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Method for controlling three-phase current transformer in photovoltaic grid-connected power generating system

A three-phase converter, grid-connected power generation technology, applied in photovoltaic power generation, conversion of irreversible DC power input to AC power output, single-net parallel feeding arrangement, etc., can solve the conversion efficiency of photovoltaic grid-connected converters Can not be lower than 97% and other issues, to achieve the effect of good abnormality crossing ability, high reliability and fast response speed

Active Publication Date: 2014-04-16
WUHAN NEW ENERGY INST OF ACCESS EQUIP & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, it is required that the conversion efficiency of photovoltaic grid-connected converters with single-stage conversion should not be lower than 97% at rated load

Method used

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  • Method for controlling three-phase current transformer in photovoltaic grid-connected power generating system
  • Method for controlling three-phase current transformer in photovoltaic grid-connected power generating system
  • Method for controlling three-phase current transformer in photovoltaic grid-connected power generating system

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Experimental program
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Effect test

Embodiment 1

[0037] Such as figure 2 Shown is a flowchart of a control method for a three-phase converter in a photovoltaic power generation system, including the following steps:

[0038] 1) In the photovoltaic converter, the three-phase voltage U of the power grid is obtained by sampling a , U b , U c, and then the digital signal processor (DSP) uses the digital delay signal cancellation algorithm (DSC) to obtain the positive and negative sequence d and q components of the grid voltage, and then uses the positive sequence q-axis component of the grid voltage as a software phase-locked loop (SPLL) The feedback input of the PI regulator controls the positive-sequence q-axis component of the grid voltage to 0 through the PI algorithm to output the adjustment amount of the converter to track the grid frequency f, thereby locking the grid frequency f and the positive-sequence phase angle θ in real time.

[0039] 2) According to the positive sequence phase angle of the power grid, the dq c...

Embodiment 2

[0060] The difference between this embodiment and Embodiment 1 is that the pulse width modulator is a voltage space vector pulse width modulator, and the modulation method adopted is a voltage space vector pulse width modulation method.

[0061] The SVPWM (voltage space vector) calculation submodule in the DSP program is based on the obtained U cdref , and U cqref The value is used to calculate the corresponding conduction time of each phase bridge arm IGBT, and write it into the corresponding comparison register in the DSP, and the DSP generates six relevant PWM signals. Finally, the IGBT drive circuit converts it into a corresponding isolated level signal to drive the IGBT to work, and completes the energy conversion process.

[0062] The advantage of adopting the voltage space vector pulse width modulation method is that it is suitable for the digital control system, and the duty ratio of the effective switching vector of the converter can be calculated according to the in...

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Abstract

The invention discloses a method for controlling a three-phase current transformer in a photovoltaic grid-connected power generating system. The method comprises the following steps of: replacing the hardware phase locked loop algorithm with the software phase locked loop algorithm based on digital delay signal cancellation algorithm so as to quickly and accurately realize phase locking even in the unbalanced grid condition, and quickly and accurately searching the overall maximum power point in a photovoltaic array by using the overall maximum power point tracking algorithm to avoid unnecessary power disturbance and loss. The current transformer has good grid voltage abnormality ride-through capability by using the AC overcurrent and short circuit fault protection method based on three-loop control, the response speed and the reliability are high. For different impact loads or short circuit, the output current can be effectively limited. The adopted space vector pulse width modulation manner is applicable to a digital control system, and the duty ratio of the effective on-off vector of the three-phase current transformer can be calculated according to input signals so as to effectively control the on-off of the current transformer.

Description

technical field [0001] The invention relates to a control method of power generation equipment, in particular to a control method of a three-phase converter in a photovoltaic grid-connected power generation system, and belongs to the application field of photovoltaic power generation system control technology. Background technique [0002] Solar energy is widely distributed and easy for people to use. Solar photovoltaic power generation, a clean, environmentally friendly and renewable new power generation method, has irreplaceable unique advantages compared with nuclear power, wind power and hydropower, and is becoming an important alternative energy source in the energy structure. It has received extensive attention from countries all over the world. The solar photovoltaic grid-connected converter is a key component connecting the photovoltaic array module and the grid. It completes the two main tasks of controlling the photovoltaic array module to operate at the maximum po...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/48H02J3/38
CPCY02E10/563Y02E10/56
Inventor 揭贵生汪光森吴振兴胡安周亮林城美阳习党朱威杨华
Owner WUHAN NEW ENERGY INST OF ACCESS EQUIP & TECH
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