Hi AbdAlla If I am not wrong, you are trying to connect a Simscape Electrical voltage source (blue) to a SimscapePowerSystems Linear Transformer (Black). Both components will not connect because they are different domain in Simscape. The quick and simple solution, you can use Simscape ideal transformer (blue) to model linear transformer, just change the winding ratio and it can connect to the voltage source (blue). I have attached a screen capture for your reference.
Or alternatively you can do it entirely in SimscapePowerSystems domain
Both should give you similar results. I also attached both model for your reference.
Please Accept and Like if I answered your question. Thanks