This can be done easily in PSAT

ok thanks sir, but i need in MATPOWER. since my problem can be solved in this software

Dear Vijay, you can do this by run the load flow of your network then apply the two equations of voltage dependent loads on P and Q to find the new P(Pn) and new Q (Qn).

assume you have linearized voltage dependent load p = a*v, a possible solution could be:

v = runpf(intial loading);

loop

update p with v;

v = runpf(new p);

end

until it converges.

tell me if it works.