Evaluation of the Performance of BTFCLs for Enhancing LVRT Capability of DFIG

Abstract

Performance of three kinds of bridge type fault current limiters (BTFCLs) for enhancing LVRT capability of DFIG is evaluated in this paper. The common BTFCL can effectively enhance the LVRT capability of DFIG. However, the fault current limiting inductor (FCLI) is periodically inserted into the stator circuit under normal operation for compensating power losses of the FCLI. The periodically insertion of the FCLI induces stator voltage spikes, which causes significant stator flux and electromagnetic torque oscillations. One feasible way to solve this problem is to use an additional current regulating circuit (CRC). However, the additional CRC increases hardware cost, reduces reliability of the whole system and induces more power losses. To solve this problem, a BTFCL with bypass resistor (BTFCL-BR) is presented. The bypass resistor absorbs the majority of the current harmonics during normal operation and eliminates the stator voltage spikes. The flux and electromagnetic torque oscillations can thus be significantly reduced. The performance of three kinds of BTFCLs is evaluated by simulation and experimental studies on a typical 1.5MW wind turbine driven DFIG system and a 2kW DFIG prototype. By simulation and experimental evaluations, it seems that the BTFCL-BR approach is the most promising solutions among the three kinds of BTFCLs.Index Terms-Doubly fed induction generator (DFIG), low voltage ride through (LVRT), bridge type fault current limiter (BTFCL).

Low voltage ride-through enhancement of DFIG-based wind turbine using DC link switchable resistive type fault current limiter

“…The performance of the three types of bridge types FCL (BTFCL) is evaluated in [23] to enhance the LVRT capability of the DFIG. The first type of the BTFCL is introduced a basic topology.…”

“…Also during the fault condition, a high percentage of the DFIG fault current (about %90) is injected through the stator. Considering these facts, and the research in [22]- [23], three similar sets of the STFCL must be connected in series with the stator of the DFIG. The rating of the STFCL devices must be selected carefully to withstand the rated voltage and current of the stator during the normal condition, as well as the fault condition.…”

“…Some configuration of the FCLs are employed to increase the LVRT capability of the DFIG based wind turbine in the power network [22][23][24][25]. A three phase FCL including an isolation transformer and a large DC inductance with a bypass resistance located in the stator side of the DFIG is used to restrict the fault current level [22,23]. A single phase bridge type FCL is utilized in the terminal of the DFIG to improve the LVRT capability of the DFIG during all gird faults [24].…”

Low-Voltage Ride-Through Control Strategy for a Grid-Connected Energy Storage System

“…The LVRT control strategies researched recently comply with the LVRT requirement. In addition, these strategies focus on the additional operations that are effective and economical, which include the continuously stable operations with dynamic breakers in the WPG systems [26][27][28][29][30] and the maximum power generation with low voltages in the SEG systems [31][32][33]. These methods for additional operations are presented by considering the characteristics of the source type.…”

A dynamic strategy to improve the ride-through capability of a fixed speed induction generator

“…To solve the problem, devices based on series compensator represented by dynamic voltage restorers (DVRs) [27][28][29][30] and bridge-type fault current limiters(BFCLs) [31][32][33] have been utilized to enhance the LVRT stability of wind farms with FSIGs. Both DVR and BFCL are connected between the grid and the FSIG, to inject a voltage to compensate the voltage sag depth when a dip happens.…”