Steamtemperaturecontroldesign

Description

Model for finding parameter values of a steam temperature controller using relay autotuning.

The experiment consists of four phases; stabilization, exponential growth, relay switching and verification. These are described briefly below. See also the autotuner model for further information.

Stabilization

The process is brought to steady state using an existing PI-controller. For stable systems, such as this, it is also possible to reach steady state using a constant input signal to the process.

Exponential growth

The input to the process is increased exponentially until the process output exceeds the hysteresis level.

Relay switching

An asymmetric relay function is used to drive the process into a limit cycle with appropriate amplitude. Once this is achieved, an estimation of the process is performed based on the limit cycle behaviour and corresponding control parameter values are calculated.

Verification

The estimated model is compared to the actual procss using a relay signal as input.

Simulation setup

Simulate for 50s using Radau with a tolerance of 1e-6.

Output

The main variables of interest from the experiment are the control parameters K, Ti and Td, which are printed when the experiment is finished. Look at the verification model to observe the performance of a controller with the calculated control parameters.

By plotting y_model and u_m during the verification phase, the estimated model can be compared with the true process.