To realize zero steady-state error current controlSof active power filter, taking three-levelSshuntSactive power filter (SAPF)Sas the object of study, unified fixed pointScoordinate transformation(UFP-CT) wasSapplied toSthree-level SAPFScurrent control in this paper.SIntroducedStheSconceptSofSa unifiedSfixed point coordinateStransformation; deduced the mathematical model of three-level SAPF in the three-phase stationary abc , two-phase stationary and unified fixed point Scoordinate system in detail; UsedStheSconventionalSvoltageSfeed-forwardScurrentSdecoupling control strategy,Sfeed-forward was also introducedSto overcomeS the impact of self-interference andScoupledSinterferenceSbrought bySUFP-CTSon output and using PI controller; thus, zero steady-state error current control can be achieved. Used simulink to carry on the simulation, and the control method has carried on the contrast with control strategy under the dq coordinate system. Simulation results show:SSthe proposedScurrent control methodScan achieveSharmonic currentScommandSwithout static errorStracking, and hasSbetterSdynamic characteristics.