Wireless - Overcoming challenges of PID control & analyzer applications - An enhanced PID controller simplifies tuning and improves loop stability and reliability for loops dominated by discontinuous measurement updates

摘要

Wireless measurements offer significant life-cycle cost savings by eliminating the installation, troubleshooting, and modification of wiring systems for new and relocated measurements. Some of the less recognized benefits are the eradication of EMI spikes from pump and agitator variable speed drives, the optimization of sensor location, and the demonstration of process control improvements. However, loss of transmission can result in process conditions outside of the normal operating range. Large periodic and exception reporting settings to increase battery life can cause loop instability and limit cycles when using a traditional PID (proportional-integral-derivative) for control. Analyzers offer composition measurements key to a higher level of process control but often have a less-than-ideal reliability record, sample system, cycle time, and resolution or sensitivity limit. A modification of the integral and derivative mode calculations can inherently prevent PID response problems, simplify tuning requirements, and improve loop performance for wireless measurements and sampled analyzers.