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A method, device and system for grid connection of microgrid based on joint control

A joint control and micro-grid technology, applied in the direction of circuit devices, electrical components, AC network circuits, etc., can solve problems such as protection misoperation, grid connection failure, DC micro-grid power oscillation, etc., to avoid power transients and current The effect of a sharp increase

Inactive Publication Date: 2021-04-27
STATE GRID HUNAN ELECTRIC POWER
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, the existing research on DC microgrids mostly focuses on how to coordinate the inverters in DC microgrid grid-connected operation or island operation mode, and does not discuss how to avoid power transients in the process of switching between the two modes. Conduct in-depth research on issues such as closing shocks caused by substations
When the DC microgrid changes from the island mode to the grid-connected mode, directly closing the PCC switch (Point of Common Coupling, public connection point switch) will cause the current flowing through the PCC switch to increase sharply, and in severe cases, it will cause the DC microgrid internal The power oscillates, which leads to protection malfunction and causes the grid-connected inverter of the DC microgrid to be blocked, that is, the grid-connected failure

Method used

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  • A method, device and system for grid connection of microgrid based on joint control
  • A method, device and system for grid connection of microgrid based on joint control
  • A method, device and system for grid connection of microgrid based on joint control

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Experimental program
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Effect test

Embodiment 1

[0037] Embodiment one, as figure 1 As shown, a microgrid grid-connected method based on joint control includes the following steps:

[0038] S1: Acquire the grid-connected signal of the DC microgrid switching from the island mode to the grid-connected mode, send the first closing command to the PCC switch according to the grid-connecting signal, and send the opening command to the grid-connected inverter after a preset delay time instruction;

[0039] S2: After the grid-connected inverter is turned on according to the start-up instruction, set the grid-connected inverter to a first control mode, and set the DC energy storage to a second control mode;

[0040] S3: In the first control mode, set the active power control command of the grid-connected inverter, and obtain the exchange of the DC energy storage in real time in the second control mode according to the active power control command Power and DC voltage;

[0041] S4: Judging whether the switching power meets a preset...

Embodiment 2

[0072] Embodiment two, such as Figure 9 As shown, a microgrid grid-connected device based on joint control, including a signal acquisition module, an instruction sending module, a mode setting module, a data acquisition module, a data analysis module and a mode switching module;

[0073] The signal acquisition module is used to acquire the grid-connected signal for switching the DC microgrid from the island mode to the grid-connected mode;

[0074] The instruction sending module is configured to send a first closing instruction to the PCC switch according to the grid-connected signal, and send an opening instruction to the grid-connected inverter after a preset delay time;

[0075] The mode setting module is configured to set the grid-connected inverter to the first control mode after the grid-connected inverter is turned on according to the start instruction, and set the DC energy storage to The second control mode; it is also used to set the active power control command of t...

Embodiment 3

[0092] Embodiment 3. A microgrid grid-connected system based on joint control, including a micro-grid grid-connected device based on joint control in Embodiment 2, and also includes a PCC switch, a grid-connected inverter, and a DC energy storage;

[0093] The microgrid grid-connected device based on joint control is electrically connected to the PCC switch, the grid-connected inverter and the DC energy storage, and the grid-connected inverter is electrically connected to the DC energy storage, The grid-connected inverter is also electrically connected to the AC power grid, and the PCC switch is set at the common connection point between the grid-connected inverter and the AC power grid, and is connected to the grid-connected inverter respectively. It is electrically connected with the AC power grid.

[0094] Based on the joint control of the grid-connected inverter and DC energy storage, it effectively avoids the closing impact problem caused by the power transient caused by ...

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Abstract

The present invention relates to a method, device and system for grid-connecting a microgrid based on joint control, which includes acquiring a grid-connecting signal of a DC micro-grid in real time, sending a first closing command to a PCC switch according to the grid-connecting signal, and switching off the PCC within a preset delay time Afterwards, an opening instruction is sent to the grid-connected inverter; when the grid-connected inverter is turned on according to the opening instruction, the grid-connected inverter is set to the first control mode, and the DC energy storage is set to the second control mode; Set the active power control command of the grid-connected inverter, and obtain the switching power and DC voltage of the DC energy storage in real time according to the active power control command; judge whether the switching power meets the switching power criterion and judge whether the DC voltage meets the DC voltage criterion, if both If so, switch the grid-connected inverter to the third control mode to complete the grid-connection. Based on the joint control of the grid-connected inverter and the DC energy storage, the invention realizes the flexible transition of the DC micro-grid to the normal operation state after the grid-connection is completed in the island mode.

Description

technical field [0001] The invention relates to the field of grid connection and control of micro grids, in particular to a method, device and system for grid connection of micro grids based on joint control. Background technique [0002] With the continuous increase of urban production and electricity consumption, the traditional fossil energy is consumed rapidly, and the problems of energy shortage and environmental pollution are becoming more and more serious. The proportion of distributed power generation mainly based on new energy power generation in the power grid continues to increase. However, in the AC microgrid, the distributed power supply needs to be synchronized with the phase angle and frequency of the large power grid through the inverter, and the control process is relatively complicated. Therefore, the AC microgrid is not suitable for large-scale access to the distributed power supply. Under this premise, the development of DC microgrid is the trend and dir...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/38H02J3/24
CPCH02J3/24H02J3/381
Inventor 张孝军徐宇新黄勇王阳光
Owner STATE GRID HUNAN ELECTRIC POWER