A Coordinated and Stable Operation Control Method for an Island DC Microgrid

A DC micro-grid, stable operation technology, applied in the direction of AC network circuit, AC network load balancing, single-network parallel feeding arrangement, etc., can solve the DC bus voltage drop, do not consider the unmatched line impedance, and reduce the economy of the micro-grid and other problems to achieve the effect of eliminating bus voltage drop, improving stability and eliminating influence

Active Publication Date: 2020-09-01
SHANGHAI UNIVERSITY OF ELECTRIC POWER
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Problems solved by technology

Some scholars have proposed an adaptive hierarchical coordination control method, which realizes the SOC balance between parallel multi-energy storage units through the coordinated control of the power distribution level and the power balance level, but this control method does not consider the influence of the mismatched line impedance; In addition, some scholars have proposed to dynamically change the droop coefficient to compensate for the influence of mismatched line impedance, but a large droop coefficient will inevitably cause a large drop in the DC bus voltage, resulting in the unstable operation of the microgrid; it can be achieved by adding a line impedance measurement device , it is convenient to correct the droop coefficient of each energy storage unit, but this control method requires additional hardware devices, which reduces the economy of the microgrid

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  • A Coordinated and Stable Operation Control Method for an Island DC Microgrid
  • A Coordinated and Stable Operation Control Method for an Island DC Microgrid
  • A Coordinated and Stable Operation Control Method for an Island DC Microgrid

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Embodiment

[0054]The purpose of the present invention is to address the low load current distribution accuracy caused by the inconsistency of line impedance parameters and energy storage characteristics among multiple parallel energy storage units when the energy storage system is activated as a loose terminal of the microgrid under the island operation mode of the DC microgrid. In order to solve the problem of large drop of DC bus voltage, a multi-energy storage control method for island DC microgrid considering mismatched line resistance and capacity is proposed. By improving the double closed-loop control of traditional converters, the improved constant voltage droop , which eliminates the impact of the mismatched line impedance and the difference in the initial characteristics of the energy storage itself on the current load distribution of the distributed energy storage units. In order to achieve the SOC balance of each energy storage unit, the SOC balance factor is introduced in the ...

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Abstract

The invention relates to a method for controlling the coordinated and stable operation of an isolated island DC micro-grid. By improving the double closed-loop control of the traditional converter and adopting the improved constant voltage droop control, a current inner loop control reference value is generated. In the current inner loop control, by introducing The SOC balance factor enables each energy storage unit to dynamically adjust the output current reference value of the current inner loop according to its own capacity and the current SOC, and finally realizes the SOC balance among the parallel energy storage units. Compared with the prior art, the present invention eliminates the influence of unmatched line impedance on the accuracy of current load distribution, and does not produce DC bus voltage drop similar to that caused by traditional droop control.

Description

technical field [0001] The invention relates to the field of direct current microgrids, in particular to a method for controlling the coordinated and stable operation of isolated island direct current microgrids. Background technique [0002] Compared with the traditional AC microgrid, the DC microgrid does not need to consider voltage phase and frequency issues due to less energy conversion process, high efficiency, and low loss, so the controllability and reliability of the system operation are greatly improved; when the island is running, the microgrid It is necessary to rely on the coordinated control of distributed power sources in the self-network to maintain the stable operation of the microgrid. Compared with the grid-connected operation mode, the control is more complicated. Since the output of many renewable new energy sources such as photovoltaics and wind power is affected by external natural factors and presents intermittent, random and unstable characteristics,...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/32H02J3/38H02J3/24
CPCH02J3/383H02J3/32H02J3/24H02J3/388Y02E10/56
Inventor 米阳喻思韩云昊何星瑭宋元元颜丽季亮时帅
Owner SHANGHAI UNIVERSITY OF ELECTRIC POWER
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