Dual-mode seamless switching control method for cascaded inverter based on voltage closed loop
A technology of seamless switching and control methods, which is applied in the direction of electrical components, circuit devices, photovoltaic power generation, etc., can solve the problem of seamless switching between current source and voltage source dual modes of inverters, and cascaded photovoltaic inverters. The problem of maximum power tracking of photovoltaic power generation is not considered
Active Publication Date: 2019-10-08
HEFEI UNIV OF TECH
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[0008] (1) The inverter current source voltage source dual-mode switching control method studied in the prior art is mostly aimed at the difference between the inverter current source and voltage source modes caused by the inverter in both grid-connected and off-grid conditions. The issue of switching between each other, seldom involves how to realize the seamless switching of current source and voltage source dual modes when the inverter is connected to the grid
[0009] (2) Current-source-voltage-source dual-mode switching control methods for inverters studied in the prior art are mostly aimed at three-phase centralized energy storage inverters, but fail to involve cascaded photovoltaic inverters
[0010] (3) The inverter current source voltage source dual-mode switching control method studied in the prior art is mostly aimed at the stable power supply on the DC side of the inverter, and does not consider the maximum power tracking of photovoltaic power generation
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[0075] 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.
[0076] figure 1 It is the topological structure of the cascaded inverter according to the embodiment of the present invention. As shown in the figure, the cascaded inverter consists of N H-bridge units with photovoltaic modules, 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 the cascaded system is connected through a 1.5mH filter inductor L S and ...
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The invention discloses a dual-mode seamless switching control method for a cascaded inverter based on a voltage closed loop. The method includes a method for switching between a current source mode and a voltage source mode. When the current source mode is switched to the voltage source mode, closed-loop tracking of a modulation wave voltage is completed by amplitude synchronization and phase synchronization, on the basis, current feedforward control is utilized to achieve seamless switching of the inverter from the current source mode to the voltage source mode. When the voltage source modeis switched to the current source mode, closed-loop tracking of the modulation wave voltage is completed by a modulation wave voltage synchronous regulator, on the basis, current feedforward control is utilized to achieve seamless switching of the inverter from the voltage source mode to the current source mode. The method is advantaged in that seamless switching of the two control modes can be realized, and maximum tracking of the photovoltaic power generation power can be achieved.
Description
technical field [0001] The invention relates to a dual-mode seamless switching control method of a cascaded inverter based on a voltage closed loop, 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. However, lar...
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IPC IPC(8): H02J3/38
CPCH02J3/385Y02E10/56
Inventor 张兴毛旺胡玉华赵涛王付胜李飞
Owner HEFEI UNIV OF TECH