Active Power Filter (APF) is a new type of power electronic device for dynamically suppressing harmonics and compensating reactive power. It can compensate harmonics with varying sizes and frequencies as well as varying reactive power. .

The reason why the active filter is called active, as the name implies, the device needs to provide power (to compensate the harmonics of the main circuit), and its application can overcome the shortcomings of traditional harmonic suppression and reactive power compensation methods such as LC filters (traditional It can only be fixed compensation), which realizes dynamic tracking compensation, and can compensate both harmonics and reactive power.