Method, system, device and medium for suppressing DC fluctuation of unbalanced down-converter

By adopting the method of signal separation and multi-state quantity linear feedback compound control in the converter, the problem of DC voltage fluctuation suppression of three-phase converter under unbalanced working conditions is solved, and the fluctuation suppression effect with high accuracy and fast response is achieved.

CN119561363BActive Publication Date: 2025-04-01STATE GRID ZHEJIANG ELECTRIC POWER CO LTD HANGZHOU POWER SUPPLY CO +1
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Patent Information

Application Number
CN202510119910.X
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2025-01-25
Publication Date
2025-04-01
Estimated Expiration
2045-01-25

AI Technical Summary

Technical Problem

The prior art is difficult to effectively suppress DC voltage fluctuations in three-phase converters under unbalanced working conditions, especially when the load has extremely unbalanced working conditions such as single-phase short circuits, the existing methods have slow response speed and cannot suppress DC voltage fluctuations in time.

Method used

Through the signal separation method based on parallel feedback of DC and AC internal mode controllers, the power fluctuation power of the converter is accurately extracted, and the decoupling capacitor power is closed-loop control based on the controller that combines the high degree of freedom proportional resonance controller of the outer ring and the multi-state quantity of the inner ring, the converter control model is designed, and the controller parameters are optimized to improve the response speed.

Benefits of technology

It realizes timely and accurately perception and effective suppression of DC voltage fluctuations in three-phase converters under unbalanced working conditions, and improves the suppression accuracy and dynamic response speed of DC fluctuations.

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Abstract

The present invention provides a method, system, device and medium for suppressing DC fluctuation of converter under unbalance. The method is applied to a two-level three-phase converter, and a preset AC signal separator is used to extract the fluctuation power of the instantaneous output power obtained according to the output voltage and output current of the AC side of the converter under unbalanced working conditions to obtain twice the instantaneous power fluctuation power of the power frequency, and the instantaneous fluctuation power is input into the converter control model as the reference value of the decoupling capacitor power and the decoupling capacitor power and the decoupling capacitor voltage to obtain the reference value of the product of the decoupling capacitor voltage and the DC side bridge arm midpoint voltage, and the reference value is divided by the decoupling capacitor voltage to obtain the DC side bridge arm midpoint voltage reference value, and the bridge arm duty ratio obtained by dividing the DC side bridge arm midpoint voltage reference value and the DC side bus voltage is used to generate the switching signal of the power device. The present invention can accurately extract the fluctuation power of the AC side of the converter, and effectively improve the suppression accuracy and dynamic response speed of DC fluctuations.
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