Integrate Typhoon HIL with helics

[eaamako]

Is there an integration between Typhoon HIL and HELICS? If not, could you offer any advice, documentation, or examples on using the Typhoon HIL API (particularly the Python API) to create a custom interface that can exchange data and synchronize with a HELICS?

Thank You

[trevorhardy]

I'm not aware of anybody that has used HELICS with Typhoon HIL so we won't be able to help directly. I think we've had people use OpalRT with HELICS so there might be some lesson learned there.

HELICS does have the ability to sync its time grants with the hosts real-time clock. Obviously there is a lot of hardware dependence but our experience on commodity hardware was the ability for the HELICS library to be able to synchronize with a tolerance on the order of 10ms. If you were able to run this on real-time, deterministic hardware (I assume Typhoon HIL provides this?), you would definitely get better tolerances.

If you could point me towards the Typhoon HIL documentation on running custom Python code I might be able to offer more guidance.

[eaamako]

Thanks for the quick response.
Yes, Typhoon HIL supports running custom Python code through TyphoonTest IDE (TyphoonTest IDE), which integrates with pytest and provides a Python API for simulation control and data exchange. The Typhoon HIL API documentation can be found here: https://www.typhoon-hil.com/documentation/typhoon-hil-api-documentation/hil_api.html.
Thanks

[trevorhardy]

OK, looking through the Typhoon API and thinking about it more, here's what I've concluded.

Fundamentally, the HELICS Python API makes calls back to a compiled library to perform the HELICS functions. That library needs to exist on the target hardware and it looks like the Typhoon IDE runs on Windows so you should be good. Because your interface to the rest of the federation is via that IDE running on Windows, you're not going to have sub-millisecond precision in your federation timing, just the normal Windows timing precision.

I think Typhoon has the APIs to allow for the two core capabilities needed for co-simulation: time synchronization and data exchange.

To handle the time synchronization, you can just set the real-time flag, define the tolerances and you're set. You can also get access to the simulation time of the HIL simulation by calling this Typhoon API to get the current simulation time; having access to this time may be helpful in making sure you're HELICS simulation time is lining up with the HIL's simulation time.

When you want to do data exchanges, it looks like this Typhoon API will allow you to get the state of any model variable out and this one lets you change the value for any model variable. Using these with the HELICS APIs will look something like:

import helics as h
import typhoon.api.hil as hil

# When something like the simulation time triggers data exchanges:
  data_from_federation = h.helicsInputGetDouble(helics_input_object)
  hil.model_read(hil_data)

  # Do something meaningful with data from the rest of the federation and the HIL simulation
  new_output_to_federation = ...
  new_output_to_hil = ...

  h.helicsPublicationPublishDouble(helics_publication_object, new_output_to_federation)
  hil.model_write(hil_variable_name, new_output_to_hil)

Hopefully that's enough to get the ball rolling; I'll be eager to see how this works out.

[eaamako]

Thanks for the detailed analysis!
I'll start implementing the real-time flag for time synchronization, as you suggested. I'll reach out with updates on how it works out or if I encounter any issues.

Thanks