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Square wave compensation control method for expanding the operating range of cascaded h-bridge photovoltaic inverters

A photovoltaic inverter, compensation control technology, applied in photovoltaic power generation, single grid parallel feeding arrangement, output power conversion device, etc. and other problems, to achieve the effect of small capacitor voltage fluctuation and expansion of the operating range

Active Publication Date: 2019-08-02
HEFEI UNIV OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] 1) When the output power of each H-bridge unit is seriously unbalanced, although the reactive power compensation control strategy can ensure that all H-bridge units are not modulated, the power factor of the inverter is low and cannot meet the grid-connected standard
[0009] 2) Although the hybrid modulation strategy can expand the operating range of the system to a certain extent, the DC side capacitor voltage fluctuates greatly, which will reduce the power generation of the system
[0010] 3) Although the third harmonic compensation strategy can make the system operate at unity power factor and the DC side capacitor voltage fluctuation is small, the ability to deal with system imbalance is weak

Method used

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  • Square wave compensation control method for expanding the operating range of cascaded h-bridge photovoltaic inverters
  • Square wave compensation control method for expanding the operating range of cascaded h-bridge photovoltaic inverters
  • Square wave compensation control method for expanding the operating range of cascaded h-bridge photovoltaic inverters

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Embodiment Construction

[0057] In order to make the purpose, 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.

[0058] figure 1 The main circuit topology of the single-phase cascaded H-bridge photovoltaic grid-connected inverter implemented for the present invention includes N identical H-bridge units, and each H-bridge unit is composed of four fully-controlled switching devices. Each H-bridge front end is connected in parallel with an electrolytic capacitor C i (i=1,2,…,N), each electrolytic capacitor is connected to a photovoltaic cell PV i (i=1, 2, . . . , N) connection. After the AC side outputs of all H-bridges are connected in series, the filter inductor L 1 and L 2 connected to the grid, where R 1 and R 2 Respectively filter inductance L 1 and L 2 equivalent resistance. V in the figure dci and I PVi (i=1,2,...,N) respective...

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Abstract

The invention discloses a square wave compensation control method for enlarging the operating range of a cascaded H-bridge photovoltaic inverter, which belongs to the field of photovoltaic power generation. The main steps are as follows: (1) Independently control the DC side capacitor voltage of all H-bridge units, and obtain the active power command value of the grid-connected current; (2) Realize the no-static control of the grid-connected current, and simultaneously generate an inverter (3) According to the square wave compensation strategy, calculate the modulation wave of each H-bridge module. Compared with the existing published literature, this method can ensure that when the input power of the cascaded H-bridge photovoltaic grid-connected inverter is seriously unbalanced, the unit power factor of the inverter operates normally and the voltage fluctuation of the DC side capacitor is small. Small.

Description

technical field [0001] The invention belongs to photovoltaic power generation technology in the field of electrical engineering, and in particular relates to a square wave compensation control method for expanding the operating range of cascaded H-bridge photovoltaic inverters. Background technique [0002] Compared with traditional inverters, cascaded H-bridge multilevel inverters have the advantages of low grid current harmonic content, low switching frequency, small filter size and easy modularization, etc., so it has attracted the attention of many scholars. In addition, the DC side of each H-bridge unit of the cascaded H-bridge multi-level inverter can be independently powered by a photovoltaic cell, making its independent maximum power point tracking (MPPT—Maximum Power Point Tracking) control possible, so the level The H-bridge multilevel topology is especially suitable for photovoltaic grid-connected inverters. [0003] Although each H-bridge unit of the cascaded H-...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/483H02J3/38
CPCH02J3/385H02M7/483H02M1/007Y02E10/56
Inventor 张兴赵涛毛旺王明达王付胜王佳宁
Owner HEFEI UNIV OF TECH