A method and system for suppressing wide frequency oscillation of offshore wind power flexible direct system

By introducing an MMC additional damping controller and a virtual resistor into the offshore wind power flexible DC system, combined with a passive damping structure and an active low-pass filter, the problem of the inability to effectively suppress broadband oscillations in existing technologies has been solved, and the stability of each frequency band on the AC and DC sides has been improved, ensuring the stability of the offshore wind power system.

CN122437102APending Publication Date: 2026-07-21SHANDONG ELECTRIC POWER ENG CONSULTING INST CORP
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
SHANDONG ELECTRIC POWER ENG CONSULTING INST CORP
Filing Date
2026-04-13
Publication Date
2026-07-21

AI Technical Summary

Technical Problem

Existing methods for suppressing offshore wind power oscillations cannot effectively suppress broadband oscillations, especially in grid-connected systems with a high proportion of renewable energy. Oscillations caused by complex interactions resulting from equipment nonlinearity, fast response of power electronics, and mismatch of control strategies, particularly the multi-type broadband oscillations caused by the interaction between wind farms and converter stations, cannot be suppressed by existing methods across the entire AC and DC frequency bands.

Method used

In offshore wind power flexible DC systems, low- and medium-frequency oscillations are suppressed by introducing an MMC additional damping controller and a virtual resistor on the DC side, combined with a passive damping structure and an active low-pass filter; on the AC side, an impedance controller and an active filter, along with passive damping from the bridge arm reactor, are used to suppress low- and medium-frequency and high-frequency oscillations.

Benefits of technology

The damping characteristics of AC and DC sides at all frequency bands are comprehensively improved, effectively suppressing multiple types of broadband oscillations, ensuring the stable and reliable operation of offshore wind power flexible DC systems, and eliminating the risks of broadband oscillations and negative damping.

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Abstract

The present application relates to the technical field of oscillation suppression, and provides a wide-band oscillation suppression method and system for offshore wind power flexible direct current system, which comprises: a direct current part transmitted from an offshore converter station to a land converter station, wherein a virtual resistance is introduced by adding a damping controller in a control system of an MMC to suppress the medium and low frequency oscillation on the direct current side; a passive damping structure and an active low-pass filter are added in the MMC bridge arm structure to suppress the high frequency oscillation on the direct current side; an impedance controller is added in the MMC alternating current side of the converter station to suppress the medium and low frequency oscillation on the alternating current side in the alternating current part from each motor of an offshore wind farm to the offshore converter station; and a passive damping structure and an active low-pass filter are added in the MMC alternating current side bridge arm structure of the converter station to suppress the high frequency oscillation on the alternating current side. The damping characteristics of each frequency band on the alternating current and direct current sides are comprehensively improved, the wide-band oscillation and negative damping risk are eliminated from the source, and multiple types of wide-band oscillation are effectively suppressed.
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