Chapter Twelve - Fault ride through techniques based on hardware circuits for DFIG based wind turbines

Abstract

This chapter discusses hardware-based low-voltage ride-through (LVRT) schemes that enhance the transient operating capability of a doubly fed induction generator (DFIG)–based wind turbine (WT) during the transient state. These strategies combine a series resistor, a DC-link chopper, and a crowbar with modified switching control strategies. The rotor-side power converter connection is maintained and hence the decoupling active-reactive power control is not lost. In fact, if the DFIG operates with a crowbar (i.e., DFIG-crowbar operating mode), it results in the generator behavior similar to that of a squirrel-cage induction generator leading to a more voltage dip at the point of common coupling terminal. However, with the improved crowbar configurations such as the combination of a crowbar and series R-L circuit, the terminal voltage dip can be minimized. Following the brief discussion of the conventional LVRT schemes, the hardware-based LVRT schemes are designed. The DFIG operating characteristics remain almost the same with a much smaller terminal voltage depression than when the conventional schemes are applied. At the end of the chapter, discussions on how to optimally tune the parameters are presented with the performance comparison between the conventional strategies and the LVRT scheme is conducted using the simulation results obtained in MATLAB®/Simulink® software.