A comparative Study of Low-Voltage Ride-Through (LVRT) Control of Grid-Interfaced Doubly-Fed Induction Generator (DFIG)

Abstract

Due to the fast increase in energy of modern human being the desire for the clean renewable energy is increasing day by day. Electrical power generation from wind is promising source. But due to the large combination of wind forms in electrical power grid the stability and security are key issues for the electrical power engineers. Amongst the required grid codes for the power utilities LVRT is very important. According to LVRT the wind form should act as conventional power plant and connect to grid for some particular time to provide stability to grid at normal and fault time. In this paper we have developed a LVRT strategy for control of active, reactive power and DC link voltage of the variable speed wind turbine. The test bed system is 9 MW DFIG wind turbine attached to 120KV grid system by 30KM long 25 KV transmission line. The modelling and simulation is done by using MATLAB/SIMULINK. The control system is implemented by using PI controller using vector or field oriented control. The LVRT strategies implemented on test bed model are (STFCL), DC chopper, Rotor Crowbar and Hybrid strategy with using RSC control, GSC control and pitch control mechanisms. The hybrid strategy provides excellent solution for LVRT of DFIG wind turbine by controlling power (active and reactive) and voltage of DC link. The results of hybrid strategy during symmetrical fault is best and well suited to the LVRT requirements as compared of STFCL, DC chopper and crowbar.

Adaptive control of DFIG-based wind turbines for fault ride-through and reactive power support based on stator current transient component

“…where UT is the voltage at the grid connection point, IN is the rated current of the wind farm, and Kp is the dynamic reactive current proportion coefficient of the wind farm. The fixed value of 1.5 for the reactive current proportion coefficient is the parameter setting requirement in the current wind power grid connection standard and is also the parameter design commonly used in most kinds [6][7] . The reactive current is generated according to Formula (24), as shown in Figure 1.…”

“…However, when the power grid fails, the rotor winding is prone to overcurrent, which will cause the wind turbine to be disconnected from the grid [4] . At present, DFIG-based wind turbine mainly improves the fault ride-through performance by weakening the stator transient flux linkage [5][6] . The voltage support in fault ride-through uses the reactive power regulation capability of the rotor converter or reactive power compensation equipment to support the voltage.…”