Single-phase cascade H-bridge grid-connected inverter control method under weak grid

A control method and inverter technology, which are applied in photovoltaic power generation, electrical components, circuit devices, etc., can solve problems such as unfavorable project implementation, inability of inverters to operate stably, less involving cascaded systems, etc., and achieve expansion and stability. The effect of the running range

Active Publication Date: 2019-08-02
HEFEI UNIV OF TECH
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Problems solved by technology

[0008] (1) The control methods of photovoltaic grid-connected inverters under weak grids studied in the prior art are mostly aimed at centralized full-bridge inverters, and seldom involve cascaded systems
[0009] (2) The virtual synchronous control method of cascaded H-bridge multi-level inverters studied in the prior art is aimed at off-grid control of inverters, and less involved in grid-connected control of inverters
The parameter design of this method is complicated, which is not conducive to engineering implementation
In addition, when the power grid is quite weak, the inverter cannot run stably with this method

Method used

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  • Single-phase cascade H-bridge grid-connected inverter control method under weak grid
  • Single-phase cascade H-bridge grid-connected inverter control method under weak grid
  • Single-phase cascade H-bridge grid-connected inverter control method under weak grid

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Embodiment Construction

[0054] In order to make the object, 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.

[0055] figure 1 It is the topological structure of the single-phase cascaded H-bridge photovoltaic grid-connected inverter according to the embodiment of the present invention. As shown in the figure, the single-phase cascaded H-bridge photovoltaic grid-connected inverter consists of N H Bridge unit, filter inductor L S and filter capacitor C f composition. Specifically, the DC sides of N H-bridge units are sequentially connected to N photovoltaic panels PV1, PV2...PVN, and 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 30.40V, each photovoltaic panel is connected to each H-bridge unit through a 14.1mF capacitor, and ...

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Abstract

The invention discloses a single-phase cascade H-bridge grid-connected inverter control method under the weak grid and aims to realize stable operation of a cascaded photovoltaic inverter under the extremely weak grid. The method comprises following steps of (1) of DC side voltage control, the DC side voltage of each H-bridge unit is realized to track the maximum power point voltage; (2) of droopcontrol, a grid side current control command is obtained through a droop control equation and an AC voltage loop; and (3) of network side current control, independent control of the active current andthe reactive current can be realized, and an inverter modulation signal is generated. The method is advantaged in that advantages of both the droop control strategy and maximum power tracking are integrated, not only can the stable operation range of the cascaded H-bridge PV grid-connected inverter be expanded, but also maximum power tracking of each H-bridge unit can be realized.

Description

technical field [0001] The invention relates to a control method for a single-phase cascaded H-bridge photovoltaic grid-connected inverter under a weak power grid, and belongs to the technical field of cascaded photovoltaic inverter 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] Since the output of the cascaded H-bridge photovoltaic inverter is directly connected to the grid, the step-up transformer at the grid-connected end is omitted, which improves the overall efficiency of the photovoltaic power generation system...

Claims

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Application Information

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IPC IPC(8): H02J3/38H02J3/48H02J3/50
CPCH02J3/385H02J3/48H02J3/50H02J2203/20Y02E10/56
Inventor 张兴毛旺胡玉华赵涛王付胜戴之强
Owner HEFEI UNIV OF TECH
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