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A phase-locking method suitable for three-phase grid voltage

A three-phase power grid and voltage technology, applied in the field of phase locking, can solve problems such as unbalanced power grid voltage, achieve precise grid phase tracking, strong grid adaptability, and improve the effect of phase locking accuracy

Active Publication Date: 2020-02-25
YANSHAN UNIV
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Problems solved by technology

[0007] The purpose of the present invention is to provide a phase-locking method suitable for three-phase grid voltage that solves the disadvantages of the existing phase-locking technology that cannot simultaneously perform accurate phase-locking on grid voltage imbalances, DC components and harmonics

Method used

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  • A phase-locking method suitable for three-phase grid voltage
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  • A phase-locking method suitable for three-phase grid voltage

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Embodiment Construction

[0028] The method of the present invention comprises the following steps:

[0029] Step 1, the three-phase grid voltage V abc After Clark transformation, the three-phase grid voltage V abc Transform from a three-phase stationary coordinate system to a two-phase stationary coordinate system v αβ , the α-axis leads the β-axis by 90 degrees in phase angle.

[0030] Step 2, two-phase stationary coordinate system v αβ The fundamental positive sequence component is obtained after the fundamental positive sequence component extraction unit and The fundamental wave positive sequence component extraction unit includes an improved second-order generalized integrator (SOGI) and a positive sequence fundamental wave logic operation unit. The transfer function of the improved SOGI is:

[0031]

[0032]

[0033] Among them, D(s) and Q(s) are the transfer function expressions of the improved SOGI, s is the Laplace transform operator, τ is the inertial time constant, qv′ is the o...

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Abstract

The invention discloses a novel phase locking method applicable to three-phase grid voltage. Through Clark transform, the three-phase grid voltage is converted to a two-phase coordinate variable v<alphabeta> from a three-phase coordinate variable V<abc>; a fundamental positive sequence component extraction unit comprises a dual improvement-type second-order generalized integrator (SOGI) and positive sequence fundamental logic operation for extracting fundamental positive sequence components nu<alpha><+> and nu<beta><+> in the three-phase grid voltage, and especially in a condition in which unbalance, DC and harmonics exit in the grid voltage at the same time, fundamental positive sequence components in the grid can be extracted accurately; and a phase-locked loop comprises Park transform and a PI regulator for carrying out accurate phase tracking on the grid according to the fundamental positive sequence components extracted by the improvement-type second-order generalized integrator to lock a grid phase theta. The method of the invention is higher in grid adaptability, the fundamental positive sequence components in the grid can be extracted accurately in a condition of unbalance of three-phase grid voltage and with harmonics and DC, accurate grid phase tracking is realized, and the phase locking precision is improved.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to a phase locking method. Background technique [0002] In single-phase and three-phase systems, phase-locking is widely used, such as grid-connected inverters and UPS, especially when doing system loop control in the dq coordinate system, accurate grid phase information is required. The locked phase contains the grid phase information we need, which is the basis of the system loop control, and the precise phase-locked result can get the precise loop control result. [0003] Single Synchronous Coordinate System Software Phase-Locked Loop (SSRF-PLL) is a relatively common phase-locking method. It has the advantages of simple control method and fast response speed. , the phase-locked result of SSRF-PLL has a large error. Although the phase-locking error can be reduced by adding a low-pass filter or changing the parameters of the PI regulator to reduce the system bandwidth, this gre...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/44
CPCH02J3/44
Inventor 张纯江赵晓君阚志忠王晓寰柴秀慧
Owner YANSHAN UNIV
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