International Journal of Engineering Research in Electrical and Electronic Engineering (IJEREEE)

Interfacing Wind Energy to Grid with Load Compensation by Cascaded Hybrid Multilevel Inverters (Chmli)

Author : Mr. Madhava Rao.J ¹ Mamatha .G.M ² Mr. B S Venkatesh Murthy ³ Dr. Pradeep B Jyoti ⁴

Date of Publication :7th November 2016

Abstract: Variable wind conditions necessitate the use of a variable speed wind turbine (VSWT) with a AC/DC/AC converter scheme in order to harvest the maximum power from the wind and to decouple the synchronous generator voltage and frequency from the grid voltage and frequency. In this paper, a combination of a three phase diode bridge rectifier (DBR) and a modified topology of the cascaded hybrid multilevel inverter (CHMLI) have been considered as an AC/DC/AC converter. A control strategy has been proposed for the CHMLI to achieve the objective of grid interface of a wind power system together with local load compensation. A novel fixed frequency current control method is proposed for the CHMLI based on the level shifted multi carrier PWM for achieving the required control objectives with equal and uniform switching frequency operation for better control and thermal management with the modified CHMLI. The condition of the controller gain is derived to ensure the operation of the CHMLI at the fixed frequency of the carrier. The converter current injected into the distribution grid is controlled in accordance with the wind power availability. In addition, load compensation is performed as an added facility in order to free the source currents being fed from the grid of harmonic distortion, unbalance and a low power factor even though the load may be unbalanced, non-linear and of a poor power factor. The results are validated using MATLAB simulation studies.

Reference :

1. G. Todeschini and A. E. Emmanuel, “Wind energy conversion systems as active filters: design and comparison of three control methods,” IET Renewable Power Generation, Vol. 4, pp. 341-353, Jul. 2010.
2. A. H. Kasem, E. F. Al-Saadani, H. H. ElTamaly and M. A. A. Wahab, “Power ramp rate control and flicker mitigation for directly connected wind turbines,” IET Renewable Power Generation, Vol. 4, No. 3, pp. 261-271, May 2010.
3. A. Chen, L. Hu and X. He, “A novel type of combined multilevel converter topologies,” 30th Annual conf. of IEEE Industrial Electronics Society, 2004
4. M. K. Mishra, A. Joshi and A.Ghosh, “Control schemes for equalization of capacitor voltages in neutral clamped shunt compensator,” IEEE Trans. Power Del., Vol. 18, No. 2, pp. 538-544, Apr. 2003.
5. A. Shukla, A. Ghosh and A. Joshi, “Control schemes for DC capacitor voltages equalization in diodeclamped multilevel inverter-based DSTATCOM,” IEEE Trans. Power Del., Vol. 23, pp. 1139-1149, Apr. 2008.