To　tackle　the　problem　of　active　cancellation　of　unknown　and　time-varying　narrowband　signal　caused　by　the　ship　power　engineering　equipment,　an　active　noise　control　algorithm　for　suppressing　unknown　and　time-varying　narrowband　noise　is　proposed　based　on　the　concept　of　signal　tracking　and　generation　in　the　phase　locked　loop　(PLL).　Firstly,　with　the　introduction　of　secondary　path　in　the　enhanced　phase　locked　loop　(EPLL),　an　active　algorithm　is　developed;　secondly,　with　the　approximation　analysis,　the　differential　equation　of　the　EPLL-based　algorithm　is　carried　out　to　derive　its　performance　relationship　with　the　input　signal　amplitude　and　the　secondary　path.　With　normalizing　of　amplitude　and　secondary　path,　an　improved　pseudolinear　(PL)-EPLL　based　active　noise　algorithm　is　derived.　Compared　to　the　EPLL-based　algorithm,　the　convergence　performance　of　the　estimated　amplitude,　frequency/phase　equation　is　independent　with　the　amplitude　of　unknown　narrowband　signal　and　secondary　path.　Besides,　the　convergence　performance　is　consistent　when　the　noise　source　is　composed　of　multi-frequency　sinusoidal　with　different　signal　noise　ratio.　Finally,　simulations　conducted　validate　the　effectiveness　of　the　proposed　PL-EPLL　based　active　noise　control.　©　2020,　Chinese　Institute　of　Electronics.　All　right　reserved.