Power equilibrium control method for reducing DC voltage fluctuation of cascaded H-bridge inverter

A balanced control and DC voltage technology, applied in the direction of converting AC power input to DC power output, AC network circuit, output power conversion device, etc., can solve the problem of reducing the power generation of photovoltaic panels, low inverter power factor, and system Unable to run stably and other issues

Active Publication Date: 2017-08-08
HEFEI UNIV OF TECH
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Problems solved by technology

[0008] (1) The existing technology can improve the power imbalance problem of the cascaded H-bridge photovoltaic inverter to a certain extent, but the adjustment range is small. When the system is seriously unbalanced, the system cannot run stably
[0009] (2) The power unbalance problem of the cascaded H-bridge photovoltaic inverter can be suppressed by compensating reactive power, but when the system is

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  • Power equilibrium control method for reducing DC voltage fluctuation of cascaded H-bridge inverter
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  • Power equilibrium control method for reducing DC voltage fluctuation of cascaded H-bridge inverter

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Embodiment Construction

[0053] 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.

[0054] figure 1 It is a single-phase cascaded H-bridge photovoltaic grid-connected inverter topology according to the embodiment of the present invention, which includes N identical H-bridge units, and N pieces of photovoltaic panels PV are connected to the N H-bridge units through switches. 1 , PV 2 …PV N , the working condition of the photovoltaic panel is at a temperature of 25C 。 , light intensity 1000W / m 2 The maximum power point voltage is 35.1V, each photovoltaic panel is connected to each H-bridge unit through a 18.8mF capacitor, and the cascaded system is connected to the grid through a 1.5mH inductor L.

[0055] The control diagram of the present invention is as figure 2 As shown, it includes three parts: total DC si...

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Abstract

The invention discloses a power equilibrium control method for reducing DC voltage fluctuation of a cascaded H-bridge inverter, and aims to solve the problem that power generation quantity is reduced caused by relatively large DC-side voltage fluctuation. The power equilibrium control method comprises the following steps of controlling a total DC-side voltage to achieve tracking of a maximum power point voltage of the DC-side voltage of each H-bridge unit and obtain an active current instruction value of a system; controlling decoupling of a network-side current, where independent control on an active current and reactive current can be achieved, and meanwhile, a total modulation wave voltage of the inverter is generated; and performing power equilibrium control between units, an accurate on-off state of each H-bridge unit is determined and power equilibrium control of each H-bridge unit and maximum power tracking of each H-bridge unit are achieved by sequencing an error of the DC-side voltage of each H-bridge unit. By the method, various working conditions can be adapted, stable running of the cascaded H-bridge photovoltaic inverter within a relatively large range can be achieved, moreover, the DC-side voltage fluctuation can be reduced, and the power generation quantity of the system is improved.

Description

technical field [0001] The invention relates to a power balance control method for reducing DC voltage fluctuations of cascaded H-bridge photovoltaic inverters, and belongs to the technical field of power balance control of cascaded H-bridge photovoltaic grid-connected inverters. Background technique [0002] Photovoltaic grid-connected power generation has attracted much attention because it provides clean energy and is environmentally friendly. Facing the problems of how to improve the efficiency of photovoltaic system and reduce the cost of power generation, the cascaded H-bridge multilevel inverter has become a popular choice due to its modularization, easy expansion, high system efficiency, and low total harmonic distortion (THD) of grid-connected current. research hotspot. In addition, each power unit of the cascaded H-bridge multi-level inverter needs an independent DC power supply, which is just in line with the characteristics of photovoltaic module power generatio...

Claims

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Application Information

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IPC IPC(8): H02J3/38H02M7/5387
CPCH02J3/383H02M7/5387H02M1/007Y02E10/56
Inventor 张兴毛旺王付胜赵涛张德辉戴之强
Owner HEFEI UNIV OF TECH
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