Output impedance remodeling method for grid-connected inverter parallel system

A technology of output impedance and inverter, applied in the direction of single-network parallel feeding arrangement, AC network to reduce harmonic/ripple, harmonic reduction device, etc., can solve system resonance, regardless of the interaction characteristics of the converter and the power grid , few output impedance reshaping methods, etc., to avoid harmonic resonance, good harmonic suppression effect, and improve passivity

Active Publication Date: 2020-01-24
UNIV OF ELECTRONIC SCI & TECH OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The traditional design method does not consider the interaction characteristics between the converter and the grid, which may cause the following two situations: under ideal grid conditions, the stand-alone operation is normal, and under non-ideal grid conditions (grid-side impedance is not ignored)

Method used

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  • Output impedance remodeling method for grid-connected inverter parallel system
  • Output impedance remodeling method for grid-connected inverter parallel system
  • Output impedance remodeling method for grid-connected inverter parallel system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0035] figure 1 It is a three-phase LCL type grid-connected inverter main circuit and its control structure diagram.

[0036] In this example, if figure 1 As shown, the three-phase LCL grid-connected inverter includes a main circuit, a current inner loop control module, a PLL control module and a modulation module. The main circuit part is composed of inverter main circuit 1, LCL filter 2, grid and its impedance 3. The inverter main circuit 1 is connected to the grid 3 through the LCL filter 2, L g Simulate grid impedance. The parameters of all inverters in the system are the same, and the parameters of the main circuit are shown in Table 1:

[0037] Table 1 is the main circuit parameter table;

[0038]

[0039]

[0040] The PLL module 6 generates the phase angle θ required for coordinate transformation. Control module 4 includes embedded repetitive control + PI controller and damping controller, specifically implemented as figure 2 shown. The control module gener...

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PUM

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Abstract

The invention discloses an output impedance remodeling method for a grid-connected inverter parallel system. According to the output impedance remodeling method, the amplitude intersection point of the output admittance Yc (s) and load admittance Yload (s) of a grid-connected inverter is determined through an impedance analysis method, so that possible resonant frequency points between a grid-connected inverter and a power grid are found out; the parameters of a PI controller and a repetitive controller are adjusted, so that the passivity of the output impedance of the grid-connected inverterat the resonant frequency points is remodeled, and therefore, interactive resonance between the grid-connected inverter and the power grid is avoided; the PI controller is designed to ensure the closed-loop stability of the system; the repetitive controller is designed to ensure the stability of the repetitive controller; the output impedance of the grid-connected inverter and the passivity of theimpedance of the power grid are analyzed, so that the possible resonant frequency points can be found out; and the parameters of the controller are corrected, so that the output impedance of the grid-connected inverter is passive at the points.

Description

technical field [0001] The invention belongs to the technical field of current control of grid-connected inverters, and more specifically, relates to a method for reshaping the output impedance of a parallel system of grid-connected inverters. Background technique [0002] Overexploitation of fossil energy and environmental pollution have made countries around the world pay more and more attention to the development and application of renewable energy such as wind energy, solar energy, and biofuels. A research report by the United Nations IPCC shows: By 2050, 50% of the world's energy can be met by renewable energy. China's 13th Five-Year Plan for Renewable Energy Development points out that by 2020, non-fossil energy will account for 15% of primary energy consumption, and the total installed capacity of renewable energy power generation will be 680 million kWh, with a power generation capacity of 1.9 trillion kWh, accounting for all power generation. 27% of the volume. In...

Claims

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Application Information

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IPC IPC(8): H02J3/38H02J3/01
CPCH02J3/01Y02E40/40
Inventor 李凯彭颖郑宏谢川邹见效徐红兵
Owner UNIV OF ELECTRONIC SCI & TECH OF CHINA
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