"Frequency and Time" simulations do not accept variable loads

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We would like to switch from the 'specialized power systems' blocks to the native simscape blocks for simulating power systems. We run exclusively in phasor mode, and would switch to the "Frequency and Time" mode as is demonstrated in the ee_loadflow_ieee9bus.slx demonstration model. However, it appears impossible to introduce variable loads into the simulation using this mode. Connecting physical signal blocks to the "Wye-Connected Variable Load (lagging)" block, produces the error:
Capture.PNG
Error compiling Simscape network for model ee_loadflow_ieee9bus.
Caused by:
  • ['ee_loadflow_ieee9bus/Wye-Connected Variable Load (lagging)']: Equations in frequency and time mode must be switched-linear, with time variables considered constant for this check. Consider modifying the model to satisfy this restriction, or changing Equation Formulation to Time on solver block. In ee.passive.rlc_assemblies.time_varying.wye_series_RL.abc
Component:Simulink | Category:Model error
Note that the varying load is moving very slowly - random, 1 change every 1 hours. If i switch to simulink blocks to generate the load profile, and using a s-ps block to get the signal into the Wye-Connected Variable Load (lagging) block, there is no error, but the block load does not change over time. Active(MW):4 in the plot below. How do i get variable loads into the "Frequency and Time" simulation without creating an array of switches, each driving a set load?
Capture.PNG
Capture.PNG

采纳的回答

Daniel Zimmerle
Daniel Zimmerle 2020-1-25
Update:
Driving the load level with Simulink inputs works; i had a scaling error in the Simulink to PS converter. Unfortunately, there is not a variable generation block, so time stepped simulations of power flow may be impossible yet.
Are there examples of how to write blocks for the "Frequency and Time" domain for electrical networks to implement a variable-generaiton block?

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