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Virtual synchronous control method for cascaded inverters based on unit active power backup

A technology of virtual synchronization and control method, applied in electrical components, single-grid parallel feeding arrangement, reducing/preventing power oscillation, etc. Cell overmodulation and other issues

Active Publication Date: 2020-09-01
HEFEI UNIV OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0011] The problem to be solved by the present invention is to overcome the limitations of the above-mentioned solutions. Aiming at the problem that the single-phase cascaded H-bridge photovoltaic inverter does not have the characteristics of a synchronous motor, and at the same time, the H-bridge unit is prone to overmodulation, a method based on unit active power backup is proposed. Virtual synchronous control method for cascaded inverters

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  • Virtual synchronous control method for cascaded inverters based on unit active power backup
  • Virtual synchronous control method for cascaded inverters based on unit active power backup
  • Virtual synchronous control method for cascaded inverters based on unit active power backup

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Embodiment Construction

[0068] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention will be further clearly and completely described below in conjunction with the accompanying drawings and embodiments.

[0069] figure 1 It is the topological structure of the single-phase cascaded H-bridge photovoltaic inverter according to the embodiment of the present invention. As shown in the figure, the single-phase cascaded H-bridge photovoltaic inverter includes N H-bridge units with photovoltaic modules and Inductance L S composition. Specifically, the DC sides of the N H-bridge units are connected to the photovoltaic panels PV1, PV2...PVN in sequence; the working conditions of the photovoltaic panels are at a rated temperature of 25°C and a rated light intensity of 1000W / m 2 The maximum power point voltage is 30.59V, each photovoltaic panel is connected to each H-bridge unit through a 14.1mF capacitor, and the cascaded system is connected...

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Abstract

The present invention is a virtual synchronous control method for cascaded inverters based on unit active power backup. Bridge unit overmodulation problem. The steps include: DC side voltage control; virtual synchronous control, using the frequency modulation power superimposed on the output power of the standby H-bridge unit, and the remaining H-bridge units operate at the maximum power point to obtain the command value of grid-connected active power and grid-connected reactive power; Grid-side current control; third harmonic injection control, by injecting the reverse third harmonic into the initial modulation signal of the standby H-bridge unit, and injecting the forward third harmonic into the initial modulation signal of the remaining H-bridge units to reduce the modulation degree of the H-bridge unit. This method can realize that the single-phase cascaded H-bridge photovoltaic inverter has the characteristics of a synchronous motor, participates in frequency modulation of the power grid, and at the same time reduces the modulation degree of the H-bridge unit to prevent over-modulation, and the algorithm is simple and the project is easy to implement.

Description

technical field [0001] The invention relates to a cascaded inverter virtual synchronous control method based on unit active power backup, and belongs to the technical field of cascaded inverter virtual synchronous control. Background technique [0002] Photovoltaic grid-connected power generation has attracted much attention because it provides clean energy and is environmentally friendly. In the face of how to improve the efficiency of photovoltaic systems and reduce power generation costs, cascaded H-bridge multilevel inverters have become a research hotspot due to their advantages such as modularization, easy expansion, high system efficiency, and low total harmonic distortion of grid-connected current. . [0003] Each DC-side photovoltaic array of a traditional cascaded photovoltaic inverter adopts an independent maximum power tracking control to achieve the maximum efficiency of the photovoltaic array. However, since the grid-connected inverter does not have moment of...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/38H02J3/24
CPCH02J3/383H02J3/385H02J3/24H02J2203/20Y02E10/56
Inventor 张兴胡玉华毛旺赵涛王付胜戴之强
Owner HEFEI UNIV OF TECH
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