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Grid connecting method of three-phase high-power inverter with power-frequency isolation transformer

A power frequency isolation and transformer technology, applied in the direction of single-network parallel feeding arrangement, etc., can solve the problems of high-power isolation transformer waste of electric energy, increase the hardware cost of the inverter, and increase the complexity of the inverter software design, etc., to achieve applicable The effect of wide range and small grid-connected impact current

Active Publication Date: 2014-04-30
中国船舶重工集团公司第七一二研究所
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This grid-connected control method brings several problems: First, because the inverter works in the voltage source mode before grid-connected, it is required to install voltage sensors on both sides of the grid-connected contactor, and the conditioning circuit undoubtedly increases the inverter The hardware cost of the inverter; second, the grid-connected inverter needs two sets of control algorithms, voltage control and current control, which increases the complexity of the inverter software design; third, the grid-connected inverter will have a period of Working in the no-load voltage source mode for a long time, the self-loss of the high-power isolation transformer will waste a lot of power

Method used

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  • Grid connecting method of three-phase high-power inverter with power-frequency isolation transformer
  • Grid connecting method of three-phase high-power inverter with power-frequency isolation transformer
  • Grid connecting method of three-phase high-power inverter with power-frequency isolation transformer

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Embodiment

[0025] Step 1, first set the line voltage U of the grid voltage ac and U cb respectively sent to the signal conditioning circuit for detection;

[0026] Step 2, send the detected signal to the digital controller in the digital control circuit, and use the digital control algorithm to calculate the frequency and phase information of the grid voltage in the digital controller; the digital controller calculates the U according to the instantaneous reactive power theory ac and U cb Transform the coordinates of the digital signal of the voltage and voltage to obtain the instantaneous active and reactive components of the voltage and voltage. At the same time, the digital PID regulator is used to adjust the reactive component of the grid voltage. When the reactive component of the grid voltage is set to 0, the obtained coordinate transformation angle is Specifies the phase angle of the phase grid voltage;

[0027] Step 3, the digital controller issues an auxiliary contactor K2 pu...

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Abstract

The invention relates to a grid connecting method of a three-phase high-power inverter with a power-frequency isolation transformer. According to the grid connecting method disclosed by the invention, PWM (Pulse-Width Modulation) pulse enabling is carried out by utilizing high-impedance characteristics of an output grid-connecting loop in the process of inputting the transformer in a limited current manner; amplitude-limiting soft start is carried out; and, because the magnitude of output current of the inverter is limited by resistors connected with the output loop in series, the grid connection operation of an inverter bridge is realized under a lower current state. The grid connecting method disclosed by the invention is applied to a three-phase grid-connected inverter which is accessed to a power grid by using a high-power transformer. The grid connecting control method is simple and reliable and has low grid-connecting impact current and wide application range.

Description

technical field [0001] The invention relates to a grid-connecting method for an inverter, in particular to a grid-connecting method for a three-phase high-power inverter with a power frequency isolation transformer. Background technique [0002] In the existing grid-connected inverters, especially some high-power grid-connected inverters with power frequency isolation transformers, a grid-connected control method is needed. The function of grid-connected control is to control the inverter. Control, to realize the automatic operation of the inverter into the grid, so as to achieve the purpose of the inverter converting various DC power into AC power and feeding it into the AC power grid safely and reliably. [0003] At present, the common grid-connected control method of the high-power inverter with isolation transformer is to first operate the inverter in the voltage source mode. When the voltage frequency, amplitude and phase of the inverter output side are synchronized wit...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/38
Inventor 张鹏余峰梁星星汪洋陈世昌
Owner 中国船舶重工集团公司第七一二研究所
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