• Energy Research

The low electrification rate in rural sub-Saharan Africa prevents access to energy services which are essential to improve living conditions. One of these energy services is electrified water pumping, which is particularly relevant for these areas where water access continues being a significant challenge. Pumping systems powered by photovoltaic energy have emerged as an interesting solution in off-grid areas. This article presents a model of photovoltaic water pumping system (PVWPS) for providing domestic water to off-grid rural communities. The model simulates the pumped flow rate and the water level in the storage tank from the climatic data (irradiance, ambient temperature) and the profile of water collection by the users of the system. The modelling of the different stages of the energy conversion chain and a method for identifying the unknown parameters of PVWPS are presented in this article. The model is applied to a pilot PVWPS situated in a rural village of Burkina Faso. The comparison between the measurements performed on the system and the model outputs allows to validate the model experimentally. Results indicate that the model permits to accurately simulate the water height in the tank both when climatic data from local sensors and from satellite are inputted in the model. The model could therefore be applied to other off-grid areas to perform techno-economic optimization and size new PVWPS as well as to evaluate the performances of existing PVWPS. The originalities of this work include the consideration of the water collection profile as a model input and the monitoring of a PVWPS in a rural village of Sub-Saharan Africa, an area where no continuous measurements on these systems has been performed, to the best knowledge of the authors. Further, the comparison of the impact of inputting satellite climatic data instead of measured ones on the PVWPS model accuracy is also a novel contribution.

Abstract Using photovoltaic energy to pump water from aquifers is an interesting solution to circumvent the low electricity grid coverage and provide improved domestic water access in off-grid areas in sub-Saharan Africa. When pumping and during the lifetime of a pumping installation, the borehole water level changes, which impacts the amount of energy required to extract water from the aquifer. In order to address alterations in energy requirements, this article develops a data-driven borehole water level model adapted to photovoltaic water pumping systems (PVWPS). The proposed model is applicable to all types of PVWPS and aquifers. It has been validated against experimental data from a pilot PVWPS located in a rural off-grid village in Burkina Faso having achieved more than 97% accuracy. Thanks to this borehole model, we have been able to assess the influence of the variability of groundwater resources on both the performance of PVWPS and on their optimal sizing. We show that the variation of the static water level can require a increase of the peak power of the PV modules of up to 100%. Nonetheless, the effect of the drawdown due to the pumping is negligible. This study can help companies, governments and non-governmental organizations to better take into account the variability and the sustainability of groundwater resources in the optimal sizing and monitoring of PVWPS.

In order to design, manage and optimize the performance of a photovoltaic (PV) installation and establish a precise power production estimation, irradiance on the plane of array (POA) in relation with the geometrical characteristics of the PV modules installation occupies a high importance. This study focuses on the development of an estimation model of the POA irradiance for a photovoltaic installation equipped with flat reflectors. The model includes solar irradiance components (global, direct and diffuse), geometrical parameters and geographical characteristics of the PV installation. Experimental validations have been performed with measurements taken at the SIRTA Observatory (48.7°N, 2.2°E) in Palaiseau, France, for the period starting from June 2017 to June 2018. Results show mean absolute errors (relative to the mean) of 6% and 7% for an installation without and with planar reflector. Finally, we present several geometrical optimization strategies of the PV-reflector installation relying on two major variables: the reflector's length (LR) compared to the length of the PV module (LPV) and the tilt angle adjustment frequency (monthly, seasonally, fixed) of the system (for both PV and the reflectors). The objective of such optimization is to discuss about a reasonable configuration to achieve a maximum POA irradiance. Results show that the length of the mirrors highly affects the efficiency and performances of the PV-Reflector system and the annual gain increased from 8.5% to 28.7% when going from LR = LPV/2 to LR = 2 × LPV compared to a monthly-optimized installation without mirrors. As for the adjustment frequency, we show that a monthly-varied architecture is the most advantageous option with a 28.2 and 31.6% increasing in annual gain compared to a seasonal varied or fixed ones, respectively.

In the switched reluctance motor with segmental rotor (SRMS) the magnetic saliency of the rotor is due to a series of magnetic segments, which allow the magnetic flux to flow on short loops. In this paper, the study of this kind of SRM is carried out, and comparisons with a conventional switched reluctance motor (CSRM) are established. Two models based on 2D finite element method are used. In the first part, the descriptions of the two motors are briefly given. Secondly, some characteristics including field distributions, inductances, flux, electromagnetic torques and particularly torque-speed curves are compared. The taking into account of optimized control parameters and the large range of speed give special attention to the latter comparison.

The exploitation of resources of renewable energy has become inescapable today. Indeed, facing the oil cost increase, the survival of the economies, particularly of the non oil-producing countries requires the evaluation and the exploitation of their energy potential. The purpose of this paper is to make an analysis of the electrical energy situation in Senegal and to show the relevance in the implementation of a hybrid power plant using renewable energy resources. The design is done to minimize the Annualized Cost of System under the constraints related to the components and the availability of the energy measured with the Loss of Supply Probability.

Ongoing oil stock depletion and growing environmental concerns lead automakers to develop more efficient powertrains. Today, the most promising way forward consists in research on hybrid systems. Defining the most efficient powertrain requires a systemic design. In this paper, three main levers are used: powertrain architecture, energy management and electric components design. Different powertrain architectures (series, parallel and combined) are compared: their optimal energetic performances are calculated for different INRETS 1 driving cycles by using dynamic programming as an optimal control strategy. The most promising hybrid powertrain is the parallel one. Its behavior is more closely analyzed so as to provide technical specifications for an optimal sizing of the electric components: electric machine and battery.