SDFT fundamental positive sequence component phase synchronization method and phase synchronization system

Abstract

The invention discloses an SDFT fundamental positive sequence component phase synchronization method and a phase synchronization system. The method comprises steps: analog signals for three-phase power grid AC voltage are discretized, discrete data are obtained through sampling in a fixed period, Clark transform is carried out on the discrete data, and transform data are obtained; according to a sampling sequence and an overlapped period, single-point DFT calculation is carried out on the transform data to obtain a correction result for an ith point, wherein the correction result for the ith point is the accumulated value between the DFT calculation result for the ith point and the correction result for an (i-1)th point; N-point recursive SDFT calculation is carried out on the transform data in the fixed period to obtain a calculation result in the current period; when i is smaller than N, the calculation result in the current period is outputted; when i is equal to N, the correction result for the ith point serves as the calculation result in the current period to be outputted; according to the calculation result outputted in the current period, an arc-tangent function is used for acquiring a fundamental positive sequence component phase angle. Thus, the problem of stability caused by recursive iterative cumulative errors can be eliminated.

Description

technical field [0001] The invention relates to the field of electrical technology, in particular to a phase synchronization method and system for positive sequence components of SDFT fundamental waves. Background technique [0002] The control of the grid-connected power conversion device needs to detect the phase angle of the grid voltage in real time, and high-precision and fast phase-locking is an extremely important part of the control system. For a three-phase grid system, it is a difficult problem to track the phase of the fundamental component in real time. Especially when the voltage amplitude of the three-phase grid is unbalanced or even harmonic, the fast synchronous tracking technology without static error is the goal pursued by the synchronous system. [0003] According to the space vector theory, any three-phase voltage in the time domain can be converted into a voltage space vector representation (equivalent to Clark transform): [0004] ...

AI Technical Summary

Problems solved by technology

However, due to the large amount of calculation in the above process, this method is not suitable for implementation on the embedded platform. A feasible way is to use the recursive iteration method to calculate

A recursive scheme, on the other hand, produces cumulative errors which, in turn, cause system stability

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