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Photovoltaic low-voltage crossing method containing reactive power current injection

A low-voltage ride-through and current injection technology, applied in the direction of AC network voltage adjustment, reactive power compensation, electrical components, etc., can solve problems such as grid fault range expansion, grid collapse, power loss, etc. The effect of providing reactive power

Inactive Publication Date: 2016-05-18
ZHEJIANG UNIV
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  • Abstract
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Problems solved by technology

After the large-scale photovoltaic power supply is connected to the grid, when the grid fails, the photovoltaic power supply cannot be simply cut off, and it should have a certain low-voltage ride-through capability. Otherwise, due to the cut-off of the photovoltaic power supply, the power will be lost, which will further lead to a voltage drop. , may cause the adjacent photovoltaic power source to go off-grid, further cause the grid to expand the fault range, and even cause the grid to collapse

Method used

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  • Photovoltaic low-voltage crossing method containing reactive power current injection
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  • Photovoltaic low-voltage crossing method containing reactive power current injection

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Embodiment Construction

[0012] The present invention will be further described below in conjunction with the drawings. As attached figure 1 As shown, the present invention has several key steps:

[0013] 1) If the voltage drop at the grid connection point is not detected, the photovoltaic inverter will be connected to the grid with a power factor of 1; if the voltage drop at the grid connection point is detected, the degree of voltage drop will be judged.

[0014] 2) If the voltage drop is small (the measured positive sequence voltage per unit value of the photovoltaic grid connection point is greater than or equal to the threshold V ref ), then set the output active power P to P 0 , And according to the active power P 0 And the current constraint conditions of the photovoltaic inverter to calculate the maximum reactive power Q that can be output max , And set to Q; otherwise, all the photovoltaic grid-connected inverters will output reactive power and no active power, that is, P=0, Q max .

[0015] 3) Ca...

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Abstract

The invention relates to a photovoltaic low-voltage crossing method containing reactive power current injection. There are many existing photovoltaic low-voltage crossing methods in the prior art, but the control effect of a photovoltaic inverter on power is not fully utilized. Under the condition of a not serious voltage drop, the photovoltaic active power output is unchanged, and reactive power is provided as far as possible; and under the condition of a serious voltage drop, no photovoltaic active power is output, and all output is reactive power. In addition, under a grid power asymmetric fault, negative sequence control is introduced to eliminate the active power fluctuation caused by negative sequence components, and a maximum reactive power set value calculation formula is derived out. According to the voltage drop conditions, the control capability of photovoltaics over the active power and the reactive power is fully utilized, and under a certain condition, the output of the active power is ensured and the reactive power is provided to the largest extent, so that the voltage recovery of grid connection points is facilitated.

Description

Technical field [0001] The invention belongs to the technical field of power systems, and in particular relates to a photovoltaic low voltage ride-through method containing reactive current injection. Background technique [0002] Today's environmental problems are becoming more and more serious. The development of new energy sources is an effective means to alleviate environmental problems. As a new energy source, photovoltaics have attracted more and more attention. The photovoltaic industry has also developed rapidly in recent years. When a large-scale photovoltaic power source is connected to the grid, when the grid fails, the photovoltaic power source cannot be simply cut off. It should have a certain low voltage ride through capability. Otherwise, due to the removal of the photovoltaic power source, the power will be lost and the voltage will be further reduced. , May cause the disconnection of adjacent photovoltaic power sources, further causing the grid to expand the faul...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38H02J3/16H02J3/24
CPCH01J3/16H01J3/24H02J3/381Y02E40/30
Inventor 王慧芳黄显斌林达
Owner ZHEJIANG UNIV
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