scholarly journals Development of a Framework for Activation of Aggregator Led Flexibility

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4950
Author(s):  
Sarah O’Connell ◽  
Marcus Martin Keane
Keyword(s):  
Mixed Integer ◽  
Flexible Systems ◽  
Renewable Integration ◽  
Contract Negotiations ◽  
Electrical Grid ◽  
Industrial Sites ◽  
Box Models ◽  
Optimization Stage ◽  
Online Implementation ◽  
Optimal Approach

This paper presents a novel framework architecture for an online, real-time flexibility assessment and activation platform targeted at unlocking the flexibility potential of commercial buildings and smaller industrial sites, thereby enabling greater levels of renewable grid integration. Renewable integration targets in Europe of up to 40% of power generation from renewable sources by 2030 and over 90% by 2050 aim to decarbonize the electrical grid and increase electrification of transport, industry, and buildings. As renewable integration targets increase, participation in flexibility programs will be required from a much greater range of buildings and sites to balance grids hosting high levels of renewable generation. In this paper, an online implementation of a standardized flexibility assessment methodology, previously developed for offline contract negotiations between stakeholders, is modified to automate the assessment. The automated assessment is then linked to an aggregator-based multi-building or site optimization stage, enabling increased participation of multiple buildings and sites. To implement the assessment, models for individual flexible systems were reviewed, selected, and adapted, including physics-based, data-driven, and grey-box models. A review of optimization for flexibility found mixed-integer linear programming to be the optimal approach for the selection of flexible systems for demand response events.

On Developing Fair and Orderly Cloud Markets

2014 ◽  
Vol 4 (3) ◽  
pp. 22-43
Author(s):  
Olga Wenge ◽  
Dieter Schuller ◽  
Christoph Rensing ◽  
Ralf Steinmetz
Keyword(s):  
Quality Of Service ◽  
Security Requirements ◽  
Mixed Integer ◽  
Optimization Approach ◽  
Exact Approach ◽  
Weakest Link ◽  
Functional Attributes ◽  
Security Properties ◽  
Optimal Approach

While cloud markets promise virtually unlimited resource supplies, standardized commodities and proper services, some providers may not be able to offer effectual physical capacity to serve large customers. A solution is cloud collaborations, in which multiple providers unite forces in order to conjointly offer capacities in the cloud markets. Supposably, both the Quality of Service and security properties of such collaborations will be determined by “the weakest link in the chain”, therefore resulting in a trade-off between the monetary aggregates, cumulative capacity and the non-functional attributes of a cloud collaboration. Based on previous research, this paper examines efficient composition of cloud collaborations from the broker's perspective, considering Quality of Service and information security requirements of multiple cloud providers and users and presents an exact approach CCCP-EXA.KOM for building cloud collaborations. Furthermore, it proposes a Mixed Integer Programming-based heuristic optimization approach CCCP-PRIOSORT.KOM and provides its quantitative evaluation in comparison with prior optimal approach.

On Developing Fair and Orderly Cloud Markets

2019 ◽  
pp. 2097-2119
Author(s):  
Olga Wenge ◽  
Dieter Schuller ◽  
Christoph Rensing ◽  
Ralf Steinmetz
Keyword(s):  
Quality Of Service ◽  
Security Requirements ◽  
Mixed Integer ◽  
Heuristic Optimization ◽  
Optimization Approach ◽  
Exact Approach ◽  
Weakest Link ◽  
Security Properties ◽  
Optimal Approach

While cloud markets promise virtually unlimited resource supplies, standardized commodities and proper services, some providers may not be able to offer effectual physical capacity to serve large customers. A solution is cloud collaborations, in which multiple providers unite forces in order to conjointly offer capacities in the cloud markets. Supposably, both the Quality of Service and security properties of such collaborations will be determined by “the weakest link in the chain”, therefore resulting in a trade-off between the monetary aggregates, cumulative capacity and the non-functional attributes of a cloud collaboration. Based on previous research, this paper examines efficient composition of cloud collaborations from the broker's perspective, considering Quality of Service and information security requirements of multiple cloud providers and users and presents an exact approach CCCP-EXA.KOM for building cloud collaborations. Furthermore, it proposes a Mixed Integer Programming-based heuristic optimization approach CCCP-PRIOSORT.KOM and provides its quantitative evaluation in comparison with prior optimal approach.

scholarly journals Quantifying the Influences on Probabilistic Wind Power Forecasts

2018 ◽  
Vol 64 ◽  
pp. 06002 ◽  
Author(s):  
Schreiber Jens ◽  
Sick Bernhard
Keyword(s):  
Sensitivity Analysis ◽  
Probabilistic Models ◽  
Decision Makers ◽  
Renewable Energy Resources ◽  
Electrical Grid ◽  
Optimal Decisions ◽  
Box Models ◽  
Predicted Probability ◽  
Probabilistic Forecasts ◽  
Black Box Models

In recent years, probabilistic forecasts techniques were proposed in research as well as in applications to integrate volatile renewable energy resources into the electrical grid. These techniques allow decision makers to take the uncertainty of the prediction into account and, therefore, to devise optimal decisions, e.g., related to costs and risks in the electrical grid. However, it was yet not studied how the input, such as numerical weather predictions, affects the model output of forecasting models in detail. Therefore, we examine the potential influences with techniques from the field of sensitivity analysis on three different black-box models to obtain insights into differences and similarities of these probabilistic models. The analysis shows a considerable number of potential influences in those models depending on, e.g., the predicted probability and the type of model. These effects motivate the need to take various influences into account when models are tested, analyzed, or compared. Nevertheless, results of the sensitivity analysis will allow us to select a model with advantages in the practical application.

scholarly journals Energy Cost-Efficient Task Positioning in Manufacturing Systems

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5034
Author(s):  
Andrzej Bożek
Keyword(s):  
Linear Programming ◽  
Tabu Search ◽  
Energy Cost ◽  
Manufacturing Systems ◽  
Mixed Integer ◽  
Efficient Production ◽  
Manufacturing Companies ◽  
Electrical Grid ◽  
Cost Of Energy ◽  
Cost Efficient

A problem to determine a production schedule which minimises the cost of energy used for manufacturing is studied. The scenario assumes that each production task has assigned constant power consumption, price of power from conventional electrical grid system is defined by time-of-use tariffs, and a component of free of charge renewable energy is available for the manufacturing system. The objective is to find the most cost-efficient production plan, subject to constraints involving predefined precedence relationships between the tasks and a bounded makespan. Two independent optimisation approaches have been developed, based on significantly different paradigms, namely mixed-integer linear programming and tabu search metaheuristic. Both of them have been verified and compared in extensive computational experiments. The tabu search-based approach has turned out to be generally more efficient in the sense of the obtained objective function values, but advantages of the use of linear programming have also been identified. The results confirm that it is possible to develop efficient computational methods to optimise energy cost under circumstances typical of manufacturing companies. The set of numerous benchmark instances and their solutions have been archived and it can be reused in further research.

Fortification Against Cascade Propagation Under Uncertainty

2021 ◽  
Author(s):  
Colin P. Gillen ◽  
Alexander Veremyev ◽  
Oleg A. Prokopyev ◽  
Eduardo L. Pasiliao
Keyword(s):  
Real Life ◽  
Integer Program ◽  
Mixed Integer ◽  
Centrality Measures ◽  
Mixed Integer Program ◽  
Cascade Process ◽  
Worst Case ◽  
Electrical Grid ◽  
Viral Spread ◽  
Critical Node

Network cascades represent a number of real-life applications: social influence, electrical grid failures, viral spread, and so on. The commonality between these phenomena is that they begin from a set of seed nodes and spread to other regions of the network. We consider a variant of a critical node detection problem dubbed the robust critical node fortification problem, wherein the decision maker wishes to fortify nodes (within a budget) to limit the spread of cascading behavior under uncertain conditions. In particular, the arc weights—how much influence one node has on another in the cascade process—are uncertain but are known to lie in some range bounded by a worst-case budget uncertainty. This problem is shown to be [Formula: see text]-hard even in the deterministic case. We formulate a mixed-integer program (MIP) to solve the deterministic problem and improve its continuous relaxation via nonlinear constraints and convexification. The robust problem is computationally more difficult, and we present an MIP-based expand-and-cut exact solution algorithm, in which the expansion is enhanced by cutting planes, which are themselves tied to the expansion process. Insights from these exact solutions motivate two novel (interrelated) centrality measures, and a centrality-based heuristic that obtains high-quality solutions within a few seconds. Finally, extensive computational results are given to validate our theoretical developments as well as provide insights into structural properties of the robust problem and its solution.

scholarly journals An Advanced Multicarrier Residential Energy Hub System Based on Mixed Integer Linear Programming

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Yue Yuan ◽  
Angel A. Bayod-Rújula ◽  
Huanxin Chen ◽  
Amaya Martínez-Gracia ◽  
Jiangyu Wang ◽  
...  
Keyword(s):  
Storage System ◽  
Residential Building ◽  
Economic Cost ◽  
Energy Storage System ◽  
Mixed Integer ◽  
Gas Network ◽  
Electrical Grid ◽  
Energy Hub ◽  
Photovoltaic Plant ◽  
The Impact

This work proposes a multicarrier energy hub system with the objective of minimizing the economy cost and the CO2 emissions of a residential building without sacrificing the household comfort and increasing the exploitation of renewable energy in daily life. The energy hub combines the electrical grid and natural gas network, a gas boiler, a heat pump, a photovoltaic plant, and a photovoltaic/thermal (PV/T) system. In addition, to increase the overall performance of the system, a battery-based energy storage system is integrated. To evaluate the optimal capacity of each energy hub component, an optimization scheduling process and the optimization problem have been solved with the YALMIP platform in the MATLAB environment. The result showed that this advanced system not only can decrease the economic cost and CO2 emissions but also reduce the impact to electrical grid.

scholarly journals Adaptive Control for Energy Exchange with Probabilistic Interval Predictors in Isolated Microgrids

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 375 ◽  
Author(s):  
Jiayu Cheng ◽  
Dongliang Duan ◽  
Xiang Cheng ◽  
Liuqing Yang ◽  
Shuguang Cui
Keyword(s):  
Energy Exchange ◽  
Programming Model ◽  
System Stability ◽  
System Capacity ◽  
Mixed Integer ◽  
Sufficient Information ◽  
Exchange Method ◽  
Optimal Dispatch ◽  
Optimization Stage ◽  
The Stability

Stability and reliability are of the most important concern for isolated microgrid systems that have no support from the utility grid. Interval predictions are often applied to ensure the system stability of isolated microgrids as they cover more uncertainties and robust control can be achieved based on more sufficient information. In this paper, we propose a probabilistic microgrid energy exchange method based on the Model Predictive Control (MPC) approach to make better use of the prediction intervals so that the system stability and cost efficiency of isolated microgrids are improved simultaneously. Appropriate scenarios are selected from the predictions according to the evaluation of future trends and system capacity. In the meantime, a two-stage adaptive reserve strategy is adopted to further utilize the potential of interval predictions and maintain the system security adaptively. Reserves are determined at the optimization stage to prepare some extra capacity for the fluctuations in the renewable generation and load demand at the operation stage based on the aggressive and conservative level of the system, which is automatically updated at each step. The optimal dispatch problem is finally formulated using the mixed-integer linear programming model and the MPC is formulated as an optimization problem with a discount factor introduced to adjust the weights. Case studies show that the proposed method could effectively guarantee the stability of the system and improve economic performance.

Practical Resources for Provision of Services to Culturally and Linguistically Diverse Users of AAC

2015 ◽  
Vol 22 (1) ◽  
pp. 25-39
Author(s):  
Elena Dukhovny ◽  
E. Betsy Kelly
Keyword(s):  
Best Practices ◽  
Augmentative And Alternative Communication ◽  
Linguistically Diverse ◽  
Intervention Strategies ◽  
Culturally And Linguistically Diverse ◽  
Limited Resources ◽  
Flexible Systems ◽  
Alternative Communication ◽  
Practical Applications ◽  
Provision Of Services

According to the 2010 U.S. Census, over 20% of Americans speak a language other than English in the home, with Spanish, Chinese, and French being the languages most commonly spoken, aside from English. However, few augmentative and alternative communication (AAC) systems offer multilingual support for individuals with limited functional speech. There has been much discussion in the AAC community about best practices in AAC system design and intervention strategies, but limited resources exist to help us provide robust, flexible systems for users who speak languages other than English. We must provide services that take into consideration the unique needs of culturally and linguistically diverse users of AAC and help them reach their full communication potential. This article outlines basic guidelines for best practices in AAC design and selection, and presents practical applications of these best practices to multilingual/multicultural clients.

Optimal Test Assembly in Practice

2013 ◽  
Vol 221 (3) ◽  
pp. 190-200 ◽  
Author(s):  
Jörg-Tobias Kuhn ◽  
Thomas Kiefer
Keyword(s):  
Particle Physics ◽  
Large Scale ◽  
Block Design ◽  
Linear Optimization ◽  
Mixed Integer ◽  
Optimal Test ◽  
Automated Test Assembly ◽  
Test Assembly ◽  
Block Level ◽  
Mixed Integer Linear Optimization

Several techniques have been developed in recent years to generate optimal large-scale assessments (LSAs) of student achievement. These techniques often represent a blend of procedures from such diverse fields as experimental design, combinatorial optimization, particle physics, or neural networks. However, despite the theoretical advances in the field, there still exists a surprising scarcity of well-documented test designs in which all factors that have guided design decisions are explicitly and clearly communicated. This paper therefore has two goals. First, a brief summary of relevant key terms, as well as experimental designs and automated test assembly routines in LSA, is given. Second, conceptual and methodological steps in designing the assessment of the Austrian educational standards in mathematics are described in detail. The test design was generated using a two-step procedure, starting at the item block level and continuing at the item level. Initially, a partially balanced incomplete item block design was generated using simulated annealing, whereas in a second step, items were assigned to the item blocks using mixed-integer linear optimization in combination with a shadow-test approach.

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