Method for detecting any-th harmonic component and reactive current of three-phase four-wire system

The invention discloses a method for detecting an any-th harmonic component and a reactive current of a three-phase four-wire system. The method is characterized by comprising the following steps that (1) phase locking is conducted, and the phase theta [+] (omega [0] t) of the positive sequence voltage of a fundamental wave is obtained; (2) the positive sequence component of the n-th harmonic is detected; (3) the negative sequence component of the n-th harmonic is detected; (4) the zero-sequence component of the n-th harmonic is detected; (5) the reactive current is detected. The method for detecting the any-th harmonic component and the reactive current of the three-phase four-wire system is based on transformation of the coordinates of the n-th harmonic and the LPF technology, and the particularity of the zero-sequence current detection is considered. According to the method for detecting the any-th harmonic component and the reactive current of the three-phase four-wire system, the loop-locked phase locking method is adopted, the accuracy of phase locking is guaranteed, and therefore a reliable phase is provided for transformation of the coordinates; the physical conception is clear, the implementation mode is simple, the application range is wide, the detection accuracy is high, and the practicability is high.