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Multi-functional grid-connected inverter and grid-connected inverter control method

A compound function and inverter control technology, which can be applied in the direction of converting equipment that can be converted to DC without intermediate conversion, converting irreversible DC power input into AC power output, reactive power compensation, etc., can solve the problem of DC bus voltage requirements High, grid-connected inverters are rare and other issues, to achieve the effect of reducing investment costs and operation and maintenance costs, clear principles, and strong operability

Active Publication Date: 2013-10-30
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The existing grid-connected inverters with composite functions mainly adopt single-phase full-bridge or three-phase full-bridge power electronic topology, and their composite functions are mainly for harmonic current control, which can simultaneously control harmonics at the grid-connected point, There are not many grid-connected inverters with composite functions of reactive power and unbalanced current
In addition, the existing grid-connected inverters with composite functions often have high requirements on the DC bus voltage, requiring multiple DC power supply (photovoltaic cells, energy storage batteries, etc.) can only be connected to its DC bus

Method used

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  • Multi-functional grid-connected inverter and grid-connected inverter control method

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Embodiment 1

[0080] The parameters of each phase for selecting the unbalanced load are: a phase is a 70Ω resistance load, the b phase is a 40Ω resistance and a 118uF capacitance series load, and the c phase is a 50Ω resistance load. Picture 9 It is given that when the non-linear load switch S1 is open and the unbalanced load switch S2 is closed, the composite function grid-connected inverter before and after the grid-connected power command is P=15kW and Q=0var. Grid side current i sb And i sc Experimental waveform, Picture 10 The corresponding grid-side active and reactive power experimental waveforms are given. From Picture 9 , Picture 10 It can be found that due to the existence of unbalanced and reactive load, before the composite function grid-connected inverter is put into the compensation function, the three-phase grid-side current is obviously unbalanced, and under the action of the unbalanced current, the grid-side power is 2 Frequency doubling fluctuations. At the same time,...

Embodiment 2

[0082] The non-linear load is selected as an uncontrolled rectifier load, and its DC load resistance is 50Ω. Still keep P=15kW, Q=0var, Picture 11 When the unbalanced composite switch S2 is open and the non-linear load switch S1 is closed, the grid-side voltage u before and after the grid-connected inverter composite function is turned on is given. sa And grid side current i sa Experimental waveform, Picture 12 The corresponding grid-side active and reactive power experimental waveforms are given. From Picture 11 with Picture 12 It is not difficult to find that since the non-linear load is an uncontrolled rectifier load with resistance on the DC side, before the combined function of the grid-connected inverter is put into use, the grid-side current is the difference between the non-linear load current and the output current of the grid-connected inverter. Superposition, under the action of non-linear load current, presents large harmonic distortion. At the same time, th...

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Abstract

The invention belongs to the field of electrical engineering, distributed power generation and power quality control, and aims to provide a multi-functional grid-connected inverter and a grid-connected inverter control method. The grid-connected inverter comprises a direct-current bus bar with a capacitor and three sets of single-phase full-bridge inverter circuits sharing the direct-current bus bar, the direct-current output ends of a distributed power supply or a grid-connected energy-storing generating set are connected to both ends of the capacitor of the direct-current bus bar, the output of each set of single-phase full-bridge inverter circuit is connected to a filter, and the output ends of each filter are connected with a distribution network of the 380V voltage class through a single-phase step-up isolation transformer. According to the invention, the grid-connected inverter equipment is effectively utilized to carry out effective control on the power quality of points of interconnection, so that the grid-connected inverter is multi-purpose and multi-functional, the cost performance of the grid-connected inverter is enhanced, the investment, operation and maintenance cost of a system can be reduced, and the reliability of the system can be enhanced. The principle of the provided control scheme is clear, and the control scheme is highly operable and reliable in operation.

Description

Technical field [0001] The invention relates to a grid-connected inverter with composite functions and a grid-connected inverter control method, belonging to the fields of electrical engineering, distributed power generation and power quality management. Background technique [0002] Since the distributed power generation system is not only an important link for connecting renewable energy to the grid, but also can improve the stability of the traditional grid to a certain extent, it has received more and more attention. Because of the intermittent and random characteristics of wind energy, photovoltaics and other renewable energy sources, they are typical uncontrollable sources. How to better integrate uncontrollable renewable energy into the power grid has been a hot research topic for a long time. In order to solve this problem, some scholars have proposed the concept of microgrid. As a local power supply system that integrates multiple renewable energy sources, energy stora...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/48H02M5/10H02J3/38H02J3/18H02J3/01
CPCY02E10/563Y02E40/30Y02E10/56Y02E40/40
Inventor 杨欢曾正赵荣祥朱明磊汤浩金磊
Owner ZHEJIANG UNIV