Multiscale design for system-wide peer-to-peer energy trading

Abstract

The integration of renewable generation and the electrification of heating and transportation are critical for the sustainable energy transition toward net-zero greenhouse gas emissions. These changes require the large-scale adoption of distributed energy resources (DERs). Peer-to-peer (P2P) energy trading has gained attention as a new approach for incentivizing the uptake and coordination of DERs, with advantages for computational scalability, prosumer autonomy, and market competitiveness. However, major unresolved challenges remain for scaling out P2P trading, including enforcing network constraints, managing uncertainty, and mediating transmission and distribution conflicts. Here, we propose a novel multiscale design framework for P2P trading, with inter-platform coordination mechanisms to align local transactions with system-level requirements, and analytical tools to enhance long-term planning and investment decisions by accounting for forecast real-time operation. By integrating P2P trading into planning and operation across spatial and temporal scales, the adoption of large-scale DERs is tenable and can create economic, environmental, and social co-benefits. The integration of renewable generation and the electrification of heating and transportation are critical for the sustainable energy transition toward net-zero greenhouse gas emissions. These changes require the large-scale adoption of distributed energy resources (DERs). Peer-to-peer (P2P) energy trading has gained attention as a new approach for incentivizing the uptake and coordination of DERs, with advantages for computational scalability, prosumer autonomy, and market competitiveness. However, major unresolved challenges remain for scaling out P2P trading, including enforcing network constraints, managing uncertainty, and mediating transmission and distribution conflicts. Here, we propose a novel multiscale design framework for P2P trading, with inter-platform coordination mechanisms to align local transactions with system-level requirements, and analytical tools to enhance long-term planning and investment decisions by accounting for forecast real-time operation. By integrating P2P trading into planning and operation across spatial and temporal scales, the adoption of large-scale DERs is tenable and can create economic, environmental, and social co-benefits. Three major components of the sustainable energy transition toward net-zero greenhouse gas emissions are the integration of renewable generation, the electrification of transport, and the electrification of heating.1Baruah P. Eyre N. Qadrdan M. Chaudry M. Blainey S. Hall J.W. Jenkins N. Tran M. Energy system impacts from heat and transport electrification.Proc. ICE - Energy. 2014; 167: 139-151Google Scholar As a result, a significant proportion of future generation and flexibility will be embedded within local distribution networks, in the form of millions of small- and medium-scale distributed energy resources (DERs), including solar and wind generation, home batteries, electric vehicles, and heat pumps.2Schoolman A. Raturi A. Nussey B. Shirley R. Knuckles J.A. de Graaf F. Magali P.R. Lu Z. Breyer C. Markides C.N. Decentralizing energy for a high-demand, low-carbon world.One Earth. 2019; 1: 388-391Google Scholar For example, under the International Energy Agency's Sustainable Development Scenario, the share of electricity generation from solar and wind will be 30% in 2030 (from 8% in 2019), electric vehicles will account for 40% of passenger car sales in 2030 (from 2.5% in 2019), and heat pumps will provide approximately 25% of the heating requirements for buildings built between 2019 and 2030.3Cozzi L. Gould T. Bouckart S. Crow D. Kim T.-Y. McGlade C. Olejarnik P. Wanner B. Wetzel D. World Energy Outlook 2020. OECD, 2020Google Scholar Given the rapid rate of DER integration necessary for the sustainable energy transition, there is an opportunity for significant additional value to be created by coordinating their planning and operation within distribution networks. Matching renewable generation with flexible demand on a localized basis reduces upstream power flows and losses, and can alleviate the need to curtail excess renewable generation due to distribution network constraints.4Pudjianto D. Gan C.K. Stanojevic V. Aunedi M. Djapic P. Strbac G. Value of integrating distributed energy resources in the UK electricity system.in: IEEE PES General Meeting. IEEE, 2010: 1-6https://doi.org/10.1109/PES.2010.5590184Google Scholar If DERs can be coordinated on a highly reliable basis, they could also defer or avoid the need for distribution, transmission, and generation infrastructure upgrades.5Carvallo J.-P. Taneja J. 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IET. 2007; 1: 10-16Google Scholar Alongside the rise of DERs, smart meters have seen major rollouts, providing the infrastructure for secure consumer-level communications and monitoring, and energy management systems are now available that can automate the control of DERs based on owner preferences, resource characteristics, and external price signals.8Pereira G.I. Specht J.M. Silva P.P. Madlener R. Technology, business model, and market design adaptation toward smart electricity distribution: insights for policy making.Energy Policy. 2018; 121: 426-440Google Scholar This creates the opportunity for DER owners to actively contribute generation and demand flexibility to the power system. This is described as the consumer-to-prosumer transition (prosumer meaning either “producer-consumer”9Schleicher-Tappeser R. How renewables will change electricity markets in the next five years.Energy Policy. 2012; 48: 64-75Google Scholar or “proactive consumer”).10Dimeas A. Drenkard S. 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The first category, unidirectional pricing, involves price signals that are sent to prosumers using one-way communication, which prosumers then consider when scheduling their flexible energy resources. Time-of-use retail tariffs are a simple example,12Grünewald P. McKenna E. Thomson M. Keep it simple: time-of-use tariffs in high-wind scenarios.IET Renew. Power Gener. 2015; 9: 176-183Google Scholar but more advanced platforms for aggregating demand-side flexibility can also operate on this principle.13Bai L. Wang J. Wang C. Chen C. Li F. Distribution locational marginal pricing (DLMP) for congestion management and voltage support.IEEE Trans. Power Syst. 2018; 33: 4061-4073Google Scholar Coordination can be improved by making prices more granular in terms of time and network location.14Edmunds, C., Bukhsh, W.A., and Galloway, S. (2018). The Impact of Distribution Locational Marginal Prices on Distributed Energy Resources: an Aggregated Approach. In 2018 15th International Conference on the European Energy Market (EEM) (IEEE), pp. 1–5.Google Scholar However, unidirectional pricing has two key limitations. First, good performance requires accurate forecasts and a detailed understanding of prosumer preferences and capabilities, since there is no negotiation process.15Toubeau J.-F. Morstyn T. Bottieau J. Zheng K. Apostolopoulou D. De Greve Z. Wang Y. Vallee F. Capturing spatio-temporal dependencies in the probabilistic forecasting of distribution locational marginal prices.IEEE Trans. Smart Grid. 2020; 12: 2663-2674Google Scholar Second, DERs are coordinated as a group relative to the rest of the system, rather than relative to one another.16Li R. Wu Q. Oren S.S. Closure to discussion on “distribution locational marginal pricing for optimal electric vehicle charging management.IEEE Trans. Power Syst. 2014; 29: 1867Google Scholar This is a problem for distribution networks with significant numbers of DERs, since desirable control actions for a particular DER will depend heavily on how other DER owners respond to the price signals they receive. The second category is direct dispatch. We use this term to encompass strategies whereby prosumers submit bids or DER capability information to a central coordinator, which calculates DER schedules and payments for each prosumer, to provide high levels of controllability.17Cornélusse B. Savelli I. Paoletti S. Giannitrapani A. Vicino A. A community microgrid architecture with an internal local market.Appl. Energy. 2019; : 547-560Google Scholar,18Mathieu J.L. Kamgarpour M. Lygeros J. Andersson G. Callaway D.S. Arbitraging intraday wholesale energy market prices with aggregations of thermostatic loads.IEEE Trans. Power Syst. 2015; 30: 763-772Google Scholar Direct dispatch can be used by distribution system operators (DSOs) to create local market platforms for trading energy and flexibility,19Nguyen D.T. Negnevitsky M. de Groot M. Pool-based demand response exchange—concept and modeling.IEEE Trans. Power Syst. 2011; 26: 1677-1685Google Scholar or by VPP aggregators to manage fleets of DERs.20Nikonowicz Ł.B. Milewski J. Virtual Power Plants - general review: structure, application and optimization.J. Power Technol. 2012; 92: 135-149Google Scholar Solving an optimal power flow problem incorporating DER characteristics and network constraints also provides locational prices, which satisfy allocative efficiency, meaning that resources are allocated up to the point at which the marginal benefit of consumption is equal to the marginal cost of generation and transmission.21Bose S. Low S.H. Some emerging challenges in electricity markets.in: Annaswamy A. Stoustrup J. Qu Z. Chakrabortty A. Smart Grid Control: Overview and Research Opportunities. Springer, 2019: 29-45Google Scholar Alternative pricing arrangements have also been proposed, for example, based on fairness criteria22Zarabie A.K. Das S. Nazif Faqiry M. Fairness-regularized DLMP-based bilevel transactive energy mechanism in distribution systems.IEEE Trans. Smart Grid. 2019; 10: 6029-6040Google Scholar or to prevent strategic bidding by prosumer coalitions.23Han L. Morstyn T. McCulloch M. Incentivizing prosumer coalitions with energy management using cooperative game theory.IEEE Trans. Power Syst. 2019; 34: 303-313Google Scholar Although direct dispatch has important theoretical advantages, there are a number of challenges for implementation, due to the reliance on a central coordinator. Prosumers need to trust that the central coordinator will operate fairly, despite limited transparency and competition. Computational scalability and privacy are also of concern.24Good N. Ellis K.A. Mancarella P. Review and classification of barriers and enablers of demand response in the smart grid.Renew. Sustain. Energy Rev. 2017; 72: 57-72Google Scholar Distributed optimization strategies have been proposed to help address these issues,25Kraning M. Chu E. Lavaei J. Boyd S. Dynamic network energy management via proximal message passing.Found. Trends Optim. 2014; 1: 70-122Google Scholar but they introduce significant communication overhead, and although these mechanisms resemble a competitive auction, convergence requires that prosumers act cooperatively, rather than purely pursuing their own individual objectives.26Boyd S. Parikh N. Chu E. Peleato B. Eckstein J. Distributed optimization and statistical learning via the alternating direction method of multipliers.Found. Trends Mach. Learn. 2011; 3: 1-122Google Scholar The third category is P2P energy trading, which has been gaining significant academic and industry interest as an alternative market design whereby prosumers negotiate directly with one another.27Sousa T. Soares T. Pinson P. Moret F. Baroche T. Sorin E. Peer-to-peer and community-based markets: a comprehensive review.Renew. Sustain. Energy Rev. 2019; 104: 367-378Google Scholar Compared with more centralized approaches, P2P energy trading offers advantages for computational scalability since prosumers retain control over their DERs and negotiate based on individual decision-making.28Morstyn T. Teytelboym A. Mcculloch M.D. Bilateral contract networks for peer-to-peer energy trading.IEEE Trans. Smart Grid. 2019; 10: 2026-2035Google Scholar This reduces processing and communications infrastructure requirements and provides greater privacy. Prosumers also have autonomy and can fulfill personal preferences and DER requirements, which might otherwise be difficult to communicate to an intermediary.29Morstyn T. McCulloch M.D. Multiclass energy management for peer-to-peer energy trading driven by prosumer preferences.IEEE Trans. Power Syst. 2019; 34: 4005-4014Google Scholar This is particularly relevant for prosumers with DERs that have a direct impact on their daily lives and comfort, such as electric vehicles and smart heating. Moreover, by providing transparent negotiation protocols by which small- and medium-scale buyers and sellers can reach agreement on mutually acceptable transactions and prices, P2P energy trading can enable greater participation and engagement, thereby increasing market competitiveness.30Morstyn T. McCulloch M.D. Peer-to-peer energy trading.in: Shorten R. Naoum-Sawaya J. Crisostomi E. Häusler F. Ghaddar B. Russo G. Analytics for the Sharing Economy: Mathematics, Engineering and Business Perspectives. Springer International Publishing, 2020: 279-300Google Scholar There is, however, unrealized potential for P2P energy trading to create economic, environmental, and social value if integrated into power system planning and operation across spatial and temporal scales. Early research and trials have focused on P2P energy trading within local distribution networks, but it has been recognized that there are significant unresolved challenges for scaling out P2P energy trading across power systems. In particular, P2P energy trading relies on bilateral negotiation and prosumer-level decisions, making it challenging to (1) enforce network constraints that depend non-linearly on the collective operation of distributed resources,31Kim J. Dvorkin Y. A P2P-dominant distribution system Architecture.IEEE Trans. Power Syst. 2020; 35: 2716-2725Google Scholar (2) manage aggregated uncertainty without excessive conservativeness,32Morstyn T. Teytelboym A. Hepburn C. McCulloch M.D. Integrating P2P energy trading with probabilistic distribution locational marginal pricing.IEEE Trans. Smart Grid. 2020; 11: 3095-3106Google Scholar and (3) mediate conflicting requirements between the transmission and distribution levels of the power system.33Hadush S.Y. Meeus L. DSO-TSO cooperation issues and solutions for distribution grid congestion management.Energy Policy. 2018; 120: 610-621Google Scholar In addition, a major source of unrealized value is the opportunity for P2P energy trading platforms to reduce generation, transmission, and distribution infrastructure requirements. Realizing the full value that P2P energy trading platforms can offer will require new scalable mechanisms for integrating them into how power systems are designed, how investment decisions are made, and how local flexibility is utilized during operation. In this perspective, we propose a novel multiscale design framework to integrate P2P energy trading as a fundamental component of how power systems are planned and operated. The proposed framework introduces new inter-platform coordination mechanisms to manage the interactions between P2P energy trading platforms and other markets where energy and flexibility are traded at different scales, as well as new analytical tools to improve the efficiency of long-term network planning and investment decisions by integrating the forecast operation of P2P energy trading platforms. This provides a new approach that addresses the unresolved challenges identified for the system-wide scale out of P2P energy trading. The proposed design framework offers new opportunities for value to be created across spatial scales (from local distribution to national transmission) and temporal scales (from seconds-ahead flexibility to years-ahead network planning). The perspective concludes with promising directions for future interdisciplinary research combining power systems engineering, economics, computer science, and social science. We focus specifically on electrical power systems, but the proposed framework could also be relevant for other energy carriers and multicarrier energy systems. Many academic studies and industry demonstrations of P2P energy trading have focused on the value offered in terms of bill savings for prosumers when trading energy at retail metering timescales (e.g., half-hourly intervals) within a single low-voltage distribution network.34Tushar W. Yuen C. Saha T.K. Morstyn T. Chapman A.C. Alam M.J.E. Hanif S. Poor H.V. Peer-to-peer energy systems for connected communities: a review of recent advances and emerging challenges.Appl. Energy. 2021; 282: 116131Google Scholar This is a reasonable first step for investigating P2P energy trading while it is restricted to small-scale trials. However, there are four main reasons this narrow focus neglects important additional sources of potential value. First, since P2P energy trading influences how prosumers manage their flexible resources, it can create value (as well as costs) for other power system stakeholders, including system operators, generators, retail suppliers, and non-participating consumers. Understanding the impact on other stakeholders is critical for business model development and regulatory reform.35Brown D. Hall S. Davis M.E. Prosumers in the post subsidy era: an exploration of new prosumer business models in the UK.Energy Policy. 2019; 135: 110984Google Scholar Second, depending on how P2P energy trading platforms are designed and used, they could create environmental and social value in addition to economic value.29Morstyn T. McCulloch M.D. Multiclass energy management for peer-to-peer energy trading driven by prosumer preferences.IEEE Trans. Power Syst. 2019; 34: 4005-4014Google Scholar Third, considering trading only within a single distribution network restricts consideration of how a large number of local P2P energy trading platforms could be coordinated to make substantial contributions to overall system operation.36Guerrero J. Gebbran D. Mhanna S. Chapman A.C. Verbič G. Towards a transactive energy system for integration of distributed energy resources: home energy management, distributed optimal power flow, and peer-to-peer energy trading.Renew. Sustain. Energy Rev. 2020; 132: 110000Google Scholar Finally, trading at retail metering timescales excludes the value that P2P energy trading platforms could offer for coordinating faster timescale flexibility services, as well as the longer term value created by deferring or avoiding infrastructure upgrades.37Ochoa L.N. Pilo F. Keane A. Cuffe P. Pisano G. Embracing an adaptable, flexible posture: ensuring that future European distribution networks are ready for more active roles.IEEE Power Energy Mag. 2016; 14: 16-28Google Scholar Figure 1 presents an overview of different categories of value that could be created by P2P energy trading and an indicative mapping of these to the required scales of integration. These categories are discussed in the following sections. P2P energy trading platforms could be used to enable the bottom-up formation of federated arrangements between coalitions of prosumers to cooperatively provide local power balancing for microgrid formation, or upstream flexibility services.38Morstyn T. Farrell N. Darby S.J. McCulloch M.D. Using peer-to-peer energy-trading platforms to incentivize prosumers to form federated power plants.Nat. Energy. 2018; 3: 94-101Google Scholar By enabling individual prosumer preferences and capabilities to be accounted for, this could provide a more flexible and technologically neutral alternative to top-down arrangements from individual aggregators. Matching flexible demand to local renewable generation can alleviate the need for DSOs to directly curtail renewable exports.32Morstyn T. Teytelboym A. Hepburn C. McCulloch M.D. Integrating P2P energy trading with probabilistic distribution locational marginal pricing.IEEE Trans. Smart Grid. 2020; 11: 3095-3106Google Scholar Matching generation and demand within local distribution networks can reduce upstream power flows and losses.39Baroche T. Pinson P. Latimier R.L.G. Ahmed H. Ben Exogenous approach to grid cost allocation in peer-to-peer electricity markets.IEEE Trans. Power Syst. 2018; 34: 2553-2564Google Scholar P2P energy trading can improve the business case for local clean energy projects, and thereby create jobs and lower energy costs within communities. In addition, prosumers can express personal preferences, such as prioritizing energy from local renewable sources or offering energy at reduced rates to organizations and businesses within their community.40Goett A. Hudson K. Train K. Customers’ choice among retail energy suppliers: the willingness-to-pay for service attributes.Energy J. 2000; 21: 1-28Google Scholar P2P energy trading can help identify households that face energy poverty by increasing data visibility, and enable direct philanthropy by individuals, as well as assistance by government and community organizations.29Morstyn T. McCulloch M.D. Multiclass energy management for peer-to-peer energy trading driven by prosumer preferences.IEEE Trans. Power Syst. 2019; 34: 4005-4014Google Scholar Longer-term support arrangements may provide greater economic stability. P2P energy trading can improve the utilization and business case for prosumer-owned DERs and satisfy individual preferences for autonomy and privacy.41Neves D. Scott I. Silva C.A. Peer-to-peer energy trading potential: an assessment for the residential sector under different technology and tariff availabilities.Energy. 2020; 205: 118023Google Scholar In addition to power system decarbonization, DER adoption is critical for the decarbonization of transportation and heating42Morvaj B. Evins R. Carmeliet J. Decarbonizing the electricity grid: the impact on urban energy systems, distribution grids and district heating potential.Appl. Energy. 2017; 191: 125-140Google Scholar and improving air quality in cities.43Tessum C.W. Hill J.D. Marshall J.D. Life cycle air quality impacts of conventional and alternative light-duty transportation in the United States.Proc. Natl. Acad. Sci. 2014; 111: 18490-18495Google Scholar By enabling local energy matching, P2P energy trading can reduce upstream congestion, which can help defer distribution line and transformer upgrades. P2P energy trading can also enhance active measures used to manage distribution network constraints. For example, prosumers who sell flexibility services to their DSO could hedge their risk of non-delivery by buying energy flexibility contracts from peers.44Zhang Z. Li R. Li F. A novel peer-to-peer local electricity market for joint trading of energy and uncertainty.IEEE Trans. Smart Grid. 2020; 11: 1205-1215Google Scholar Alternatively, in networks where the DSO imposes capacity constraints on individual prosumers, they could trade unused capacity to constrained peers, which would improve economic efficiency.45Tushar W. Saha T.K. Yuen C. Smith D. Ashworth P. Poor H.V. Basnet S. Challenges and prospects for negawatt trading in light of recent technological developments.Nat. Energy. 2020; 5: 834-841Google Scholar Once a significant number of prosumers are operating within local P2P energy trading platforms, there is an opportunity to coordinate these platforms to defer the need for new generation plants and transmission lines.46Tushar W. Saha T.K. Yuen C. Morstyn T. Nahid-Al-Masood Poor H.V. Bean R. Grid influenced peer-to-peer energy trading.IEEE Trans. Smart Grid. 2019; 11: 1407-1418Google Scholar However, this requires mechanisms for integrating the operation of local P2P energy trading platforms into system-level markets for energy and flexibility, and requires transmission system operators (TSOs) to account for this when making long-term investment decisions. Despite significant industry interest and venture capital investment, P2P energy trading has been limited to small-scale trials, preventing much of the potential value from being realized.47Jason Deign Peer-to-Peer Energy Trading Still Looks like a Distant Prospect. Greentech Media, 2019Google Scholar Three major unresolved challenges can be identified for integrating P2P energy trading platforms into power systems at scale. First is the challenge of enforcing network constraints through bilateral negotiation. This is difficult without a central coordinator, since power flows and voltages depend non-linearly on the collective operation of prosumers. The large-scale adoption of DERs will make actively managing their impact on network constraints increasingly important.48Schermeyer H. Vergara C. Fichtner W. Renewable energy curtailment: a case study on today’s and tomorrow’s congestion management.Energy Policy. 2018; 112: 427-436Google Scholar,49Crozier C. Morstyn T. McCulloch M. The opportunity for smart charging to mitigate the impact of electric vehicles on transmission and distribution systems.Appl. Energy. 2020; 268: 114973Google Scholar Compared with transmission networks, distribution networks are more complex, since they connect thousands of individual consumers and have more non-linear characteristics due to reactive power flows and unbalanced lines.50Bazrafshan M. Gatsis N. Comprehensive modeling of three-phase distribution systems via the bus admittance matrix.IEEE Trans. Power Syst. 2018; 33: 2015-2029Google Scholar One approach is for P2P energy trading platforms to ignore network constraints, but then for the DSO to resolve constraint violations by actively procuring flexibility through a separate local flexibility market.51Morstyn T. Teytelboym A. McCulloch M.D. Designing decentralized markets for distribution system flexibility.IEEE Trans. Power Syst. 2019; 34: 2128-2139Google Scholar However, this is inefficient and could create opportunities for strategic gaming if prosumers can trade in both the P2P energy market and the local flexibility market. Another approach is for the DSO to be introduced as a central authority to check the outcomes of P2P negotiation.31Kim J. Dvorkin Y. A P2P-dominant distribution system Architecture.IEEE Trans. Power Syst. 2020; 35: 2716-2725Google Scholar,52Guerrero J. Chapman A.C. Verbic G. Decentralized P2P energy trading under network constraints in a low-voltage network.IEEE Trans. Smart Grid. 2018; : 1-10Google Scholar If a constraint violation is identified, transactions leading to the violation would be blocked and the prosumers directed to renegotiate. However, this approach may require many iterations to converge and counteracts the advantages of P2P energy trading in terms of scalability and market transparency. The second challenge is the difficulty of managing uncertainty within P2P energy trading platforms. These can be separated into internal sources of uncertainty, which are associated with participants, and external sources, which concern the interface between the platform and the wider power system. Internal sources of uncertainty include the weather dependence of renewable generation and the behavior dependence of flexible loads. Since there is always a delay between the negotiation of transactions and real-time operation, the actual load and generation of prosumers will not perfectly match market outcomes. Forcing prosumers to individually hedge against uncertainty will lead to overly conservative operation, due to the limited accuracy of individual level forecasting53Sevlian R.A. Rajagopal R. A model for the effect of aggregation on short term load forecasting.in: 2014 IEEE PES General Meeting | Conference & Exposition. IEEE, 2014: 1-5Google Scholar and the lack of aggregation with other uncorrelated sources of uncertainty.54Elombo A.I. Morstyn T. Apostolopoulou D. McCulloch M.D. Residential load variability and diversity at different sampling time and aggregation scales.in: 2017 IEEE AFRICON Sci. Technol. Innov. Africa, AFRICON 2017. IEEE, 2017: 1331-1336Google Scholar External sources of uncertainty include upstream energy prices and network congestion.55Ji Y. Thomas R.J. Tong L. Probabilistic forecasting of real-time LMP and network congestion.IEEE Trans. Power Syst. 2017; 32: 831-841Google Scholar These are introduced because of the decoupling between local P2P energy trading platforms and other coordination mechanisms, including system-level markets, as