Is the issue that your load profile is power but you can't provide power directly to the Simscape network?
If you have R2014b or later:
The Machines sublibrary has "Machine Mechanical Power (pu)" and "Machine Mechanical Power (si)" blocks you can use to actuate the machine. Just make sure the parameters of this block match your machine block.
If you have R2014a or earlier:
First, you will need to provide inertia to the machine with a "Machine Inertia" block.
Next, you could always measure the rotational speed of the motor with an Ideal Rotational Motion Sensor and divide it by that input signal to get a torque input.
That is, POWER = TORQUE * SPEED or TORQUE = POWER / SPEED.
- Sebastian
