how can i use multiobjective ga toolbox with input of initial population of bit string but the variables of the objective function are real number?

im doing project on service restoration in distribution system and i represent the switch with binary string that is closed(1) and open(0) but the objective function variable are voltage and current. i have the code for finding the voltage of each bus and current in the system from the switch bit string. so how can i use the switch bit string as initial population and other operation like crossover and mituation to be performed on it while the objective function that is minimizing power and voltage deviation performed?