Co-ordinated control of offshore wind farms and HVDC transmission grid

With the rapid development of large scale offshore wind farms, HVDC (High Voltage DC) grid becomes a prospective way to transmit wind power generated from wind farms over long distance. Because of the fluctuations of both the wind power and the frequency of onshore AC grid, the active power generated by wind farms needs to be controlled appropriately to ensure the stability of AC grid. This paper studies control strategies of both the active power generated by offshore wind farms and DC voltage of 3 ternimal HVDC transmission grid. On the base of these studies, a coordinated control strategy between the active power generated by offshore wind farms and the DC voltage of HVDC transmission grid under frequency fluctuation of AC gird is proposed. The proposed control strategies can enhance the regulation ability of HVDC transmission grid in order to both smooth wind power fluctuation and ensure the stability of AC grid. The validation of control strategies under the frequency fluctuation of AC grid is proved by simulation in case studies.