Long-Term Forecasts of Optimal Approximations to the Load Duration Curve

1980 ◽  
Vol 31 (4) ◽  
pp. 343-347 ◽  
Author(s):  
Noel D. Uri ◽  
John S. Maybee
Keyword(s):  
Load Duration ◽  
Load Duration Curve

scholarly journals Generation Expansion Models including Technical Constraints and Demand Uncertainty

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
P. Deossa ◽  
K. De Vos ◽  
G. Deconinck ◽  
J. Espinosa
Keyword(s):  
Demand Uncertainty ◽  
Control Method ◽  
Computational Time ◽  
Load Duration ◽  
Planning Decisions ◽  
Generation Expansion ◽  
Load Duration Curve ◽  
Expansion Model ◽  
Operational Constraints

This article presents a Generation Expansion Model of the power system taking into account the operational constraints and the uncertainty of long-term electricity demand projections. The model is based on a discretization of the load duration curve and explicitly considers that power plant ramping capabilities must meet demand variations. A model predictive control method is used to improve the long-term planning decisions while considering the uncertainty of demand projections. The model presented in this paper allows integrating technical constraints and uncertainty in the simulations, improving the accuracy of the results, while maintaining feasible computational time. Results are tested over three scenarios based on load data of an energy retailer in Colombia.

Method for Redesign of District Heating Networks within Transition from the 2nd to the 3rd Generation

2014 ◽  
Vol 657 ◽  
pp. 689-693
Author(s):  
Răzvan Corneliu Lefter ◽  
Daniela Popescu ◽  
Alexandrina Untăroiu
Keyword(s):  
District Heating ◽  
Design Stage ◽  
Heating Systems ◽  
Load Duration ◽  
Load Duration Curve ◽  
District Heating Systems ◽  
Consumption Rates ◽  
Heat Loads ◽  
Heating Networks

Important investmentsare made lately in the area of district heating, as a technology capable ofhelping countries to reach sustainability goals. In Romania, European fundswere spent for transition from the 2nd to the 3rdgeneration of district heating systems. The lack of appropriate monitoringsystems in old district heating systems makes optimisation nowadays very difficult,especially because nominal values used in the first design stage areoverestimated. Realistic nominal heat loads are necessary to make goodestimations of hydraulic parameters to be used for redesign. This studyproposes a method that uses the heat load duration curve theory to identify theappropriate nominal heat loads to be used for redesign. Comparison betweenresults obtained by applying the nominal heat loads of each consumer, as theywere established in the first design stage, and the ones identified by theproposed method are analyzed in a case study. The results show that errors arein the +/- 3% band, between the metered heat consumption rates and the proposedrates. The new method can be used for the sizing of pumps and district heatingnetworks after retrofit, in order to get better adjustments of the circulationpumps and increase of the energy efficiency.

scholarly journals Probability Calibration Of Load Duration Modification Factor For Timber Roofs In The Polish Mountain Zones

2014 ◽  
Vol 60 (2) ◽  
pp. 195-208
Author(s):  
T. Domański
Keyword(s):  
Limit State ◽  
High Stress ◽  
Life Time ◽  
Probabilistic Methods ◽  
Limit States ◽  
Term Limit ◽  
Load Duration ◽  
Maximum Likelihood Methods ◽  
Short And Long Term

Abstract The resistance parameters of timber structures decrease with time. It depends on the type of load and timber classes. Strength reduction effects, referred to as creep-rupture effects, due to long term loading at high stress ratio levels are known for many materials. Timber materials are highly affected by this reduction in strength with duration of load. Characteristic values of load duration and load duration factors are calibrated by means of using probabilistic methods. Three damage accumulation models are considered, that is Gerhard [1] model, Barret, Foschi[2] and Foshi Yao [3] models. The reliability is estimated by means of using representative short- and long-term limit states. Time variant reliability aspects are taken into account using a simple representative limit state with time variant strength and simulation of whole life time load processes. The parameters in these models are fitted by the Maximum Likelihood Methods using the data relevant for Polish structural timber. Based on Polish snow data over 45 years from mountain zone in: Zakopane – Tatra, Świeradów – Karkonosze, Lesko – Bieszczady, the snow load process parameters have been estimated. The reliability is evaluated using representative short – and long –term limit states, load duration factor kmod is obtained using the probabilistic model.

A Study of the Load Allocation using Watershed Model and Load Duration Curve in TMDL

2018 ◽  
Vol 22 (9) ◽  
pp. 3222-3232 ◽  
Author(s):  
Eun Jeong Lee ◽  
Tae Geun Kim ◽  
Kyoung-sik Choi
Keyword(s):  
Watershed Model ◽  
Load Duration ◽  
Load Duration Curve

scholarly journals Development of load duration curve system in data-scarce watersheds based on a distributed hydrological model

2019 ◽  
Vol 50 (3) ◽  
pp. 886-900
Author(s):  
Jia Wang ◽  
Xin-hua Zhang ◽  
Chong-Yu Xu ◽  
Hao Wang ◽  
Xiao-hui Lei ◽  
...  
Keyword(s):  
Hydrological Model ◽  
Assessment Tool ◽  
Swat Model ◽  
River Basins ◽  
Point Sources ◽  
Guizhou Province ◽  
Polluted Water ◽  
Distributed Hydrological Model ◽  
Load Duration ◽  
Load Duration Curve

AbstractMany developing countries and regions are currently facing serious water environmental problems, especially the lack of monitoring systems for medium- to small-sized watersheds. The load duration curve (LDC) is an effective method to identify polluted waterbodies and clarify the point sources or non-point sources of pollutants. However, it is a large challenge to establish the LDC in small river basins due to the lack of available observed runoff data. In addition, the LDC cannot yet spatially trace the specific sources of the pollutants. To overcome the limitations of LDC, this study develops a LDC based on a distributed hydrological model of the Soil and Water Assessment Tool (SWAT). First, the SWAT model is used to generate the runoff data. Then, for the control and management of over-loaded polluted water, the spatial distribution and transportation of original sources of point and non-point pollutants are ascertained with the aid of the SWAT model. The development procedures of LDC proposed in this study are applied to the Jian-jiang River basin, a tributary of the Yangtze River, in Duyun city of Guizhou province. The results indicate the effectiveness of the method, which is applicable for water environmental management in data-scarce river basins.

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