scholarly journals A Planning Tool for Reliability Assessment of Overhead Distribution Lines in Hybrid AC/DC Grids

2021 ◽  
Vol 13 (11) ◽  
pp. 6099
Author(s):  
Giovanna Adinolfi ◽  
Roberto Ciavarella ◽  
Giorgio Graditi ◽  
Antonio Ricca ◽  
Maria Valenti

Integration of DC grids into AC networks will realize hybrid AC/DC grids, a new energetic paradigm which will become widespread in the future due to the increasing availability of DC-based generators, loads and storage systems. Furthermore, the huge connection of intermittent renewable sources to distribution grids could cause security and congestion issues affecting line behaviour and reliability performance. This paper aims to propose a planning tool for congestion forecasting and reliability assessment of overhead distribution lines. The tool inputs consist of a single line diagram of a real or synthetic grid and a set of 24-h forecasting time series concerning climatic conditions and grid resource operative profiles. The developed approach aims to avoid congestions criticalities, taking advantage of optimal active power dispatching among “congestion-nearby resources”. A case study is analysed to validate the implemented control strategy considering a modified IEEE 14-Bus System with introduction of renewables. The tool also implements reliability prediction formulas to calculate an overhead line reliability function in congested and congestions-avoided conditions. A quantitative evaluation underlines the reliability performance achievable after the congestion strategy action.

Author(s):  
Athanasios Chatzidimitriou ◽  
Manolis Kaliorakis ◽  
Dimitris Gizopoulos ◽  
Maurizio Iacaruso ◽  
Mauro Pipponzi ◽  
...  

Author(s):  
I Žutautait˙e ◽  
J Augutis ◽  
R Krikštolaitis ◽  
G Dundulis ◽  
M Valinčius ◽  
...  

2021 ◽  
Author(s):  
Mathias Neumann ◽  
Hubert Hasenauer

Abstract Competition for resources (light, water, nutrients, etc.) limits the size and abundance of alive trees a site can support. This carrying capacity determines the potential carbon sequestration in alive trees as well as the maximum growing stock. Lower stocking through thinning can change growth and mortality. We were interested in the relations between stand structure, increment and mortality using a long-unmanaged oak-hornbeam forest near Vienna, Austria, as case study. We expected lower increment for heavy thinned compared to unmanaged stands. We tested the thinning response using three permanent growth plots, whereas two were thinned (50% and 70% basal area removed) and one remained unmanaged. We calculated stand structure (basal area, stem density, diameter distribution) and increment and mortality of single trees. The heavy thinned stand had over ten years similar increment as the moderate thinned and unthinned stands. Basal area of the unthinned stand remained constant and stem density decreased due to competition-related mortality. The studied oak-hornbeam stands responded well even to late and heavy thinning suggesting a broad “plateau” of stocking and increment for these forest types. Lower stem density for thinned stands lead to much larger tree increment of single trees, compared to the unthinned reference. The findings of this study need verification for other soil and climatic conditions.


2021 ◽  
Vol 13 (3) ◽  
pp. 11030
Author(s):  
Vanrajsinh SOLANKI ◽  
Susheel SINGH ◽  
Rohan KANSARA ◽  
Kelvin GANDHI ◽  
Nitisha PATEL ◽  
...  

Sapota, a prominent and economically important fruit crop of India is susceptible to several species of insect and mite pests. Several pesticides formulations are used to control the pest damage in sapota. The present investigation was aimed to study the dissipation and persistence behaviour of combi-product profenofos 40% + cypermethrin 4% (44EC) at the standard dose (SD) (1162 g a.i. ha-1+106 g a.i. ha-1) and double to standard dose (2×SD) (2324 g a.i. ha-1+212 g a.i. ha-1) in/on sapota under tropical agro-climatic conditions of South Gujarat in India. Prior to quantitative analysis of pesticide residue on Gas chromatography with electron captured detector (GC-ECD), the modified Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) based method was validated on its accuracy, precision, linearity and sensitivity. Profenofos persisted in sapota up to 30 days with the half-lives of 5.65 and 7.34 days at SD and 2×SD, respectively. Cypermethrin dissipated at a rapid pace and was below quantitation limit (BQL) on 7 days at either dose of application; the half-life values recorded were 3.27 and 4.43 days at SD and 2×SD, respectively. This is the first case study that reflects 14 days as a waiting period after the last spray of combi-product (44EC) at standard dose facilitates the residue-free sapota fruits. Further, the health risk index (HRI<1) and Health Index (HI %< 100%) indicates that the application of combi-product profenofos 40% + cypermethrin 4% (44EC) at standard dose could not pose any health risk to Indian consumers.


2016 ◽  
Vol 9 (2) ◽  
pp. 297-305 ◽  
Author(s):  
E. Mesquita ◽  
P. Antunes ◽  
A. A. Henriques ◽  
A. Arêde ◽  
P. S. André ◽  
...  

ABSTRACT Optical systems are recognized to be an important tool for structural health monitoring, especially for real time safety assessment, due to simplified system configuration and low cost when compared to regular systems, namely electrical systems. This work aims to present a case study on structural health monitoring focused on reliability assessment and applying data collected by a simplified optical sensing system. This way, an elevated reinforced concrete water reservoir was instrumented with a bi-axial optical accelerometer and monitored since January 2014. Taking into account acceleration data, the natural frequencies and relative displacements were estimated. The reliability analysis was performed based on generalized extreme values distribution (GEV) and the results were employed to build a forecast of the reliability of the water elevated reservoir for the next 100 years. The results showed that the optical system combined with GEV analysis, implemented in this experimental work, can provide adequate data for structural reliability assessment.


2020 ◽  
Vol 7 (2) ◽  
pp. 053-059
Author(s):  
Sunil Prasad ◽  
◽  
Dhanpal Singh Chauhan ◽  

The state Jharkhand is one of the Non-Timber Forest Products (NTFPs) rich states of the country because of diverse physiographic and climatic conditions. It is known for its mineral wealth, tribal population and forests. NTFPs play an important role in supporting rural livelihoods and food security in tribal Jharkhand. The present study was carried out in three distinct villages of Jharkhand to explore the range of livelihood contributions of NTFPs. The study was based on empirical fieldwork using both quantitative and qualitative data. A structured interview schedule was managed for the respondents. Comparing income sources, we found that most of the households collect NTFPs and earn a handsome amount of income from NTFPs ranges from 33% to 59%. We also prioritized potential NTFPs along with their basic value chain.


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