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Control method of quasi-z source cascaded inverter system based on module power difference

A technology of module power and control method, which is applied in the direction of AC network circuit, electrical components, single-network parallel feeding arrangement, etc., and can solve problems such as mutual constraints, unstable operation of the system, and grid-connected current distortion.

Active Publication Date: 2021-01-22
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When the difference in module output power is large, using the existing grid-connected control method will cause grid-connected current distortion, and the system will not be able to operate stably in severe cases
This is because the quasi-Z source cascaded multilevel inverter module is based on multiplexing the zero state of the switch tube to realize the single-stage system boost and invert functions, so the module input voltage, DC bus voltage and the overall output power of the system The voltage has a strong coupling relationship, and there will be mutual constraints

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  • Control method of quasi-z source cascaded inverter system based on module power difference
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  • Control method of quasi-z source cascaded inverter system based on module power difference

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Embodiment Construction

[0037] The control method of the invention is applied to a quasi-Z source cascaded inverter system based on module power differences. The system is composed of N independent photovoltaic cells, N quasi-Z source H-bridge inverter modules, filters and an AC power grid, where N is an integer.

[0038] The method includes a system parameter determination step and an MPPT control step of automatic power balance.

[0039] The system parameter determining step is used to determine the system parameters according to the power difference among the various quasi-Z source inverter modules in the system.

[0040] The MPPT control step of the automatic power balance is used to control the system according to the effective value of the modulation signal of the quasi-Z source H-bridge inverter module, so as to prevent the output voltage of the system from being distorted.

[0041] Before explaining the above two steps, the principle of the quasi-Z source cascaded multilevel inverter is firs...

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Abstract

The invention provides a modular power difference-based control method of a quasi-Z source cascaded inverter system. The system comprises N independent photovoltaic cells, N quasi-Z source H-bridge inverter modules, a filter and an AC power grid, wherein N is an integer. The method comprises the steps of system parameter determination and automatic power balancing maximum power point tracking (MPPT) control. By employing the system, an output waveform without distortion still can be maintained when the modular power difference is relatively large.

Description

technical field [0001] The invention relates to the field of photovoltaic technology, in particular to a control method for a quasi-Z source cascaded inverter system based on module power differences. Background technique [0002] With the deepening of photovoltaic civilian use, more and more photovoltaic systems are connected to the grid in the form of distributed power generation, and they are closer to the user side. "Economy, reliability, safety, and ease of use" are further requirements for the comprehensive performance of distributed photovoltaic power generation systems. There are many advantages when cascaded H-bridge inverters are used in distributed photovoltaic grid-connected power generation systems, such as: modular design, independent DC bus voltage control and distributed maximum power point tracking, and power devices with lower voltage levels Realize transformerless grid connection and so on. At present, a new idea is to add a quasi-Z source impedance netw...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/38
CPCH02J3/383H02J3/385H02J2203/20Y02E10/56
Inventor 李媛张芮
Owner SICHUAN UNIV