Control Using Wireless Devices – Control Performance Part 1

When the PIDPlus is used with a wireless transmitter in a control application the performance will be comparable to that achieved using a wired transmitter with a wired transmitter. To demonstrate this, the module shown below was created in DeltaV that allows the control using PIDPlus using s wireless communication to be compared to the control achieved using PID and a wired transmitter.

The simulated processes controlled by the PIDPlus and PID were identical and designed to utilize the same unmeasured disturbances. Also, using a module parameter, the setpoint value to the PID and PIDPlus can be changed at the same time. Using this capability, tests were conducted in which changes were made in the setpoint and unmeasured disturbance. The PID and PIDPlus control response is shown in the following trend.

For this test shown above, the communications Window trigger mode was utilized with a maximum update period of 10 seconds and a trigger value of 1%. As is illustrated, the control performance using wireless was comparable to that achieved using a PID and wired transmitter executing once per second. However, by using Window trigger mode, the wireless communications used by the PIDPlus were 96% less than the number of new measurement values provided by the wired transmitter to the PID. The impact of non-periodic measurement updates on control performance as measured by Integral of Absolute Error (IAE) is minimized through the use of PIDPlus for wireless communication as summarized below.