Modeling of permanent magnet linear generator and state estimation based on sliding mode observer: A wave energy system application

summary:This paper synopsis a new solution for Permanent Magnets Linear Generator (PMLG) state estimation subject to bounded uncertainty. Therefore, a PMLG modeling method is presented based on an equivalent circuit, wherein a mathematical model of the generator adapted to wave energy conversion is established. Then, using the Linear Matrix Inequality (LMI) optimization and a Lyapunov function, this system's Sliding Mode Observer (SMO) design method is developed. Consequently, the proposed observer can give a robust state estimation. At last, numerical examples with and without uncertainty are included to exemplify the effectiveness and applicability of the suggested approaches

Gold octahedra nanoparticles (Au_0.03 and Au_0.045): Synthesis and impact on marine clams Ruditapes decussatus

The increased use of gold nanoparticles (AuNPs) in several applications has led to a rise in concerns about their potential toxicity to aquatic organisms. In addition, toxicity of nanoparticles to aquatic organisms is related to their physical and chemical properties. In the present study, we synthesize two forms of gold octahedra nanoparticles (Au_0.03 and Au_0.045) in 1.3-propandiol with polyvinyl-pyrrolidone K30 (PVPK30) as capping agent using polyol process. Shape, size and optical properties of the particles could be tuned by changing the molar ratio of PVP K30 to metal salts. The anisotropy in nanoparticles shape shows strong localized surface plasmon resonance (SPR) in the near infrared region of the electromagnetic spectrum. Environmental impact of Oct-AuNPs was determined in the marine bivalve, Ruditapes decussatus exposed to different concentrations of Au_0.03 and Au_0.045. The dynamic light scattering showed the stability and resistance of Au_0.03 and Au_0.045 in the natural seawater. No significant modification in vg-like proteins, MDA level and enzymatic activities were observed in treated clams with Au_0.03 even at high concentration. In contrast, Au_0.045 induced superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GST) activities, in a concentration dependent manner indicating defense against oxidative stress. Enhanced lipid peroxidation represented by malondialdehyde content confirmed oxidative stress of Au_0.045 at high concentration. These results highlight the importance of the physical form of nanomaterials on their interactions with marine organisms and provide a useful guideline for future use of Oct-AuNPs. In addition, Vitellogenin is shown not to be an appropriate biomarker for Oct-AuNPs contamination even at high concentration. We further show that Oct-AuNPs exhibit an important antioxidant response without inducing estrogenic disruption

H ∞ -Sliding mode control of one-sided Lipschitz nonlinear systems subject to input nonlinearities and polytopic uncertainties

International audienceThis paper is concerned with the control problem for different types of one-sided Lipschitz (OSL) nonlinear systems subject to input nonlinearities, unmatched polytopic uncertainties and external perturbations. The design framework gathers the high robustness qualities of the sliding mode control (SMC) and the technique. The aims is to consider the bounded disturbance attenuation measure in the analysis of sliding mode dynamics, thus to ameliorate the performance of the SMC system. An integral switching surface function is chosen and related synthesis conditions for the sliding mode dynamics are formulated in terms of linear matrix inequalities (LMIs). Then, an appropriate control law is synthesized such that reachability of the switching manifold is ensured. At last, simulation examples are provided to prove the feasibility of the proposed approach

Design of Robust Supertwisting Algorithm Based Second-Order Sliding Mode Controller for Nonlinear Systems with Both Matched and Unmatched Uncertainty

This paper proposes a robust supertwisting algorithm (STA) design for nonlinear systems where both matched and unmatched uncertainties are considered. The main contributions reside primarily to conceive a novel structure of STA, in order to ensure the desired performance of the uncertain nonlinear system. The modified algorithm is formed of double closed-loop feedback, in which two linear terms are added to the classical STA. In addition, an integral sliding mode switching surface is proposed to construct the attractiveness and reachability of sliding mode. Sufficient conditions are derived to guarantee the exact differentiation stability in finite time based on Lyapunov function theory. Finally, a comparative study for a variable-length pendulum system illustrates the robustness and the effectiveness of the proposed approach compared to other STA schemes

Sliding Mode Control of Hybrid Renewable Energy System Operating in Grid Connected and Stand-Alone Mode

This paper studies innovative application of sliding mode control (SMC) for a Hybrid Renewable Energy System (HRES) in grid-connected and autonomous modes of operation. The considered HRES includes a photovoltaic (PV), wind turbine (WT) based on a Permanent Magnet Synchronous Generator (PMSG). The PV generator is coupled to the common DC bus via a DC/DC converter. The latter is controlled by an MPPT algorithm based on the Adaptive Perturbation and Observation Algorithm Method (APOAM) to search the optimum working of this source. A SMC is utilized to manage the PV voltage to achieve the Maximum Power Point (MPP) by altering the obligation duty cycle. The battery interfaced by a bidirectional buck-boost DC/DC converter can be charged or discharged depending on the production situation. On the one hand, the wind turbine conversion chain is equipped with a PMSG and a rectifier controlled to regulate the operating point of the wind turbine to its optimum value. During a Stand-Alone Mode (SAM) operation, the Voltage Source Converter (VSC) was used for controlling the output voltage in terms of amplitude and frequency delivered to the AC load. However, in Grid-Connected Mode (GCM) operation, the VSC was adapted to control the electrical parameters of the grid. To better appreciate the advantages of the proposed SMC approach, we have proposed a series of comparative tests with the conventional PI control in the operating modes GC and SA and under different scenarios. The proposed control strategy has undeniable advantages in terms of control performance and very low total harmonic distortion THD value compared with the conventional PI control. Finally, It is concluded that the proposed approach improves the quality and provides a stable operation of the HRES

Sliding Mode Control of DFIG for a Variable Speed Wind Turbine

International audienceThis paper presents the study of a variable speed wind turbine. The power conversion system is based on a double-fed induction generator (DFIG). The parameters involved in this study are the active and reactive powers exchanged between the DFIG stator and the grid. For this purpose, sliding mode control will be adopted to ensure the control of these powers and obtain the appropriate voltages and currents. The validity of the sliding mode control will be verified with simulations performed on Matlab/Simulink software. In fact, the results obtained verify the performance of such a control to ensure a good quality of energy that will be injected into the electrical network

Uncertain Saturated Discrete-Time Sliding Mode Control for A Wind Turbine Using A Two-Mass Model

International audienceThe aim of this paper is to propose a new design variable speed wind turbine control by discrete-time sliding modeapproach. The control objective is to obtain a maximum extraction of wind energy, while reducing mechanical loadsand rotor speed tracking combined with an electromagnetic torque. For this application, we designed a discrete timesliding mode control using the equivalent discrete time reaching law. Furthermore, a systematic and improved designprocedure for uncertainties discrete-time sliding mode control (SMC) with saturation problem is provided in this paper.The saturation constraint is reported on inputs vector. LMI technique and polytopic models are used in the design ofthe switching surface. To achieve some performance requirements and good robustness, in the sliding mode, the poleclustering method is investigated. Based on the unit vector control approach, a robust control is developed, then, todirect and maintain the system states onto the sliding manifold in finite time. Finally, a systematic design procedure forDSMC required to achieve a given performance level is provided and its effectiveness is varied by applying it to variablespeed wind turbine systems

Fuzzy Supervisor Approach Design Based-Switching Controller for Pumping Station: Experimental Validation

This paper proposes a discrete-time switching controller strategy for a hydraulic process pumping station. The proposed solution leads to improving control system performances with two tests: combination of Fuzzy-PD and PI controllers and Fuzzy-PID and PI controllers. The proposed design methodology is based on accurate model for pumping station (PS), which is developed in previous works using Fuzzy-C Means (FCM) algorithm. The control law design is based on switching control; a fuzzy supervisor manages the switching from one to another and regulates the rate of participation of each order, in order to satisfy various objectives of a stable pumping station like the asymptotic stability of the tracking error. To validate the proposed solution, experimental tests are made and analyzed. Compared to the conventional PI and fuzzy logic (FL) approaches, the results show that the switching controller allows exhibiting excellent transient response over a wide range of operating conditions and especially is easier to be implemented in practice