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A power balance control method for cascaded h-bridge photovoltaic grid-connected inverters

A balanced control and inverter technology, applied in photovoltaic power generation, control/regulation systems, output power conversion devices, etc., can solve problems such as power unbalance, in-phase module power unbalance, and no problem, to maximize The effect of power generation

Active Publication Date: 2022-05-03
QINGDAO UNIV
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

[0004] However, the common DC bus cascaded H-bridge photovoltaic grid-connected inverter introduced above still has the problem of power imbalance between modules in the phase, the literature "Xing Zhang, Mingda Wang, Tao Zhao, Wang Mao, Yuhua Hu, Renxian Cao. Topological Comparison and Analysis of Medium-Voltage and High-Power Direct-linked PV inverter[J]. CES Transactions on Electrical Machines and Systems, 2019, 3(4): 327-334. (Xing Zhang, Mingda Wang, Tao Zhao , Wang Mao, YuhuaHu, Renxian Cao, Topology comparison and analysis of medium-voltage high-power direct-mounted photovoltaic grid-connected inverters, CES Journal of Electric Machines and Systems, 2019, Volume 3, Issue 4, Pages 327 to 334)” No detailed analysis of the power imbalance between modules in the phase of this topology has been carried out, and no relevant control strategy has been proposed to solve this problem

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  • A power balance control method for cascaded h-bridge photovoltaic grid-connected inverters
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  • A power balance control method for cascaded h-bridge photovoltaic grid-connected inverters

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Embodiment Construction

[0096] 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.

[0097] figure 1 It is the topological structure of the cascaded H-bridge grid-connected inverter in the embodiment of the present invention. It can be seen from the figure that the cascaded H-bridge photovoltaic grid-connected inverter applying this control method is a three-phase photovoltaic grid-connected inverter. Contains 3N modules, each of which has exactly the same structure, and is composed of a three-level full-bridge LLC converter connected in series with an H-bridge converter, where A-phase, B-phase and C-phase each contain N modules, and N is A positive integer greater than 1; record any one of the 3N modules as a module φ ij , j represents the phase, j=A, B, C, i is the serial number of the module in the three phases,...

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Abstract

The invention discloses a power balance control method for cascaded H-bridge photovoltaic grid-connected inverters, the purpose of which is to enable three-phase common DC bus cascaded H-bridge photovoltaic grid-connected inverters to output power between photovoltaic arrays It can still operate normally when it is seriously unbalanced. The steps are: control the voltage of N public DC buses; select the output power command value of N public DC buses; control the grid current without static difference; judge the working mode of the system, and use different modulation wave calculation methods , Calculate the modulation waves of all H-bridges; control the output voltages of all three-level full-bridge LLC converters. Using this method, the system can still operate normally when the modulation degree of some H-bridge converters is greater than 1.155, which greatly improves the ability of the three-phase common DC bus cascaded H-bridge photovoltaic grid-connected inverters to cope with power imbalance.

Description

technical field [0001] The invention belongs to photovoltaic power generation technology in the field of electrical engineering, and in particular relates to a power balance control method for cascaded H-bridge photovoltaic grid-connected inverters. Background technique [0002] According to the "Global Renewable Energy Status Report 2019", the new installed capacity of photovoltaic power generation in 2018 was about 100GW, of which photovoltaic power plants with a power level greater than 5WM contributed about 50% of the installed capacity. In the future, large-scale photovoltaic power plants will still occupy a large market share. This is because the power generation cost per watt of high-power systems is lower than that of low-power systems, which will help realize photovoltaic power grid parity and become more commercially attractive. Compared with the centralized and string topology, the three-phase isolated cascaded H-bridge photovoltaic inverter has outstanding advant...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/38H02J3/26H02M3/158H02M7/5387
CPCH02J3/381H02J3/26H02M3/1582H02M7/53871H02J2300/24Y02E10/56Y02E40/50
Inventor 赵涛陈道炼冯之健
Owner QINGDAO UNIV
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