Research On The Coordinate Control Of DFIG And VSC-HVDC In Off-Shore Wind Farm

With the shortage of land and the declining cost of wind power generation on the sea, off-shore wind farm grows popular in more and more countries. The double-fed induction generator prevails in the wind industry and VSC-HVDC is becoming one of the significant ways integrating wind farm into the grid due to its flexible power control capabilities.The characters of off-shore wind farm, its integrating technology and development in the world are introduced in the first part. Then the article studies the double-fed wind generator applying vector control scheme and its coordinate control with VSC-HVDC. Fixed active power and coordinate ac voltage and frequency control scheme are put forward in sea converter while the fixed dc voltage control and fixed reactive power control scheme are applied in land converter, which aims at realizing independent control of P, Q flow and enlarge the speed range of DFIG with the help of SVPWM. Electrical configuration and control module parameters of DFIG and VSC converters are designed and built in PSCAD/EMTDC. On the basis of the simulation, it is concluded that the double-fed wind generator can achieve independent output of active and reactive power so that it can capture the maximum of wind power while connecting the grid without impact current and improve the static and transient stability under this control strategy. VSC-HVDC achieves to control the voltage and frequency of wind farm, enlarge the scope of maximal wind power capture and transfer decoupled active and reactive power as demand to stabilize grid voltage when the output of wind farm varies as well as isolate the grid fault in the process of transient operation.