http://hdl.handle.net/10174/917 2026-09-18T21:04:15Z 2026-09-18T21:04:15Z Mesbahi, Oumaima Kandoussi, Khalid El otmani, Rabie Hajjaji, Abdeloawahed Janeiro, Fernando M. Tlemçani, Mouhaydine http://hdl.handle.net/10174/30664 2026-02-20T12:25:36Z 2020-11-01T00:00:00Z

Title: Global MPP Tracking for Photovoltaic Panel under Shading Conditions using Robust Numerical Algorithm Authors: Mesbahi, Oumaima; Kandoussi, Khalid; El otmani, Rabie; Hajjaji, Abdeloawahed; Janeiro, Fernando M.; Tlemçani, Mouhaydine Abstract: This paper presents a new numerical approach for the modelling of the PV panels under partial shading conditions. It also solves the major drawback of the PV systems, which is the tracking of maximum power point under partial shading conditions where the P-V characteristic has a more complex structure with many local maximums on the graph. This paper aims to resolve this phenomenon using Newton method in order to find the global maximum power point.

2020-11-01T00:00:00Z Rodrigues, Nuno M. Carvalho, João P. Janeiro, Fernando M. Ramos, Pedro M. http://hdl.handle.net/10174/30663 2022-01-07T22:18:55Z 2020-05-31T23:00:00Z

Title: Electrical Power Grid Frequency Estimation with Fuzzy Boolean Nets Authors: Rodrigues, Nuno M.; Carvalho, João P.; Janeiro, Fernando M.; Ramos, Pedro M. Abstract: Power quality analysis involves the measurement of quantities that characterize a power supply waveform such as its frequency. The measurement of those quantities are regulated by internationally accepted standards from IEEE or IEC. Monitoring the delivered power quality is even more important due to recent advances in power electronics and also due to the increasing penetration of renewable energies in the electrical power grid. The primary suggested method by IEC to measure the power grid frequency is to count the number of zero crossings in the voltage waveform that occur during 0.2 s. The standard zero crossing method is usually applied to a filtered signal that has a non deterministic and frequency dependent delay. For monitoring the power grid a range between 42.5 and 57.5 Hz should be considered which means that the filter must be designed in order to attenuate the delay compensation error. Fuzzy Boolean Nets can be considered a neural fuzzy model where the fuzziness is an inherent emerging property that can ignore some outliers acting as a filter. This property can be useful to apply zero crossing without false crossing detection and estimate the real timestamp without the non deterministic delay concern. This paper presents a comparison between the standard frequency estimation, a Goertzel interpolation method, and the standard method applied after a FBN network instead of a filtered signal.

2020-05-31T23:00:00Z Baena-Moreno, F. M. Rodríguez‐Galán, Mónica Vega, Fernando Malico, Isabel Navarrete, Benito http://hdl.handle.net/10174/29662 2021-04-01T14:53:13Z 2021-02-01T00:00:00Z

Title: Potential Processes for Simultaneous Biogas Upgrading and Carbon Dioxide Utilization Authors: Baena-Moreno, F. M.; Rodríguez‐Galán, Mónica; Vega, Fernando; Malico, Isabel; Navarrete, Benito Editors: Ramirez-Reina, T.; Odriozola, J. A.; Arellano-Garcia, H. Abstract: In this chapter, potential processes for coupling biogas upgrading to obtain bio‐methane with carbon dioxide capture and utilization are presented. Bio‐methane is an attractive source of clean energy, and its utilization as fuel is becoming more and more important during the past years. Biogas comes from the anaerobic digestion of organic matter and it is mainly composed of methane and carbon dioxide. Thus, an upgrading to remove carbon dioxide and obtain bio‐methane is necessary. The upgrading stage can be carried out by several technologies such as water‐organic physical scrubbing, chemical absorption, adsorption, cryogenic separation, and membrane processes. Some of these technologies have proved to be industrially feasible. Nevertheless, there is a need to improve the economic viability of these processes placing bio‐methane as a competitive green energy against traditional fossil fuels. One way to do it is to use the captured carbon dioxide as a raw material in other industries. Many applications for carbon dioxide are reported in the literature such as direct utilization in food–drink industry, chemical production from carbon dioxide, mineral carbonation – carbonates production, enhanced oil recovery, supercritical solvent, and dry ice production. Nevertheless, the majority of these applications have a demand that is very low in comparison with the carbon dioxide production worldwide. Inasmuch, carbon dioxide coming from biogas upgrading has a relative range that can fit into carbon utilization technologies. In this chapter, biogas upgrading technologies are coupled with carbon utilization technologies as potential processes already described in the literature or as potential ideas that can be further developed.

2021-02-01T00:00:00Z Malico, Isabel Gonçalves, Ana Cristina Sousa, Adélia M. O. http://hdl.handle.net/10174/29656 2021-04-01T14:49:17Z 2021-02-01T00:00:00Z

Title: Evergreen Oak Biomass Residues for Firewood Authors: Malico, Isabel; Gonçalves, Ana Cristina; Sousa, Adélia M. O. Editors: Gonçalves, A. C.; Sousa, A. M. O.; Malico, I. Abstract: This chapter presents the assessment of the availability for residential heating of residual biomass from cork and holm oaks in a 12,188 ha agroforest area in Portugal. First, the above-ground biomass of evergreen oaks using very high spatial resolution satellite images was determined, followed by the definition of different scenarios for residues removal from the stands. The useful energy potential of the firewood that can be collected from the study area under the various silviculture scenarios was determined considering different energy conversion technologies: open fireplaces (still popular in Portugal) and more efficient closed burning appliances. Additionally, emissions of airborne pollutants from combusting all the available residual biomass in the study area were determined. Depending on the percentage of residues collected when the trees are pruned and on the conversion technologies used, the energy potential of evergreen oak firewood ranged from 5.0 × 106 MJ year−1 to 7.5 × 107 MJ year−1. Heavier pruning combined with the use of open fireplaces generates less useful heat and much higher emissions of pollutants per unit useful energy produced than lighter pruning combined with a more efficient technology. This case study illustrates the need to promote the transition from inefficient to more efficient and cleaner technologies.

2021-02-01T00:00:00Z