Offshore wind power output control system through hybrid direct current and control method thereof

Abstract

The invention discloses a control system and a control method for sending out offshore wind power through hybrid direct current, and the control method comprises the steps: unlocking an onshore converter station when the system is started, controlling the direct current voltage of the onshore converter station to be a first preset voltage value, then unlocking an offshore MMC converter valve, then starting a part of wind turbine generator sets, by reducing the direct-current voltage of an onshore converter station, after the direct-current voltage of an offshore DR converter valve is reduced to a preset voltage threshold, switching on the offshore DR converter valve to start to transmit direct-current power, starting the remaining offshore wind turbine generators, and controlling the direct-current voltage of the onshore converter station to be further reduced, so that the transmission power of the offshore DR continues to rise; therefore, all direct-current power is injected into the direct-current side through the offshore DR converter valve instead of the offshore MMC converter valve, loss of the small-capacity offshore MMC converter valve during long-term operation is reduced, economical efficiency is improved, overload of the offshore MMC converter valve is avoided, and safe and stable operation of the system is guaranteed.

Description

technical field [0001] The invention relates to the technical field of direct current transmission, in particular to a control system and a control method for sending offshore wind power through hybrid direct current. Background technique [0002] In recent years, flexible direct current transmission technology (English full name voltage source converter based high-voltage direct current, English abbreviation VSC-HVDC) has achieved rapid development. At the same time, because the flexible DC can quickly and flexibly control the output power of the wind farm, and can independently control the bus voltage and frequency of the grid-connected point of the wind farm, use the flexible DC method to connect the power of the wind farm and transmit it to the onshore grid. It is applied to practical projects at home and abroad. [0003] However, the existing offshore wind power is sent to offshore converter stations and onshore converter stations via flexible DC. Increase, the volume...

AI Technical Summary

Problems solved by technology

However, the above control method changes the AC voltage amplitude of the offshore wind farm significantly and frequently, and the voltage fluctuation range may exceed 0.1pu

Substantially changing the AC voltage on the AC side of the entire offshore wind farm and offshore converter station will have a large impact range, which may cause frequent switching of reactive power compensation devices equipped with wind farms, and may even affect the safe and stable operation of offshore wind turbines. Cause the fan to go off the grid

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