Low-voltage ride through practice of double-fed wind turbine system

With unit capacity of wind turbine enlarging and total capacity of wind power expanding, the mutual influence between wind power and grid become more apparent. Especially when grid voltage drops, wind farm overall cutting out grid will lead to electric power system tidal current changing greatly, and even cause a large area blackout accident. So it is imperative to reconstruct current wind power to obtain low-voltage ride through (LVRT) ability. This article studied the influence of grid voltage dip on double-fed wind turbine of someone wind farm and put out LVRT reconstruction scheme. The retrofit schemes mainly contain adding crowbar behind dc side of frequency converter, modifying frequency converter´s control power supply circuit, and replacing control program as well as parameters of the master control and frequency converter control etc. LVRT test result showed that, when three-phase balanced or unbalanced voltages dropped in grid, by keeping grid-connected state, the reconstructed turbines can help grid achieve LVRT. Wind farm LVRT reconstruction is important for distributed power integrating into grid in large scale.