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Control method for improving grid-connected voltage source inverter system stability

A system stability and control method technology, which is applied in the field of control to improve the stability of the grid-connected voltage source inverter system, and can solve problems such as system instability and sacrifice of grid-side current controller bandwidth.

Inactive Publication Date: 2015-12-02
XI AN JIAOTONG UNIV
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  • Claims
  • Application Information

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Problems solved by technology

However, the tradeoff for obtaining sufficient stability margin is to sacrifice the bandwidth of the grid-side current controller
In addition, in the case of a weak grid, even if the grid-connected voltage source inverter system based on the LCL filter is stable, when it is connected to the grid, the entire system is prone to instability.

Method used

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  • Control method for improving grid-connected voltage source inverter system stability
  • Control method for improving grid-connected voltage source inverter system stability
  • Control method for improving grid-connected voltage source inverter system stability

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Embodiment Construction

[0042] The present invention is described in further detail below in conjunction with accompanying drawing:

[0043] refer to figure 1 and image 3 , a control method for improving the stability of a grid-connected voltage source inverter system, characterized in that it includes the following steps:

[0044] 1) Generate the initial command v of the modulation wave of the grid-connected converter ca0_ref , v cb0_ref and v cc0_ref , wherein, the concrete operation of step 1) is:

[0045] 1.1) Detect the grid-side voltage v of the three-phase grid system sa , v sb and v sc , and then according to the grid-side voltage v of the three-phase grid system sa , v sb and v sc Obtain the angular frequency ω of the current power grid through the phase-locked loop PLL 0 with phase θ;

[0046] 1.2) The angular frequency ω of the current power grid obtained according to step 1.1) 0 and phase θ to get the three-phase grid side current command i sa_ref i sb_ref and i sc_ref ,i...

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Abstract

The invention discloses a control method for improving grid-connected voltage source inverter system stability. The method comprises the steps of (1) generating a grid-connected converter modulating wave initial order; (2) calculating a power grid side current control circuit gain T, obtaining corresponding cut-off frequency omega 1 and cut-off frequency omega 2 when an amplitude-versus-frequency curve of the T passes through 0dB twice before a resonant frequency omega r of an LCL filter, and obtaining an s-domain transfer function of a lag compensation link according to the cut-off frequency omega 1 and the cut-off frequency omega 2; (3) performing discretization on the s-domain transfer function of the lag compensation link, and bringing the grid-connected converter modulating wave initial order obtained in the step (1) into an express form, in a digital controller, of the s-domain transfer function of the lag compensation link obtained through the discretization, so as to obtain a final modulating wave order value of the converter; (4) obtaining a modulating signal according to the final modulating wave order value of the converter obtained in the step (3), and controlling various switching elements of the converter according to the modulating signal; the control method provided by the invention can effectively improve the system stability.

Description

technical field [0001] The invention belongs to the field of automatic control and relates to a control method for improving the stability of a grid-connected voltage source inverter system. Background technique [0002] In recent years, with the rapid development of my country's economy, problems such as energy shortage and environmental pollution have become increasingly serious. In order to solve the above problems, renewable energy represented by wind power and photovoltaic power generation has been developed and utilized on a large scale, so that grid-connected voltage source inverters required to connect new energy to the grid have been widely used. Most of the voltage source inverters use fully-controlled power electronic switching devices and PWM modulation strategies to work. Therefore, in order to improve the power quality of the grid-connected point and reduce the switching ripple, the filter between the converter and the grid is essential. Compared with the tra...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38
Inventor 刘进军刘腾刘增窦青云
Owner XI AN JIAOTONG UNIV
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