Minimization of fluctuations of output power and terminal voltage of wind generator by using STATCOM/SMES

Due to random variations of wind speed, the output power and terminal voltage of a fixed speed wind generator fluctuate continuously. These irregularities in power output are characteristic of intermittent energy sources such as wind energy, affecting both the power quality and planning of the energy storage system. It is reported that STATCOM/SMES (superconducting magnetic energy storage) topology can significantly decrease voltage and power fluctuations of grid connected fixed speed wind generator. But the main problem in wind generator output power smoothing is setting of the reference output power. Constant output power reference can cause large energy storage capacity in the cases when wind speed is very low. In this paper, the STATCOM/SMES topology is proposed, in which both SMA (simple moving average) and EMA (exponential moving average) are used to generate output power reference. Real wind speed data is used in the simulation analyses, which validates the effectiveness of the proposed control strategy. Simulation results clearly show that the proposed STATCOM/ SMES topology can smooth well the wind generator output power and also maintain the terminal voltage at rated level in both cases when SMA or EMA is used to generate output reference power. Finally, it is shown that reference output power generated by EMA provides better performance with reduced SMES storage capacity than that generated by SMA.