Microgrid multi-inverter parallel-control method based on frequency division virtual complex impedance

A virtual complex impedance and multi-inverter technology, which is applied in the direction of converting irreversible DC power input to AC power output, electrical components, circuit devices, etc., can solve the problem of large amount of calculation, fast and real-time response of the system affected by the calculation program, etc. problem, to achieve the effect of improving dynamic performance and reducing calculation delay

Inactive Publication Date: 2015-04-29
国网山东省电力公司聊城供电公司 +1
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  • Application Information

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Problems solved by technology

In this way, the calculation of the implementation program is relatively large, and the complexity of the calculation program will inevitably affect the rapid and real-time response of the system.
[0009] In summary, the technical problem of the influence of harmonic currents on the parallel control of inverters in low-voltage microgrids has not been well resolved in the prior art

Method used

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  • Microgrid multi-inverter parallel-control method based on frequency division virtual complex impedance
  • Microgrid multi-inverter parallel-control method based on frequency division virtual complex impedance
  • Microgrid multi-inverter parallel-control method based on frequency division virtual complex impedance

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Effect test

Embodiment 1

[0060] The realization of the microgrid multi-inverter parallel control method based on the frequency division virtual complex impedance is described in detail below, and the specific steps of the method are as follows:

[0061] 1) At the beginning of each sampling period, the processor outputs the voltage U from the micro source dc , filter capacitor voltage u c , filter inductor current i L , line current i o Sampling and processing respectively;

[0062] 2) According to the two-beat numerical power calculation method, the filter capacitor voltage u c , filter inductor current i L Calculate the average value of active power P and the average value of reactive power Q;

[0063] 3) According to the robust droop control principle of resistive equivalent output impedance, the filter capacitor voltage u is calculated by discrete Fourier transform DFT c The rms value of a cycle U c , no-load voltage amplitude reference value E * minus U c , the obtained difference is mult...

Embodiment 2

[0070] According to a method for parallel control of micro-grid multi-inverters based on frequency-division virtual complex impedance described in Embodiment 1, further, in step 2), the average value of active power P and the average value of reactive power Q The specific formula is:

[0071] P = U ck I Lk + U c ( k + 1 ) I ...

Embodiment 3

[0094] According to a method for parallel control of microgrid multi-inverters based on frequency-division virtual complex impedance described in Embodiment 1, further, in step 3), the specific relationship between the reference voltage amplitude E and the reference voltage angular frequency ω The calculation formula is:

[0095] E = 1 s [ K ( E * - U c ) - nP ] ω = ω * ...

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Abstract

The invention discloses a microgrid multi-inverter parallel-control method based on frequency division virtual complex impedance, which is suitable for a multi-inverter parallel-control system with a nonlinear load for a low-voltage microgrid. The microgrid multi-inverter parallel-control method comprises the following steps: performing frequency division on a line current by virtue of a band pass filter by adopting a robust droop control strategy of resistance equivalent output impedance, simultaneously multiplying a fundamental current by a virtual complex impedance containing a resistance-capacitance component, designing that each parallel connection inverter output impedance is resistive in a fundamental band; and respectively multiplying each high-frequency current by different virtual inductive impedances, indicating that a harmonic frequency band inverter output impedance is inductive so as to be limited by the robust droop control strategy of resistance equivalent output impedance, so that the influence of a high-frequency harmonic current to inverter parallel-control is avoided. According to the microgrid multi-inverter parallel-control method, the defect of a conventional method is overcome, and good control effect is achieved in the multi-inverter parallel-control system with the nonlinear load for the low-voltage microgrid.

Description

technical field [0001] The invention relates to a multi-inverter parallel control method of a micro-grid based on frequency-division virtual complex impedance, which belongs to the technical field of distributed power generation and power electronics. Background technique [0002] In order to solve the technical problems of connecting distributed power sources to the power grid, scholars related to power systems have proposed the concept of micro-grids. A microgrid is a local power generation system that is composed of distributed micro sources, energy conversion devices, and local loads interconnected through a network, and can realize self-control, protection, and management. In the microgrid, most distributed micro-sources are connected to the AC bus through the inverter interface, thus forming a multi-inverter parallel operation environment. [0003] The key difficulty of the low-voltage microgrid operating in an island is that the line resistance is much greater than t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/48H02J3/38
CPCH02J3/381H02M7/493Y02P80/14
Inventor 张庆海刘安华李洪博梁甲文蔡军
Owner 国网山东省电力公司聊城供电公司
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