Control Strategy of Offshore Wind Farm Grid-Connection Through VSC-HVDC Transmission
In view of the problems of large-scale wind-farm grid connection,power transmission of grid-connection methods suitable for large offshore wind farms are analyzed.Based on the application of flexible HVDC (VSC-HVDC) transmission,mathematical model and control strategy of the transmission system are studied.Considering that the output power of variable-speed constant-frequency generator in offshore wind farm changes with wind speed,the control of offshore converter station requires to maintain stability of the voltage and frequency of wind farm bus,and therefore a modified direct voltage control method is proposed to control wind farm voltage and frequency according to the transient equation.Control of grid-side converter station is controlled by the double-loop direct current method in order to control the DC voltage and reactive power into the grid.Finally,based on PSCAD / EMTDC simulation platform,the offshore wind farm equivalent model and flexible HVDC power transmission system simulation model are built up,whereby the wind speed changes,the local cut-in and reactive power command changes are simulated,and the results verify the correctness and effectiveness of the proposed control strategy.
offshore wind farmvoltage source converter (VSC)flexible HVDCmodified direct voltage control
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维普
