Are you using SimPowerSystems? If so, there is a Three-Phase Dynamic Load block you can use. Alternatively, you can look at the example for this named power_dynamicload.
The above block lets you import a load profile from some external signal, in the form of active power (P) and reactive power (Q). Therefore, it does assume a balanced load. If you want to implement your own unbalanced load, you could always implement it using single-phase blocks like current or voltage sources.
As far as the data for the time-varying load itself, what are you looking at? Are you generating your own load profile, loading it from a file, something else?
- Sebastian
