Voltage phase sequence self-recognition and self-adaption device and method embedded in active power filter

The invention discloses a voltage phase sequence self-recognition and self-adaption device and method embedded in an active power filter. The system comprises a system voltage conditioning module, a system current conditioning module, an emitted current conditioning module, a second-order low-pass filtering orthogonal module, a phase discrimination module, a second-order direct current and alternating current switching module, a phase sequence judgment module, a voltage phase sequence switching module, a system current phase sequence switching module and an emitted current phase sequence switching module. According to the invention, a second-order low-pass filter and a second-order direct current and alternating current passing and blocking module are adopted, so that the influence of harmonic waves and interference on phase sequence judgment is eliminated; hysteresis comparison is adopted as the basis of commutation judgment, it is guaranteed that commutation judgment is accurate and reliable within the norm