Grid Integration of Large DFIG-Based Wind Farms Using VSC Transmission

TLDR

The study proposes using VSC‑based HVDC to connect large DFIG wind farms over long distances and introduces control strategies for normal and fault conditions. The system controls the wind‑farm VSC as an infinite voltage source to absorb power and stabilize the local AC network, while fault‑ride‑through is achieved through frequency‑based power balancing and DFIG frequency control. Simulations confirm the system’s robust performance under varying wind speeds and power levels and validate its fault‑ride‑through capability.

Abstract

This paper describes the use of voltage source converter (VSC)-based HVDC transmission system (VSC transmission) technology for connecting large doubly fed induction generator (DFIG)-based wind farms over long distance. The operation principles of the proposed system are described, and new control strategies for normal and grid fault conditions are proposed. To obtain smooth operation, the wind farm side VSC (WFVSC) is controlled as an infinite voltage source that automatically absorbs power generated by the wind farm and maintains a stable local ac network. Fault ride through of the system during grid ac faults is achieved by ensuring automatic power balancing through frequency modulation using WFVSC and frequency control using DFIG. PSCAD/EMTDC simulations are presented to demonstrate robust performance during wind speed and power variations and to validate the fault ride through capability of the proposed system.