Grid Voltage Synchronization Method Based on Adaptive Filter in Weak Grid Condition

Synchronization signal detection for Grid voltage is related to the operation performance and stability of grid-connected converter. Aiming at the problem of insufficient accuracy for traditional grid voltage synchronization signal detection methods in complex power grid conditions, this paper proposes a method based on the combination of complex decoupling filter and adaptive filter. The complex decoupling filter is used to separate the positive and negative sequence components, and then an adaptive filter algorithm is used to carry out secondary separation and harmonic suppression. At the same time, the influence of the DC component caused by the fault transient can be eliminated. The frequency adaptation link eliminates the detection deviation caused by the frequency fluctuation of the power grid. Simulation and experimental results show that the proposed method can achieve accurate detection of grid voltage synchronization signals in weak grid condition such as three-phase imbalance, harmonic distortion, DC disturbance, and voltage mutation, which verifies the correctness and effectiveness of the proposed method.