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Low-voltage microgrid distributed control method and system based on adaptive virtual impedance

A technology of distributed control and virtual impedance, which is applied in the direction of single-network parallel feeding arrangement, can solve the problems of over-discharge of energy storage batteries, incomplete application of low-voltage micro-grid, and unknown line parameters, so as to reduce active power and reactive power Effects of power coupling, reducing uneven distribution of active power, and improving operation stability

Active Publication Date: 2019-09-24
SHANDONG UNIV
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Problems solved by technology

The line characteristics of the low-voltage microgrid are different from the inductive impedance of the large power grid, and its lines are resistive. Therefore, the traditional P / f and Q / U droop control methods are not completely suitable for low-voltage microgrids.
At present, there are literatures that use virtual negative resistance to offset the resistance of the line, but the line parameters are unknown and difficult to measure during actual operation.
In addition, the randomness of the geographical location of each distributed power supply makes the line impedances unequal, and the micro-sources using droop control cannot output power in proportion to the rated capacity, which will lead to overloading of some micro-sources and over-discharge of energy storage batteries. Even affect the stable operation of the system
[0004] In order to reduce the deviation of output power, the inventors found that at present, communication means are used to obtain inverter power and bus voltage data for compensation control. reliability

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  • Low-voltage microgrid distributed control method and system based on adaptive virtual impedance
  • Low-voltage microgrid distributed control method and system based on adaptive virtual impedance
  • Low-voltage microgrid distributed control method and system based on adaptive virtual impedance

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[0045] It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0046] It should be noted that the terminology used herein is only for describing specific embodiments, and is not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural, and it should also be understood that when the terms "comprising" and / or "comprising" are used in this specification, they mean There are features, steps, operations, means, components and / or combinations thereof.

[0047] Explanation of terms:

[0048] DG: Distributed Generation, distributed power.

[0049] For an island microgrid, the in...

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Abstract

The invention provides a low-voltage micro-grid distributed control method and system based on adaptive virtual impedance. The method comprises the following steps: generating adaptive virtual resistance by using a product of a ratio of active power output by a local inverter and voltage magnitude and a virtual impedance coefficient; determining virtual negative inductance according to an inductive reactance part of equivalent output impedance of the local inverter, so that the equivalent output impedance of the local inverter has a resistance property; obtaining the adaptive virtual impedanceaccording to the complex accumulation of the adaptive virtual resistance and the virtual negative inductance; according to a dq-axis current component of the adaptive virtual impedance and local inverter outlet three-phase current, generating dq-axis virtual voltage; and using the dq-axis virtual voltage to compensate a voltage reference value obtained by resistance droop control to obtain finalreference voltage.

Description

technical field [0001] The disclosure belongs to the field of micro-grid control, and in particular relates to a low-voltage micro-grid distributed control method and system based on adaptive virtual impedance. Background technique [0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art. [0003] A microgrid is a micro-power network that combines distributed power sources, energy storage systems, and loads. It can operate in two operating modes: islanded and grid-connected. Micro-source inverters in micro-grids generally adopt V / f control, PQ control and droop control. Among them, the droop control mode is based on the primary frequency modulation technology of synchronous generators in traditional power grids, and adaptively adjusts the power output according to the droop relationship. Communication can automatically realize the power distribution of each micro-source, with ...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/38
Inventor 侯梅毅耿英明朱国防张黎明卢兆楠刘洋朱振于昊
Owner SHANDONG UNIV
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