A Photovoltaic Low Voltage Ride Through Method Containing Reactive Current Injection

A technology of low-voltage ride-through and current injection, applied in the direction of AC network voltage adjustment, reactive power compensation, electrical components, etc., can solve problems such as grid collapse, grid fault range expansion, and power loss, so as to provide reactive power and help Effect on grid-connected point voltage

Inactive Publication Date: 2018-05-29
ZHEJIANG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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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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  • A Photovoltaic Low Voltage Ride Through Method Containing Reactive Current Injection
  • A Photovoltaic Low Voltage Ride Through Method Containing Reactive Current Injection
  • A Photovoltaic Low Voltage Ride Through Method Containing Reactive Current Injection

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Embodiment Construction

[0012] The present invention will be further described below in conjunction with accompanying drawing. as attached figure 1 Shown, the present invention has several key steps:

[0013] 1) If no voltage drop at the grid-connected point is detected, the photovoltaic inverter will run in grid-connected operation with a power factor of 1; if a voltage drop at the grid-connected point is detected, the degree of voltage drop will be judged.

[0014] 2) If the degree of voltage drop is small (the measured per unit value of the positive sequence voltage of the photovoltaic grid-connected point is greater than or equal to the threshold V ref ), then set the output active power P as P 0 , and according to the active power P 0 And the photovoltaic inverter current constraints to calculate the maximum reactive power Q that can be output max , and set it to Q; otherwise, all photovoltaic grid-connected inverters output reactive power and do not output active power, that is, P=0, Q max...

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Abstract

The invention relates to a photovoltaic low-voltage ride-through method including reactive current injection. There are many existing photovoltaic low-voltage ride-through methods, but they do not make full use of the power control function of photovoltaic inverters. When the voltage drop is not serious, the present invention keeps the photovoltaic active power output unchanged, and provides reactive power as much as possible; when the voltage drop is serious, the photovoltaic does not output active power, and outputs all reactive power. At the same time, under the asymmetrical fault of the power grid, the negative sequence control is introduced to eliminate the active power fluctuation caused by the negative sequence component, and the calculation formula of the maximum reactive power setting value is deduced. The invention can make full use of the control ability of photovoltaics on active power and reactive power according to the voltage drop situation, guarantee the output of active power and provide the maximum reactive power under certain circumstances, and contribute to the recovery of the grid-connected point voltage.

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 including reactive current injection. Background technique [0002] Today's environmental problems are becoming more and more serious, and the development of new energy is an effective means to alleviate environmental problems. As a new energy source, photovoltaics have attracted more and more attention, and the photovoltaic industry has also developed rapidly in recent years. 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...

Claims

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Application Information

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Patent Type & Authority Patents(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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