PR-000-14216-R02 An Alternative to PID Control for Critical Control Functions

Previous work identified cases where relatively minor changes in air manifold pressure led to engine detonation. This occurred under lean combustion conditions where detonation is believed to be unlikely. This indicates that it is as equally important to have stable engine control functions as it is to have the proper air/fuel setpoint. The objective of this work is to identify alternatives to conventional control techniques that can be employed on reciprocating engines used in the natural gas transportation industry to enhance air/fuel control stability which in turn should improve combustion stability.

The report identifies an alternate control method that adds symmetric/asymmetric dynamic integral control to the standard PID control method. While the example here is applied to reciprocating engine air/fuel control specifically, the control method can apply to many other complicated control methods such as surge control, flow control, temperature control, and pressure control. The report includes an example implementation for Allen-Bradley controlers using IEC 61131-3 Function Blocks.