Phase-to-phase power balance control method for three-phase cascaded h-bridge photovoltaic inverter

A photovoltaic inverter, balanced control technology, applied in photovoltaic power generation, multi-phase network asymmetry reduction, multi-phase network elimination/reduction of asymmetry and other directions, can solve problems such as phase-to-phase power imbalance, grid-connected current distortion, etc.

Active Publication Date: 2020-07-07
HEFEI UNIV OF TECH
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  • Claims
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Problems solved by technology

[0009] The problem to be solved by the present invention is to overcome the limitations of the above-mentioned solutions, aiming at the problem of grid-connected current distortion caused by the un

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  • Phase-to-phase power balance control method for three-phase cascaded h-bridge photovoltaic inverter
  • Phase-to-phase power balance control method for three-phase cascaded h-bridge photovoltaic inverter
  • Phase-to-phase power balance control method for three-phase cascaded h-bridge photovoltaic inverter

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Embodiment Construction

[0093] 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.

[0094] figure 1 It is a three-phase cascaded H-bridge photovoltaic inverter topology according to the embodiment of the present invention, including three phases A, B, and C, and each phase consists of N H-bridge units with photovoltaic modules and an inductor L S The H-bridge unit is composed of four power switching devices, and the DC side of each H-bridge is independently powered by photovoltaic modules. The rated operating conditions of the photovoltaic modules are at a temperature of 25C° and a light intensity of 1000W / m 2 The maximum power point voltage is 30.59V, each photovoltaic module is connected to each H-bridge unit through a 18.8mF capacitor, and each phase is connected to a 1.8mH inductor L S Connect to grid.

[009...

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Abstract

The invention discloses a three-phase cascade H-bridge photovoltaic inverter interphase power balance control method, and aims to solve the problem of grid-connected current distortion caused by inputpower imbalance of a direct-current side photovoltaic module of an existing three-phase cascade H-bridge photovoltaic inverter. The method includes the steps: (1) total direct-current side voltage control for tracking the total maximum power point voltage of a total direct-current side of an H-bridge unit to obtain a systematic active current instruction value; (2) grid-side current control, to be specific, independently controlling active current and reactive current and generating three-phase inverter modulating wave signals; (3) interphase power balance control, to be specific, tracking instruction voltage of an actual value of total voltage of each phase by an interphase voltage regulator to obtain a regulating factor of the total voltage of each phase and to correct the inverter modulating wave signals, and accordingly distributing output modes of the H-bridge unit to realize interphase power balance control. The method can effectively adapt to various working conditions, and interphase power imbalance is inhibited within a wide range.

Description

technical field [0001] The invention relates to a method for controlling phase-to-phase power balance of a three-phase cascaded H-bridge photovoltaic inverter, and belongs to the technical field of power balance control of cascaded photovoltaic 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 generation, making MPPT control of...

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Application Information

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IPC IPC(8): H02J3/38H02J3/26
CPCH02J3/26H02J3/383H02J3/385Y02E10/56Y02E40/50
Inventor 张兴毛旺赵涛胡玉华王付胜戴之强
Owner HEFEI UNIV OF TECH
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