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Method for improving robustness of droop control system of multi-inverter parallel low-voltage microgrid

A system robustness, multi-inverter technology, applied to electrical components, circuit devices, AC network circuits, etc. Frequency fluctuation, the effect of improving voltage stability

Inactive Publication Date: 2020-11-10
XIAN THERMAL POWER RES INST CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in the actual operation process of multi-inverter parallel low-voltage microgrid, there are various interference signals, the conventional droop control cannot realize the static error-free tracking of the control signal, and the robustness of the control system is poor

Method used

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  • Method for improving robustness of droop control system of multi-inverter parallel low-voltage microgrid
  • Method for improving robustness of droop control system of multi-inverter parallel low-voltage microgrid
  • Method for improving robustness of droop control system of multi-inverter parallel low-voltage microgrid

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Embodiment Construction

[0040] The technical solution of the present invention will be described in further detail below with reference to the accompanying drawings.

[0041] Such as figure 1 As shown, there are i (i=1, 2, 3,...n) distributed power points and inverters in the multi-inverter parallel low-voltage microgrid structure, and the output interface of each inverter is connected by LCL filter device used to suppress higher harmonics, R 1,i=1,2,3,...n Indicates the equivalent resistance in series with the inductance on the inverter side, and the line impedance Z line = R line +JX line , R line is the line resistance, X line is the line inductance, in the low-voltage microgrid R line > > X line . P i=1,2,3,...n , Q i=1,2,3,...n Indicates the output active and reactive power of the inverter, Z load is the load equivalent impedance.

[0042] Such as figure 2 As shown, the Thevenin equivalent circuit diagram of two distributed parallel power points is established, where: U 1 ∠δ 1 , ...

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Abstract

The invention discloses a method for improving the robustness of a droop control system of a multi-inverter parallel low-voltage microgrid. The method comprises the following steps: 1) establishing amathematical model represented by active power and reactive power output by inverters in the multi-inverter parallel low-voltage microgrid; 2) simplifying the mathematical models of active power and reactive power output by the inverter in the step 1); 3) obtaining a conventional droop control equation according to the P-omega and Q-U droop characteristic schematic diagrams; 4) adding a frequencyand voltage compensation module in the conventional droop control equation in the step 3) to obtain a new droop control equation; 5) performing small signal model analysis on the inverter output active and reactive power simplified mathematical model obtained in the step 2) and the new droop control equation obtained in the step 4), and verifying the stability of the control system. According to the invention, the frequency stability of the multi-inverter parallel low-voltage microgrid can be effectively improved, and the frequency fluctuation phenomenon in the mode switching process is reduced.

Description

technical field [0001] The invention relates to a method for improving the robustness of a multi-inverter parallel low-voltage micro-grid droop control system. It is verified through dynamic stability analysis that adding frequency and voltage compensation modules will not affect the stability of the system. Background technique [0002] Inverter parallel low-voltage microgrid is an independently controllable system composed of distributed power sources, distributed energy storage devices, inverter devices, transmission lines and related loads, and can operate in grid-connected and island modes. [0003] In the multi-inverter parallel low-voltage microgrid inverter control system, most of them adopt PQ droop control and constant voltage constant frequency (V-f) control. The traditional droop control strategy simulates the droop characteristics of the traditional synchronous generator, and performs independent decoupling control on the output active power-frequency and reacti...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38H02J3/48H02J3/50
CPCH02J3/381H02J3/388H02J3/48H02J3/50H02J2203/20
Inventor 李志鹏王小辉薛磊贺婷赵俊博毛文君耿如意康付平杨柳
Owner XIAN THERMAL POWER RES INST CO LTD
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