Pape A. Ndiaye

Hybrid Modeling for Performance Evaluation of Multisource Renewable Energy Systems

This paper is devoted to multisource renewable energy systems. A modeling approach is proposed that brings a detailed understanding of the coupling and uncoupling of DC/DC power converters on a DC bus including the regulation of the DC bus voltage and the driving of current provided by each converter to the load. This approach is systematic and the resulting average state-space model depends only on the number and characteristics of the converters. The model has a generic expression the parameters of which switch according to the converters coupling and uncoupling on the DC bus. The model has been identified and validated with an experimental device developed by GREAH Research Group for the optimization of energies transfers for multisource renewable energy systems. Our approach can be used in the context of power management as support for performance evaluation (converter design, supervisory control design, and so on).

Petri nets control design for hybrid electrical energy systems

This paper describes a supervisory control strategy based on Petri nets for electrical energy transfers in multisource renewable energy systems. The aim is to optimize the energy transfers, according to the sources power variations and the load characteristics. For this purpose, the proposed Petri net controller calculates the operating mode of the multisource renewable energy system. This high level controller is combined with a low level one that tunes the power ratio provided by each source according to sources power (climatic conditions) and load variations. An estimation of the duty cycle value of the dc/dc power converters is used to fire the Petri nets transitions, to switch the power sources and also to drive the power ratios.

Control design for multisource systems based on DC/DC converters duty cycle value

Purpose – The purpose of this paper is to describe a two‐level hierarchical control strategy for electrical energy transfers in multisource renewable energy systems. The aim of the control design is to perform the energy transfers, according to the sources power variations and the load characteristics.Design/methodology/approach – The controller determines the operating mode of the multisource renewable energy system and the power ratio provided by each source to satisfy the load demand. The study is based on an accurate model of the DC/DC converters coupled on the DC bus. The performance of the controller is compared with the usual method based on the measurements of the system variables with sensors (solar radiation, shaft speed, voltages, and currents).Findings – The proposed method does not need extra sensors to measure the available power for each source.Research limitations/implications – The method is developed for an hybrid system with two sources (photovoltaic and lead‐acid battery bank) and spec...

A Study of the Wind Potential in Climatic Zones of Chad

This paper focuses on the assessment of wind energy potential in the three climatic zones of Chad: the Saharan (north), the Sahel (center) and the Sudan (south) zones. For each zone, three representative meteorological locations were chosen and assessed based on satellite data provided by NASA. The data comes from MERRA (Modern-Era Retrospective Analysis for Research and Applications) and covers the period 2005–2014. The wind speed frequency distribution of locations was found by using Weibull distribution function. From this statistical data analysis, we found that the wind regime is different in the three regions. It is higher in the Saharan region (with annual mean wind speed of 5.78 m/s) followed by the Sahel (4.32 m/s) and Sudanian (3.7 m/s) regions. There are two distinct seasons in Chad: the dry and the rainy seasons with varying periods, with respect to the regions (2 months of rain in the Saharan zone vs 7 months in the Sudanian zone). For all regions the mean wind speed is higher in the dry season. Diurnal variations of mean wind speed show two regimes characterized respectively by high values in the early morning and the night and low values during the day. The corresponding power density was 193 w/m2, 76.15 w/m2 and 29.0 w/m2, resp. for the Saharan, Sahelian and Sudanian regions. The wind regimes are globally stable with dominant directions North-East (for Saharan region), East (Sahelian), South-Southwest (Sudanian).