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Method of detecting grid voltage phase with single-phase photovoltaic grid-connected inverter

A grid voltage and inverter technology, applied to the phase angle between voltage and current, instruments, measuring devices, etc., can solve the problems of poor phase-locking accuracy, inability to filter out harmonic interference, and poor phase-locking accuracy , to achieve the effect of strong anti-interference ability, good adaptability and quick response

Active Publication Date: 2016-06-15
宁夏隆基宁光仪表股份有限公司
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Problems solved by technology

Among them, the delay method only needs to construct an array, which has a simple structure, but because it cannot filter out the harmonic interference in the collected grid voltage signal, the phase-locking accuracy is poor; while the phase-shifting method based on the generalized second-order integrator It cannot solve the problem of poor phase-locking accuracy when DC components appear in the collected grid voltage signal

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  • Method of detecting grid voltage phase with single-phase photovoltaic grid-connected inverter

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Embodiment Construction

[0027] The specific way of its realization mainly has five steps: the first step is to filter the signal through the band-pass filter module. This filter has a great attenuation for the signal outside the resonance frequency. Filtering of harmonics and DC components. In the second step, the filtered signal Vα is passed through the quadrature signal generation module to generate a voltage signal Vβ with a lag of 90 degrees. In the third step, Vα and Vβ are transformed by d-q using the last estimated angle θ' and the result Vq is subtracted from 0. The fourth step is to perform a proportional integral (PI) operation on the difference. In the fifth step, the calculation result in the fourth step is summed with the base angular frequency of the power grid to obtain the estimated angular frequency of the power grid. The sixth step is to integrate the estimated angular frequency to obtain the estimated value θ' of the current angle of the grid. One thing needs to be explained: wh...

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Abstract

The invention relates to a method for detecting the voltage phase of a grid by using a single-phase photovoltaic grid-connected inverter. It is characterized in that it includes the following steps: Step 1: filter the collected power grid voltage signal, filter out the DC component and high-order harmonics other than the fundamental frequency, and obtain a Vα signal; Step 2: then phase-shift the obtained Vα signal 90 degrees, the signal Vβ is generated, that is, a set of quadrature signals is generated; Step 3: d-q transform the obtained quadrature signals Vα and Vβ signals using the estimated angle θ' of the power grid to obtain Vd and Vq; wherein the estimated angle θ of the power grid 'The initial value is set to 0, and then the operation value of step 4 and step 5 will be updated, so that the estimated angle θ' will reach the real grid voltage phase after the transient process ends. The method of the invention has the advantages that the harmonic interference in the collected power grid voltage signal can be filtered out and the DC component signal in the collected power grid voltage signal can be filtered out, thereby achieving higher phase locking precision.

Description

technical field [0001] The invention relates to a method for detecting grid voltage phases by using a single-phase photovoltaic grid-connected inverter. Background technique [0002] At present, most single-phase (photovoltaic) grid-connected inverters use zero-crossing detection to track the grid voltage phase, which has poor anti-interference performance. In addition, there is also a single-phase phase-locked technology based on a synchronous coordinate system based on a three-phase phase-locked loop. This type of method needs to construct a pair of orthogonal signals. Currently, the methods commonly used to construct orthogonal signals include the delay method using array storage and A phase shift of 90° is realized based on a generalized second-order integrator. Among them, the delay method only needs to construct an array, which has a simple structure, but because it cannot filter out the harmonic interference in the collected grid voltage signal, the phase-locking acc...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R25/04
Inventor 赵四海李建炜裴云庆武晓勇金新张万菊屈子旭李波
Owner 宁夏隆基宁光仪表股份有限公司
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