Control method for reducing photovoltaic power generation system grid-connected point voltage unbalance

A photovoltaic power generation system, voltage unbalanced technology, applied in the direction of photovoltaic power generation, single grid parallel feeding arrangement, etc., can solve the problem of high harmonic content of current injected into the grid, affecting the friendship between the inverter and the grid, safe operation, and grid voltage distortion And other issues

Active Publication Date: 2015-11-11
NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Among them, the grid-connected inverter control problem is particularly prominent under grid voltage imbalance caused by factors such as grid asymmetrical faults or asymmetrical loads.
[0003] When the grid voltage is unbalanced, there will be a negative sequence component in the grid voltage, which will lead to the generation of AC negative sequence current, so that the DC voltage will generate a second harmonic voltage, and the AC side will generate a third harmonic current, and the transmitted power will have a second harmonic A series of problems such as high harmonic content of the current injected into the grid and further distortion of the grid voltage will seriously affect the friendly and safe operation of the inverter and the grid

Method used

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  • Control method for reducing photovoltaic power generation system grid-connected point voltage unbalance
  • Control method for reducing photovoltaic power generation system grid-connected point voltage unbalance
  • Control method for reducing photovoltaic power generation system grid-connected point voltage unbalance

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Embodiment 1

[0061] Such as figure 1 As shown, a control method for reducing the voltage unbalance at the grid-connected point of a photovoltaic power generation system includes the following steps:

[0062] Step 1: Calculate the reference current: including the following specific steps:

[0063] Step 1-1: Calculate the positive sequence current of the positive sequence circuit:

[0064] I P · = U 1 - U 2 P Z ∠ - δ - - - ( 1 )

[0065] where, where, U 1 is the rated voltage of grid-connected point, U 2 P is the positive sequence component of the fault point voltage, Z is the equivalent impedance modulus of the line, δ is the impedance...

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Abstract

The present invention discloses a control method for reducing photovoltaic power generation system grid-connected point voltage unbalance. The method comprises the steps of calculating reference current and setting the reference current. The limited factors of a distributed PV power generation system capacity, grid voltage negative sequence imbalance, a line equivalent impedance, and grid-connected point maximum current are considered, and the reference current setting of a grid-connected point voltage support effect is realized. According to the method, when the grid voltage is unbalanced, by using PV system power capacity, through the injection of given appropriate reference current, the grid-connected point voltage support is realized, the grid-connected point negative sequence voltage unbalance is reduced.

Description

technical field [0001] The invention relates to a control method for reducing the voltage unbalance degree of a distribution network, in particular to a control method for reducing the voltage unbalance degree of a grid-connected point of a photovoltaic power generation system, and belongs to the technical field of grid-connected control of new energy power generation in a power system. Background technique [0002] With the rapid increase of grid-connected capacity of photovoltaic power generation systems, the interaction between photovoltaic power generation systems and power grids has become increasingly prominent, and the control research of photovoltaic power generation systems under abnormal grid conditions is receiving more attention. Among them, the grid-connected inverter control problem is particularly prominent under the unbalanced grid voltage caused by grid asymmetrical faults or asymmetrical loads. [0003] When the grid voltage is unbalanced, there will be a n...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38
CPCY02E10/56
Inventor 李建文齐飞李永刚
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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