Resonance wave detecting and phase-locking method and device for active power filter

Abstract

The embodiment of the invention discloses a resonance wave detecting and phase-locking method and a resonance wave detecting and phase-locking method for an active power filter. The method comprises the following steps of: carrying out phase shift filtering to a sampled three-phase voltage signal to obtain a first-grade processing signal; substituting the first-grade processing signal into an sequence-dividing formula to obtain a three-phase voltage fundamental positive sequence component; and adopting a dq synchronous coordinate system to lock phase of the three-phase voltage fundamental positive sequence component. The embodiment of the invention extracts the three-phase voltage fundamental positive sequence component in an unbalanced grid by using a way of dividing sequence first and locking phase consequently, locks phase of the positive sequence component by using a dq synchronous coordinate system phase-locking algorithm to obtain a positive sequence fundamental phase angle and eliminate the influence of grid imbalance on the phase locking link, so that the phase locking precision is wholly improved and the technical effect that the real-time and precise phase locking can also be carried out in the situation of unbalanced voltage in the grid is achieved.

Description

Technical field [0001] The invention relates to the technical field of power system control, and more specifically, to a method and device for harmonic detection and phase locking of an active power filter. Background technique [0002] Active power filter (APF) is a new type of power electronic device for dynamically suppressing harmonics and compensating reactive power. It can compensate for harmonics with varying sizes and frequencies as well as varying reactive power. The detection of harmonic current by the active power filter is the key to ensuring the APF compensation performance. [0003] The existing harmonic detection methods mostly use the ip-iq method, that is, the three-phase instantaneous active current ip and reactive current iq are calculated through the phase angle information obtained by phase locking, so as to obtain the harmonic and reactive current to be compensated. The rationality of the power current and phase-locking method directly affects the accuracy of...

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Problems solved by technology

[0004] However, when the voltage signal is distorted and unbalanced in the power network, various interference signals in the detection circuit in the APF make it difficult to detect the zero-crossing point, so that the output signal of the above-mentioned phase-locking method oscillates, not only Affects the real-time performance of phase-locking, and leads to low phase-locking accuracy or even phase-locking failure, which in turn affects the compensation effect of the APF

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