Microgrid grid-connected method, device and system based on joint control

A joint control and micro-grid technology, applied to circuit devices, electrical components, AC network circuits, etc., can solve problems such as grid connection failure, protection malfunction, DC micro-grid power oscillation, etc., to avoid the sharp increase of current and avoid Effects of Power Transients

Inactive Publication Date: 2020-04-21
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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  • Microgrid grid-connected method, device and system based on joint control
  • Microgrid grid-connected method, device and system based on joint control
  • Microgrid grid-connected method, device and system based on joint control

Examples

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 invention relates to a microgrid grid-connected method, device and system based on joint control, and the method comprises the steps: obtaining a grid-connected signal of a DC microgrid in real time, transmitting a first switching-off instruction to a PCC switch according to the grid-connected signal, and transmitting a switching-on instruction to a grid-connected inverter after preset delay time; after the grid-connected inverter is started according to the starting instruction, setting the grid-connected inverter to be in a first control mode, and setting direct-current energy storage tobe in a second control mode; setting an active control instruction of the grid-connected inverter, and acquiring exchange power and direct-current voltage of direct-current energy storage in real time according to the active control instruction; and judging whether the exchange power meets an exchange power criterion or not and judging whether the direct current voltage meets a direct current voltage criterion or not, and if so, switching the grid-connected inverter into a third control mode to finish grid connection. The direct-current microgrid can be flexibly transited to a normal operation state after grid connection is completed in an island mode based on the joint control of the grid-connected inverter and direct-current energy storage,.

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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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
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