Voltage equalization circuit suitable for IIOS type photovoltaic DC boost collection system
A technology of voltage equalization circuit and DC boost, which is applied in the field of power grid, can solve the problems of increased loss, the inability of the equalization unit to realize soft switching, and the reduced efficiency of the photovoltaic DC boost collection system, so as to achieve the effect of reducing current stress
Pending Publication Date: 2021-12-24
CHONGQING UNIV
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[0008] The literature "Tian Yanjun, Gao Haonan, Wang Yi, et al. Hierarchical optimization MPPT control strategy for independent input series output photovoltaic DC collection system under uneven illumination [J]. High Voltage Technology, 2020, 46(10): 9." proposed A power weight hierarchical control strategy for photovoltaic DC collection system, which adjusts the working mode of the converter by calculating the power weight of each power generation module. less effective in severe cases
The document "Ning Guangfu, Chen Wu, Cao Xiaopeng, et al. Voltage equalization strategy suitable for modular cascaded photovoltaic power generation DC grid-connected system[J]. Electric Power System Automation, 2016,40(19):66-72." A topology scheme in which a full-bridge or half-bridge voltage regulation circuit is added to the rear stage of each converter module. By controlling the duty cycle of the switching devices in the rear-stage voltage regulation circuit, the output voltage can be balanced, but the two-stage structure leads to Increased loss and reduced efficiency of photovoltaic DC boost collection system
Literature "LiuY, Abu-RubH, Ge B. Front-End Isolated Quasi-Z-Source DC–DC Converter Modules in Series for High-Power Photovoltaic Systems—Part II: Control, Dynamic Model, and Downscaled Verification [J]. IEEE Transactions on Industrial Electronics, 2016, 64(1): 359-368." proposed an IIOS-type DC converter composed of converter units based on quasi-Z source impedance network topology, which can realize multi-channel MPPT control for photovoltaic power generation, and To a certain extent, the ability of the converter to cope with power mismatch is enhanced, but the number of passive components in the quasi-z source structure is large, resulting in a decrease in the stability of the pooling system
Literature "Li X, Zhu M, Su M, et al.Input-Independent and Output-Series Connected Modular DC–DCConverter With Intermodule Power Balancing Units for MVdc Integration of Distributed PV[J].IEEE Transactions on Power Electronics,2019,35( 2): 1622-1636." proposed a power equalization circuit, through the power equalization unit, the output voltage of each sub-converter can be well balanced, and only the mismatched power is transmitted in the power equalization unit, compared with the two In terms of the cascade structure, the loss is significantly reduced, but the equalization unit cannot realize soft switching, and the loss cannot be ignored under high power conditions.
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[0078] Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the diagrams provided in the following embodiments are only schematically illustrating the basic concept of the present invention, and the following embodiments and the features in the embodiments can be combined with each other in the case of no conflict.
[0079] Wherein, the accompanying drawings are for illustrative purposes only, and represent only schematic diagrams, rather than physical drawings, and should...
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The invention relates to a voltage equalization circuit suitable for an IIOS type photovoltaic DC boost collection system, and belongs to the technical field of power grids. The voltage equalization circuit comprises an IIOS type photovoltaic DC boost collection system, an IBFBC unit and an additional voltage balancing circuit DPBU. The IIOS type photovoltaic DC boost collection system comprises n independent sub-modules SM and n / 2 additional voltage equalization circuits, and each sub-module adopts an isolated DC-DC unit, wherein the isolation DC-DC unit adopts an isolation boost full-bridge converter topology to realize independent maximum power tracking control MPPT; and point-to-point balance of power among the collection system sub-modules is effectively realized through the DPBU, so that output voltage of each SM is balanced. While the balance of the output voltage of the IIOS type direct current collection system is effectively realized, the use number of switching tube devices can be reduced, and the current stress of the switching tubes can be reduced.
Description
technical field [0001] The invention belongs to the technical field of power grids, and relates to a voltage equalization circuit suitable for an IIOS type photovoltaic DC step-up collection system. Background technique [0002] With the intensification of global environmental pollution and fossil energy crisis, clean and renewable energy such as solar energy has received more and more attention, and the photovoltaic power generation industry has developed rapidly. At the same time, due to the advantages of low loss and high stability, the application of DC transmission technology in the field of new energy is gradually becoming a research hotspot. Based on this, some relevant scholars have proposed photovoltaic DC boost integration technology. , which has the following advantages: I) the photovoltaic cell itself outputs DC, and the use of DC collection can reduce the AC-DC conversion link and improve efficiency; II) no harmonic problems, no frequency and reactive power prob...
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Login to View More IPC IPC(8): H02M3/335H02M3/158H02J3/38
CPCH02M3/33569H02M3/33523H02M3/1582H02J3/381H02J2300/26Y02E10/56Y02B70/10
Inventor郭珂朱立尧周林毛明轩郝高锋
OwnerCHONGQING UNIV