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Method for suppressing direct current side voltage ripples of alternating current and direct current hybrid micro-grid

A technology of AC-DC mixing and DC side voltage, which can be applied in the direction of reducing harmonics/ripples in DC circuits, AC-DC network circuit layout, and DC network circuit devices, etc. Actions, affecting the normal operation of the power grid on both sides of the AC and DC, to achieve the effect of reducing governance costs, widening bandwidth, and high gain

Active Publication Date: 2021-10-19
ELECTRIC POWER RES INST STATE GRID SHANXI ELECTRIC POWER +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In the case of unbalanced voltage of the AC subnet in the AC-DC hybrid microgrid, the AC subnet and the DC subnet will have twice the frequency of power transfer, and at the same time, the double frequency ripple voltage will be generated on the DC voltage bus, which will affect the load. Stable operation, causing the protection action of the AC-DC hybrid microgrid, affecting the normal operation of the grid on both sides of the AC and DC, etc., the invention provides a method for suppressing the voltage ripple on the DC side of the AC-DC hybrid microgrid

Method used

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  • Method for suppressing direct current side voltage ripples of alternating current and direct current hybrid micro-grid
  • Method for suppressing direct current side voltage ripples of alternating current and direct current hybrid micro-grid
  • Method for suppressing direct current side voltage ripples of alternating current and direct current hybrid micro-grid

Examples

Experimental program
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Effect test

Embodiment 1

[0088] An AC / DC hybrid microgrid model system ( figure 1 ): including DC subnetwork, AC subnetwork, AC / DC converter DC / AC and filter, among which the AC subnetwork is connected to the AC subnetwork through the AC / DC converter DC / AC and filter LCL; the DC subnetwork includes distributed Power supply, converter DC / DC, DC load, DC active filter and DC bus, the distributed power supply of the system is connected to the DC bus through the DC / DC converter, and the DC bus is connected to the DC load and DC active filter ; The AC subnet includes system distributed power supply, DC / AC, AC busbar, and AC load. The system distributed power supply is connected to the AC busbar through the DC / AC converter, and the AC busbar is connected to the AC load.

Embodiment 2

[0090] Establishment of Mathematical Model of Converter

[0091] according to figure 2 The converter model establishes the dynamic equation of the AC side of the converter as follows:

[0092]

[0093] The above dynamic equations are transformed into the dq rotating coordinate system by using the Parker transformation. where i 1A i 1B i 1C Convert to i in the dq coordinate system 1d i 1q i 2A i 2B i 2C Convert to i in the dq coordinate system 2d i 2q ; A , U B , U C Convert to U in the dq coordinate system d , U q ; cA , U cB , U cC Convert to U in the dq coordinate system cd , U cq ; gA , U gB , UgC Convert to U in the dq coordinate system gd , U gq ; L 1A = L 1B = L 1C =L 1 ; L 2A = L 2B = L 2C = L 2 ;C A =C B =C C =C; w is the angular frequency of AC subnetwork voltage;

[0094]

[0095] image 3 It is the block diagram of the converter control.

Embodiment 3

[0097] Suppression Method of DC Voltage Ripple in AC-DC Hybrid Microgrid

[0098] 1. Perform a suppression of the DC voltage ripple on the AC side, including the following steps:

[0099] Step 1. Use the all-pass filter method to decompose the AC subnetwork voltage and the current into the AC subnetwork into positive and negative sequence components in the αβ coordinate system, and transform the positive and negative sequence components in the αβ coordinate system into the positive and negative sequence components in the dq coordinate system. Negative sequence component; specifically:

[0100] The specific principle of the all-pass filter method is as follows: First, the unbalanced component X is moved to 90°

[0101]

[0102] In the formula The positive and negative sequence components can be obtained by multiplying the unbalanced component X by ρ and adding and subtracting the unbalanced component, namely:

[0103]

[0104] Use an all-pass filter during simulation ...

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Abstract

The invention belongs to the field of electric power systems, and particularly relates to a method for suppressing direct current side voltage ripples of an alternating current and direct current hybrid micro-grid. In order to solve the problem of direct current side frequency doubled ripple caused under the condition of voltage imbalance of an alternating current sub-grid, the method considers the alternating current side and the direct current side of the alternating current and direct current hybrid micro-grid cooperatively, and performs primary suppression on direct current voltage ripple on the alternating current side, namely, a negative sequence component compensation strategy is used; secondary suppression is carried out on direct current voltage ripples on the direct current side, that is, an improved direct current active power filter (DC-APF) is used, and the improved DC-APF uses a quasi-proportional resonance controller (QPR) to accurately track frequency doubled pulsation on the direct current side. Meanwhile, an alternating current and direct current hybrid micro-grid model system is built by utilizing MATLAB / Simulink, and a simulation result shows that compared with a traditional method for controlling on an alternating current side or a direct current side, the suppression method disclosed by the invention has the advantages that the direct current voltage ripple content can be reduced by about 4 times, so that the fluctuation of the direct current side bus voltage of the alternating current and direct current hybrid micro-grid can be effectively suppressed.

Description

technical field [0001] The invention belongs to the field of electric power systems, and specifically relates to a method for suppressing voltage ripple on a DC side of an AC-DC hybrid microgrid. Background technique [0002] The AC-DC hybrid microgrid is considered to be the development direction of the future smart grid because of its reliability, flexibility and ability to accommodate renewable energy to a greater extent. Compared with the AC and DC microgrids, the AC-DC hybrid microgrid has Its own characteristics, AC-DC hybrid microgrid DC side voltage fluctuation is a topic worthy of in-depth research and discussion. The DC side voltage fluctuation causes the DC side voltage bus to lose stability, which will affect the stable operation of the load and cause AC-DC hybrid microgrid. The protection action affects the normal operation of the AC and DC power grids. [0003] The voltage fluctuation on the DC side of the AC-DC hybrid microgrid can be divided into disturbance...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J4/00H02J5/00H02J1/00H02J1/02
CPCH02J4/00H02J5/00H02J1/00H02J1/02
Inventor 常潇高乐王金浩雷达毛瑞李慧蓬刘翼肇樊瑞赵军王腾鑫肖莹赵旭伟赵兴勇田志慧
Owner ELECTRIC POWER RES INST STATE GRID SHANXI ELECTRIC POWER
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