Steady-State Detector for Early Stop in Twin Activate
Altair EmployeeOverview
This is a Twin Activate block which stops the simulation when the response of a system stays within an allowed range from the desired system response.
It can be used with any system in which the desired response and actual response can be compared.
Usage
This is how the block should be implemented in a Twin Activate block diagram:
Inputs:
- S: System response
- Starget: Reference / input signal / desired response of the system
- Error%: Maximum allowable deviation from reference during steady state [%]
Outputs:
- Flag: This event activation port sends a signal once steady state has been reached.
Implementation
As the superblock has been masked, the user can double-click on it to edit the only parameter available, window length. The detector segments signals using a window of length N and calculates the mean before comparing this value to the reference.
Depending on the system and the time step size, this parameter should be set within the range of approximately 8 to 600 (try out different values).
This is how steady-state detection is implemented:
The process consists of three steps:
- Window Average: A windowed average is obtained from a segment of length N of the signal.
- Threshold Check: This part of the block check whether the obtained average is within the allowed range of reference value +/- allowed error percentage.
- Stability Check: Two consecutive segments must comply for steady state to be detected.
Usage/Installation Instructions
Load the superblock (.scb file) into your Twin Activate model from File > Import > Twin Activate Block.
Three different examples of different systems are attached:
- A simple transfer function block
- A water tank with its level controlled through a PID controller
- A PSIM - Twin Activate co-simulation of an average current mode control of a buck converter