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Multiple-resonance inhibition method for connecting multiple inverters into weak grid in parallel

A resonance suppression, multi-inverter technology, applied in AC networks to reduce harmonics/ripples, harmonic reduction devices, single-network parallel feeding arrangements, etc., can solve problems such as resonance suppression methods that have not been studied. Achieve the effect of reducing hardware cost and power consumption, strong feasibility and improving stability

Inactive Publication Date: 2015-12-30
北京科诺伟业科技股份有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, there is no research on the resonance suppression method for the two resonance points

Method used

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  • Multiple-resonance inhibition method for connecting multiple inverters into weak grid in parallel
  • Multiple-resonance inhibition method for connecting multiple inverters into weak grid in parallel
  • Multiple-resonance inhibition method for connecting multiple inverters into weak grid in parallel

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Embodiment Construction

[0016] The present invention will be further described below in conjunction with the drawings and specific embodiments.

[0017] Such as figure 1 As shown, the multiple current source inverter parallel systems with LCL filters applied in the present invention include a weak grid system 10 and multiple current source inverters 20 with control systems 30. The multiple resonance suppression method of the present invention is implemented by the control system 30 of each inverter.

[0018] The switching signal output by the control system 30 is input into the power switch tube 203 of the corresponding current source inverter 20, and a plurality of current source inverters 20 are connected to the weak grid system 10.

[0019] The weak grid system 10 can be equivalent to a physical model in which an ideal voltage source 101 and a resistive line 102 are connected in series.

[0020] The multiple current source inverters are composed of a DC side voltage source 201, a supporting capacitor 202...

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PUM

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Abstract

The invention discloses a multiple-resonance inhibition method for connecting multiple inverters into a weak grid in parallel. The method comprises the steps that capacitor voltage feedback quantities are introduced into current control ring forward channels of all the inverters and closed-loop links where the feedback quantities are located are set to be trap filter characteristics through control of active trap filters of capacitor voltage feedback of LCL filter circuits on the basis of the principle that in a parallel system of the multiple same-type current source inverters containing LCL filters, resonance peaks occur at the resonant frequencies of a transfer function of the parallel system, and therefore on the basis of active correction of the trap filters, the negative resonance peaks are achieved at the multiple resonant frequencies, and signals at the resonance points are shielded from the interiors of the inverters.

Description

Technical field [0001] The invention relates to a method for inhibiting multiple resonances connected to multiple inverters of a weak grid system. Background technique [0002] With the continuous development of photovoltaic power generation, it has become a trend for large-scale inverters to connect to the weak grid and operate in the form of current sources. The weak grid is characterized by its larger network impedance and smaller short-circuit capacity, which leads to the mutual influence of multiple connected inverters. For the same type of inverter with LCL filter, the same equipment parameters cause regular resonance phenomenon: two obvious resonance point frequency harmonics appear on the grid-connected current, this resonance point One is fixed, while the other moves to low frequency as the number of parallel inverters increases. In order to suppress the parallel resonance at the resonant frequency, extensive research has been done at home and abroad, and the passive d...

Claims

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Application Information

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IPC IPC(8): H02J3/01H02J3/38
CPCY02E40/40
Inventor 段江曼许洪华
Owner 北京科诺伟业科技股份有限公司
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