Study On Low Voltage Ride Through Technology Of Doubly Fed Induction Generator

Wind energy is a clean and renewable energy, under the global concern forenvironmental protection. The developed countries are focused on the development ofthe use of non-polluting or less polluting renewable energy and new energy, both toprotect the environment and energy conservation. Wind power generationtechnologies, including large-scale wind turbine and grid-connected technology havebeen basically mature. The installed capacity of the wind farm is also increasing.Because of the increase in the capacity of the wind turbine, stable operation of thewind farm is more important to the power system. When the grid fault occurs, it alsorequires the wind turbines to be able to continue working. So, the study on lowvoltage ride-through capability of doubly-fed wind turbine is of great significance.This paper studies the structure and principle of double-fed wind powergeneration system, and analyzes the mathematical model in static three-phase ABCcoordinate system of the doubly-fed wind power generator and in two-phase rotatingdq coordinate system of the mathematical model, which provides theoretical guidancefor the low voltage ride-through technology research of DFIG. According to themathematical model of the generator, it analyzes the DFIG transient electromagneticrelation, and gives further analysis of the DFIG rotor overvoltage and overcurrent,which is verified by simulation.Using Tianjin Shajingzi wind farm as an example, simulation model of thedouble-fed wind power system is established in the Matlab/Simulink platform. Then,detailed analysis and simulation of active Crowbar protection is been done, and theinfluence of Crowbar resistance value on the LVRT capability is been studied. Thesimulation results verify the validity of the crowbar protection circuit. The size of theCrowbar resistor should be appropriate. If the protection circuit resistance is too large,it will increase the inverter DC bus voltage. If protection circuit resistance is too small,it will attenuate the inhibition effect of the rotor overcurrent greatly.