文档介绍：Elect r ic Power Systems Research Extending the pensation range ofa direct AC-AC FACTS device for offshore grids ABSTRACT The authors suggest to use hybrid modulation schemes to improve the reactive pensation capabilities of the direct AC– AC FACTS posed ofa matrix converter and a permanent machine. Because of the intrinsic limitations of the conventional matrix converter modulation schemes, the device has so far displayed a poor reactive pensation capability when the output power factor is low. Even worse, the direct AC– AC FACTS device could not provide pure reactive pensation. The paper presents an analysis demonstrating how the hybrid Three-Vector-Scheme extends the pensation range beyond the level that the conventional indirect space vector modulation exhibits. The reactive pensation capabilities of the FACTS device with both modulations puted pared analytically and finally verified bya simulation study. 1. Introduction Large scale integration of wind energy will call forth an increased use of Flexible AC Transmission Systems (FACTS). For offshore AC grids, appropriate FACTS device should possess the two following features: high power density and high direct AC-AC FACTS posed ofa matrix converter and a permanent (PM) synchronous machine, see Fig. 1, is pact and reliable mainly because the DC link capacitor is Eliminated. In[ 1,2J was introduced the idea of benefiting From the features of the matrix converter and provide power conditioning in drives and power conversion applications. A dedicated direct AC-AC FACTS device was presented in [3,4] for pensation and reactive power support to the grid. The device can provide reactive pensation like a by controlling directly the input current fed to the grid, see Fig. l. In addition active power control can be provided if there isa load on the shaft of the PM machine. The functioning of the device was experimentally verified in[1 ], however reactive pensation capability was poor for low output power