Jamel Belhadj

Control and energy management of a wind-photovoltaic hybrid system

In this paper, we have designed a micro-generation energy system obtained by interconnecting a wind turbine with a photovoltaic generator and characterized by very low voltage (VLV) node coupled to a battery storage and DC loads. The control strategies of the sources are based on power, voltage and current control with maximum power point tracking (MPPT). Experiments based on a physical emulator of the hybrid system with a lead acid accumulator and its DC load is considered. The development of experiments is necessary to validate theoretical studies. The real time supervision and the energy management of the hybrid system is presented and detailed. Experimental results are presented and discussed showing the relevant behavior of the energy management strategy.

Theoretical and experimental study of control and energy management of a hybrid wind-photovoltaic system

This paper aims at the theoretical and experimental analysis of control and energy management of a standalone hybrid renewable energy system comprising wind and photovoltaic sources with battery storage. This system is characterized by a Very Low Voltage (VLV) node connection coupled to DC loads. An average model of a hybrid wind-photovoltaic generating system is proposed in this paper. It is shown that this model is interesting for analysing the dynamic behaviour of the system and for synthesising the control strategy. The control strategies of the sources are based on power, voltage and current control with Maximum Power Point Tracking (MPPT). Experiments based on a physical emulator of the hybrid system with a lead acid accumulator and its DC load are considered to validate theoretical studies. The real time supervision and the energy management of the hybrid system is presented and detailed. The proposed energy management strategy has been simulated and experimentally implemented. Numerical and experimental results are presented and discussed, showing the effectiveness of the proposed hybrid system.

Experimental characterization of a Reverse Osmosis desalination process fed by hybrid power source

A brackish water Reverse Osmosis (BWRO) desalination unit is studied in this paper. This unit is designed to be fed by a renewable energy based on hybrid source (wind and photovoltaic: hybrid system) with/without storage battery. The energy will be directly transmitted to the motos-pump of the BWRO process. An appropriate energy management starts from the understanding of the BWRO desalination process with its energy consumption. To optimize the energy transfer towards the load, it is useful to study the mechanical and the hydraulic system behaviour. Experimental characterizations of the motos-pumps and hydraulic load are elaborated from which significant results are drawn.

DPC for three-phase inverter to improve the integration of wind turbine associated to Flywheel Energy Storage System into the grid

A Flywheel Energy Storage System (FESS) is associated to Wind Turbine (WT) to increase its penetration rate into the grid and to improve its contribution to the ancillary services. In this paper, the authors investigated a FESS associated to PMSM-wind turbine connected to the grid via a three-phase PWM inverter. The FESS is controlled by a FOC (Flux Oriented Control) strategy cascaded with an external power loop for the supervision of the power reference value. A Direct Power Control (DPC) strategy is proposed to control the grid-connected converter due to its high transient capability and its constant switching behavior.

Energy management of a Reverse Osmosis desalination process powered by renewable energy sources

This work deals with complex and typical problem in order to optimize both water and energy management for water pumping and desalination processes. This contribution aims at proposing a management strategy for a Brackish Water Reverse Osmosis (BWRO) desalination plant. This unit is powered by a hybrid source mixing photovoltaic and wind resources. The main objective of the developed strategy is to maximize fresh water production taking advantage of the available renewable energy. This strategy ensures the DC link stability and manages the power flows between the hybrid source and the motor-pumps of the BWRO desalination process. The proposed method gives correct results confirmed by simulation results and experimental tests.

Battery sizing for a stand alone passive wind system using statistical techniques

In this paper, an original optimization method to jointly determine a reduced study term and an optimum battery sizing is investigated. This storage device is used to connect a passive wind turbine system with a stand alone network. A Weibull probability density function is used to generate different wind speed data. The passive wind system is composed of a wind turbine, a permanent magnet synchronous generator feeding a diode rectifier associated with a very low voltage DC battery bus. This study is essentially based on a similitude model applied on an 8 kW wind turbine system. Our reference model is taken from a 1.7 kW optimized system. The wind system generated power and the load demand are coupled through a battery sized using a statistical approach.

Optimal system management of a water pumping and desalination process supplied with intermittent renewable sources

This paper aims at defining energy management strategy for a water pumping and desalination process which would be powered by a hybrid (solar PV & wind) renewable generation system. Several pumping subsystems for well pumping, water storage and desalination are coupled. The particularity of the proposed architecture with its management deals with the absence of electrochemical storage, only taking benefit of hydraulic storage in water tanks: in such an autonomous device, given a certain level of intermittent power following wind and sun irradiation conditions, and given hydraulic characteristics of water pumping subsystems, this study puts forward the prime importance of a water and power flow management optimization. For this purpose, both dynamic and quasi static models are proposed before stetting the management strategy based on optimal power dispatching. Subsequent results are analyzed in terms of robustness and performance.

Smart power management of a hybrid photovoltaic/wind stand-alone system coupling battery storage and hydraulic network

An off-grid energy system based on renewable photovoltaics (PV) and wind turbines (WT) generators is coupled via converters to electric and hydraulic networks. The electric network is composed of consumers and of a battery bank for electrical storage, while the hydraulic part is made of motor-pumps and hydraulic tanks for water production and desalination. Both battery and water tanks are used to optimize the power management of both electric and hydraulic subsystems by ensuring electric load demand and by reducing at the same time water deficit following the operation of the renewable intermittent source. Thus, both electric and hydraulic subsystems are strongly coupled in terms of energy making necessary to manage the power flows provided by renewable sources to optimize the overall system performance. In this paper, two kinds of management strategies are then compared in the way they share the hybrid power sources between the storage devices (battery and tanks) and the electrical/hydraulic loads. The first approach deals with an “uncoupled power management” in which the operation of electrical and hydraulic loads does not depend on the state of the intermittent renewable sources: in particular, hydraulic pumps are operated only taking account of water demand and tank filling but without considering power sources. On the contrary, given the available power produced by the sources, the second class of strategy (i.e. the “coupled management strategy”) consists of a “smart” power sharing between the electrical and hydraulic networks with regard to the battery SOC and the tank L1 and L2. A dynamic simulator of the hybrid energy system has been developed and tested using a MATLAB environment. The system performance is shown under the two investigated approaches (uncoupled vs coupled). Several tests are carried out using real meteorological data of a remote area and a practical load demand profile. The simulation results show that the “coupled strategy” clearly outperforms the classical “uncoupled” management strategies.

Development of a methodology for wind energy estimation and wind park design

This study presents a thorough methodology for wind park design and micro-siting. It encompasses all aspects of wind project development and prefeasibility analysis. This approach uses the long-term wind data taken from on site measurements. Collected data are analyzed statistically. Then, wind resources are estimated and a choice of the best fitted wind turbines is performed. An optimal layout for wind turbines is proposed using the Windstation and 3DEM software. The main contribution of this paper is to evaluate the amount of accuracy given by this methodology in terms of predicting the future annual energy production of wind projects. To achieve this objective, the methodology was applied to a specific site which already contains an installed wind park. The test case wind farm is located in the north-east of Tunisia. The evaluation is performed by comparing the estimated energy production with real-time operation database of the wind park. Finally, the paper discusses the prospects of wind farm upgradi...

Synthesis of a compact wind profile using evolutionary algorithms for wind turbine system with storage

In this paper, the authors investigate two methodologies for synthesizing compact wind speed profiles by means of evolutionary algorithms. Such profile can be considered as input parameter in a prospective design process by optimization of a passive wind system with storage. Compact profiles are obtained by aggregating elementary patterns in order to fulfil some target indicators. The main difference between both methods presented in the paper is related to the choice of these indicators. In the first method, they are related to the storage system features while they only depend on wind features in the second.