Leakage　faults　are　common　occurrence　in　low-voltage　power　grids,　and　residual　current　device　(RCD)　are　the　primary　protective　device　against　such　faults.　However,　in　practical　applications,　frequent　tripping　of　RCD　has　become　a　focal　issue,　highlighting　the　conflict　between　power　supply　safety　and　reliability,　causing　to　the　deactivation　of　many　RCDs.　To　address　this　problem,　the　paper　analyzes　both　the　impedance　characteristics　of　low-voltage　distribution　net-work　and　the　operating　principles　of　RCD　protection.　The　study　shows　that　the　current　low-voltage　distribution　network　exhibits　complex　RLC　impedance　char-acteristics,　comprising　resistive,　inductive,　and　capacitive　components.　Under　the　influence　of　various　disturbances,　the　residual　current　in　the　distribution　network　may　include　high-amplitude,　wide-frequency,　and　short-duration　impact　harmonic　current,　which　affect　the　correct　operation　of　RCD.　To　adapt　to　the　current　distribution　network　conditions,　this　paper　proposes　adding　a　second-order　Butterworth　low-pass　filter　to　the　residual　current　signal　processing　stage　of　the　RCD　to　eliminate　the　influence　of　harmonic　current.　Simulation　results　show　that　the　improved　RCD　can　significantly　enhance　its　resistance　to　impact　harmonic　residual　current,　reducing　false　trips　and　thereby　improving　power　supply　safety　and　reliability.　©　Beijing　Paike　Culture　Commu.　Co.,　Ltd.　2025.