The reliability of conventional photovoltaic (PV) structure in shaded situations can undergo different issues related to internal and external conditions. The internal condition accounts for the ...inhomogeneity of the properties of electrothermal cells, while the external conditions connote optimal power maximum tracking techniques and protection circuit limitations. This article proposes a new technique to improve the reliability of shaded panels, considering the internal and the external issues. Our study begins with an extensive analysis to assess the vulnerability of PV cells to second-quadrant thermal stress and operational limits of bypass diode protection against hot spot. Consequently, we proposed a new system that concurrently operates with the maximum power extraction process to assist bypass diodes with hot-spot protection. This proposition results in a reconfigured panel with both a local detection circuit that defines the conduction states of bypass diodes and additional mosfet s that switch shaded subgroups. In this article, an algorithm was developed that is capable of controlling the optimal maximum operation point tracking with an on-demand deployment of the protection mosfet s, using the signals provided by the local detection circuit. A set of experiments were carried out in order to demonstrate the capability of the proposed method to prevent hot-spot damages over all shading rates and operating points. The novelty of the proposed approach is its low cost of implementation as well as its simple and efficient design. Therefore, it has the potential to be easily integrated along side existing infrastructure and maximum power point tracking algorithms.
•Decoupled Trigonometric Saturated (DTS) droop controller for stable power sharing applied to parallel DGs in islanded microgrids is proposed.•Droop control is employed to guarantee the bus voltage ...and frequency stability and stable power sharing between parallel DGs.•The proposed controller eliminates the undesired oscillations in the output power, without total real and reactive power sharing error.•The transient and steady state performances of the proposed droop-control are verified by simulations.•Simulation results demonstrate efficiency of the developed DTS droop control based on decoupled trigonometric characteristics.
This paper proposes a novel droop control based on Decoupled Trigonometric Saturated (DTS) controller for stable power sharing applied to meshed parallel inverter systems in islanded microgrids. The novel DTS control scheme is introduced to improve the power-sharing accuracy with a better stability and to provide a proper dynamic decoupling of active and reactive power in the presence of different impedances. Moreover, this method not only achieves the aforementioned decoupling; but also, guarantees both voltage and frequency stability. The theoretical concept of the proposed novel droop control strategy is presented in detail. The DTS controller is applied to a common AC bus microgrid structure and a meshed parallel inverter system structure in islanded microgrids with mainly inductive or resistive line impedances. An offline time-domain simulation is conducted in MATLAB®/SimPowerSystems environment using RT-EVENTS toolbox from OPAL-RT to model the inverters. Resulting waveforms from a three-phase microgrid with four distributed generators are presented along with a comparison against the conventional droop control strategy and show the effectiveness of the proposed method in allocating both real and reactive power.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
•A combination of Markov chain and an optimal control solved by Pontryagin’s Minimum Principle is presented.•This strategy is applied to hybrid electric vehicle dynamic model.•The hydrogen ...consumption is analyzed for two different vehicle mass and drive cycle.•The supercapacitor and fuel cell behavior is analyzed at high or sudden required power.
In this article, a real time optimal control strategy based on Pontryagin’s Minimum Principle (PMP) combined with the Markov chain approach is used for a fuel cell/supercapacitor electrical vehicle. In real time, at high power and at high speed, two phenomena are observed. The first is obtained at higher required power, and the second is observed at sudden power demand. To avoid these situations, the Markov chain model is proposed to predict the future power demand during a driving cycle. The optimal control problem is formulated as an equivalent consumption minimization strategy (ECMS), that has to be solved by using the Pontryagin’s Minimum Principle. A Markov chain model is added as a separate block for a prediction of required power. This approach and the whole system are modeled and implemented using the MATLAB/Simulink. The model without Markov chain block and the model is with it are compared. The results presented demonstrate the importance of a Markov chain block added to a model.
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IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SAZU, SBCE, SBJE, UL, UM, UPUK
•We present a real time fuzzy logic power management strategy.•This strategy is applied to hybrid electric vehicle dynamic model.•Three configurations evaluated during a drive cycle.•The hydrogen ...consumption is analysed for the three configurations.
This paper presents real time fuzzy logic controller (FLC) approach used to design a power management strategy for a hybrid electric vehicle and to protect the battery from overcharging during the repetitive braking energy accumulation. The fuel cell (FC) and battery (B)/supercapacitor (SC) are the primary and secondary power sources, respectively. This paper analyzes and evaluates the performance of the three configurations, FC/B, FC/SC and FC/B/SC during real time driving conditions and unknown driving cycle. The MATLAB/Simulink and SimPowerSystems software packages are used to model the electrical and mechanical elements of hybrid vehicles and implement a fuzzy logic strategy.
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IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SAZU, SBCE, SBJE, UL, UM, UPUK
In this paper, a regulated output Buck-Boost DC–DC converter is designed and simulated for photovoltaic energy system. The presented Buck-Boost converter has two power switches; moreover, its output ...voltage is regulated to a constant value regardless of its input. In the presented work, the Buck-Boost is used as a second converter after a Single-Ended Primary-Inductance Converter (SEPIC) that is controlled with a maximum power point tracking technique (MPPT); Incremental Conductance MPPT algorithm is chosen to be used because of its simplicity and easy implementation. The Buck-Boost converter is controlled in a way to have a suitable output voltage by introducing the right duty cycle of the pulse width modulation signals that control the switches of the converter.
The proposed configuration of Buck-Boost converter has been simulated in Matlab/Simulink environment; the simulation results show that it is a good choice to take in order to maintain the output voltage constant while ensuring a good energy transfer.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK, ZRSKP
The introduction of microgrids in distribution networks based on power electronics facilitates the use of renewable energy resources, distributed generation (DG) and storage systems while improving ...the quality of electric power and reducing losses thus increasing the performance and reliability of the electrical system. The hierarchical control structure, which consists of primary, secondary, and tertiary levels for microgrids that mimic the behavior of the mains grid, is reviewed. The main objective of this article is to give a description of state of the art for distributed power generation systems (DPGS) based on renewable energy and explore the power converters connected in parallel to the grid which are distinguished by their contribution to the formation of the grid voltage and frequency and are accordingly classified in three classes. This analysis is extended focusing mainly on the three classes of configurations: grid-forming, grid-feeding, and grid-supporting. The article ends up with an overview and a discussion of the control structures and strategies to control distribution power generation system (DPGS) units connected to the network.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK
Multi-drive systems are frequently used in many industry applications such as in paper, textile, and plastic winding process. Adjustable speed drives are very sensitive to power quality problems in ...particular to voltage sags, short-duration reductions in the rms voltage. This paper presents a multi-drive management strategy to mitigate voltage sags based on the self-kinetic process energy recovery. Simulation and experimental results are shown to demonstrate the efficiency of the proposition.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK
This paper presents a new autonomous standalone circuit for HS protection. This circuit is designed to automatically detect and locate the shaded subgroup, to protect it against HS formation and ...recover its normal operating conditions. It is cost-effective and perfectly sized to embed existing conventional PV panel infrastructure since no sensors, data analysis, external sources, or heat sinks are required. This circuit includes a MOSFET to connect/disconnect the shaded subgroup. This MOSFET is controlled through digital signals provided by either an optoisolator or an oscillator. The optoisolator detects the shading occurrence while the oscillator reactivates the MOSFET and gives flexibility for global and local MPPT synchronization. Experimental results under various shading scenarios demonstrate the feasibility and the efficiency of our suggested approach.
This study proposes a cascaded voltage–current robust control strategy for a distributed generator (DG) in microgrids. The main objective of the proposed controller is to improve the performance and ...power quality of a DG by injecting simultaneously a good sinusoidal voltage/current to the different loads connected to the DG. The proposed cascaded voltage/current controller consists of three degree-of-freedom controller, which is designed by using H∞ control theory based on mixed sensitivity specifications. The choices of appropriate weighting functions Wt, Wu, Wy that satisfy the preset goals to get a robust controller and a transform to a standard H∞ control design problem based on pre-compensator, feedforward and feedback connections are presented. The 3DOF-controller is based on MATLAB R/SimPowerSystems and using RT-EVENTS-toolbox. The controller is evaluated under different scenarios: transient responses with a resistive local load, and loads disturbances in steady-state responses with resistive, resistive inductive, resistive capacitive, and non-linear loads. Simulation and experimental results of resulting waveforms from a DG unit are presented, it confirms the effectiveness of the proposed method in effectively rejecting perturbation and robustness to loads disturbances; both good reference tracking and good transient response, and finally significantly lead to a very low total harmonic distortion.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Implementation of ac drives insensitive to parameter variations is an important need in the field of high performance drives. For drives controlled by the indirect rotor flux oriented control method ...(IRFOC), the rotor time constant (/spl tau//sub r/ = L/sub r//R/sub r/) exerts a dominant role in the loss of dynamic performance and its variation results in an undesirable coupling between flux and torque of the machine. This paper presents a new scheme for on-line estimation of rotor time constant using dq representation of the model in the stationary reference frame and measurements of accessible motor variables only (voltages, currents and speed). The estimator is tested by simulation in the MATLAB/SIMULINK environment and validated experimentally on a 1/4 hp squirrel cage motor and a 1/4 hp wound rotor motor with implementation on a TMS320C31 digital signal processor.
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