Application of Parallel Resonance Fault Current Limiter for Fault Ride Through Capability Augmentation of DFIG Based Wind Farm Gilmanur Rashid Department of Electrical and Computer Engineering The University of Memphis 215 Engg Science Bldg, Memphis, TN-38152, USA grashid@memphis.edu Mohd Hasan Ali Department of Electrical and Computer Engineering The University of Memphis 212 Engg Science Bldg, Memphis, TN-38152, USA mhali@memphis.edu Abstract—Doubly fed induction generator (DFIG) based wind generators are vulnerable to the grid faults, as their stator windings are directly connected to the grid. Fault ride through (FRT) capability of a wind farm is very important, as it is a common requirement by the grid codes practiced all over the world. In this work, to enhance the FRT capability of a DFIG based wind farm, the parallel resonance fault current limiter (PRFCL) is proposed. To check the effectiveness of the proposed PRFCL, its performance is compared with that of the bridge-type fault current limiter (BFCL). A three-phase-to-ground (3LG) fault was applied to one of the double circuit transmission lines at the wind farm connection point of the multi-machine system to investigate the FRT capability. Simulations were carried out in Matlab/Simulink environment. Simulation results show that the PRFCL is a very effective auxiliary device to achieve better FRT. Moreover, it was found that the PRFCL outperforms the BFCL. Index Terms—Bridge-type fault current limiter (BFCL), dou- bly fed induction generator (DFIG), fault ride through (FRT), grid code, parallel resonance fault current limiter (PRFCL), wind farm. I. I NTRODUCTION Wind energy is thought to be the most prominent solution to the global energy crisis with an estimation that about 10% of the global electricity demand will be supplied from wind energy by the year 2020 [1]. Doubly fed induction generator (DFIG) is one of the most popular choices in wind energy industry due to its ability of higher energy capture from wind, higher output power, better electro-mechanic efficiency, improved power quality, variable speed operation, lower me- chanical stress on turbine, lower maintenance and decoupled control of the active and reactive power [2]. Even though the DFIGs offer some additional benefits compared to the other variable speed wind generators, the DFIG based wind farms are more vulnerable to the grid faults or disturbances as its stator windings are directly connected to the grid while the rotor windings are interfaced to the grid via partially rated back to back power electronic converters. Voltage sag at the DFIG terminal resulting from fault at the power system, makes impact on the air gap flux and thus may interrupt the energy conversion process. This will induce high voltage at the rotor circuit resulting in high current, the magnitude being controlled by the fault severity. This high current is a menace to the stable operation and may blow the DFIGs along with the power electronic converters. The rotor side converter (RSC) can limit the fault current to some extent but the converters are designed to handle only 20-30% of the rated power. Also the RSC is constrained by the modulation index. If no auxiliary method is employed to support the RSC, it loses the current control ability and transient current handling capacity is exceeded at fault. Apart from the electrical side, the mechanical part also faces severe mechanical stress at the shaft, bearing and the gear box due to pulsating torque [3]. To protect from fault incidents, traditionally wind generators were disconnected from the grid. As more and more wind power is integrated into the grid, it has become necessary that the wind turbines stay connected to the grids during fault, which is to ride through the fault to help the system stabilize after fault. Fault ride through (FRT) is a common requirement in grid codes of most of the power systems throughout the world [4]. So it is very important to augment the FRT capability of the DFIG based wind farms. To achieve the FRT of the DFIG based wind generators, many solutions have been proposed, which can be categorized into two groups. The first group paid attention on using new converter modeling and control techniques [3], [5], but these solutions are suited for new installations. The second group showed use of the auxiliary devices, like crowbar protection [6], energy storages [7], [8], bridge-type fault current limiters [2], [9], [10], series compensator [11] or extra converters [12]. The parallel resonance type fault current limiter (PRFCL) is a new auxiliary controller that has promising application in power systems [13]. So, it is worth investigating its per- formance in FRT capability augmentation of the DFIG based wind farms. In this work, the PRFCL is proposed to enhance the FRT of the DFIG based wind farm. In order to show the usefulness of the proposed approach in augmenting FRT capability, its performance is compared with that of the bridge-type fault current limiter (BFCL). Simulations were carried out using the Matlab/Simulink software. Copyright IEEE Non Commercial & personal use only Copyright IEEE Non Commercial & personal use only Copyright IEEE Non Commercial & personal use only Copyright IEEE Non Commercial & personal use only