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Stability Analysis Method of Grid-connected Inverter under Coexistence of Multi-frequency Coupling Factors

An analysis method and inverter technology, applied to AC network circuits, single-network parallel feeding arrangements, circuit devices, etc., can solve the problems of inability to analyze the stability of the grid-connected inverter system and fail to obtain it, so as to avoid The effect of error, strong applicability and high precision

Active Publication Date: 2020-03-31
ZHEJIANG UNIV +1
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Problems solved by technology

[0006] However, none of the above researches on the frequency coupling characteristics of grid-connected inverters has obtained a unified grid-connected inverter that can accurately describe the coexistence of multiple frequency coupling reasons such as phase-locked loops, current controller asymmetry, and DC bus influence. The analytical model of transformer impedance cannot analyze the stability of the grid-connected inverter system under the coexistence of multi-frequency coupling factors; therefore, a more complete stability analysis method for the grid-connected inverter system is urgently needed

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  • Stability Analysis Method of Grid-connected Inverter under Coexistence of Multi-frequency Coupling Factors
  • Stability Analysis Method of Grid-connected Inverter under Coexistence of Multi-frequency Coupling Factors
  • Stability Analysis Method of Grid-connected Inverter under Coexistence of Multi-frequency Coupling Factors

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[0032] In order to describe the present invention more specifically, the technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0033] Such as figure 1 As shown, the grid-connected inverter system stability analysis method of the present invention includes the following steps:

[0034] (1) According to the structure and control block diagram of the grid-connected inverter system, the control link of the grid-connected inverter is modeled to obtain the relationship between the harmonic voltage and harmonic current at the output port of the inverter, and then with the phase sequence domain The average model equations of the lower grid-connected inverter are combined. Taking a 1.5MW grid-connected inverter as an example, the system block diagram is as follows: figure 2 shown.

[0035] Among them, the voltage and current of the grid-connected point are recorded as v a , v b , v ...

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Abstract

The invention discloses a stability analysis method for a grid-connected inverter system under the coexistence condition of multiple frequency coupling factors. The method is applied to a grid-connected inverter system, wherein the situation that multiple frequency coupling factors coexist is considered. A frequency coupling characteristic analysis model of a grid-connected inverter is establishedin a phase sequence coordinate system, and a power grid impedance matrix is obtained through calculation under the condition that the frequency coupling is considered. The method is realized based onthe generalized Nyquist stability criterion, and the stability of the grid-connected inverter system is judged by utilizing the generalized impedance ratio matrix of the grid impedance matrix and thefrequency coupling characteristic matrix of the grid-connected inverter. Therefore, the method can be used for analyzing the system stability under the complex condition of the coexistence of multi-frequency coupling factors. Compared with an existing stability analysis method based on the impedance of the grid-connected inverter, the method is more complete. Therefore, analysis errors caused byignoring frequency coupling are avoided. The stability of the grid-connected inverter system under the complex condition can be analyzed more accurately.

Description

technical field [0001] The invention belongs to the technical field of grid-connected inverters, and in particular relates to a method for analyzing the stability of a grid-connected inverter system under the coexistence of multi-frequency coupling factors. Background technique [0002] With the large-scale access of new energy in the grid, grid-connected inverters are widely used as the energy transmission interface between new energy and the grid, such as new energy grid-connected, HVDC transmission system, flexible AC transmission system, etc. The large-scale integration of power electronic devices such as grid-connected inverters in the grid has caused new stability problems in the interconnected system, such as the subsynchronous oscillation problem that occurs between the control system of power electronic devices and the series compensation device of transmission lines. [0003] The stability analysis method based on the impedance model obtains the port impedance char...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/38H02J3/44
CPCH02J3/38H02J3/44H02J2203/20
Inventor 年珩徐韵扬陈亮黄弘扬马骏超吕文韬宣晓华陆承宇楼伯良吴跨宇
Owner ZHEJIANG UNIV
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