title: Change Equation set in FMU for Model Exchange
body: <p>we want to publish an Open-Source for integrating Reinforcement Learning to Smartgrid optimization. 
  We use OpenModelica as GUI, PyFMI for the import to Python and Gym. </p>
  
  <p>Nearly everything is running, but a possibility to connect or disconnect additional loads during the simulation is missing. Everything we can do for now is a variation of the parameters of existing loads, which gives some flexibility, but way less then the possibility to switch loads on and off. </p>
  
  <p>Using the implemented switches in OpenModelica is not really an option. They just place a resistor at this spot, giving it either a very low or very high resistance. First, its not really decoupled, and second, high resistances make the ODE-system stiff, which makes it really hard (and costly) to solve it. In tests our LSODA solver (in stiff cases basically a BDF) ran often in numerical errors, regardless of how the jacobian was calculated (analytically by directional derivatives or with finite differences). </p>
  
  <p>Has anyone an idea how we can implement a real "switching effect"? </p>
  
  <p>Best regards,</p>
  
  <p>Henrik </p>