5. Conclusion

From the simulated results, it is observed that the load requirements are directly met by the generated power itself but not by the battery power when the wind power is plenty. The mechanical power reaches its nominal value of 11.3 kW. The simulated results for both openloop and closed-control modes have been compared and tabulated in Table 3. The generated power P at the load bus terminals for closed-loop control mode is greater than the power attained in the open-loop control mode.

Also, it seems that there is a steady increase in the output power, while it is fluctuating in the open-loop control mode with respect to the wind speed. According to the variations in the wind velocity, there is a remarkable change observed in the output power generated in bus 1. When the wind speed is of 8 m/s, the power generated attains 5 kW while it fluctuates between 9 and 11 m/s, there is a gradual increase in power. It reaches nearly the peak value of 14 kW, which is undesirable as wind speed goes beyond 12 m/s.

When the wind speed fluctuates between 8 and 12 m/s, the reactive power is zero initially and reaches a constant value of 2200 VA in its steady state. The speed curve of the rotor attains its steady-state value when the time t is 0.5 s. Also, it is observed that the terminal voltage in the stator in all three phases is regulated and boosted up to 330 V in the first stage and then to 635 V in the second stage, and the three-phase stator current is found to be around 25 A.

During the closed-loop control mode, though drastic change in the power has not been observed in the boost converter stages, the generated power exceeds the load power, and hence apart from meeting the load demands, it supplies the battery load which is clearly visible from its charging current. Also, the battery voltage is getting its full rated value of 670 V. Further, the generated stator voltage is boosted up, and hence optimum power is observed in both grid and loads, that is, the generated voltage at the stator terminals gradually builds up and attains its steady-state value after 0.9 s. The magnitude of generated power at the load bus


Table 3. Simulated results for PMSG-based WECS.

seems increasing around 10.4 kW while reactive power reaches 1725 VA but with some ripples. The mechanical power also gets its steady value of 11.2 kW within a time frame of 1 s.

In addition, the load power management is excellent in closed-loop control method using fuzzy logic controller. Also, if the generated power is found in excess, it would be stored in the battery for future power salvage. There is a notable increase in the magnitude of stator voltage and hence the generated power; ripples are considerably reduced compared to openloop control mode, thus improving the power quality as well.
