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Composite robust control method of high-frequency SiC photovoltaic grid-connected inverter under weak power grid

A compound robust and control method technology, applied in the field of compound robust control of high-frequency SiC photovoltaic grid-connected inverters under weak power grids, can solve the impedance mismatch stability between high-frequency SiC photovoltaic inverters and high power grids, etc. problem, to achieve the effect of high power density

Active Publication Date: 2020-06-05
HARBIN INST OF TECH
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AI Technical Summary

Benefits of technology

This patented technology describes an improved way for reducing electrical noise interference between different electronic devices connected together through wires or cables. It achieves this by introducing Active Dampening (AD) methods that can effectively reduce unwanted signals from nearby sources without adding extra equipment like filters. By considering these issues, it provides technical benefits such as increased efficiency at higher frequencies while minimizing impacts upon other components' performance.

Problems solved by technology

This patented technical solution describes how to improve the efficiency and reliancy of solar cells' ability to operate under varying conditions due to changes caused from external factors like weather patterns over time. By measuring the electrical properties of the cell itself during its manufacture process, we aim to ensure consistently good results for different types of applications where these variations affect the overall functioning of the battery.

Method used

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  • Composite robust control method of high-frequency SiC photovoltaic grid-connected inverter under weak power grid
  • Composite robust control method of high-frequency SiC photovoltaic grid-connected inverter under weak power grid
  • Composite robust control method of high-frequency SiC photovoltaic grid-connected inverter under weak power grid

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specific Embodiment 1

[0057] according to figure 1 As shown, the topological structure diagram of the three-phase grid-connected inverter based on SiC power devices mainly includes the DC side voltage U dc , switching device SiC MOSFET, L 1 , L 2 , LCL filter composed of C, L g is the line equivalent impedance, u g It is a three-phase AC power grid, and PCC is a public coupling point.

[0058] In order to solve the stability problem caused by the impedance mismatch between the high-frequency SiC photovoltaic inverter and the high-grid grid under the weak grid, a composite robust control method for the high-frequency SiC photovoltaic grid-connected inverter is proposed, such as figure 2 Shown: It mainly includes PQ outer loop control, active damping control, fundamental wave and harmonic control and improved grid voltage feedforward control.

[0059] Step 1: Design the parameters of the output LCL filter according to the power level, switching frequency and current ripple requirements of the h...

specific Embodiment 2

[0094] In order to further specify the correctness and feasibility of the method of the present invention, the method of the present invention is simulated and verified in combination with this specific example. The simulation parameters in this example are: DC voltage U dc is 300V, the effective value of the grid rated voltage is 110V, and the power level of the inverter is 1.5kW. The operating frequency of the Si inverter is selected to be 10kHz, and the parameters of the LCL filter are designed to be L 1 =5mH,L 2 =1.25mH, C=4.7μF, the operating frequency of SiC inverter is 50kHz, and the parameters of LCL filter are designed as L 1 =1mH,L 2 = 0.2mH, C = 4.7µF.

[0095] In order to verify that the stability of the high-frequency SiC inverter is more susceptible to the influence of the weak grid impedance, for the Si inverter and the SiC inverter in the weak grid impedance L g Simulations were performed at 0 and 2mH, respectively. Figure 5 (a) and Figure 5 (b) are re...

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Abstract

The invention relates to a composite robust control method of a high-frequency SiC photovoltaic grid-connected inverter under a weak power grid. A reference value of a current loop is obtained throughcalculation by designing parameters of an LCL filter; the power density of the high-frequency SiC photovoltaic grid-connected inverter is improved, grid-connected current is fed back, an active damping feedback function H<ad>(s) is designed, and an open-loop transfer function G<open>(s) of the high-frequency SiC photovoltaic grid-connected inverter is determined; and a power grid voltage feed-forward function is improved, a first-order low-pass filter is configured, a new power grid voltage transfer function G<v>(s) is obtained, an odd number of repeated quasi-PR current controllers are usedfor restraining harmonic waves of all orders, modulation waves u<[alpha][beta]><*> are obtained, and an SVPWM module obtains switch driving signals to be used for driving a SiC switch tube. Accordingto the method, no extra sensor is needed, and the second-order differential link and the proportional link are adopted to jointly achieve power grid voltage feedforward so as to eliminate the influence of weak power grid impedance on the stability of the high-frequency inverter.

Description

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Claims

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Application Information

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Owner HARBIN INST OF TECH
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