H∞ Control of Wrim Driven Flywheel Storage System to Ride-Through Grid Voltage Dips

Flywheel Energy Storage Systems (FESSs) are commonly integrated with wind farms to help them to provide many grid services, including frequency control, voltage control, and power smoothing. Although such systems are not concerned by the severe grid code requirements, their ability to ride-through voltage dips is important to ensure better stability of the power grid. In this paper, the authors propose a robust H∞ current controller for a Wound Rotor Induction Machine (WRIM) based FESS during grid voltage dips. The proposed H∞ controller decreases the negative effects of voltage dips in the WRIM system, such as the rotor over-currents and the active power oscillations. On the other hand, it also guarantees the robustness in the presence of parameter perturbation. The proposed controller is designed using a modified mixed-sensitivity H∞ technique to take into consideration grid disturbances and parameter perturbation. Finally, simulations are made in MATLAB/Simulink using SimPowerSystems to verify the effectiveness of the H∞ controller under grid voltage dips with WRIM parameter perturbation. The simulation results show that the proposed H∞ controller can improve the stability of the WRIM based FESS subject to grid voltage dips and guarantee the robustness with parameter perturbation

Real time implementation of a super twisting control of a BLDC motor

This paper presents and implements a Super-Twisting high order sliding mode control for a BLDC motor. Conventional sliding mode controller has a very fast response, it allows the convergence in finite time and characterized by its robustness against disturbances and uncertainties; However, the chattering phenomenon due to the discontinuous nature of its control organ degrades its performance, especially in case of mechanical membranes control. To overcome this disadvantage, the most commun solutions are based on the adaptation of its discontinuous nature at static regime, it reduces effectively the chattering phenomenon, but on the other hand impacts performance in terms of robustness. The Super-Twisting is an algorithm of high order sliding mode applicable on systems with relative degree 1, it produces a continuous control which cancels the chattering phenomenon and preserve all traditional sliding mode command performances. To validate the effectiveness and the robustness of the Super-Twisting controller for controlling brushless motors, experimental results using a 3KW BLDC motor are provided and compared with those of a conventional sliding mode controller

dSPACE Implementation for a Fuzzy Logic Voltage Control using a Self-Excited Induction Generator and a Voltage Source Inverter

The present work describes the analysis  of a control scheme for keeping  the  RMS voltage output  constant, the system is  supplying  by a self-excited induction generator with variable speed and load. A comparison is examined between simulation and experimental results using dSPACE board. the results are provided to verify the effectiveness of this approach and gives very high performance

Low-voltage ride-through capability improvement of type-3 wind turbine through active disturbance rejection feedback control-based dynamic voltage restorer

Disconnections due to voltage drops in the grid cannot be permitted if wind turbines (WTs) contribute significantly to electricity production, as this increases the risk of production loss and destabilizes the grid. To mitigate the negative effects of these occurrences, WTs must be able to ride through the low-voltage conditions and inject reactive current to provide dynamic voltage support. This paper investigates the low-voltage ride-Through (LVRT) capability enhancement of a Type-3 WT utilizing a dynamic voltage restorer (DVR). During the grid voltage drop, the DVR quickly injects a compensating voltage to keep the stator voltage constant. This paper proposes an active disturbance rejection control (ADRC) scheme to control the rotor-side, grid-side and DVR-side converters in a wind-DVR integrated network. The performance of the Type-3 WT with DVR topology is evaluated under various test conditions using MATLAB®/Simulink®. These simulation results are also compared with the experimental results for the LVRT capability performed on a WT emulator equipped with a crowbar and direct current (DC) chopper. The simulation results demonstrate a favourable transient and steady-state response of the Type-3 wind turbine quantities defined by the LVRT codes, as well as improved reactive power support under balanced fault conditions. Under the most severe voltage drop of 95%, the stator currents, rotor currents and DC bus voltage are 1.25 pu, 1.40 pu and 1.09 UDC, respectively, conforming to the values of the LVRT codes. DVR controlled by the ADRC technique significantly increases the LVRT capabilities of a Type-3 doubly-fed induction generator-based WT under symmetrical voltage dip events. Although setting up ADRC controllers might be challenging, the proposed method has been shown to be extremely effective in reducing all kinds of internal and external disturbances

Physical volcanology and emplacement mechanism of the Central Atlantic Magmatic Province (CAMP) lava flows from the Central High Atlas, Morocco

The best preserved and most complete lava flow sequences of the Central Atlantic Magmatic Province (CAMP) in Morocco are exposed in the Central High Atlas and can reach up to 300 m in thickness. Four distinct formations, emplaced in subaerial environments, are classically recognized: the Lower, Intermediate, Upper and Recurrent formations. These formations are separated by paleosoils and sedimentary sequences (mudstones, siltstones, sandstones, limestones), that are in general less than two meter-thick and may exceptionally reach a thickness of 80 m, representing minor periods of volcanic quiescence. CAMP lava flows of the Central High Atlas can be grouped into two main categories: subaerial compound pahoehoe flows and simple flows. The former type is exclusively confined to the Lower and Intermediate Formations, while simple flows occur in the Upper and Recurrent Formations. The dominance of compound flows in the two lowermost units of the CAMP suggests a slow emplacement during successive sustained eruptive episodes. Instead the thick single flows characterizing the Upper and Recurrent units indicate higher effusive rates. Basaltic pillow lavas (always of short lateral extent: 10 to 100 m), showing radial jointing and vitreous rinds, identical to those found in the Western Meseta, are occasionally associated with hyaloclastites in the base of the Intermediate Formation, immediately above clastic sediments, or in the Upper Formation. The occurrence of pillow lavas does not imply a generalized subaqueous environment at the time of the lava emission. Instead, they represent subaerial flows that entered small lakes occupying depressions on the volcanic topography of the Lower and Intermediate Formations. The short lateral extent of the pillow lavas and their constant stratigraphic position, the existence of lava flows with unequivocal subaerial characteristics associated to sediments containing fossilized wood, clearly indicate onshore emplacement.info:eu-repo/semantics/publishedVersio

Voltage Balance Control Analysis of Three-Level Boost DC-DC Converters: Theoretical Analysis and DSP-Based Real Time Implementation

In this paper, a step-by-step description to get a unique three-level boost DC⁻DC converter (TLBDC) (DC—direct current) small signal model is first presented and validated through simulations and experiments. This model allows for overcoming the usage of two sub-models as in the conventional modeling approach. Based on this model, voltage balance (VB) controllers are designed and VB control analysis is presented. Two VB controllers, namely Proportional Integral (PI) and Fuzzy, were analyzed when the VB control was applied on both TLBDC switches or only one. According to the obtained simulation and experimental results, the proposed model gives an accurate approximation in dynamic, small perturbations around an operating point and steady state modes. Moreover, it has been shown that VB is achieved in a reduced time when VB control is applied on both the TLBDC’s switches. Furthermore, the Fuzzy controller performs better than PI controller for VB control

Power switch failures tolerance of a photovoltaic fed three-level boost DC-DC converter

International audienceIn this paper, both switches open/short circuit faults diagnosis and a fault tolerant diagram of a photovoltaic (PV) fed Three-Level Boost DC-DC Converter (TLBDC) are addressed. Diodes voltages are used to detect open or short circuit faults. These voltages are also used to ensure voltage balance control of the TLBDC. Hence, the number of sensors would be the same as the number of sensors used in a conventional TLBDC controller scheme. The proposed method identifies and locates the faulty switch easily. The TLBDC is reconfigured where the ensured input power and output voltage remain unchanged. This is achieved by adding only one extra power switch to the TLBDC topology. Simulation and experimental results confirm the effectiveness of the proposed fault diagnosis method and the TLBDC fault tolerant scheme

Biaxial Equatorial Solar Tracker with High Precision and Low Consumption: Modelling and Realization

The solar tracker is a mechanism that helps the photovoltaic panel to maximize its performance, while keeping it oriented towards direct solar radiation. In order to specify tracking, most solar trackers use two axes, one horizontal and the other vertical, which implies an increase of the consumed energy and a decrease in precision, since we have to make both motors operate simultaneously. This paper is a modelling of a biaxial solar tracker, with the principle of an equatorial mount, allowing it to precisely follow the sun via a single axis (equatorial axis), while the second axis (tilt axis) makes a small daily correction of few seconds at sunrise. In this way, our model keeps precision to the maximum, with minimum energy consumption. A detailed simulation clearly shows that the proposed model receives the maximum solar irradiation that a normal surface to solar radiation can receive and may in a certain period of the year receive a gain in the amount of solar irradiation; we have up to 63.47% compared to a fixed installation. The study details the different tracking methods, in order to adapt the concept model to the type of solar panel used. We closed finish the study with the realization of the prototype with a detailed explanation of the concept movement. To validate the simulation, we have made an experience that gives us the same results as given by simulation