On the optimal composition of electricity grids with unreliable units: solvable models

1985 ◽  
Vol 17 (2) ◽  
pp. 367-385 ◽  
Author(s):  
D. J. Gates
Keyword(s):  
Load Distribution ◽  
Rayleigh Distribution ◽  
Explicit Solutions ◽  
Optimal Composition ◽  
Solvable Models ◽  
Electricity Grid ◽  
Load Duration ◽  
Load Duration Curve ◽  
Electricity Grids ◽  
Total Capacity

For a large electricity grid comprising many units (plants) of various types, such as coal, oil, nuclear, hydro, etc., with known unreliabilities (outage rates) we study the optimal (i.e. the cheapest) total capacity, or numbers, of each type of unit. Existing treatments of the problem involve numerical methods and approximations of unknown accuracy. For a range of cases, we find explicit solutions. This extends the known explicit solutions, which are confined to completely reliable units. The cases we analyse are (I) a demand (load) which has a shifted Rayleigh distribution—a good approximation to the real load-duration curve—with some restriction on reliability (big units are more reliable) and (II) an exponential load distribution—which is unrealistic—with no restrictions on reliability. In both cases, the solutions reduce to transformed versions of the exact solutions for totally reliable units and, like the latter, can be exhibited by means of a cost polygon.

On the optimal composition of electricity grids with unreliable units: solvable models

1985 ◽  
Vol 17 (02) ◽  
pp. 367-385
Author(s):  
D. J. Gates
Keyword(s):  
Load Distribution ◽  
Rayleigh Distribution ◽  
Explicit Solutions ◽  
Optimal Composition ◽  
Solvable Models ◽  
Electricity Grid ◽  
Load Duration ◽  
Load Duration Curve ◽  
Electricity Grids ◽  
Total Capacity

For a large electricity grid comprising many units (plants) of various types, such as coal, oil, nuclear, hydro, etc., with known unreliabilities (outage rates) we study the optimal (i.e. the cheapest) total capacity, or numbers, of each type of unit. Existing treatments of the problem involve numerical methods and approximations of unknown accuracy. For a range of cases, we find explicit solutions. This extends the known explicit solutions, which are confined to completely reliable units. The cases we analyse are (I) a demand (load) which has a shifted Rayleigh distribution—a good approximation to the real load-duration curve—with some restriction on reliability (big units are more reliable) and (II) an exponential load distribution—which is unrealistic—with no restrictions on reliability. In both cases, the solutions reduce to transformed versions of the exact solutions for totally reliable units and, like the latter, can be exhibited by means of a cost polygon.

scholarly journals A New Approach to Estimate from Monitored Demand Data the Limit of the Coverage of Electricity Demand through Photovoltaics in Large Electricity Grids

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4390
Author(s):  
Francisco Baena ◽  
Francisco José Muñoz-Rodriguez ◽  
Pedro Gómez Vidal ◽  
Gabino Almonacid
Keyword(s):  
Electricity Demand ◽  
New Method ◽  
Electrical System ◽  
Limit Values ◽  
New Approach ◽  
Electricity Grid ◽  
Load Duration ◽  
Load Duration Curve ◽  
Electricity Grids ◽  
Pv Generation

In a traditional large electricity grid without storage, there is a limit to the maximum photovoltaic energy that can be consumed as the demand and generation may not match, either in magnitude or in time. This paper aims to provide a new method to estimate the limit of the coverage of electricity demand by photovoltaics in large electricity grids. This new method eliminates the random and the periodic variability over time as it is based either on the load duration curve for demand and the output duration curve for PV generation. We will assume there is no energy storage or inter-network exchanges. Moreover, conditions for the best scenario for photovoltaics are provided in order to estimate the upper limit: photovoltaic overgeneration is not considered and a complete system flexibility is assumed. The knowledge of this limit will manage to provide not only a reference for the planning of the energy sector but also to analyze the viability of the integration of future photovoltaic projects in the electrical system. In order to illustrate the method, several large electricity grids have been analysed in order to determine the aforementioned limit. Values between 19.3% and 29.9% have been obtained.

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.

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 The smart grid as commons: Exploring alternatives to infrastructure financialisation

Urban Studies ◽  
2018 ◽  
Vol 56 (7) ◽  
pp. 1386-1403 ◽  
Author(s):  
Stephen Hall ◽  
Andrew EG Jonas ◽  
Simon Shepherd ◽  
Zia Wadud
Keyword(s):  
Air Quality ◽  
Smart Grid ◽  
Government Regulation ◽  
New Technologies ◽  
Urban Systems ◽  
Smart Devices ◽  
Electricity Grid ◽  
Common Ownership ◽  
Electricity Grids ◽  
The Uk

This article explores a tension between financialisation of electricity infrastructures and efforts to bring critical urban systems into common ownership. Focusing on the emerging landscape of electricity regulation and e-mobility in the United Kingdom (UK), it examines how electricity grid ownership has become financialised, and why the economic assumptions that enabled this financialisation are being called into question. New technologies, such as smart electricity meters and electric vehicles, provide cities with new tools to tackle poor air quality and greenhouse gas emissions. Electricity grids are key enabling infrastructures but the companies that run them do not get rewarded for improving air quality or tackling climate change. UK government regulation of electricity grids both enables financialisation and forecloses opportunities to manage the infrastructure for wider environmental and public benefit. Nonetheless, the addition of smart devices to this network – the ‘smart grid’ – opens up an opportunity for common ownership of the infrastructure. Transforming the smart grid into commons necessitates deep structural reform to the entire architecture of infrastructure regulation in the UK.

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.

Load duration curve: A tool for technico-economic analysis of energy solutions

2008 ◽  
Vol 40 (1) ◽  
pp. 29-35 ◽  
Author(s):  
Alain Poulin ◽  
Michel Dostie ◽  
Michaël Fournier ◽  
Simon Sansregret
Keyword(s):  
Economic Analysis ◽  
Load Duration ◽  
Load Duration Curve
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