Abstract: Because the electric locomotive load has the nonlinear characteristic, the voltage distortion rate of traction substation is high and the harmonic is high. Traction load absorbs the fundamental current from the grid, also injectes a lot of harmonic current to the grid, generates voltage distortion who threat power supply security. By establishing three-phase model of traction substation, collecting different experimental data, the voltage distortion rate caused by V/v type traction transformer in power system is studied on basis of Matlab simulation, and the parameters are modified by adaptive control fusion algorithm, reasonable control of original parameter model and state. The results show that adaptive control can avoid the high distortion rate of local power grid, voltage flicker and harmonic current exceeding. The improving power quality and grid security effect is obvious.