Transient energy analysis and dissipation of a bipolar MTDC wind power integrating system during MMC outage

摘要

Using high-voltage direct current grid (HVDC grid) to integrate wind power is an effective solution to improve the flexibility and reliability of power transmission. Since the DC grid requires fault ride-through capability, hybrid modular multilevel converter (hybrid MMC) is adopted to form the bipolar DC grid. The MMC non-blocking operation strategy of unipolar converter outage is proposed. During the fault, the AC voltage at the integration point is stable, and the wind turbine can maintain its normal operation. To satisfy various dissipation requirements of the surplus wind power during the fault period, an adaptive control strategy of dissipation resistors is designed. Finally, the simulation based on PSCAD/EMTDC platform verifies the MMC unblocking fault ride-through operation of hybrid MTDC grid and proves the effectiveness of its fault energy dissipation.