The　LCL　filter　is　widely　used　in　grid　connected　converters　for　good　harmonic　mitigation　performance.　With　pulse　width　modulation　strategy,　converter　terminal　voltage　contains　various　sideband　harmonic　components　together　with　expected　components　corresponding　to　the　modulation　wave,　especially　under　a　low　switching　frequency.　Considerable　resonant　current　can　be　generated　if　the　undesired　sideband　harmonic　voltage　is　located　around　the　LCL　resonant　frequency.　With　the　background　of　a　medium　voltage　three-level　wind　power　converter,　where　the　switching　frequency　is　as　low　as　1.5 kHz,　a　resonant　current　depression　strategy　is　proposed　against　undesired　sideband　harmonic　voltage　under　low　switching　frequency.　Additional　compensators　are　adopted　in　the　converter　current　loop.　Depending　on　the　system　mathematical　model,　two　solutions,　a　Butterworth　low　pass　filter　and　a　notch　filter,　based　on　phase　compensation　and　amplitude　compensation,　are　proposed　in　this　paper.　It　is　shown　that　the　Butterworth　low　pass　filter　exhibits　better　resonant　current　depression　performance,　while　the　notch　filter　performance　is　better　in　terms　of　system　stability.　Simulation　and　experimental　results　validated　the　proposed　control　method.　©　2020,　The　Korean　Institute　of　Power　Electronics.