lca_algebraic: a library bringing symbolic calculus to LCA for comprehensive sensitivity analysis

Abstract Purpose In this paper, we present new tools to ease the analysis of the effect of variability and uncertainty on life cycle assessment (LCA) results. Methods The tools consist of a standard protocol and an open-source library: lca_algebraic. This library, written in Python and based on the framework Brightway2 (Mutel in J Open Source Softw 2(12):236, 2017) provides functions to support sensitivity analysis by bringing symbolic calculus to LCA. The use of symbolic calculus eases the definition of parametric inventories and enables a very fast evaluation of impacts by factorizing the background activities. Thanks to this processing speed, a large number of Monte Carlo simulations can be generated to evaluate the variation of the impacts and apply advanced statistic tools such as Sobol indices to quantify the contribution of each parameter to the final variance (Sobol in Math Comput Simul 55(1–3):271–280, 2001). An additional algorithm uses the key parameters, identified from their high Sobol indices, to generate simplified arithmetic models for fast estimates of LCA results. Results and discussion The protocol and library were validated through their application to the assessment of impacts of mono crystalline photovoltaic (PV) systems. A comprehensive sensitivity analysis was performed based on the protocol and the complementary functions provided by lca_algebraic. The proposed tools helped building a detailed parametric reference LCA model of the PV system to identify the range of variation of multi-criterion LCA results and the key foreground-related parameters explaining these variations. Based on these key parameters, we generated simplified arithmetic models for quick and simple multi-criteria environmental assessments to be used by non-expert LCA users. The resulting models are both compact and aligned with the reference parametric LCA model of crystalline silicon PV systems. Conclusion This work brings powerful and practical tools to the LCA community to better understand, identify, and quantify the sources of variation of environmental impacts and produce simplified models to spread the use of LCA among non-experts. The library mainly explores the uncertainties of the foreground activities. Further work could also integrate the uncertainty of background activities, described, for example, by pedigree matrices.

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A Techno-Economic Comparative Study of a Grid-Connected Residential Rooftop PV Panel: The Case Study of Nahr El-Bared, Lebanon

Engineering, Technology & Applied Science Research ◽

10.48084/etasr.4078 ◽

2021 ◽

Vol 11 (2) ◽

pp. 6956-6964

Author(s):

H. Camur ◽

Y. Kassem ◽

E. Alessi

Keyword(s):

Crystalline Silicon ◽

Renewable Energy Sources ◽

Average Energy ◽

Electrical Energy ◽

Energy Output ◽

Small Scale ◽

Pv System ◽

Pv Systems ◽

Pv Panel

Lebanon suffers from daily electricity shortages. The country has paid much attention to renewable energy sources, particularly solar, to gradually replace conventional energy. Installing a photovoltaic (PV) system becomes increasingly attractive for residential consumers due to the rising electricity tariff rates while it reduces the dependency on domestic power generators. No known study has dealt with the investigation of potential grid-connected rooftop PV systems with various sun-tracking modes and PV technologies in Nahr El-Bared, Lebanon. Consequently, the main objective of the current paper is to investigate the feasibility of a 5kW grid-connected PV system of various technologies (mono-crystalline silicon and poly-crystalline silicon) and sun-tracking modes including fixed tilt and 2-axis systems for rooftop households in Lebanon. The Nahr El-Bared camp was the case study was of the paper. RETScreen Expert software was used to evaluate the techno-economic performance of the proposed systems. The results show that the annual electrical energy from a fixed 5kW PV panel tilted at an optimal angle ranged from 8564.47kWh to 8776.81kWh, while the annual electrical energy from the PV tracking system was within the range of 11511.67-12100.92kWh. This amount of energy output would contribute significantly to reduce the energy shortage in the country. A typical household was selected to establish a load profile and load supply during both grid availability and outage periods. The highest energy consumption that can be covered by the PV systems was recorded during the spring and summer seasons. Also, the average energy production cost ranged from 0.0239 to 0.0243$/kWh for all the proposed systems. It was concluded that a 5kW grid-connected rooftop PV system could be economically justifiable. Finally, this study tried to increase the awareness about utilizing PV sun-tracking systems and the feasibility of small-scale grid-connected rooftop PV systems in the selected regions. The results of this research can help investors in the energy and building sectors.

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Energy Prediction of PV Systems with Sun Tracking

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.448-453.1491 ◽

2013 ◽

Vol 448-453 ◽

pp. 1491-1496

Author(s):

Meng Nan Cao ◽

Ying Ning Qiu ◽

Hao Wang

Keyword(s):

Large Scale ◽

Crystalline Silicon ◽

Performance Ratio ◽

Energy Yield ◽

Power Fluctuation ◽

Pv System ◽

Energy Prediction ◽

Pv Systems ◽

Declination Angle ◽

Shading Effects

The energy yield of PV system with different material, declination angle and land covering ratio are presented. Comparisons are made between two Chinese cities, Beijing and Nanjing. Shading effects are also investigated for the PV systems energy yield calculation. It shows that by neglecting the losses due to weather and the temperature effects, for the location with higher latitude (such as Beijing) the PV system installed with double junction solar cells (micromorph silicon) is predicted to have lower Performance Ratio than that with mono-crystalline silicon and multi-crystalline silicon. An optimum row spacing of a PV system should be considered for limited occupation area. The criteria above are important for large scale PV system design and its efficiency maximization. The simulation is useful to predict the power fluctuation delivered by PV system due to the spectral, seasonal variation and geometry difference.

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A Model for the Thermal Behaviour of an Offshore Cable Installed in a J-Tube

Proceedings ◽

10.3390/wef-06936 ◽

2020 ◽

Vol 58 (1) ◽

pp. 31

Author(s):

Jeremy Arancio ◽

Ahmed Ould El Moctar ◽

Minh Nguyen Tuan ◽

Faradj Tayat ◽

Jean-Philippe Roques

Keyword(s):

Sensitivity Analysis ◽

Numerical Model ◽

Thermal Behaviour ◽

Energy Production ◽

Power Transmission ◽

Temperature Fields ◽

Sobol Indices ◽

Lumped Element ◽

Thermal Phenomena ◽

The Impact

In the race for energy production, supplier companies are concerned by the thermal rating of offshore cables installed in a J-tube, not covered by IEC 60287 standards, and are now looking for solutions to optimize this type of system. This paper presents a numerical model capable of calculating temperature fields of a power transmission cable installed in a J-tube, based on the lumped element method. This model is validated against the existing literature. A sensitivity analysis performed using Sobol indices is then presented in order to understand the impact of the different parameters involved in the heating of the cable. This analysis provides an understanding of the thermal phenomena in the J-tube and paves the way for potential technical and economic solutions to increase the ampacity of offshore cables installed in a J-tube.

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Reconfigurable Distributed Power Electronics Technique for Solar PV Systems

Electronics ◽

10.3390/electronics10091121 ◽

2021 ◽

Vol 10 (9) ◽

pp. 1121

Author(s):

Kamran Ali Khan Niazi ◽

Yongheng Yang ◽

Tamas Kerekes ◽

Dezso Sera

Keyword(s):

Energy Yield ◽

Solar Pv ◽

Charge Redistribution ◽

Pv System ◽

Partial Shading ◽

Pv Systems ◽

Simulation Based ◽

In Series ◽

A Cell ◽

Power Balancing

A reconfiguration technique using a switched-capacitor (SC)-based voltage equalizer differential power processing (DPP) concept is proposed in this paper for photovoltaic (PV) systems at a cell/subpanel/panel-level. The proposed active diffusion charge redistribution (ADCR) architecture increases the energy yield during mismatch and adds a voltage boosting capability to the PV system under no mismatch by connected the available PV cells/panels in series. The technique performs a reconfiguration by measuring the PV cell/panel voltages and their irradiances. The power balancing is achieved by charge redistribution through SC under mismatch conditions, e.g., partial shading. Moreover, PV cells/panels remain in series under no mismatch. Overall, this paper analyzes, simulates, and evaluates the effectiveness of the proposed DPP architecture through a simulation-based model prepared in PSIM. Additionally, the effectiveness is also demonstrated by comparing it with existing conventional DPP and traditional bypass diode architecture.

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State-Space Model of Quasi-Z-Source Inverter-PV Systems for Transient Dynamics Studies and Network Stability Assessment

Energies ◽

10.3390/en14144150 ◽

2021 ◽

Vol 14 (14) ◽

pp. 4150

Author(s):

Lluís Monjo ◽

Luis Sainz ◽

Juan José Mesas ◽

Joaquín Pedra

Keyword(s):

Power Systems ◽

State Space ◽

State Space Model ◽

Pv System ◽

Pv Systems ◽

Renewable Power ◽

Ac Networks ◽

Transient Interactions ◽

The Stability ◽

Averaged Model

Photovoltaic (PV) power systems are increasingly being used as renewable power generation sources. Quasi-Z-source inverters (qZSI) are a recent, high-potential technology that can be used to integrate PV power systems into AC networks. Simultaneously, concerns regarding the stability of PV power systems are increasing. Converters reduce the damping of grid-connected converter systems, leading to instability. Several studies have analyzed the stability and dynamics of qZSI, although the characterization of qZSI-PV system dynamics in order to study transient interactions and stability has not yet been properly completed. This paper contributes a small-signal, state-space-averaged model of qZSI-PV systems in order to study these issues. The model is also applied to investigate the stability of PV power systems by analyzing the influence of system parameters. Moreover, solutions to mitigate the instabilities are proposed and the stability is verified using PSCAD time domain simulations.

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Analysis and Design of a Multi-Port DC-DC Converter for Interfacing PV Systems

Energies ◽

10.3390/en14071943 ◽

2021 ◽

Vol 14 (7) ◽

pp. 1943

Author(s):

Bader N. Alajmi ◽

Mostafa I. Marei ◽

Ibrahim Abdelsalam ◽

Mohamed F. AlHajri

Keyword(s):

High Frequency ◽

Computer Aided Design ◽

Electromagnetic Transients ◽

Pv System ◽

Analysis And Design ◽

Pv Systems ◽

Point Tracking ◽

Power Point Tracking ◽

Power Point ◽

Aided Design

A high-frequency multi-port (HFMP) direct current (DC) to DC converter is presented. The proposed HFMP is utilized to interface a photovoltaic (PV) system. The presented HFMP is compact and can perform maximum power point tracking. It consists of a high-frequency transformer with many identical input windings and one output winding. Each input winding is connected to a PV module through an H-bridge inverter, and the maximum PV power is tracked using the perturb and observe (P&O) technique. The output winding is connected to a DC bus through a rectifier. The detailed analysis and operation of the proposed HFMP DC-DC converter are presented. Extensive numerical simulations are conducted, using power system computer aided design (PSCAD)/electromagnetic transients including DC (EMTDC) software, to evaluate the operation and dynamic behavior of the proposed PV interfacing scheme. In addition, an experimental setup is built to verify the performance of the HFMP DC-DC converter.

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An Optimized PV Control System Based on the Emperor Penguin Optimizer

Energies ◽

10.3390/en14030751 ◽

2021 ◽

Vol 14 (3) ◽

pp. 751

Author(s):

Mariam A. Sameh ◽

Mostafa I. Marei ◽

M. A. Badr ◽

Mahmoud A. Attia

Keyword(s):

Duty Cycle ◽

Optimization Technique ◽

Pso Algorithm ◽

Boost Converter ◽

Emperor Penguin ◽

Pv System ◽

Partial Shading ◽

Pv Systems ◽

Point Tracking ◽

Grid Connected Inverter

During the day, photovoltaic (PV) systems are exposed to different sunlight conditions in addition to partial shading (PS). Accordingly, maximum power point tracking (MPPT) techniques have become essential for PV systems to secure harvesting the maximum possible power from the PV modules. In this paper, optimized control is performed through the application of relatively newly developed optimization algorithms to PV systems under Partial Shading (PS) conditions. The initial value of the duty cycle of the boost converter is optimized for maximizing the amount of power extracted from the PV arrays. The emperor penguin optimizer (EPO) is proposed not only to optimize the initial setting of duty cycle but to tune the gains of controllers used for the boost converter and the grid-connected inverter of the PV system. In addition, the performance of the proposed system based on the EPO algorithm is compared with another newly developed optimization technique based on the cuttlefish algorithm (CFA). Moreover, particle swarm optimization (PSO) algorithm is used as a reference algorithm to compare results with both EPO and CFA. PSO is chosen since it is an old, well-tested, and effective algorithm. For the evaluation of performance of the proposed PV system using the proposed algorithms under different PS conditions, results are recorded and introduced.

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A Modification of the Perturb and Observe Method to Improve the Energy Harvesting of PV Systems under Partial Shading Conditions

Energies ◽

10.3390/en14092521 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2521

Author(s):

Alfredo Gil-Velasco ◽

Carlos Aguilar-Castillo

Keyword(s):

Maximum Power ◽

Global Maximum ◽

Pv System ◽

Maximum Power Point ◽

Partial Shading ◽

Pv Systems ◽

Point Tracking ◽

Power Point Tracking ◽

Power Point ◽

Computational Resources

There are multiples conditions that lead to partial shading conditions (PSC) in photovoltaic systems (PV). Under these conditions, the harvested energy decreases in the PV system. The maximum power point tracking (MPPT) controller aims to harvest the greatest amount of energy even under partial shading conditions. The simplest available MPPT algorithms fail on PSC, whereas the complex ones are effective but require high computational resources and experience in this type of systems. This paper presents a new MPPT algorithm that is simple but effective in tracking the global maximum power point even in PSC. The simulation and experimental results show excellent performance of the proposed algorithm. Additionally, a comparison with a previously proposed algorithm is presented. The comparison shows that the proposal in this paper is faster in tracking the maximum power point than complex algorithms.

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Different Techniques to Mitigate Partial Shading in Photovoltaic Panels

Energies ◽

10.3390/en14133863 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3863

Author(s):

Tiago Alves ◽

João Paulo N. Torres ◽

Ricardo A. Marques Lameirinhas ◽

Carlos A. F. Fernandes

Keyword(s):

Cell Model ◽

Research Work ◽

Experimental Tests ◽

Operating Conditions ◽

Pv System ◽

Partial Shading ◽

System Architectures ◽

Pv Systems ◽

Advantages And Disadvantages ◽

Pv Panel

The effect of partial shading in photovoltaic (PV) panels is one of the biggest problems regarding power losses in PV systems. When the irradiance pattern throughout a PV panel is inequal, some cells with the possibility of higher power production will produce less and start to deteriorate. The objective of this research work is to present, test and discuss different techniques to help mitigate partial shading in PV panels, observing and commenting the advantages and disadvantages for different PV technologies under different operating conditions. The motivation is to contribute with research, simulation, and experimental work. Several state-of-the-artsolutions to the problem will be presented: different topologies in the interconnection of the panels; different PV system architectures, and also introducing new solution hypotheses, such as different cell interconnections topologies. Alongside, benefits and limitations will be discussed. To obtain actual results, the simulation work was conducted by creating MATLAB/Simulink models for each different technique tested, all centered around the 1M5P PV cell model. The several techniques tested will also take into account different patterns and sizes of partial shading, different PV panel technologies, different values of source irradiation, and different PV array sizes. The results will be discussed and validated by experimental tests.

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CONCEPTUAL DESIGN FOR ASSEMBLY IN AEROSPACE INDUSTRY: SENSITIVITY ANALYSIS OF MATHEMATICAL FRAMEWORK AND DESIGN PARAMETERS

Proceedings of the Design Society ◽

10.1017/pds.2021.73 ◽

2021 ◽

Vol 1 ◽

pp. 731-740

Author(s):

Giovanni Formentini ◽

Claudio Favi ◽

Claude Cuiller ◽

Pierre-Eric Dereux ◽

Francois Bouissiere ◽

...

Keyword(s):

Sensitivity Analysis ◽

Conceptual Design ◽

Design Parameters ◽

Design For Assembly ◽

Mathematical Framework ◽

Commercial Aircraft ◽

System Architectures ◽

Complex Engineering ◽

Aircraft System ◽

Definition Of

AbstractOne of the most challenging activity in the engineering design process is the definition of a framework (model and parameters) for the characterization of specific processes such as installation and assembly. Aircraft system architectures are complex structures used to understand relation among elements (modules) inside an aircraft and its evaluation is one of the first activity since the conceptual design. The assessment of aircraft architectures, from the assembly perspective, requires parameter identification as well as the definition of the overall analysis framework (i.e., mathematical models, equations).The paper aims at the analysis of a mathematical framework (structure, equations and parameters) developed to assess the fit for assembly performances of aircraft system architectures by the mean of sensitivity analysis (One-Factor-At-Time method). The sensitivity analysis was performed on a complex engineering framework, i.e. the Conceptual Design for Assembly (CDfA) methodology, which is characterized by level, domains and attributes (parameters). A commercial aircraft cabin system was used as a case study to understand the use of different mathematical operators as well as the way to cluster attributes.

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