scholarly journals Demand Response Coupled with Dynamic Thermal Rating for Increased Transformer Reserve and Lifetime

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1378
Author(s):  
Ildar Daminov ◽  
Rémy Rigo-Mariani ◽  
Raphael Caire ◽  
Anton Prokhorov ◽  
Marie-Cécile Alvarez-Hérault
Keyword(s):  
Ambient Temperature ◽  
Demand Response ◽  
Thermal Model ◽  
Critical Period ◽  
Optimization Problem ◽  
Integrated Management ◽  
Critical Periods ◽  
Network Access ◽  
Maximal Amplitude ◽  
Demand Response Program

(1) Background: This paper proposes a strategy coupling Demand Response Program with Dynamic Thermal Rating to ensure a transformer reserve for the load connection. This solution is an alternative to expensive grid reinforcements. (2) Methods: The proposed methodology firstly considers the N-1 mode under strict assumptions on load and ambient temperature and then identifies critical periods of the year when transformer constraints are violated. For each critical period, the integrated management/sizing problem is solved in YALMIP to find the minimal Demand Response needed to ensure a load connection. However, due to the nonlinear thermal model of transformers, the optimization problem becomes intractable at long periods. To overcome this problem, a validated piece-wise linearization is applied here. (3) Results: It is possible to increase reserve margins significantly compared to conventional approaches. These high reserve margins could be achieved for relatively small Demand Response volumes. For instance, a reserve margin of 75% (of transformer nominal rating) can be ensured if only 1% of the annual energy is curtailed. Moreover, the maximal amplitude of Demand Response (in kW) should be activated only 2–3 h during a year. (4) Conclusions: Improvements for combining Demand Response with Dynamic Thermal Rating are suggested. Results could be used to develop consumer connection agreements with variable network access.

scholarly journals Critical period of weeds interference in pineapple (Ananas comosus [L.] Merr.) crops

2021 ◽  
pp. 120-128
Author(s):  
Silvana Pimentel de Oliveira ◽  
Jefferson Costa Santos ◽  
Bruna Nogueira Leite ◽  
Géssica Aline Nogueira dos Santos ◽  
José Ferreira da Silva
Keyword(s):  
Critical Period ◽  
Crop Production ◽  
Integrated Management ◽  
Production Capacity ◽  
Management Program ◽  
Ananas Comosus ◽  
Critical Periods ◽  
Total Period ◽  
Weeds Control ◽  
Crop Weed Competition

Description of the subject. In crop-weed competition, some periods are critical because they may interfere with the crop production capacity. Therefore, knowing these periods is crucial when deciding on the best time for control and preparation of the Integrated Management Program. Objectives. To determine the Period Prior to Interference, Total Period for Interference Prevention, and the Critical Interference Period in pineapple cultivation. Method. The experimental design consisted of randomized blocks in 2 x 15 factorial arrangement, four replications, and two management systems: weeds control and crop-weeds coexistence; 15 increasing periods of 30 days each after planting: 0, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 360, 390, 420. In the control treatments, since planting, manual weeding (with hoe) and mechanical weeding (with brush cutter) were done during increasing periods of time, and in the coexistence treatments, the weeds lived together with pineapple plants and, at the end of each period, weeds control was made with mechanical and chemical weeding. Results. The best yields were achieved in the periods of less coexistence with weeds. The critical periods for interference prevention with 5 and 10% of yield losses were 259 and 204 days, respectively. Conclusions. The critical period for interference prevention lasted 14-259 days after planting of the pineapple offsets.

scholarly journals Techno-Economic Planning and Operation of the Microgrid Considering Real-Time Pricing Demand Response Program

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4597
Author(s):  
Zi-Xuan Yu ◽  
Meng-Shi Li ◽  
Yi-Peng Xu ◽  
Sheraz Aslam ◽  
Yuan-Kang Li
Keyword(s):  
Real Time ◽  
Demand Response ◽  
Positive Impact ◽  
Environmental Aspects ◽  
Component Size ◽  
Cost Of Energy ◽  
Four Seasons ◽  
Demand Response Program ◽  
Real Time Pricing

The optimal planning of grid-connected microgrids (MGs) has been extensively studied in recent years. While most of the previous studies have used fixed or time-of-use (TOU) prices for the optimal sizing of MGs, this work introduces real-time pricing (RTP) for implementing a demand response (DR) program according to the national grid prices of Iran. In addition to the long-term planning of MG, the day-ahead operation of MG is also analyzed to get a better understanding of the DR program for daily electricity dispatch. For this purpose, four different days corresponding to the four seasons are selected for further analysis. In addition, various impacts of the proposed DR program on the MG planning results, including sizing and best configuration, net present cost (NPC) and cost of energy (COE), and emission generation by the utility grid, are investigated. The optimization results show that the implementation of the DR program has a positive impact on the technical, economic, and environmental aspects of MG. The NPC and COE are reduced by about USD 3700 and USD 0.0025/kWh, respectively. The component size is also reduced, resulting in a reduction in the initial cost. Carbon emissions are also reduced by 185 kg/year.

Critical periods for functional and anatomical compensation in lateral suprasylvian visual area following removal of visual cortex in cats

1984 ◽  
Vol 52 (5) ◽  
pp. 941-960 ◽  
Author(s):  
L. Tong ◽  
R. E. Kalil ◽  
P. D. Spear
Keyword(s):  
Visual Cortex ◽  
Critical Period ◽  
Ocular Dominance ◽  
Direction Selectivity ◽  
Visual Area ◽  
Critical Periods ◽  
Cortex Lesion ◽  
Thalamic Projections ◽  
Adult Cats ◽  
Visual Cortical

Previous experiments have found that neurons in the cat's lateral suprasylvian (LS) visual area of cortex show functional compensation following removal of visual cortical areas 17, 18, and 19 on the day of birth. Correspondingly, an enhanced retino-thalamic pathway to LS cortex develops in these cats. The present experiments investigated the critical periods for these changes. Unilateral lesions of areas 17, 18, and 19 were made in cats ranging in age from 1 day postnatal to 26 wk. When the cats were adult, single-cell recordings were made from LS cortex ipsilateral to the lesion. In addition, transneuronal autoradiographic methods were used to trace the retino-thalamic projections to LS cortex in many of the same animals. Following lesions in 18- and 26-wk-old cats, there is a marked reduction in direction-selective LS cortex cells and an increase in cells that respond best to stationary flashing stimuli. These results are similar to those following visual cortex lesions in adult cats. In contrast, the percentages of cells with these properties are normal following lesions made from 1 day to 12 wk of age. Thus the critical period for development of direction selectivity and greater responses to moving than to stationary flashing stimuli in LS cortex following a visual cortex lesion ends between 12 and 18 wk of age. Following lesions in 26-wk-old cats, there is a decrease in the percentage of cells that respond to the ipsilateral eye, which is similar to results following visual cortex lesions in adult cats. However, ocular dominance is normal following lesions made from 1 day to 18 wk of age. Thus the critical period for development of responses to the ipsilateral eye following a lesion ends between 18 and 26 wk of age. Following visual cortex lesions in 2-, 4-, or 8-wk-old cats, about 30% of the LS cortex cells display orientation selectivity to elongated slits of light. In contrast, few or no cells display this property in normal adult cats, cats with lesions made on the day of birth, or cats with lesions made at 12 wk of age or later. Thus an anomalous property develops for many LS cells, and the critical period for this property begins later (between 1 day and 2 wk) and ends earlier (between 8 and 12 wk) than those for other properties.(ABSTRACT TRUNCATED AT 400 WORDS)

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