Improved adaptive droop control method for parallel inverters in low-voltage microgrid

A control method and inverter technology, applied in the field of micro-grid, can solve the problem of the inherent contradiction between load sharing and output voltage quality, which is difficult to compromise, and achieve the effect of solving the problem of voltage sag.

Active Publication Date: 2016-11-09
安徽博衡电力科技有限公司
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Problems solved by technology

[0004] Sun Xiaofeng, Yang Yalin, Zhao Wei, Shen Hong, Tan Guangjun. In 2014, they published the paper "Adaptive Droop Control Strategy for Micro-Grid Inverters" in "Grid Technology" and proposed an adaptive droop control strategy. The inherent contradiction of output voltage quality is difficult to compromise

Method used

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  • Improved adaptive droop control method for parallel inverters in low-voltage microgrid
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  • Improved adaptive droop control method for parallel inverters in low-voltage microgrid

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Embodiment 1

[0060] Using Simulink as the simulation platform, two three-phase inverters are connected to the same AC bus. The equivalent mathematical model is as follows figure 1 shown. The main parameters of the main circuit of the parallel inverter are: the input DC voltage is 700V, the output voltage is 220V / 50Hz, the rated active power of a single inverter is 1.7KW, the rated reactive power is 500Var, the filter inductor is 3.14mL, and the filter capacitor is 100uF, and the corner frequency of the power filter is 20rad / s. Take a set of sag coefficient m as 0.00004 and n as 0.0012. The simulation waveform is as follows Figure 7 As shown in (7a) and (7b), after the two parallel inverters are running stably, at the time t is 0.06s, the public load is suddenly increased to 2.6KW. It can be seen that the improved droop control algorithm introduces the dynamic adjustment coefficient , the current waveform changes very gently, and when the output current of the two inverters rises rapidl...

Embodiment 2

[0062] Take two 1.7KW three-phase two-level inverters in parallel as the experimental platform. The control system uses the TMS320FM2812 control chip, and the switching frequency is set to 12.8KHz. In the experiment, a resistive line impedance of 1Ω is added to simulate the impedance on the traditional low-voltage power line. The experimental parameters are consistent with the simulation. The load current sharing waveform of the parallel inverter in stable operation can be obtained, and the dynamic experimental waveform of the parallel inverter current when the load suddenly increases at 0.06s. Experimental waveforms such as Figure 8 As shown, it shows that the improved droop control algorithm adopted can better realize load power sharing when two inverters are connected in parallel, and the dynamic performance of output current is better when the load changes suddenly. The effectiveness of the improved control algorithm is verified.

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Abstract

The invention relates to an improved adaptive droop control method for parallel inverters in a low-voltage microgrid. The method includes the following steps that: virtual complex impedance is introduced, so that the equivalent output impedance of the parallel inverters can be inductive, and a droop control equation can be obtained; linear function terms of power and droop coefficients are introduced to replace droop coefficients in the droop control equation, so that an adaptive droop control equation can be obtained; and voltage drop caused by the extraction of the virtual complex impedance is considered, so that an improved adaptive droop control equation is obtained. Improved adaptive droop control on the parallel inverters is realized through the improved adaptive droop control method. Compared with the prior art, the improved adaptive droop control method of the invention has the advantages of quick dynamic response and high stability, and can realize a compromise between the load sharing and output voltage quality of the parallel inverters.

Description

technical field [0001] The invention relates to the field of micro-grids, in particular to an improved adaptive droop control method for parallel inverters in low-voltage micro-grids. Background technique [0002] With the development of distributed energy, the distribution network side has higher requirements for power supply quality, power supply reliability, and system capacity. The parallel connection of multiple inverters can increase the power of the system. After forming a microgrid, it can provide users with high-quality electric energy and increase the reliability of the power supply of the system. Inverter parallel connection technology is divided into control methods with tie lines and without interconnection lines. There is a connection line method, mainly through the detection of the information of each parallel module in the system, and the host computer issues instructions to complete the parallel connection. Its main disadvantage is that the communication l...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38
CPCH02J3/38
Inventor 陈坤曹以龙赵乐孔亚非
Owner 安徽博衡电力科技有限公司
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