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Active damping control method for series virtual impedance of multi-inverter grid-connected system

A multi-inverter and virtual impedance technology, which is applied in the direction of reducing the flicker of the AC network, the AC network circuit, and the parallel feeding arrangement of the single network, can solve the problem of stable and reliable operation of the system, and achieve the effect of suppressing harmonic resonance

Active Publication Date: 2019-07-26
HUNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

When the harmonic voltage frequency caused by grid distortion is equal to or close to the series resonance frequency of the impedance network, it will also cause series resonance or quasi-resonance of the network, which is a potential threat to the stable and reliable operation of the system

Method used

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  • Active damping control method for series virtual impedance of multi-inverter grid-connected system
  • Active damping control method for series virtual impedance of multi-inverter grid-connected system
  • Active damping control method for series virtual impedance of multi-inverter grid-connected system

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Embodiment Construction

[0026] figure 1 It is the structural diagram of the three-phase inverter grid-connected system. When the photovoltaic array and DC / DC converter or the fan unit and AC / DC converter are connected to the distribution network through the LCL-type grid-connected inverter, the LCL-type grid-connected The input of the inverter can be equivalent to a DC source. m=1,2,...,n; inverter side inductance L 1m , filter capacitor C 1m and grid side inductance L 2m form the LCL filter, R L1m and R L2m L respectively 1m and L 2m The parasitic resistance, Z g is the grid impedance, U dc is the DC side voltage, u invm is the output voltage of the inverter, u C1m is the filter capacitor voltage, u PCC is the common coupling point voltage, u g is the grid voltage, i L1m i C1m i om and i g They are inverter side inductor current, filter capacitor current, grid side inductor current and grid-connected current.

[0027] figure 2 is the control block diagram of the grid-connected inv...

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Abstract

The invention discloses an active damping control method for series virtual impedance of a multi-inverter grid-connected system. According to the method, grid-side inductive current feedback of a band-stop filter is introduced, and equivalently, parallel virtual impedance and series virtual impedance are added to output impedance of a grid-connected inverter. The series virtual impedance is in lowimpedance at the fundamental frequency, so that fundamental current flows into a power grid. According to the method, network impedance of the integrated system is directionally changed through changing the output impedance of the grid-connected inverter, thereby effectively suppressing possible harmonic resonance in a network.

Description

technical field [0001] The invention relates to the field of new energy distributed power generation, in particular to a method for active damping control of a series virtual impedance of a multi-inverter grid-connected system. Background technique [0002] As an important means of utilizing renewable energy, distributed power generation can not only support the economic operation of the power grid, but also be clean and environmentally friendly, and its proportion of capacity in the power grid continues to increase. In power electronic devices using renewable energy, the grid-connected inverter, as the main power interface unit, plays an important role in converting the electrical energy generated by renewable energy into AC form and feeding it to the grid. [0003] However, when multiple inverters are connected to the same grid common coupling point, the grid equivalent impedance corresponding to any grid-connected inverter at the common coupling point will increase as the...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/38
CPCH02J3/002H02J3/38H02J3/382
Inventor 罗安杨苓陈燕东周乐明周小平伍文华谢志为徐千鸣王逸兴
Owner HUNAN UNIV