Robust Sliding Mode H∞ Controller of DFIG Based on Variable Speed Wind Energy Conversion System

In this study, a Sliding Mode (SM) methodology combined with a robust H∞ control scheme (SM-H∞) was proposed to control the stator active and reactive power generated by the Doubly Fed Induction Generator (DFIG). The purpose of the proposed controller is to improve the DFIG stator active and reactive power tracking performances by reducing chattering phenomena under variable wind speed, which provides major drawbacks of conventional SM controllers. The H∞ technique was used to define the SM attractive control part, which helps to reduce chattering phenomena and improves robustness in the presence of parameter variations and wind speed changing. The DFIG stator was directly connected to the grid and, its rotor was linked to the grid through a back-to-back converter. The proposed approach was tested using Matlab/Simulink and a comparison with the conventional SM and the SM fuzzy logic controllers was carried out. The results of simulation illustrated an effectiveness of the proposed SM-H∞ controller even in the presence of the DFIG parameter variations and speed changing compared with the other techniques

Investigating the Secondary Education Context of School Violence Case of Three Secondary Schools within the District of Ain Meranein Chlef/Algeria

Abstract: During the latest decades, schools have witnessed many phenomena, some of which are regarded as intruders to the field of education. One of these strange behaviours is that of school violence, which should be, by principle, distanced and abstracted from the educational environment. This contradictious fact is the subject of this investigation as it has unfolded very quickly and then, leading to the creation of a taxonomy. This research is deep-rooted to the behaviourist theory. It rather deals with the inside and outside school variables that govern the occurrence of this unusual comportment. This attempt investigates “the context” of violent actions in the Algerian secondary schools. The aim of the study is to examine the issue of school violence among students. A mixed method is used to gather data. As a sample of this research, we opted for 24 teachers (13males and 11females) and 20 pupils (7males and 13 females) from three secondary schools within the district of Ain Merane in chlef. The results showed that the issue of school violence affects negatively the learning atmosphere, and it has several causes and consequences. This exploratory analysis concerns providing recommendation at least to reduce the occurrence of school violence that is causing the education process to be a truncated perspective.  Keywords: Attitudes; Context; Educational environment; Impact; School violence

Učinkovitost biološkog uklanjanja šesterovalentnog kroma suspendiranom i imobiliziranom mikrobnom biomasom na pucolanu: proučavanje mehanizma samočišnjenja

Hexavalent chromium is one of the hazardous metals that can be found in industrial effluents such as wood treatment units, mining, leather tanning, pigment, steel and electroplating industry. The present work aimed to evaluate the self-purification capacity of the microbial flora taken from the domestic wastewater effluent of Chlef City, with the perspective of designing a microbial bed in the secondary sewage treatment to prevent an industrial Cr(VI) contamination. Under various operating conditions, the bioremoval performance of Cr(VI) was evaluated by using suspended biomass and immobilised biomass (fixed onto pozzolana grains). The results showed that the immobilised biomass was more efficient and more resistant to Cr(VI) toxicity than the suspended biomass. Indeed, the Cr(VI) was totally eliminated within 96 h for an initial concentration of 50 mg l–1 by the immobilised biomass, while this rate was obtained after 120 h for the suspended biomass. The kinetic data fit well to the pseudo-first order kinetic model. The intraparticle diffusion kinetic model suggested that the diffusion process of Cr(VI) was greatly influenced by the initial concentration. The microbial flora present in domestic wastewater is a promising biosorbent that is able to treat effluent containing Cr(VI). This work is licensed under a Creative Commons Attribution 4.0 International License.Šesterovalentni krom je jedan od opasnih tvari koja se može naći u otpadnim tokovima drvne industrije, rudarstva, štavljenja kože, industrije pigmenta, čelika i galvanizacije. Cilj ovog rada bio je procijeniti kapacitet samopročišćavanja mikrobne flore uzete iz komunalnih otpadnih voda grada Chlefa, s perspektivom projektiranja mikrobnog sloja primjenjivog za sekundarnu obradu industrijskih voda s ciljem sprječavanja kontaminacije kromom(VI). Učinak biološkog uklanjanja šesterovalentnog kroma procijenjen je pri različitim radnim uvjetima primjenom suspendirane te imobilizirane biomase (fiksirane na zrna pucolana). Rezultati su pokazali da je imobilizirana biomasa učinkovitija i otpornija na toksičnost kroma(VI) od suspendirane biomase. Primjenom imobilizirane biomase, 50 mg l–1 kroma(VI) je potpuno uklonjeno tijekom 96 h dok je uz primjenu suspendirane biomase bilo potrebno 120 h. Kinetika odgovara modelima pseudo prvog reda. Kinetički model unutarčestične difuzije ukazao je na veliki utjecaj početne koncentracije kroma(VI) na proces njegove difuzije. Mikrobna flora prisutna u komunalnim otpadnim vodama obećavajući je sorbens koji se može primijeniti za pročišćavanje voda koje sadrže krom(VI). Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna

Neural High Order Sliding Mode Control for Doubly Fed Induction Generator based Wind Turbines

Wind energy has many advantages because it does not pollute and is an inexhaustible source of energy. In this paper Neural High Order Sliding Mode (NHOSM) control is developed for Doubly Fed Induction Generator (DFIG) based Wind Turbine (WT). The stator winding is directly coupled with the main network, whereas a Back-to-Back converter is installed to connect its rotor to the grid. The proposed control scheme is composed of Recurrent High Order Neural Network (RHONN) trained with the Extended Kalman Filter (EKF), which is used to build-up the DFIG models. Based on such identifier, the High Order Sliding Mode (HOSM) using Super-Twisting (ST) algorithm is synthesized. To show the potential of the selected scheme, a comparison study considering the NHOSM, Conventional Sliding mode (CSM), and the HOSM control is done. To ensure maximum power extractions and to protect the system, the Maximum Point Power Tracking (MPPT) algorithm and the h control are also implemented. Simulation results demonstrate the effectiveness of the proposed scheme for enhancing robustness, reducing chattering, and improving quality and quantity of the generated power.

Modeling, Control and Diagnosis of Electrical Machines and Devices

Nowadays, the increasing use of electrical machines and devices in more critical applications has driven the research in condition monitoring and fault tolerance [...

Zero-Compensator Filter for Power Sharing Between Battery/Supercapacitor in a Grid-Connected Photovoltaic System

This paper contributes to the energy man- agement of a Hybrid Energy Storage System (HESS), comprising a lithium-ion battery and Supercapacitors (SCs) for a grid-connected photovoltaic system. In gen- eral, an Energy Storage System (ESS) can offset the in- termittency of renewable energy. However, ESS can absorb large amounts of energy with slow dynamics, but can only absorb fast dynamics when subjected to high currents, which quickly contributes to their wear. To avoid this, SCs are added to energy storage as a supplement to batteries. There are various meth- ods for power-sharing, including the most common, which uses the Low-Pass Filter (LPF). This article proposes a new technique to distribute power between the battery and the SCs using the zero-compensator fil- ter of the battery regulator. Also, this technique is based on the compensation of the energy dissipated by the bat- tery through the SCs. Besides, the State of Charge (SoC) of the battery is kept within safe boundaries. The proposed technique is compared to the ESS and classical HESS techniques. The simulation results con- firmed the efficacy of the proposed method of rapidly restoring the DC-link voltage and improving the bat- tery lifespan. In addition, this technique is adaptable to the stand-alone site, and the AC currents showed good quality

Neural Inverse Optimal Control of a Regenerative Braking System for Electric Vehicles

This paper presents the development of a neural inverse optimal control (NIOC) for a regenerative braking system installed in electric vehicles (EVs), which is composed of a main energy system (MES) including a storage system and an auxiliary energy system (AES). This last one is composed of a supercapacitor and a buck–boost converter. The AES aims to recover the energy generated during braking that the MES is incapable of saving and using later during the speed increase. To build up the NIOC, a neural identifier has been trained with an extended Kalman filter (EKF) to estimate the real dynamics of the buck–boost converter. The NIOC is implemented to regulate the voltage and current dynamics in the AES. For testing the drive system of the EV, a DC motor is considered where the speed is controlled using a PID controller to regulate the tracking source in the regenerative braking. Simulation results illustrate the efficiency of the proposed control scheme to track time-varying references of the AES voltage and current dynamics measured at the buck–boost converter and to guarantee the charging and discharging operation modes of the supercapacitor. In addition, it is demonstrated that the proposed control scheme enhances the EV storage system’s efficacy and performance when the regenerative braking system is working. Furthermore, the mean squared error is calculated to prove and compare the proposed control scheme with the mean squared error for a PID controller