Performance Comparison of Grid Connected Small Wind Energy Conversion Systems

Abstract

A small scale Wind Energy Conversion System (WECS) has tremendous diversity of use and operating conditions, and consequently is evolving rapidly along with the large scale WECS for generation of electricity in either on grid or off grid applications. In recent years, the grid connected Small Wind Turbine (SWT) industry is primarily dominated by the Permanent Magnet Generators (PMGs) based topology. The Power Conditioning Systems (PCS) for grid connection of the PMG based topology requires a rectifier, boost converter and a grid-tie inverter. However, a small wind turbine may be based on Wound Rotor Induction Generators (WRIGs). The WRIG based topology can employ a rectifier, a chopper and an external resistor in the rotor side while the stator is directly connected to the grid. These two topologies have diverse losses that fluctuate with the wind speed. This paper presents a comparative study of a PMG and WRIG based topologies for SWT systems. The study employs numerical simulation to investigate the conversion losses for both topologies. It is demonstrated that a WRIG based topology offers less losses than a PMG based topology. The comparison is further enhanced by investigating the annual energy capture, annual energy loss and efficiency for the wind speed data and Weibull distribution of three different locations of Newfoundland, Canada. The study shows that a WRIG based topology is an optimum alternative in terms of performance characteristics within a slip variation of 15%.