Multivariable control of a grid-connected wind energy conversion system with power quality enhancement

This document is the Accepted Manuscript version of the following article: Kaddour Fouad, Houari Merabet Boulouiha, Ahmed Allali, Ali Taibi, and Mouloud Denai, ‘Multivariable control of a grid-connected wind energy conversion system with power quality enhancement’, Energy Systems, Vol. 9 (1): 25-57, February 2018. The final publication is available at Springer via: https://doi.org/10.1007/s12667-016-0223-7This paper proposes the design of a multivariable robust control strategy for a variable-speed WECS based on a SCIG. Optimal speed control of the SCIG is achieved by a conventional PI controller combined with a MPPT strategy. DTC-SVM technique based on a simple Clarke transformation is used to control the generator-side three-level converter in the variable speed WECS. The flow of real and reactive power between the inverter and the grid is controlled via the grid real and reactive currents and the DC link voltage using multivariable H∞ control. The overall WECS and control scheme are developed in Matlab/Simulink and the performance of the proposed control strategy is evaluated via a set of simulation scenarios replicating various operating conditions of the WECS such as variable wind speed and asymmetric single grid faults. The power quality of the WECS system under H∞ control control approach is assessed and the results show a significant improvement in the total harmonic distorsion as compared to that achieved with a classical PI control.Peer reviewedFinal Accepted Versio

Papillomas of the External Ear Canal: Report of Ten cases in Chinese Patients with HPV In Situ Hybridization

Squamous papilloma is a benign exophytic proliferation which can occur occasionally in the external ear canal. It is widely assumed that the Human Papilloma Virus (HPV) is an etiologic factor of papillomas. Available techniques for detection of HPV genomes include immunohistochemistry, Southern blot hybridization, in situ hybridization (ISH), and polymerase chain reaction. To our knowledge, HPV typing has not been reported on tissue sections of papillomas in the external ear canal. We report HPV ISH analysis in ten cases of papillomas, involving the external ear canal in Chinese patients. These papilloma excrescences were less than 1 cm in diameter, and were benign morphologically. Automated HPV ISH analysis was performed for the hybridization of DNA probes, including both low-risk and high-risk HPV subtypes. HPV ISH results revealed that seven out of ten cases were positive for low-risk HPV (6, 11), three cases demonstrated no hybridization for low-risk HPV probe, and none of the cases revealed any detection of high-risk HPV (16, 18, 31, 33, 35, 39, 51, 52, 56, 58, and 66). On follow-up after 18–29 months (average 24.5 months), eight patients were doing well, with no local recurrence after excision. Two patients were lost to follow-up. Our results confirm that benign papillomas of the external ear canal are associated with low-risk HPV infection with benign behavior and neither recurrence nor high grade dysplasia