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Method for improving power transmission capability of grid-connected inverter under extremely weak power grid

A power transmission and inverter technology, applied in reactive power compensation, photovoltaic power generation, AC network voltage adjustment, etc., can solve problems such as insufficient power transmission capacity of grid-connected inverters, improve power transmission capacity, and expand output current The effect of the cap

Active Publication Date: 2022-04-05
STATE GRID HEILONGJIANG ELECTRIC POWER CO LTD ELECTRIC POWER RES INST +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the problem of insufficient power transmission capability of existing grid-connected inverters under extremely weak grids, and propose a method for improving the power transmission capabilities of grid-connected inverters under extremely weak grids

Method used

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  • Method for improving power transmission capability of grid-connected inverter under extremely weak power grid
  • Method for improving power transmission capability of grid-connected inverter under extremely weak power grid
  • Method for improving power transmission capability of grid-connected inverter under extremely weak power grid

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specific Embodiment approach 1

[0027] Specific implementation mode one: combine figure 1 with figure 2 Describe this implementation mode, a method for improving the power transmission capacity of a grid-connected inverter under an extremely weak grid described in this implementation mode, the method includes the following content:

[0028] Step 1. Collect the common coupling point voltage v p Input the voltage sampling function, the output value is transformed by the Parker converter, and the d-axis component v of the common coupling point voltage is obtained d and the common coupling point voltage q-axis component v q ;

[0029] Step 2. Common coupling point voltage q-axis component v d After the proportional-integral controller, the obtained value is consistent with the given angular frequency ω N The sum is obtained to obtain the output angular frequency ω of the phase-locked loop c Send it to the integration link to get the output phase θ of the phase-locked loop c , the output phase θ of the PL...

specific Embodiment approach 2

[0039] Embodiment 2: This embodiment is to further limit the method for improving the power transmission capacity of grid-connected inverters under extremely weak power grids described in Embodiment 1. In this embodiment, it is characterized in that the reactive power compensation coefficient K d Expressed as:

[0040]

[0041] In the formula, V g is the grid voltage amplitude, I 1 is the given value of inverter d-axis current, X g is the grid impedance.

specific Embodiment approach 3

[0042] Specific Embodiment 3: This embodiment further limits the method for improving the power transmission capacity of grid-connected inverters under extremely weak power grids described in Specific Embodiment 2. In this embodiment, the inverter output current q-axis refers to Value I qr Expressed as:

[0043] I qr =(v d -V g )K d G df (s) Formula 2,

[0044] In the formula, I qr is the inverter output current q-axis reference value, v d is the q-axis component of the common coupling point voltage, K d is the reactive power compensation coefficient, G df (s) is a low-pass filter.

[0045] In this embodiment, the PCC voltage amplitude information is introduced into the q-axis current reference quantity of the inverter current loop to realize feedforward control, and the reference quantity is changed from 0 to: I qr =(v d -V g )K d G df (s); I qr is the inverter output current q-axis reference value, v d is the d-axis component of the PCC voltage, that is, i...

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Abstract

The invention discloses a method for improving the power transmission capability of a grid-connected inverter under an extremely weak power grid, relates to the technical field of grid-connected inverter control and power electronics, and aims to solve the problem of insufficient power transmission capability of the existing grid-connected inverter under the extremely weak power grid. PCC voltage amplitude information is introduced into a grid-connected current control structure, reactive power output is adaptively adjusted according to grid-connected current and power grid impedance to compensate PCC voltage amplitude drop caused by increase of output current, and the output range of the grid-connected current is expanded. The method is used for improving the power transmission capacity of the grid-connected inverter and the adaptive capacity of the grid-connected inverter to different output working conditions and different access sites.

Description

technical field [0001] The invention relates to a method for improving the power transmission capability of a grid-connected inverter under an extremely weak power grid, and relates to the technical fields of grid-connected inverter control and power electronics. Background technique [0002] In order to solve the problem of environmental pollution caused by traditional fossil energy, photovoltaic, wind power and other new energy power generation technologies have received extensive attention. In order to achieve the goals of "carbon peak" and "carbon neutrality" put forward by my country in 2021, vigorously developing new energy power generation has become a major strategic demand in China. As the grid-connected interface of the new energy power generation unit, the grid-connected inverter exchanges power with the grid by controlling its grid-connected current, which is an indispensable key link for new energy power generation. New energy power generation systems are gener...

Claims

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Application Information

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IPC IPC(8): H02J3/16H02J3/38
CPCY02E10/56Y02E40/30
Inventor 关万琳李浩昱徐明宇陈晓光荣爽刘延龙尤超宋柏越董尔佳刘志鹏张明江胡远婷崔佳鹏吕飞孔郝文波穆兴华
Owner STATE GRID HEILONGJIANG ELECTRIC POWER CO LTD ELECTRIC POWER RES INST
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