Active energy control method under alternating current fault of offshore wind power flexible direct current grid-connected system

Abstract

The invention discloses an active energy control method for an offshore wind power receiving end AC fault through a flexible DC grid-connected system, and the method comprises the steps: controlling aDC voltage station to carry out the passive energy recovery, enabling a capacitor in the station to be passively charged to a first preset value and kept, controlling an AC switch to be switched offand switched on during the period, and controlling an energy consumption device to be switched on and off; controlling the direct-current voltage station to release energy, so that the capacitance energy of the direct-current voltage station is reduced to a rated value; in the passive energy recovery period of the direct-current voltage station, controlling the alternating-current voltage stationto perform active energy recovery, so that a capacitor in the station is actively charged to a second preset value and kept; and when the capacitance energy of the direct-current voltage station is reduced to a rated value, the capacitance energy of the alternating-current voltage station being reduced to the rated value. According to the method, the problem of power surplus caused by the receiving end alternating current fault of the offshore wind power flexible direct current grid-connected system can be solved with low economic cost, direct current overvoltage is restrained, and meanwhile the technical requirements for a communication system and an energy consumption device are greatly reduced.

Description

technical field [0001] The invention belongs to the field of power transmission and distribution of electric power systems, and more specifically relates to an active energy control method for an offshore wind power grid-connected system through flexible straight grids under AC faults. Background technique [0002] Due to the urgent need of new energy development, the flexible DC transmission technology based on Modular multilevel converter (MMC) has been developed rapidly. When the flexible direct current transmission system (hereinafter referred to as the flexible direct transmission system) is used for offshore wind power grid connection, the AC voltage station at the sending end provides an AC voltage that meets the requirements for the offshore wind farm through the AC voltage controller; The controller controls the DC voltage of the flexible direct transmission system. Since the AC voltage station at the sending end cannot control the active power injected by the offs...

AI Technical Summary

Problems solved by technology

[0004] The present invention provides an active energy control method under the AC fault of the offshore wind power grid-connected system through the flexible grid, aiming at solving the DC overvoltage problem of the grid-connected system caused by the failure of the AC grid at the receiving end at a relatively low economic cost, and at the same time Significantly reduce technical requirements for communication systems and energy-consuming devices

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