Single-phase power generation employing VFC for standalone three-phase doubly wound asynchronous generator

Abstract

Dwag (DOUBLY Wound Asynchronous Generator) is prominent choice in variable speed energy conversion system due to its improved conversion efficiency and reduced rating converters [1]. In general, DWAG's are considered suitable choice for large rating installations [2]. To supply rural community located in small pockets and far away from grid utility, standalone energy conversion system fed through renewable energy prime movers such as pico-hydro and wind are gaining its popularity [2]–[3]. For such small scale energy conversion systems, single-phase distribution system is preferred choice to feed such consumers to minimize capital investment. Three-phase isolated asynchronous generator (lAG) has been reported in the literature for such applications [4]–[6]. However, it has been observed that even with a three-phase lAG, utilization of machine rating is not more than 40% [7]. Recently, a topology has been reported for the power generation to feed single-phase loads employing three-phase lAG to optimize the utilization of generating machine [8]. However, when the prime-movers are of variable speed in nature such as a wind turbine, these lAG based generating systems which are controlled for fixed speed operation, do not achieve MPT (Maximum Power Tracking) under varying wind speeds [9]. The lAG for variable speed operation requires two full rating converters [10]. A DWAG with back-back connected partial rating converters at rotor terminals allows variable speed operation of prime-mover to achieve MPT along with regulated stator terminal voltage and its frequency [11]–[16]. In the literature, DWAG based wind power installations have been explored mainly for grid connected WPGS (Wind Power Generation Systems) in large unit ratings [17]–[22]. However, a DWAG has never been explored in the literature for single-phase standalone power generation.