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LCL type inverter grid-connected device based on parameter joint design and control method

A control method and inverter technology, which are applied in harmonic reduction devices, single-grid parallel feeding arrangements, and AC networks to reduce harmonics/ripples, etc., can solve the problems of LCL filter resonance suppression and control difficulties, etc.

Pending Publication Date: 2020-06-19
NANJING UNIV OF SCI & TECH
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  • Abstract
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  • Application Information

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Problems solved by technology

However, in actual situations, the power grid is not an ideal fundamental wave power grid, and there will be low-frequency harmonics in the power grid. Under non-ideal power grid conditions, multiple PR controllers need to be controlled in parallel, which requires the system to have sufficient open-loop bandwidth. Difficulty in Resonance Suppression Control of Actively Damped LCL Filters

Method used

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  • LCL type inverter grid-connected device based on parameter joint design and control method
  • LCL type inverter grid-connected device based on parameter joint design and control method
  • LCL type inverter grid-connected device based on parameter joint design and control method

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Embodiment 1

[0139] In this embodiment, the Simulink tool in MATLAB is used to build a three-level inverter circuit. After the DC power passes through the DC bus capacitor, the three-level inverter circuit inverts and outputs the three-phase voltage, and the LCL filter circuit outputs a stable three-phase sinusoidal voltage.

[0140] The electrical parameter settings in the simulation process are shown in Table 1:

[0141] Table 1

[0142]

[0143] Define the Lagrangian function as follows:

[0144]

[0145] where ω i is the Lagrangian multiplier of the inequality constraint, v j is the Lagrangian multiplier of the equality constraints, g i (K p ,H,ω h ,ω res ') represents inequality constraints, h j (K p ,H,ω h ,ω res ') represents equality constraints, g i (K p ,H,ω h ,ω res ') and h j (K p ,H,ω h ,ω res ')It can be expressed as:

[0146]

[0147] h 2 (K p ,H,ω h ,ω res ')=a(ω res ')H 4 +b(ω res ')H 3 +c(ω res ')H 2 +d(ω res ')H+e(ω res ')=0

[01...

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Abstract

The invention discloses an LCL type inverter grid-connected device based on parameter joint design and a control method. The device comprises a three-level inverter, a digital processing control module and a driving circuit, wherein the digital processing control module comprises a sampling unit, a closed-loop control unit, an active damping unit and a sine pulse width modulation unit. The methodcomprises the following steps: selecting the capacitance value of an LCL filter capacitor, a network side inductor and an inverter side inductor inductance value; determining a feasible range of a PRcontroller proportion parameter and an active damping feedback coefficient through Nyquist stability analysis in combination with a resonance suppression condition; and in the determined feasible region, using a Lagrange multiplier method to select a proper PR controller proportion parameter and an active damping feedback coefficient so that the control system obtains a large bandwidth and good dynamic performance. The device and the method have the advantages of being low in hardware cost, accurate in control and wide in application range, the harmonic component of the resonant frequency of the LCL filter can be effectively restrained, and the distortion rate of the network access current is reduced.

Description

technical field [0001] The invention belongs to the technical field of power electronic conversion, in particular to an LCL inverter grid-connected device and a control method based on joint design of parameters. Background technique [0002] Due to its simple structure, good high-frequency filtering performance, and low output harmonic content, LCL filters have been widely used in new energy distributed grid-connected power generation occasions. However, due to the inherent characteristics of the LCL filter, the resonance characteristics of the LCL filter will greatly reduce the power quality at the output side. At present, there are two main solutions to the problem of the resonance frequency of the LCL filter: (1) use an external hardware damping circuit to suppress the LCL resonance; (2) use a software control method to suppress the LCL resonance. Since the first method will increase the hardware cost, the latter method is generally used. Under ideal grid conditions, t...

Claims

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Application Information

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IPC IPC(8): H02J3/38H02J3/01
CPCH02J3/38H02J3/01Y02E40/40
Inventor 吕建国阎亦然徐炜基胡文斌孙状
Owner NANJING UNIV OF SCI & TECH
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