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Virtual-capacitor-based power sharing control method for micro-grid inverter parallel connection

A technology of virtual capacitors and inverters, which is applied in the field of power sharing control of microgrid inverters based on virtual capacitor algorithms, and can solve problems such as load power sharing by inverters

Active Publication Date: 2016-01-06
黄山科创中心有限责任公司
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0012] The purpose of the present invention is to solve the problem that each inverter cannot share the load power according to its rated capacity when the micro-grid inverters are running in parallel in an isolated island, and to provide a parallel-connected and equal-sharing control method for micro-grid inverters based on virtual capacitors, without the need for inverters. Interconnection communication between inverters and line impedance detection can adaptively compensate line impedance voltage drop and improve the reactive power sharing ability and output voltage accuracy of each inverter

Method used

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  • Virtual-capacitor-based power sharing control method for micro-grid inverter parallel connection

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Embodiment Construction

[0070] The present embodiment will be specifically described below in conjunction with the accompanying drawings.

[0071] figure 1 It is a parallel system of 2 microgrid inverters with the same capacity, and the inverter numbers are #i=1,2. The DC voltage of inverter #i is 600V, the rated output line voltage is 380V / 50Hz, the filter inductance value is 0.5mH, the filter capacitor value is 200uF, and the rated capacity of the inverter is 100KVar. Inverter #1 wiring impedance is Z L1 =0.001+j0.004Ω, inverter #2 wiring impedance is Z L2 =0.075+j0.025Ω.

[0072] figure 2 It is a block diagram of inverter control structure according to the embodiment of the present invention. The steps of control method of the present invention are as follows:

[0073] Step 1: Set the number of microgrid inverters as n, and n≥2, #i represents the inverter number, and i∈[2,n].

[0074] In this embodiment, n=2, and inverter numbers #i are #1 and #2 respectively.

[0075] Step 2: Sampling th...

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Abstract

The invention discloses a virtual-capacitor-based power sharing control method for micro-grid inverter parallel connection. The method is characterized in that a voltage amplitude value and a phase angle value are obtained by using a power outer ring of a power outer ring control algorithm; and a virtual capacitor algorithm is added to obtain an output voltage amplitude value and a phase angle instruction, and dual-closed-ring control of the output voltage and the capacitive current is carried out. According to the virtual capacitor algorithm, parallel capacitor characteristics of output terminals of inverters are simulated by a control algorithm and the output voltages and reactive powers of the inverters are adjusted; and a virtual capacitance value is obtained by calculation based on outputted reactive powers of all inverters and a capacitance sagging formula. According to the invention, interconnection communication among inverters and connecting impedance detection are not required; the line impedance voltage drop can be compensated in a self-adaption mode; and reactive power sharing capabilities and output voltage precision of all inverters can be improved.

Description

technical field [0001] The invention belongs to the field of power equalization control when micro-grid inverters operate in parallel in isolated islands, and in particular relates to a method for controlling power equalization of micro-grid inverters based on a virtual capacitance algorithm. Background technique [0002] With the increasingly serious environmental and energy problems and the development and wide application of distributed power generation technologies such as photovoltaics and wind power, the microgrid system has become a research hotspot. In order to improve the reliability and redundancy of the system and reduce the dependence on communication, the voltage source inverter network with droop control or virtual synchronous motor control is mostly used to realize effective load power distribution. [0003] Since there are inductive components such as filter inductors and isolation transformers in the inverter circuit structure, its output impedance and line ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/46
Inventor 张兴徐海珍刘芳石容亮毛福斌
Owner 黄山科创中心有限责任公司
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