train rail matlab help

i am building simulink model for traction system, to achieve harmonic distortion and voltage sag the model consists of two parts fixed parts (substation,catenery,third rail .,,,)and moving part(train) the fixed part was built i want a help with moving part that achieve harmonic and voltage sag study including (multi train in multi substation ,acceleration deceleration position of the train and take in consideration mass of the train traction effort ) the train fed by 1500 vdc series motor