A new approach for passive filter design of the third winding of rectiformer used in aluminum electrolysis project is proposed in this paper.First

the grid and the transformer are subjected to equivalent conversion and the equivalent model of power supply for aluminum electrolysis is obtained.Then

taking into account impedance of transformer

capacitors engineering parameters

and the manufacturer’s requirement

the minimum installed capacity is taken as the objective function.The optimization calculation are carried out by using Matlab simulation software

and the aluminum electrolysis passive filter optimization design parameters are obtained

which meet IEEE std 519-1992 on harmonic standard and reactive compensation requirement.The calculation results of example show that the proposal is feasible.