How to create a three-phase variable load using Simscape

Hi, guys!

I have built a distribution network model in Simulink, where all loads are configured as Three-Phase Parallel RLC Load with the constant PQ mode enabled.

Now I want to replace the load at one of the nodes (purple area) with a variable load whose P and Q values can be modified during the simulation. I initially tried using the Dynamic Load block from Simscape with the External PQ Control option enabled, but this resulted in extremely abnormal voltage waveforms at the bus 23（with significant noise？）. What exactly is causing this issue? Alternatively, are there other methods in Simscape to achieve the functionality I need?

I have also seen others mention the Variable Resistor block, but I have no idea how to connect it into my existing circuit. Or do I need to create a custom block?

bus 23 voltage

dynamic load （positive sequence voltage、P、Q）