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Journal Paper Accepted: The need for holistic enterprise control assessment methods for the future electricity grid

The LIINES is happy to announce the publication of the journal article The need for holistic enterprise control assessment methods for the future electricity grid, by Prof. Amro M. Farid (Dartmouth), Bo Jiang (MIT), Aramazd Muzhikyan (Dartmouth), and Prof. Kamal Youcef-Toumi (MIT) in the journal Renewable and Sustainable Energy Reviews.

In this comprehensive literature-based study, the LIINES presents a logical case for integrating power grid assessment methods into a holistic enterprise control framework.  Such a framework is explicitly techno-economic and merges methods power systems engineering and economics.   To support the argument, the LIINES has conducted the most comprehensive review of renewable energy integration studies completed to date.

The paper discusses the need for change in the assessment of the electricity grid as a result of five driving forces.  The driving forces are identified as: decarbonization, growth of electricity demand, transportation electrification, electric power deregulation, and increasing numbers of responsive (“smart”) consumers.  These five drivers require the steadily increasing penetration of solar and wind generation as well as evolving capabilities to support demand side management for the tremendous diversity of loads that connect to the electrical grid.  The integration of these three new grid technologies of renewable energy, electric vehicles, and demand side resources ultimately imposes fundamental changes to the grid’s structure and behavior.

The paper argues that the future electric grid’s needs for reliability, cost efficiency and sustainability necessitates a holistic assessment approach.  Figure 1 shows a guiding structure that leads to five techno-economic control objectives.  This work also uses five lifecycle properties to integrate rather than decompose the engineering design.  The lifecycle properties core to the power grid are dispatchability, flexibility, forecastability, stability, and resilience. The use of these five properties avoids overlap in function of solutions.

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Figure 1: Guiding Structure of Argument

Using such a holistic paradigm for techno-economic assessment, the journal paper conducts the most comprehensive review of renewable energy studies completed to date. It found several limitations to the existing renewable energy integration studies. Firstly, in order to address the holistic nature of the power grid, the real potential of demand side resources needs to be included. Additionally, for power grid balancing, validated simulations rather than statistical methods based on questionable assumptions need to be used.  Furthermore, the consistency between future development of the real market structure and modeling methods needs to be assured. Finally, the investment costs related to the support of the future power grid need to be considered in simulation.

Thus, the paper concludes based on the defined model requirements and the assessment of the current literature, that a framework for holistic power grid enterprise control assessment needs to satisfy the following requirements:

  1. Allows for an evolving mixture of generation and demand as dispatchable energy resources
  2. Allows for an evolving mixture of generation and demand as variable energy resources
  3. Allows for the simultaneous study of transmission and distribution systems
  4. Allows for the time domain simulation of the convolution of relevant grid enterprise control functions
  5. Allows for the time domain simulation of power grid topology reconfiguration in operation time scale
  6. Specifically addresses the holistic dynamic properties of dispatchability, flexibility, forecastability, stability, and resilience
  7. Represents potential changes in enterprise grid control functions and technologies as impacts on these dynamic properties
  8. Accounts for the consequent changes in operating cost and the required investment costs.

These requirements have been realized in a power grid enterprise control simulator that was used for an extensive study of renewable energy integration in the power grid [Link 1], [Link 2].  The simulator includes the physical electrical grid layer and incorporates primary, secondary, and tertiary control functions. This model fits the requirements of the holistic enterprise control method as defined previously.

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 Figure 2: The Enterprise Control Power Grid Simulator

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Journal Paper Accepted at Applied Energy – Demand Side Management in Power Grid Enterprise Control: A Comparison of Industrial & Social Welfare Approaches

The LIINES is happy to announce that our recent paper entitled: Demand Side Management in Power Grid Enterprise Control: A Comparison of Industrial & Social Welfare Approaches, has been accepted to the Applied Energy Journal. This study comes as a result of collaboration between three universities; MIT, Masdar Institute, and Dartmouth. The work is authored by Bo Jiang (MIT), Aramazd Muzhikyan (Masdar Institute), Prof. Amro M. Farid (Dartmouth) and Prof. Kamal Youcef-Toumi (MIT).

Demand response is an integral part of a reliable and cost-effective power grid.  As wind and solar energy become two important power generation sources that reduce CO2 emissions and ensure domestic energy security, their intermittent and uncertain nature poses operational challenges on the electrical grid’s reliability. Instead of relying solely on dispatchable generation, power grid operators, called ISOs, are adopting Demand Response (DR) programs to allow customers to adjust electricity consumption in response to market signals. These DR programs are an efficient way to introduce dispatchable demand side resources that mitigate the variable effects of renewable energy, enhance power grid reliability and reduce electricity costs. Fortunately, the U.S. Supreme Court’s recent ruling Federal Energy Regulatory Commission vs. Electric Power Supply Association, has upheld the implementation of Demand Response allowing its role to mature in the coming years.

Despite the recognized importance and potential of DR, the academic and industrial literature have taken divergent approaches to its implementation. The popular approach in the scientific literature uses the concept of “Transactive Energy” which works much like a stock market of energy; where customers provide bids for a certain quantity of electricity that they wish to consume. Meanwhile industrial implementations (such as those described by FERC order 745) compensate customers according to their load reduction from a predefined electricity consumption baseline that would have occurred without DR. Such a counter-factual baseline may be erroneous. At the LIINES, we have rigorously compared the two approaches. Our previous journal paper published at Applied Energy “Demand side management in a day-ahead wholesale market: A comparison of industrial & social welfare approaches” conducted the comparison in a day-ahead wholesale market context.  It showed, both analytically and numerically, that the use of power consumption baselines in demand response introduces power system imbalances and costlier dispatch.

Our recent paper now expands the analysis from a single day-ahead electricity market to the multiple layers of wholesale markets found in many regions of the North American power grid. This holistic analysis includes the day-ahead, real-time, and ancillary service markets. The integration of these multiple layers of power system operations captures the coupling between them and reveals the the impacts of DR implementation over the course of a full-day with a granularity of tens of seconds. The paper quantifies both the technical and economic impacts of industrial baseline errors in the day-ahead and real-time markets, namely their impacts on power system operating reserve requirements, operating costs and market prices.

The paper concludes that the presence of demand baseline errors – present only in the industrial implementaiton – leads to a cascade of additional system imbalances and costs as compared to the Transactive Energy model. A baseline error introduced in the day-ahead market will increase costs not just in the day-ahead market, but will also introduce a greater net load error residual in the real-time market causing additional costs and imbalances. These imbalances if left unmitigated degrade system reliability or otherwise require costly regulating reserves to achieve the same reliability.

Figure 1: Cascading Cost Increase of Demand Response Baseline Errors in Day-Ahead Energy Market

An additional baseline error introduced in the real-time market further compounds this cascading effect with additional costs in the real-time market, amplified downstream imbalances, and further regulation capacity for its mitigation.

Figure 2: Cascading Cost Increase of Demand Response Baseline Errors in Real-Time Energy Market

Based on these results, the potential for baseline inflation should be given attention by federal energy policy-makers. The effects of industrial baseline errors can be mitigated with effective policy. As a first solution, ISOs could calculate demand response baselines using the same methods of load prediction normally used in energy markets. Such an approach leaves less potential for baseline manipulation. A more comprehensive solution to this problem will be the upcoming trend of transactive energy and would eliminate the concept of baselines and their associated uncertainties entirely.

In depth materials on LIINES smart power grid research can be found on the LIINES website.

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Journal Paper Accepted: Relative Merits of Load Following Reserves & Energy Storage Market Integration Towards Power System Imbalances

We are happy to announce that our recent paper entitled: “Relative Merits of Load Following Reserves & Energy Storage Market Integration Towards Power System Imbalances”, has been published in the International Journal of Electrical Power & Energy Systems (IJEPES). This study comes as a result of collaboration between three universities; Masdar Institute, Dartmouth, and MIT. The work is authored by Aramazd Muzhikyan (Masdar Institute), Prof. Amro M. Farid (Dartmouth) and Prof. Kamal Youcef-Toumi (MIT).

The existing energy storage resource (ESR) studies bound their discussion to a single timescale of power system operations, such as day-ahead scheduling or real-time balancing. As a result, these studies are only able to capture the impact of the ESR integration on the associated timescale, while any effects that may span across adjacent timescales are omitted. Recently, power grid enterprise control has been developed that integrates different timescales of balancing operations into a multi-layer control hierarchy. The benefits of such holistic power system modeling have been demonstrated for studies on renewable energy integration, the determination of the power system imbalances and the assessment of reserve requirements.

This paper integrates ESRs into the power system enterprise control for the first time. While the ESR integration is expected to mainly affect its associated timescale, such methodology also allows capturing the potential impact on adjacent timescales. If such coupling of timescales exists, it can be exploited to reduce the system resource requirements. This methodology is also used to demonstrate the differences in imbalance mitigation performance of ESRs and load following reserves. While both these resources can be used for balancing the system, the enterprise control methodology unveils their differences and relative merits for different balancing scenarios. The notion of ‘‘utilization efficiency’’ of a given resource is introduced here which is defined as the amount of that resource required to mitigate 1MW of imbalance.

A novel ESR scheduling method has also been developed in this paper that beneficially exploits the coupling between different timescales. Since the day-ahead market has hourly time step, the obtained generation schedule has a stair-like profile with constant values for each hourly interval. However, such stair-like profile does not capture the intra-hour variations of the demand, leading to higher load following reserve requirement. Taking advantage of the timescale coupling, a sub-hourly ESR profile is designed based on the day-ahead market output that, in addition to the traditional benefits of shaving the peak load and reducing the operating cost, also simultaneously reduces the load following reserves requirement. The newly designed ESR schedule is based on piecewise linear harmonic functions and resembles the smooth demand profile within hourly intervals.

The results show that the ESR and the load following reserves have different performances and are better suited for applications in different circumstances. While the utilization efficiency is nearly constant for the load following reserves, the performance of the ESR significantly depends on the temporal characteristics, namely the net load variability and the day-ahead market time step. Higher variability and smaller day-ahead market time step result in better ESR utilization efficiency. The results also show that the generation schedule of the system without ESR has a stair-like form, while the total generation+ESR schedule of the system with ESR integration has a much smoother form and more closely resembles the actual demand profile. This difference defines the actual load following reserve requirement for each system. The results show that the load following reserve requirement of the system with ESR integration is significantly lower compared to the traditional system without ESR.

 

The comparison of the schedules for a system without ESR and a system with ESR scheduled according to the proposed method

The difference of load following reserve requirements for systems without and with ESR.

In depth materials on LIINES smart power grid research can be found on the LIINES website.

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Journal Paper Accepted: Opportunities for energy-water nexus management in the Middle East and North Africa

by Brian Keare

We are happy to announce that our paper “Opportunities for Energy-Water Nexus management in the Middle East and North Africa”, has been accepted for publication by the academic journal Elementa: Science of the Anthropocene. This study was the result of collaboration between William N. Lubega (Illinois at Urbana-Champaign) and Prof. Amro M. Farid and William W. Hickman (Dartmouth).

Electric power is required to produce, treat, distribute, and recycle water while water is required to generate and consume electricity. Naturally, this energy-water nexus is most evident in multi-utilities that provide electricity and water but still exists when the nexus has distinct organizations as owners and operators. Therefore, the sustainability question that arises from energy-water trade-offs and synergies is very much tied to the potential for economies of scope.

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Furthermore, in the Middle East and North Africa (MENA) region, multi-utilities are not only common, but also the nexus is particularly exacerbated by the high energy intensity of the water supply due to limited fresh water resources. Several accelerating trends are increasingly stressing the existing supply systems of MENA countries: Increased demand due to population and economic growth, a more extreme and unpredictable climate mostly affecting water supply and power demand, and multiple drivers for more electricity-intensive water and more water-intensive electricity including aging infrastructure and certain regulations and standards. This paper identifies and motivates several opportunities for enhanced integrated operations management and planning in the energy-water nexus in multi-utilities in the MENA.

From the discussion of the coupling points between the energy and water systems and operations management strategies to optimize these coupling points, several policy implementations can be drawn. First, the existing approaches to dispatch of the individual products of power and water could be replaced by integrated energy-water dispatch. Second, existing fixed power and water purchase agreements can be replaced with a seamlessly integrated energy-water dispatch. As in liberalized power systems, multiple time horizon markets with their respective clearing mechanisms would be required so as to provide dynamic incentives for greater cost and resource efficiency.  Fourth, the energy-water nexus also presents coupling points that engage the demand side of both power and water. Carefully designed demand-side management schemes, perhaps in the form of public-private partnerships, could present a vehicle for coordinating these coupling points in a cost-effective fashion.

The report also leads to several central policy implications. First, if water consumption and withdrawal of power generation were monetized, the investment case for renewable energy would inevitably be a stronger one. Next, while reverse osmosis desalination plants limit the energy-intensity of water production, from an integrated systems perspective, multi-stage flash plants provide a coproduction functionality that may be preferred over individual reverse osmosis and power generation facilities. Third, while many water utilities across the region have made extensive efforts towards reducing water leakages, such efforts could be strengthened by considering the embedded energy and the associated economic and environmental cost of these leakages. Lastly, there exists both a necessity and opportunity to reduce the energy footprint of water supply in MENA countries through increased water recycling. Utilizing a decentralized treatment system providing multiple water qualities and treatment levels will allow more opportunities for recycled water use in industry, agriculture, and other areas.

In all, the integrated energy-water nexus planning models and optimization programs presented and cited in this work provide deeper perspectives than their single product alternatives found in the existing literature. Their application in the policy domain has a high potential for future work and extension in the MENA region. Furthermore, these techniques have the potential for use in regions of similar climate (e.g. South-West United States & Australia) or other electricity-water utilities around the globe.

In depth materials on LIINES energy-water nexus research can be found on the LIINES websitte.

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Prof. Amro M. Farid joins the University of Massachusetts Transportation Center as an affiliated Researcher

We are happy to announce that Prof. Amro M. Farid has joined the University of Massachusetts Transportation Center (UMTC) as an affiliated researcher.  The announcement can be found as a blog post here.  By entering the UMTC affiliated researcher network, the LIINES and UMTC will be able to more closely collaborate on interesting transportation research.  Naturally, some of these areas include transportation electrification, intelligent transportation systems, and connected & automated vehicles.
The University of Massachusetts Transportation Center (UMTC) is located at the University of Massachusetts – Amherst, 214 Marston Hall. The UMTC conducts research on all aspects of Transportation including Travel Behavior, Transportation Modeling, Sustainability, Freight, Transit, Intelligent Transportation Systems, Optimization, Transportation Finance and Policy, Emission Estimation and Modeling, Commercial Motor Vehicle research, Safety, Human Factors, GIS, Climate Change and Economic Development.
The UMTC is funded in part by the MassDOT, New England Transportation Consortium and National UTC Consortiums.
In depth materials on LIINES electrified transportation systems research can be found on the LIINES website.
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Prof. Amro M. Farid presents at Transactive Energy Systems Conference

On Tuesday May 17, 2016, Prof. Amro M. Farid presented at the Third International Conference and Workshop on Transactive Energy Systems in Portland, Oregon.   The presentation entitled:  “Microgrids as a Key Enabling Transactive Energy Technology for Resilient Self-Healing Power Grid Operation” featured some of the LIINES’ recent research on resilience in power systems.

Building upon the recent IEEE Vision for Smart Grid Controls, the presentation advocated the concept of resilience self-healing operation in future power grids.  This continues to be an important area of LIINES research and has been the subject of several recent blogposts.  (See here, here and here).  The concept of resilient power systems effectively means that healthy regions of the grid can continue to operate while disrupted and perturbed regions bring themselves back to normal operation.   A key technology enabling this resilience is microgrids because they are often able to island themselves from the rest of the grid and continue to operate successfully.   In this presentation, the microgrids were controlled with a transactive energy control architecture that couples several control layers to achieve both technical reliability as well as cost effectiveness.  Furthermore, the presentation showed the ability for several microgrids to self-coordinate so as to demonstrate “strength-in-numbers” when adverse power grid conditions like net load ramps and variability arise.   The presentation concluded with the need for significant new research where transactive energy control concepts are intertwined with recent work on power grid enterprise control.

 

In depth materials on LIINES smart power grid research can be found on the LIINES website.

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Prof. Amro M. Farid gives invited lecture at UVIG

On April 27th, 2016, Prof. Amro M. Farid gave an invited lecture at the Utility Variable-Generation Integration Group (UVIG) Spring Technical Workshop held in Sacramento, CA.  The presentation entitled:  “Enterprise Control as a Holistic Assessment Method for Variable Generation & Demand Response Integration” featured many of the LIINES’ research on renewable energy integration assessment methodologies.

The presentation advocated the concept of “Power Grid Enterprise Control” which has been the subject of several recent blogposts.  (See here and here).  Traditionally, power system operation & control methods are conducted individually.  In contrast, “Power Grid Enterprise Control” integrates these methods into a single simulation of how a power system enterprise behaves as a physical power grid tied to multiple layers of control, optimization and market behavior.  Such an integrated approach provides techno-economic performance results of the power grid.  Furthermore, it highlights trade-off decisions between technical reliability and cost performance.  The presentation showed how enterprise control simulation can be used to study renewable energy, energy storage, and demand-side energy resources.

In depth materials on LIINES smart grid research can be found on the LIINES website.

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Journal Paper accepted at IEEE Transactions on Industrial Informatics – An Axiomatic Design of a Multi-Agent Reconfigurable Mechatronic System Architecture

The LIINES is pleased to announce the acceptance of the paper “An Axiomatic Design of a Multi-Agent Reconfigurable Mechatronic System Architecture” to the IEEE Transactions on Industrial Informatics. The paper is authored by Prof. Amro M. Farid and Prof. Luis Ribeiro.

Recent trends in manufacturing require production facilities to produce a wide variety of products with an increasingly shorter product lifecycle. These trends force production facilities to adjust and redesign production lines on a more regular basis.

Reconfigurable manufacturing systems are designed for rapid change in structure; in both hardware and software components to address the required changes in production capacity and functionality.

Qualitative methods have recently been successful in achieving reconfigurability through multi-agent systems (MAS). However, their implementation remains limited, as an unambiguous quantitative reference architecture for reconfigurability has not yet been developed.

A design methodology based on quantitative reconfigurability measurement would facilitate a logical, and seamless transition between the five stages of the MAS design methodology, as shown below.

DesMethodology

Previous work on the reconfigurability of automated manufacturing systems has shown that reconfigurability depends primarily on architectural decisions made in stages 1, 2, 3, and 5. Operational performance of the manufacturing system after the reconfiguration is also important, but is often overlooked by the existing literature. As a result, it’s not clear:

  1. The degree to which existing designs have achieved their intended level of reconfigurability.
  2. Which systems are quantitatively more reconfigurable.
  3. How these designs may overcome their inherent design limitations to achieve greater reconfigurability in subsequent design iterations.

In order to address the previously mentioned issues with existing design methodologies, this paper develops a multi-agent system reference architecture for reconfigurable manufacturing systems driven by a quantitative and formal design approach, directly in line with the above Figure.

The paper uses Axiomatic Design for Large Flexible Engineering Systems to support a well-conceptualized architecture, which is necessary for excellent production system performance. Additionally, Axiomatic Design highlights potential design flaws at an early conceptual stage. This results in the first formal and quantitative reference architecture based on rigorous mathematics.

About the Author

Wester C.H. Schoonenberg completed his B.Sc. in Systems Engineering and Policy Analysis Management at Delft University of Technology in 2014. After his bachelors’ degree, Wester started his graduate work for the LIINES at Masdar Institute, which he continues as a doctoral student at Thayer School of Engineering at Dartmouth College in 2015. Currently, Wester is working on the integrated operation of electrical grids and production systems with a special interest in Zero Carbon Emission Manufacturing Systems.

A full reference list of LIINES publications can be found here:
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The LIINES Commitment to Open-Information

 Good science is reproducible.   This means that it must be publicly available, its contributions transparently communicated, and its data accessible.  These are principles that drive the everyday work of every individual’s research at the LIINES.  We now wish to go further and make a commitment to Open-Information.
Beginning today, the LIINES will seek to leverage its website to make all of its research 100% reproducible by the public at large.   This includes:
  • Sharing all input datasets used to conduct the research for which no prior proprietary or security commitments have been made.
  • Producing scientific publications in such a way that scientific peers can accurately verify & validate the work.
  • Making the content of all conference, journal and book-chapter publications freely available in author preprint form.  (Note: Most publishers allow self-archiving and open-distribution of author preprints).
We believe that the LIINES’ research has broad applicability to academia, industry, government and the public at large.   However, traditional publication venues are often only subscribed by academic universities and a handful of well-funded industrial companies.   All-too-often the people that can benefit from this work, never get a chance to see it.   This slows down the work’s potential impact and is counter to the LIINES mission.   It is for these reasons, that the LIINES makes its Open-Information commitment.
While it is natural that making all of this information available will take some time, we will be sure to keep blogging to keep you up to date of new additions to the LIINES website.  For now, feel free to visit the LIINES Datasets Repository which includes both data from our publications as well as a collation of several relevant and openly available datasets.
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Journal Paper Accepted at Applied Energy Journal – Demand Side Management in a Day-Ahead Wholesale Market: A Comparison of Industrial & Social Welfare Approaches

The LIINES is pleased to announce the acceptance of the paper entitled: “Demand Side Management in a Day-Ahead Wholesale Market: A Comparison of Industrial & Social Welfare Approaches” to Applied Energy Journal for publication. The paper is authored by Bo Jiang, Prof. Amro M. Farid, and Prof. Kamal Youcef-Toumi.

The intermittent and unpredictable nature of renewable energy brings operational challenges to electrical grid reliability. The fast fluctuations in renewable energy generation require high ramping capability which must be met by dispatchable energy resources. In contrast, Demand Side management (DSM) with its ability to allow customers to adjust electricity consumption in response to market signals has been recognized as an efficient way to shape load profiles and mitigate the variable effects of renewable energy as well as to reduce system costs. However, the academic and industrial literature have taken divergent approaches to DSM implementation. While the popular approach among academia adopts a social welfare maximization formulation, defined as the net benefit from electricity consumption measured from zero, the industrial practice introduces an estimated baseline.   This baseline represents the counterfactual electricity consumption that would have occurred without DSM, and customers are compensated according to their load reduction from this predefined electricity consumption baseline.

DR

In response to the academic and industrial literature gap, our paper rigorously compares these two different approaches in a day-ahead wholesale market context. We developed models for the two methods using the same mathematical formalism and compared them analytically as well as in a test case using RTS-1996 reliability testing system. The comparison of the two models showed that a proper reconciliation of the two models might make them dispatch in fundamentally the same way, but only under very specific conditions that are rarely met in practice. While the social welfare model uses a stochastic net load composed of two terms, the industrial DSM model uses a stochastic net load composed of three terms including the additional baseline term. While very much discouraged, customers have an implicit incentive to surreptitiously inflate the administrative baseline in order to receive greater financial compensation. An artificially inflated baseline is shown to result in a higher resource dispatch and higher system costs.

The high resource scheduling due to inflated baseline likely require more control activity in subsequent layers of enterprise control including security constrained economic dispatch and regulation service layer. Future work will continue to explore the technical and economic effects of erroneous industrial baseline.

About the Author:

Bo Jiang conducted this research in collaboration with her Master’s thesis advisor Prof. Amro M. Farid and Prof. Kamal Youcef-Toumi at Massachusetts Institute of Technology. Her research interests include renewable energy integration, power system operations and optimization. Bo is now pursuing her PhD at MIT Mechanical Engineering Department.

A full reference list of Smart Power Grids and Intelligent Energy Systems research at LIINES can be found on the LIINES publication page: http://engineering.dartmouth.edu/liines

 

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