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This paper presents a simulation of an insulated micro-grid system based on the three-level converters control for energy management. Different renewable power sources (wind turbine and Photovoltaic (PV) energy systems) are used to energize the micro-grid. However, a battery energy storage system (BESS) and a variable diesel generator are also used to improve the reliability of the system. The contribution of this research is focused on the power control method based on improving the quality of energy transfer, mastering dynamic interactions and maximum energy production from renewable energies to reduce the fuel consumption by the diesel. Firstly, the proposed control model for each renewable energy was carried out through simulation in the environments of Matlab and Simulink to test the robustness and performance. The second part of this research is dedicated to managing the sharing of power between load, generators, and storage systems by extracting the references of power. The three-level PWM rectifiers for variable speed diesel generators was used to maintain and control the DC bus voltage of the isolated micro-grid. The results obtained from simulations show a good correlation between static and dynamic systems even for fluctuating sun power and wind speed.

An ultrahigh step-down converter with a low number of semiconductor devices is presented in this article. Important features of this converter are simple structure with low size and cost, low voltage and current stress on components, low output current ripple, and low conduction and switching losses. In this converter, the power switches are turned on under zero current switching (ZCS) condition, whereas the output diodes commutate under ZCS condition without any auxiliary circuit. Thereby, in addition to the converter efficiency improvement, the diodes reverse recovery problem is alleviated. The proposed topology has employed a two-phase interleaved structure to reduce current stress, three windings coupled inductors to further decrease the voltage gain, and two series capacitors to diminish the voltage stress on the semiconductors elements and recover the leakage inductances energy. The experimental results of an implemented prototype are provided to evaluate the effectiveness of the proposed topology at 100 kHz and 200 W, which converts a 400-V input voltage into a 12-V output voltage.

Vienna converters have several advantages, including low construction costs, improved total harmonics, and considerable reliability. Generally, they are used in applications with a high switching frequency, particularly in telecommunications, and their use in power generation systems is recent but promising. They can be an interesting solution for medium and large wind power systems as they have the advantage of a high power density compared to traditional two-level converters. In this paper, a wind energy production system based on a Vienna rectifier and the permanent magnet synchronous generator (PMSG) is proposed. The main objective of this work is to evaluate the performance of the vector control strategy of the PMSG associated with the Vienna rectifier considering the real conditions of wind power systems. The feasibility and effectiveness of the proposed control strategy are evaluated through the simulations in MATLAB/Simulink and experimental tests based on a laboratory prototype. The outcomes present interesting performances in terms of dynamics and stability.

Reliability of power electronics is one most critical challenge to face in order to improve the reliability of wind turbine system (WTS). As the power of the wind turbine is increasing, different topologies of power converters are developed for wind turbine applications. The three-level Neutral-Point Clamped (NPC) converter is widely used in WTS, since it has many advantages like a large output capacity, high output voltage and low current Total Harmonic Distortion (THD). However, the topology of these converters has a large number of switches which are fragile components. Open circuit is one of the most common failures in these converters and causes considerable economic damage in wind power systems. This paper presents an open-circuit fault diagnosis method for a three-level NPC inverters based on current and charge distortion in the output of the inverter. The operation of the NPC inverter under normal and open-circuit fault are analyzed. Simulations results of the converter control and the fault diagnosis method are presented and discussed.

The load flow into hybrid grid needs to manage the level of electrical power generations and storage energy. The efficient control of energy storage to match the fluctuation of load demand and estimated generation of wind energy is the main contribution of this paper. The strategy used to control the constant time of frequency approach applied to batteries depend on the operation condition of wind farm turbine system. The charge and discharge of batteries is consider on the control strategy to keep its state of health and deliver the energy at bad weather conditions. The obtained results of proposed control are adopted to manage the efficient performance of the hybrid wind system.

Mining sites that combine energy-intensive operations with community living in areas remote from the electricity grid are increasingly developing dedicated micro-grids. Fossil oil gensets hybridization with renewable energy resources has gained momentum. Difficulties in assessing performance are experienced by operators who wish to benefit from improved performances. The designers of such systems also need additional knowledge to anticipate the solutions of the particular problems related to the power plant’s implementation area characteristics. The proposed approach gives more suitable tools on the effectiveness evaluation of hybridized microgrid, combining a Heavy Fuel Oil (HFO) thermal power station with photovoltaic generator powering mine activities in the Sahelian area. The authors provide key analyses and improvement factors by seasonal behavioral modelling (SBM) of the fuel consumption of the gensets related to the overall irradiance dynamics of the PV array. Several years of data analysis results have been integrated for sharper considerations on the transient interactions impact of the PV/Diesel Hybrid Power Plant operation. The results of simulations carried out using the proposed new models, including the case of an extended system with storage unit, have been used to evaluate the levelized cost of energy, and to discuss competitiveness. This very relevant approach provides additional knowledge for designers and energetic effectiveness analysts.

In this paper, an effective control strategy is proposed to manage energy distribution from fuel cells and batteries for hybrid electric boat applications. The main objectives of this real-time control are to obtain fast current tracking for the batteries’ system, the DC bus voltage stability by using a fuel cell, and energy load distribution for a hybrid electric boat under varying demand conditions. The proposed control strategy is based on a combination of frequency approach and current/voltage control of interleaved boost converters to reduce the hydrogen consumption by the fuel cell and improve the quality of energy transfer. The frequency approach was dedicated to managing the DC power-sharing between the load, the fuel cell, and the batteries’ storage system by extracting the power references. The closed loop control system utilized to control the energy is based on the DC/DC converters. The performance evaluation of the proposed control strategy has been tested through a real-time experimental test bench based on a dSPACE board (DS1104).

International audience; This paper presents the aging characterization and modeling of lithium iron phosphate (LiFePO4) batteries. The research work suggested here aims to characterize the aging of the resistances and the capacities of the batteries as a function of using temperature and direct current undulations. The proposed model of the LiFePO4-batteries is for multi-source systems such as distributed power generation systems based renewable energies. The performances of the batteries used in these systems can be affected by the temperature and the DC-current undulations. The characterization system takes into account the temperature and the DC-current undulations as thermal and electric constraints for batteries. The experimental tests are performed through charging and discharging operations using calibrated fluctuating DC-current waveforms. The experimental measurements and simulations results found are similar with a deviation less than 1%. Hence the proposed model is very appropriate to predict the degradation of battery parameters caused by combined impacts of direct current undulations and the temperature.

International audience; A freight transport hybrid electric boat (HEB) is investigated in order to improve the dynamic response of the boat during the rapid variations of the onboard load such as the acceleration/deceleration, the braking, the docking maneuvers operations, and the goods package lifting system. The propulsion architecture is based on a variable-speed diesel generator (DG) used as the main energy source, with the multiple energy storage system based on the supercapacitors (SC) and the batteries which are used in the HEB to answer the intermittent power due to a sudden load change. This solution compensates the fluctuations from the load by reducing their impacts for diesel engine. The variable-speed diesel generator is connected to the dc-bus using three-phase controlled rectifier to manage dc-bus voltage. The SC and the batteries are linked to dc-bus through two bidirectional dc/dc converters to control the high-frequency component independently to those of the average-frequency component. Two identical thrusters are, respectively, placed in the front of and the behind of the boat to emulate the propulsion operations. The HEB power demand includes the thruster's requirements and embedded appliances (elevator, package lifting system, heating system, TV, computer, and electronics device for navigation). The main contribution of this paper is focused on the HEB dynamic response improvement during the rapid variations of the load using the SC and the batteries. Other significant contributions are based on the LiFePO4-battery modeling using solartron analytical impedance spectroscopy and the load current sharing between the DG and the SC/batteries, where the high-frequency component of the load is assigned to SC due to its fast dynamic response and that of the average frequency is allocated to the batteries. The proposed energy management strategy is verified by the simulation and experimental tests in reduced scale using a specific driving cycle of the HEB for one trip.

Wind energy is an alternative to meet the growing energy demand. Control of wind turbines should help the reliability and stable operation of the power grid. Furthermore, they should respect the technical requirements according to the grid codes to inject the wind energy into the grid. In this paper, a well-known field-oriented control (FOC) method and a new control method based on the flatness properties (FBC) are presented and compared. These control methods are applied to a wind energy conversion system (WECS), which connects a variable-speed wind turbine (WT) based on a permanent magnet synchronous generator (PMSG) to the grid via a back-to-back converter. The main aim of both control methods is to extract the maximum power from the wind. For this purpose, the mathematical model of each subsystem, i.e., WT, PMSG, and electrical grid, is presented. To evaluate and to compare the dynamic behavior of the high-power wind energy conversion system, it is modeled and the control strategies are developed using SimPowerSystems Toolbox in MATLAB. The simulation results obtained in the time domain show that the FBC performs better at managing the energy in the studied system. Indeed, the proposed FBC is a high bandwidth control method with only one closed-loop control, which leads to a high dynamic performance. Therefore, that strategy can be used to provide ancillary services such as frequency control and spinning reserves according to the grid codes.

In this paper, a bidirectional zero voltage switching (ZVS) resonant converter with narrow control frequency deviation is proposed. Wide input–output voltage range applications, such as flywheel or supercapacitors storage units are targeted. Due to symmetrical topology of resonant circuit interfaces, the proposed converter has similar behavior in bidirectional operating mode. We call it Dual Active Bridge Converter (DABC). The proposal topology of the converter is subjected to multi resonant circuits which make it necessary to study with multiscale approaches. Thus, first harmonic approximation and use of selective per unit parameters are established in (2) Methods. Then, the forward direction and backward direction of power flux exchange are detailed according to switching sequences. Switching frequency control must be completed within a narrow range. So, the frequency range deterministic parameters are emphasized in the design procedure in (3) Methods. A narrow range of switching frequency and a wide range voltage control must be ensured to suit for energy storage units, power electronic devices capabilities and electromagnetic compatibility. A 3 kW test bench is used to validate operation principles and to proof success of the developed design procedure. The interest of proposed converter is compared to other solutions from the literature in (4) Results.

The main challenges for renewable energy integration in electrical grid system are their variability and prediction. Tidal renewable energy is considered low variability in comparison to wind energy generation and due to tides regular periodicity, it is often quoted as predictable. This paper presents the modeling of Orkney's distribution network with the integration of tidal energy. This multi-physics model is based on the graphical formalism tool, Energetic Macroscopic Representation (EMR). This tool has been used to analyze the Tidal energy conversion (TEC) system based on the behavior of permanent magnet synchronous machine (PMSM). The daily, monthly and yearly variations of marine water speed in Orkney were observed. The EMR has been efficiently used in the representation of Orkney energy system integration of Orbital O2 tidal systems, and showing its effectiveness to adopt the control strategy. More precisely, the data of current water profile for 2009 has been chosen from 10 years big data to test the adopted deduced control technique. The methodology of this tool is described in details and the simulation results obtained in MATLAB environment are presented.