of approach, the rate control module takes control of the anti-surge valve. The setpoint of the rate control module is adjusted to open the anti-surge valve to control the rate of approach to the surge control line to minimize the overshoot of the PID control.

Abstract: A control system prevents recurrence of surge in a dynamic compressor. An anti-surge valve bypasses flow and is operated by the control system between a low limit and a full open position. The low limit is initially established to be zero, or a fully closed anti-surge valve. In the event of a compressor surge, the system detects a position of the anti-surge valve at the onset of surge, and stores a position related to the detected position as a new low limit. The stored position is preferably the detected position plus a small increment in order to prevent recurrence of the surge event.