As per my understanding, you are tring to implement a three phase unbalanced dynamic load. You want the external inputs “P” (Active power) and “Q” (reactive power) for controlling it.
As correctly pointed out by you, the “Dynamic Load (Three-Phase)” is used for balance three-phase dynamic load. In order to implement unbalanced dynamic load, you can go via any of methods as suggested by @Sabin in the MATLAB answer post: Those methods are very good to simulate unbalanced three phase supply. But as per my understanding, if you want to simulate three-phase unbalance dynamic loads with “P” and “Q” as inputs, the below given workarounds will be good to start with.
1) Use “Dynamic Load” block
This block is found inside the library “Simscape / Electrical / Passive”. Refer to its documentation:
It is used to simulate unbalanced dynamic load for single phase supply. However , you can use it with three phase by making the following changes:
1) Open the “block parameters” and change the “Load Type” property to “AC” as shown in below figure:
2) You can connect them in star or delta configuration for three phase as shown below:
As it is an unbalanced dynamic three-phase load, you have to provide the active power and reactive power inputs for all the three phases as seen in the above attached images.
I hope you find it useful !