Hello Jesnon,
the powergui block does a lot behind the scenes to enable specialized power systems models to run. You can actually look under the powergui block's mask after compiling a system. You will find an s-function, that is connected by goto blocks, to all the different blocks in your model (if they have a simulink implementation, resistors and other simple devices are inside the s-function). This circled component is essentially used to determine what blocks are connected and how. Then the simulink model beneath is actually used to determine the output values. Those goto tags are where the simulation data actually comes in and out of. So the circled block isn't do anything durring simulation, but is used to set up all the equations when compiling the model. I'm not really doing the implemenation full justics given the short response, but hopefuly it gives you some insight.
Regards,
Joel
