Power transfer capability improvement of an induction generator wind energy conversion system

Wind energy is considered the most viable proposition among the renewable energy options. Of various Wind Energy Conversion Systems (WECS), fixed speed induction generator based WECS directly connected to the grid is the cheapest and simplest option and has the largest market share. This type of WECS does not require any power electronic interface to allow the grid connection unlike the variable speed WECS. Despite some disadvantages variable speed WECS allow maximum energy capture. So far, there has not been any effort to develop a maximum energy capture scheme for induction generators connected directly to the grid. This paper aims to maximize the power transfer capability of fixed speed Squirrel Cage Induction Generator (SCIG) WECS through the use of variable excitation capacitors and On-load Tap Changer Transformer (OLTC). The developed controller is aimed to improve the power transfer capability of the system while keeping a reasonably constant voltage and frequency at the point of common coupling (PCC) within acceptable limits. This is performed while keeping the power factor close to unity at this connection point. The proposed system increases the effectiveness of the utilization of wind energy as one of the future energy sources, while mitigating the cost and complexity of the system. Simulation results as well as laboratory test model results are presented in this paper to validate the findings.