AC fault ride-through control method, apparatus and device for DC power transmission system, and storage medium

By adopting a coordinated control strategy of flexible regulation of sub-module capacitor energy and dynamic optimization of the sending-end MMC AC voltage in the offshore wind power flexible direct current interconnection system, the problem of the impact of sending-end AC faults on the receiving-end power grid frequency is solved, and the frequency support and power transmission stability of the flexible direct current system are achieved.

CN120728690APending Publication Date: 2025-09-30NORTHEAST DIANLI UNIVERSITY
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Patent Information

Application Number
CN202510908273.4
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-07-02
Publication Date
2025-09-30

AI Technical Summary

Technical Problem

The existing technology fails to effectively take into account the impact of the receiving-end power grid frequency when an AC fault occurs at the sending end of the offshore wind power flexible direct current interconnection system, and lacks the ability to support the transient frequency of the flexible direct current system, resulting in frequency security and stability problems.

Method used

A collaborative control strategy for AC fault ride-through at the sending end that takes transient frequency support into consideration is proposed. Through the flexible DC system inertia active support control strategy based on flexible regulation of sub-module capacitor energy and the fault ride-through control strategy based on dynamic optimization of the AC voltage of the sending-end MMC, the sub-module switching logic of the sending and receiving MMCs is reconstructed, the number of sub-modules put into operation and the AC voltage reference value are adaptively adjusted, the capacitor energy regulation margin is expanded, and power transmission and frequency stability are maintained.

Benefits of technology

It significantly improves the frequency inertia support capability of the flexible DC system for the receiving power grid, improves the safe operation of the equipment and the frequency stability of the receiving power grid, and effectively suppresses overcurrent and short-term power shortage caused by AC faults at the sending end.

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Abstract

The invention provides a DC power transmission system AC fault ride-through control method and device, equipment and a storage medium. Relates to the technical field of fault ride-through. The method comprises the following steps: during a sending end AC fault period, based on an active power change rate and a power difference value, reconstructing a sub-module switching logic of a sending end converter station, and dynamically adjusting a sub-module input number of a sending end MMC; based on the frequency change rate and the frequency deviation of a receiving-end power grid, reconstructing the sub-module switching logic of a receiving-end converter station, and dynamically adjusting the input number of sub-modules of a receiving-end MMC (Modular Multilevel Converter); and when the AC voltage outlet voltage of the sending end MMC drops to be less than or equal to 0.9 p.u and the transmission power drops to be 80% of a steady-state value, starting an AC voltage reference value dynamic optimization scheme. The invention provides a sending-end alternating-current fault ride-through cooperative control strategy considering power grid transient frequency support, and the frequency stability of a receiving-end power grid can be improved while the safe operation of equipment is maintained.
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