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Method for compensation and handling of asymmetric sag of power grid based on negative-sequence current

A negative-sequence current, power grid technology, applied in the directions of reducing the asymmetry of the multiphase network, eliminating/reducing the asymmetry of the multiphase network, parallel feeding arrangement of the single network, etc. achieve the effect of reducing unbalance

Active Publication Date: 2015-04-22
BEIJING ETECHWIN ELECTRIC
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] However, although the existing technology realizes the stable operation of the grid-connected inverter under the asymmetric drop of the grid, it does not compensate for the unbalance of the grid, so it cannot reduce the unbalance of the grid voltage

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  • Method for compensation and handling of asymmetric sag of power grid based on negative-sequence current
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  • Method for compensation and handling of asymmetric sag of power grid based on negative-sequence current

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Embodiment Construction

[0018] Embodiments of the invention will now be described in detail, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like parts throughout. The embodiments are described below in order to explain the present invention by referring to the figures.

[0019] figure 1 is a flow chart illustrating a method for dealing with asymmetric power grid dips based on negative sequence current compensation according to an exemplary embodiment of the present invention.

[0020] refer to figure 1 , in step S101, the grid voltage drop is detected by the grid-connected inverter. Here, the grid-connected inverter can determine whether grid voltage sag occurs through effective value detection method, peak voltage method or dq decomposition. In the effective value detection method, the grid-connected inverter monitors the grid voltage in real time, and calculates the effective value of the segment voltage once in one cycle or half a cycle ...

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Abstract

The invention discloses a method for compensation and handling of asymmetric sag of a power grid based on negative-sequence current. The method comprises the following steps of detecting voltage sag of the power grid through a grid-connected inverter; and delivering the negative-sequence current to the power grid through the grid-connected inverter so as to reduce unbalance degree of power grid voltage when the voltage sag of the power grid is detected, wherein the grid-connected inverter delivers the negative-sequence current to the power grid based on calculation of the following equation, I-d and I-q represents components of the negative-sequence current on the d-axis and the q-axis of a negative-sequence rotating coordinate system respectively, KN represents rate adjustment coefficient, Ed and Eq represents negative-sequence components of the power grid voltage on the d-axis and the q-axis of the negative-sequence rotating coordinate system respectively, the Erated represents rated voltage of the power grid, and Irated represents rated current of the grid-connected inverter.

Description

technical field [0001] The invention relates to the field of wind power generation, and more specifically, relates to a method for dealing with asymmetric drop of a power grid by performing negative sequence current compensation through a grid-connected inverter. Background technique [0002] With the development of technology, the attention and utilization of renewable energy are increasing day by day. Among them, wind power generation is a relatively mature energy technology. Wind turbines are connected to the grid through grid-connected inverters. However, in the case of a phase-to-phase short circuit on the grid side of grid-connected inverters (such as wind power full power converters, doubly-fed rotor converters, photovoltaic inverters, etc.) Symmetrical voltage drop. According to the requirements of the national standard, when the depth and time of the asymmetric grid voltage drop do not exceed the range specified by the national standard, the grid-connected inverte...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/26H02J3/38
CPCY02E40/50
Inventor 郭锐刘炳蒋中川尹进峰
Owner BEIJING ETECHWIN ELECTRIC