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Generalized impedance criterion calculation method for stability analysis of grid-connected inverter and application

A calculation method and a technique of stability analysis, applied to AC network circuits, single-network parallel feeding arrangements, electrical components, etc., can solve the problems of unusable Nyquist criterion, complex analysis, loss, etc.

Active Publication Date: 2017-03-22
ZHEJIANG UNIV
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Problems solved by technology

So the usual Nyquist criterion still cannot be used
Although the system stability can be analyzed by using the generalized Nyquist criterion, this analysis is more complicated and loses the advantage of using the impedance method to simplify the analysis

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  • Generalized impedance criterion calculation method for stability analysis of grid-connected inverter and application
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  • Generalized impedance criterion calculation method for stability analysis of grid-connected inverter and application

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Embodiment Construction

[0054] The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

[0055] The embodiment and flow process thereof of adopting the method of the present invention to carry out system stability judgment are as follows: figure 1 shown.

[0056] The first step is to establish the small-signal impedance model of the inverter-side network port and the small-signal impedance model of the grid-side network port in polar coordinates;

[0057] combine figure 2 As shown in the specific example, consider an inverter single-unit infinite system, where the filter adopts a typical LCL filter, and the control strategy of the inverter adopts the most common phase-locked plus double-loop vector control, and the inverter satisfies the following assumptions:

[0058] Assumption 1: The inner loop control of the inverter has voltage feedforward and decoupling items, and fully compensates for voltage feedforward.

[00...

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Abstract

The invention discloses a generalized impedance criterion calculation method for stability analysis of a grid-connected inverter and an application. The method comprises the following steps of building a small signal impedance model of an inverter side network port and a small signal impedance model of a power grid side network port under polar coordinates; and calculating generalized impedances of the inverter side network port and the power grid side network port according to the built small signal impedance model of the inverter side network port and small signal impedance model of the power grid side network port under the polar coordinates, and dividing the two generalized impedances obtained in the second step to obtain the ratio of the generalized impedances of the inverter side network port and the power grid side network port as a generalized impedance criterion. The obtained generalized impedance criterion can be used for small signal stability analysis of a grid-connected inverter system, the problem that the analysis accuracy is affected by a traditional impedance method due to the presence of coupling is solved, a foundation is laid for clearing power grid oscillation generated when new energy is connected to a power grid on a large scale, and the method disclosed by the invention is an important method for designing an inverter controller to improve the stability.

Description

technical field [0001] The invention relates to a calculation method and application of a grid stability criterion, in particular to a calculation method and application of a generalized impedance criterion for stability analysis of a grid-connected inverter. Background technique [0002] With the development of the power system, more and more power electronic devices have been applied to the power system, including grid-connected inverters for new energy access, HVDC transmission systems and flexible AC transmission systems. Although power electronic equipment has the advantages of flexibility and controllability, the switching devices of power electronic equipment will generate harmonics in the power grid, which will endanger the quality of power supply and system stability. When new energy is connected to the grid, in order to improve the power transmission capacity and save line costs, series capacitor compensation is often used in the transmission line, but the interact...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/00H02J3/38
CPCH02J3/00H02J3/38H02J2203/20
Inventor 辛焕海李子恒董炜
Owner ZHEJIANG UNIV
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