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Active damping method of LCL grid-connected inverter system and circuit for realizing active damping method

An inverter and damping technology, which is applied to electrical components, output power conversion devices, and AC networks to reduce harmonics/ripples, etc. It can solve the influence of grid voltage harmonics and distortion interference, and the quality of grid current waveforms. The improvement effect is limited, etc., to achieve the effect of suppressing the impact

Inactive Publication Date: 2012-06-27
SOUTHEAST UNIV
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Problems solved by technology

[0005] The above-mentioned active damping methods can realize the effective damping of the resonant pole of the LCL filter, but they have a limited effect on improving the quality of the grid current waveform, and are especially susceptible to the influence of grid voltage harmonics and distortion interference.

Method used

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  • Active damping method of LCL grid-connected inverter system and circuit for realizing active damping method
  • Active damping method of LCL grid-connected inverter system and circuit for realizing active damping method
  • Active damping method of LCL grid-connected inverter system and circuit for realizing active damping method

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Embodiment Construction

[0016] The invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

[0017] Explanation of the symbols and labels of the accompanying drawings: U PV ——Inverter input voltage; S 1 ~S 4 ——power switch tube; u g — grid voltage; L 1 , L 2 ——Inductance of network filter; i 1 , I 1 , u 1 , U 1 、r 1 ——Filter inductance L 1 current, voltage and internal resistance; i 2 , I 2 , u 2 , U 2 、r 2 ——Filter inductance L 2 current, voltage and internal resistance; C 1 ——filter capacitor; i C , I C , u C u C , - filter capacitor C 1 current and voltage; u inv ——the output voltage between the bridge arms of the inverter; I 2ref ——Incoming grid current reference; K——Inverter equivalent proportional link; G 2 (s)——incoming grid current controller; k 1 - Differential feedback coefficient.

[0018] The present invention introduces the grid-side inductance L 2 Voltage u 2 The feedback achieves resonance damping of the LC...

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Abstract

The invention relates to an active damping method of an LCL grid-connected inverter system. The active damping method is realized through the following steps of: setting conjugated zero points or independent zero points to set off conjugated resonance limit points generated by an LCL filter in the grid-connected inverter system or to draw the conjugated resonance limit points to a stable area, and adopting grid-side inductive current to feed back and introduce a state variable in the LCL filter to conduct feedback compensation. By conducting feedback compensation on grid-side inductive voltage, the resonance damping of the LCL filter is controlled, the waveform and the amplitude of grid current of the grid-connected inverter system are controlled and the influence of grid voltage harmonic wave on the grid current can be effectively suppressed. The active damping method is a simple and effective realization method. A realization circuit comprises parallel and series active damping circuits.

Description

technical field [0001] The invention relates to an active damping method of an LCL grid-connected inverter system and a circuit thereof, belonging to the technical field of grid converter control. Background technique [0002] The voltage source type grid-connected inverter is the interface for the current booming new energy to enter the grid, and is used in various distributed grid-connected power generation systems (such as photovoltaic power generation systems, direct-drive wind power generation systems, fuel cell systems, etc.), AC The inverter interface in the microgrid and the interface between the DC bus and the power grid in the DC microgrid are in great demand. [0003] In order to reduce and limit their pollution to the power grid, international standards such as IEEE Std 929-2000 and UL1741 set strict index restrictions on the grid-connected inverter current, including total harmonic content and single harmonic content. Combining with the implementation technolog...

Claims

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Application Information

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IPC IPC(8): H02M1/12H02J3/01
CPCH02M1/126H02M7/5387Y02E40/40
Inventor 肖华锋谢少军许津铭
Owner SOUTHEAST UNIV
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