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Control method for improving adaptability of LCL type grid-connected inverter for weak grid

A technology of adaptability and inverter, which is applied in the direction of single-network parallel feeding arrangement, etc., can solve the problems of simultaneously correcting the output impedance modulus and phase of the inverter, and it is difficult to take into account stability requirements and anti-interference performance at the same time. Achieve high sine effect

Inactive Publication Date: 2014-05-21
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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Problems solved by technology

However, it is difficult to simultaneously correct the modulus and phase of the output impedance of the inverter using only the current controller 5, so it is difficult to simultaneously meet the requirements of stability and immunity

Method used

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  • Control method for improving adaptability of LCL type grid-connected inverter for weak grid
  • Control method for improving adaptability of LCL type grid-connected inverter for weak grid
  • Control method for improving adaptability of LCL type grid-connected inverter for weak grid

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Embodiment

[0060] For contrasting the control method of the present invention and prior art, a concrete example that the present invention provides, its each main parameter is all as follows:

[0061] ●Voltage V of DC power supply 1 in =360VDC;

[0062] ●Voltage V of the public grid 4 g =220VAC;

[0063] ●Rated power P o =6kW;

[0064] ●Switching frequency f sw =15kHz;

[0065] ●Filter inductance L 1 =330μH;

[0066] ●Filter inductance L 2 =330μH;

[0067] ●Filter capacitance C=10μH;

[0068] ●Capacitive current i C The sampling factor H i1 =0.05;

[0069] ●Grid current i gThe sampling factor H i2 =0.15;

[0070] ●Grid-connected point voltage v pcc The sampling factor H v1 =0.25;

[0071] ●Filter inductance L 2 Voltage sampling factor H v2 =0.25;

[0072] Using a programmable AC power supply (Chroma6590) to simulate grid voltage, respectively inject 3rd, 5th, 7th, 9th, 11th, 13th, 21st, 33rd, 40th harmonics, relative to the fundamental wave amplitude are 10%, 5%, 3%...

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Abstract

The invention discloses an output impedance correcting method suitable for an LCL type grid-connected inverter. The output impedance correcting method suitable for LCL type grid-connected inverter includes: step (1), detecting capacitance current iC, grid-connected current ig, grid-connected point voltage vpcc and voltage VL2 of a filter inductor L2, and obtaining feedback signals iC-of, ig-of, vpcc-of and vL2-of thereof; (2) inputting the feedback signals iC-of, ig-of and vpcc-of to a current controller, and processing to output vr1; (3) inputting the signals vpcc-of and vL2-of to an impedance regulator, and processing to output vr2; (4) adding vr1 and vr2 together to obtain a modulating signal vm, inputting to a PWM generator to generate a PWM signal to control a switching tube of an inverter bridge. The output impedance correcting method suitable for the LCL type grid-connected inverter corrects the output impedance of the grid-connected inverter through the impedance regulator and is capable of effectively improving the closed loop stability and the interference rejection of the grid-connected inverter.

Description

technical field [0001] The invention relates to a control method of an LCL type grid-connected inverter, specifically a method for correcting the output impedance of the inverter through a virtual impedance, which can effectively improve the adaptability of the grid-connected inverter to weak grid conditions, That is to say, when there is a wide range of grid impedance and serious voltage background harmonics in the grid, it can still ensure the stable and reliable operation of the grid-connected inverter, and at the same time ensure that the harmonics in the grid-connected current meet the grid-connected standards. Background technique [0002] As one of the main ways of utilizing renewable energy, the distributed generation system can not only support the economic operation of the existing distribution network, but also be clean and environmentally friendly. The proportion of the capacity in the power grid will continue to increase. [0003] However, with the increase of t...

Claims

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Application Information

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IPC IPC(8): H02J3/38
Inventor 杨东升阮新波吴恒
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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