Three-phase power converter grid-tied synchronous method in power grid fault

Abstract

The invention discloses a double harmonic filter and a positive and negative sequence component extraction method based on the double harmonic filter. With the adoption of the positive and negative sequence component extraction method based on the double harmonic filter, the defect that the condition that the grid-tied synchronous requirements cannot be ensured by the traditional SRF (synchronous reference frame)-PLL (phase locked loop) under the condition that the power grid is in fault is overcome; and the method can be used for a power converter grid-tied synchronous system. A grid-tied synchronous strategy has quick dynamic response time, has strong inhibiting ability on five-order and seven-order harmonic components and the like, and can be used for making up the defect that the inhibiting ability on the five-order and seven-order harmonic components is insufficient by adopting other structures at the same dynamic response time; (2) the double harmonic filter is simple in structure, does not need complex calculation, is good in instantaneity, is not sensitive to the condition that when a fundamental frequency offsets within a permission range (50+ / -0.5Hz), so that the grid-tied synchronous strategy is more suitable for a grid-tied power generation system of high-capacity wind power and the solar energy that the grid-tied common point voltage is easy to distort.

Description

technical field [0001] The invention belongs to the technical field of power grids, and in particular relates to a grid-connected synchronization method for three-phase power converters when the power grid fails. Background technique [0002] In recent years, renewable energy such as wind energy and solar energy has developed rapidly. When connecting power electronic devices to realize grid-connected power generation control, one of the most important issues is how to maintain synchronization with the grid voltage of the grid-connected public point. Although under normal operating conditions, the three-phase grid voltage is balanced and the distortion is small, but when there are faults such as short circuit and disconnection in the grid, or due to the influence of nonlinear loads, the grid-connected voltage near the fault point of the grid is prone to three-phase Unbalanced, voltage distortion and other abnormal operating conditions. Therefore, in this case, how to extract...

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Problems solved by technology

[0006] Aiming at the problem that the voltage amplitude and phase detected by the traditional synchronous reference frame phase-locked loop (SRF-PLL) have low-frequency interference when the power grid fails, and cannot guarantee the synchronization requirements of the grid connection, this paper proposes a A grid-connected synchronization algorithm for three-phase power converters

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