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Current grid codes stipulate wind power plants to stay connected to the network under sever fault conditions. In some countries, the fault ride-through (FRT) requirements are applicable to not only new installation but also to the already existing wind power plants that are usually constituted of fixed-speed wind generators. This paper proposes a new control scheme for the DFIG-based wind generators installed adjacent to the existing cage generators. The proposed controller enables DFIGs to provide significant reactive power support during the fault period and thereby, contribute to the stabilization of the nearby fixed-speed generators. Time-domain simulation studies are carried out to show the effectiveness of the proposed controller scheme under various fault conditions. [ABSTRACT FROM PUBLISHER]

This paper presents a new vector-based average current controller (ACC) with constant frequency for three-phase voltage source rectifiers (VSR). The goal of this method is to utilize advantage of both ACC and SVM technique. ACC technique is widely used in DC-DC applications and four-wire converter; however the implementation of this method in three-phase ac applications has not been studied yet. ACC technique is mostly robust to the variations of the load parameters, demonstrates rapid transient performance, and is appropriate for uncomplicated implementation. The method provides the best possible current waveforms with constant switching cycle which makes it suitable for high power applications with low switching frequencies. The developed method follows the reference current value in a single switching cycle very much similar to well-known hysteresis controllers. In addition, this method benefits from constant switching frequency, also by using SVM control technique reduce switching losses. Due to important role of battery chargers for electric vehicles in smart grid systems using this method the problems associated with variable switching frequency would be minimized also a better power efficiency would be achieved. Simulation results are illustrated to show the feasibility of this method. [ABSTRACT FROM PUBLISHER]