Islanded system for flexible direct current transmission of new energy and black start method therefor

By configuring energy storage equipment at the receiving converter station and adopting a network-type control strategy, the problem of the new energy island's flexible direct transmission system relying on the receiving AC power grid during black startup is solved, and the independent black startup of the system and the grid connection of new energy units are realized, reducing the operation and maintenance cost of energy storage equipment.

WO2025066842A1 Publication Date: 2025-04-03NR ELECTRIC CO LTD +2
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Patent Information

Application Number
PCT/CN2024/117096
Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
Priority Date
2023-09-25
Filing Date
2024-09-05
Publication Date
2025-04-03

AI Technical Summary

Technical Problem

The new energy island through flexible direct transmission system needs to rely on the receiving AC power grid when the black starts, and lacks a black startup strategy that does not rely on the receiving AC power grid.

Method used

The energy storage equipment is configured at the receiving converter station and directly and connected to the low-voltage winding side of the multi-winding connection transformer. The grid-type control strategy and an improved pole starting strategy are adopted to achieve the black start of the system.

Benefits of technology

Through this method, the new energy island through the flexible direct transmission system can independently complete the black start when the power grid is lost at the receiving power, realizing the grid connection of the new energy unit and the voltage and frequency support to the receiving power grid, reducing the installation and operation and maintenance costs of energy storage equipment.

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Abstract

The present application provides an islanded system for flexible direct current transmission of new energy and a black start method therefor. The islanded system for flexible direct current transmission of new energy comprises a sending end connection transformer, a sending end converter valve, a direct current circuit, a receiving end converter valve, a starting resistor and a bypass isolator therefor, a receiving end connection transformer, and an energy storage device; the energy storage device is in parallel connection with a low-voltage winding side of the receiving end connection transformer, and the receiving end connection transformer is configured as a multi-winding connection transformer. According to some embodiments, by means of configuring the energy storage device in a receiving end converter station and directly connecting same to the low-voltage winding side of the multi-winding connection transformer, a multi-stage boosting transformer is omitted, and the means of energy storage access is effectively simplified. When the islanded system for flexible direct current transmission of new energy is isolated from a receiving end alternating current power grid, the energy storage device can control and maintain an alternating current side voltage of the receiving end converter station. When the system finishes a black start, voltage and frequency support can be provided for the receiving end alternating current power grid.
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