Active Power Filter

Active Power Filter (APF) is a new type of power electronic device used for dynamically suppressing harmonics and compensating reactive power. It can compensate for harmonics and reactive power that vary in size and frequency. The use of active filters can improve the stability of communication and distribution systems, extend the service life of communication and power equipment, and make the distribution system more in line with the design specifications of harmonic environments. An active filter uses a current transformer to collect the current on a DC line. After sampling, the obtained current signal is processed by a harmonic separation algorithm to obtain a harmonic reference signal, which is used as a modulation signal. Compared with a triangular wave, the switch signal is obtained to control a single-phase bridge. According to the principle of technology, the switch signals of the upper and lower bridge arms are reversed to obtain harmonic currents that are equal in magnitude and opposite in direction to the harmonic signals on the line, and the harmonic currents on the line are cancelled out.