Harmonic compensation control method of cascade H bridge photovoltaic grid-connected inverter

A photovoltaic inverter and harmonic compensation technology, applied in photovoltaic power generation, single-network parallel feeding arrangement, output power conversion device, etc., can solve large fluctuations in capacitor voltage, reduce system power generation, and low system power factor and other problems, to achieve the effect of small fluctuations in capacitor voltage and expand the operating range

Active Publication Date: 2018-01-09
HEFEI UNIV OF TECH
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Problems solved by technology

[0008] 1) When the output power of each H-bridge module is seriously unbalanced, although the reactive power compensation control strategy can ensure that all H-bridge modules are not modulated, the system power factor is low and cannot meet the grid-connected standard
[0009] 2) Although the hybrid modulation strategy can expand the operating range o

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  • Harmonic compensation control method of cascade H bridge photovoltaic grid-connected inverter
  • Harmonic compensation control method of cascade H bridge photovoltaic grid-connected inverter
  • Harmonic compensation control method of cascade H bridge photovoltaic grid-connected inverter

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[0057] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following describes the present invention clearly and completely with reference to the accompanying drawings and embodiments.

[0058] figure 1 The main circuit topology structure of the single-phase cascaded H-bridge photovoltaic grid-connected inverter implemented in the present invention includes N identical H-bridge units, and each H-bridge unit is composed of four fully-controlled switching devices. An electrolytic capacitor C is connected in parallel at the front end of each H bridge 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, they pass through 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 The equivalent resistance. V in the picture dci And I PVi (i=1, 2,.....

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Abstract

The present invention discloses a harmonic compensation control method of a cascade H bridge photovoltaic grid-connected inverter, belonging to the photovoltaic generation field. The method mainly comprises the following steps: (1) performing independent control of capacitor voltages at direct current sides of all the H bridge units, and obtaining an active instruction value of a power grid current; (2) realizing astatic control of the power grid current, and generating total modulation voltage of an inverter and modulation degrees of all the H bridge units; and (3) calculating a modulation wave of each H bridge module according to a harmonic wave compensation strategy. Compared to literatures disclosed in the prior art, the harmonic compensation control method of the cascade H bridge photovoltaic grid-connected inverter can ensure normal operation of inverter unit power factors and small fluctuation of capacitor voltages at the direct current sides when the input power of the H bridgephotovoltaic grid-connected inverter is severely imbalance.

Description

technical field [0001] The invention belongs to the photovoltaic power generation technology in the field of electrical engineering, and in particular relates to a harmonic compensation control method for cascaded H-bridge photovoltaic grid-connected inverters. Background technique [0002] Compared with the traditional inverter, the cascaded H-bridge multilevel inverter has the advantages of low harmonic content of grid current, 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-bridge ph...

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Application Information

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IPC IPC(8): H02M7/483H02M1/12H02J3/38
CPCY02E10/56
Inventor 张兴赵涛毛旺王明达王付胜李飞
Owner HEFEI UNIV OF TECH
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