Cited by 96Electric Vehicles and InfrastructureSmart Grid Energy ManagementOptimal Power Flow Distribution

Distributed Coordination of Charging Stations Considering Aggregate EV Power Flexibility

Open access
Yan, Dongxiang, Ma, Chengbin, Chen, Yue·2023·IEEE Transactions on Sustainable Energy

Abstract

In recent years, electric vehicle (EV) charging stations have witnessed rapid growth. However, effective management of charging stations is challenging due to individual EV owners' privacy concerns, competing interests of different stations, and the coupling distribution network constraints. To cope with this challenge, this paper proposes a two-stage scheme. In the first stage, the aggregate EV power flexibility region is derived by solving an optimization problem. We prove that any trajectory within the obtained region corresponds to at least one feasible EV dispatch strategy. By submitting this flexibility region instead of the detailed EV data to the charging station operator, EV owners' privacy can be preserved and the computational burden can be reduced. In the second stage, a distributed coordination mechanism with a clear physical interpretation is developed considering the AC power flow based network constraints. We prove that the proposed mechanism converges to the centralized optimum. Case studies validate the theoretical results. Comprehensive performance comparisons are carried out to demonstrate the advantages of the proposed scheme.

AI snapshot

Written from the paper’s full text.

TL;DR

The paper proposes a two-stage scheme for coordinating EV charging stations: first deriving an aggregate EV power flexibility region that preserves EV owner privacy, then using a distributed coordination mechanism with AC power flow constraints. It proves the mechanism converges to the centralized optimum and reports lower costs, reduced power losses, and improved battery storage utilization in case studies.

Key findings

  • The aggregate EV power flexibility region is approximated by lower and upper power trajectories, and Proposition 1 proves that any trajectory within the region corresponds to at least one feasible EV dispatch strategy.
  • The distributed coordination mechanism is guaranteed to converge to the centralized optimum (Proposition 2), reaching convergence in about 42 iterations in the simulation.
  • Compared with the conventional uniform-price baseline, the proposed mechanism reduces charging-station total cost from 293.36 USD to 212.00 USD (27.73%), DSO cost from 547.89 USD to 517.86 USD, and overall system total cost from 841.24 USD to 729.87 USD (13.24%).
  • The proposed method reduces power losses, promotes local energy transactions, and greatly improves battery storage utilization; scalability tests show CSO and DSO computational times remain about 7 s and 150 s as the number of charging stations increases from 4 to 20.

Methods

  • Two-stage optimization: Stage 1 solves an optimization problem to approximate each charging station’s aggregate EV power flexibility region; Stage 2 uses a distributed iterative coordination mechanism between charging station operators and the DSO, with locational energy trading prices accounting for power losses and AC power flow constraints.
  • Simulation setup: modified IEEE 33-bus test system with four charging stations (CS1–CS4) equipped with PV and batteries, a 24-hour horizon with 1-hour slots, and specified EV, battery, charger, and network parameters.
  • Analysis: case studies validate Propositions 1 and 2, check second-order conic relaxation exactness, compare costs and power losses against a conventional baseline, examine energy trading prices and battery SOC, and test scalability.

Limitations

  • The paper does not include an explicit limitations section.
  • Evident from the text: the aggregate EV power flexibility is an approximation (F_i ≈ ˜F_i), and the second-order conic relaxation’s exactness is stated to hold for radial distribution networks when power injections are not too large and bus voltages remain around nominal values.
  • Evident from the text: privacy protection is described as preserved “to some extent,” and the numerical validation is limited to a modified IEEE 33-bus system with four charging stations and specific parameter settings.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1109/tste.2022.3213173

Cites

45 of 45 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

3 of 9 cited sources checked · 0 supported · 0 flagged · accuracy not yet measured

  • Premisecitation
    § I. INTRODUCTION · p. 1

    The sudden pulse-like and high charging load of charging stations strains the distribution grid because of random and relatively high EV charging power.

    “However, due to the random and relatively high EV charging power [2], the sudden pulse-like and high charging load of the charging stations strains the distribution grid [3].”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites [2] [2] Z. J. Lee, G. Lee, T. Lee, C. Jin, R. Lee, Z. Low, D. Chang, C. Ortega, and S. H. Low, 'Adaptive charging networks: A framework for smart electric vehicle charging,' IEEE Transactions on Smart Grid , vol. 12, no. 5, pp. 4339-4350, 2021. - source

      The Abstract (page unavailable) says limited infrastructure capacity prevents many sites from installing more than a few charging ports, and §C, “Energy Delivery With Constrained Infrastructure” (page unavailable), describes congestion at an oversubscribed transformer. These passages support a concern about charging loads straining local infrastructure, but they do not establish that sudden, pulse-like station loads strain the wider distribution grid. The sentence cites a different source for random and relatively high EV charging power. (LLM, conf=0.83)

      Experimental — accuracy not yet measured
    • cites [3] [3] K. Clement-Nyns, E. Haesen, and J. Driesen, 'The impact of charging plug-in hybrid electric vehicles on a residential distribution grid,' IEEE Trans. Pow. Syst. , vol. 25, no. 1, pp. 371-380, 2010. - source

      Section VI, “Impact on the Distribution Grid” (page unavailable), says uncoordinated PHEV charging increases loads and voltage drops and affects grid performance. But “Charging Periods” (page unavailable) focuses on charging at home on residential grids; the copy does not establish a sudden, pulse-like load from charging stations. The separate statement about random and relatively high EV charging power is attached to [2], not this source. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
  • Premisecitation
    § 3: repeat · p. 6

    The exactness of the second-order conic relaxation has been verified for the radial distribution network when the power injection at each bus is not too large, and the bus voltage maintains around the nominal value.

    “The exactness of relaxation has been verified for the radial distribution network [30] when the power injection at each bus is not too large, and the bus voltage maintains around the nominal value.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [30] [30] M. Farivar and S. H. Low, 'Branch flow model: Relaxations and convexification-Part I,' IEEE Trans. Pow. Syst. , vol. 28, no. 3, pp. 25542564, 2013. - source

      The Summary states that the conic relaxation is exact for radial networks, but gives a different condition: no upper bounds on real and reactive loads. The cited paper does not establish exactness specifically when each bus’s power injection is not too large and voltage stays near nominal; its Extensions section instead discusses other sufficient conditions involving load and voltage bounds. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
  • Findingnone given
    § I. INTRODUCTION · p. 2

    Compared with the traditional method, the proposed method greatly improves the utilization of battery storage in charging stations.

    “Compared with the traditional method, the proposed method can achieve significant total cost savings, reduce power losses, and greatly improve the utilization of battery storage in charging stations.”
    Quote in the paperSubstantial claim
  • Findingnone given
    § I. INTRODUCTION · p. 2

    Compared with the traditional method, the proposed method reduces power losses.

    “Compared with the traditional method, the proposed method can achieve significant total cost savings, reduce power losses, and greatly improve the utilization of battery storage in charging stations.”
    Quote in the paperSubstantial claim
  • Findingown data
    § Distributed Coordination of Charging Stations Considering Aggregate EV Power Flexibility · p. 1

    Case studies validate the theoretical results.

    “Case studies validate the theoretical results.”
    Quote in the paperNot a substantial claim
  • May combine two claims. 15
  • Classified as probably not a substantial claim. 8
  • May combine two claims.

    Findingown data
    § B. Aggregate EV Power Flexibility · p. 7

    Within the aggregate power flexibility area, any power trajectory is dispatchable and can satisfy the EVs' charging requirements.

    “Within this area, any power trajectory is dispatchable and can satisfy the EVs' charging requirements.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim.

    Findingnone given
    § B. Aggregate EV Power Flexibility · p. 7

    The area between the upper and lower power trajectories is the aggregate power flexibility that is available to dispatch by charging stations in the second stage.

    “The area between the upper and lower power trajectories is the aggregate power flexibility that is available to dispatch by charging stations in the second stage.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data
    § D. Performance Evaluation · p. 8

    The proposed mechanism achieves a total cost of 212 USD for charging stations, compared with 293.36 USD for the baseline, a reduction of 27.73%.

    “The proposed mechanism (212 USD) performs better than the baseline (293.36 USD) with a significant total cost reduction (27.73%).”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data
    § D. Performance Evaluation · p. 9

    Under the proposed mechanism, the battery SOCs of the four charging stations vary in the same trend and experience a complete charging and discharging cycle.

    “while under the proposed mechanism, the battery SOCs of the four charging stations vary in the same trend and experience a complete charging and discharging cycle.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning
    § A. Proof of Proposition 1 · p. 11

    The constructed EV dispatch strategy is feasible and satisfies the EV charging constraints.

    “We prove that it is a feasible EV dispatch strategy as follows.”
    • Also stated in: § A. Proof of Proposition 1 · p. 11 · boosted
      “Therefore, we have constructed a feasible EV dispatch strategy, which completes the proof.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data
    § D. Performance Evaluation · p. 8

    In the circled area covering the charging stations and bus 1, the proposed method generates much thinner lines than the baseline, indicating less power loss in these lines.

    “In the circled area covering the charging stations and bus 1, the proposed method (Fig. 10 (a)) generates much thinner lines than the baseline (Fig. 10 (b)). This indicates less power loss in these lines”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S1 (asserted), S2 (checkable), S4 (based).

    Premisenone given
    § I. INTRODUCTION · p. 2

    How to characterize the maximal potential power flexibility of EVs in a charging station remains to be investigated.

    “Despite the above efforts, how to characterize the maximal potential power flexibility of EVs in a charging station remains to be investigated.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given
    § I. INTRODUCTION · p. 1

    Existing studies on energy trading mechanisms mainly focus on the design of the mechanism without consideration of distribution network constraints.

    “However, the above studies mainly focus on the design of energy trading mechanism without consideration of distribution network constraints.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning
    § D. Distributed Coordination Mechanism · p. 6

    The private data of individual charging stations and the network parameters owned by the DSO are well protected.

    “Therefore, the private data of individual charging stations and the network parameters owned by the DSO are well protected.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisereasoning
    § B. Energy Trading with Other Charging Stations/Utility Grid · p. 4

    Power transmissions in the distribution network result in power losses, so giving charging stations the same price is unfair and the DSO may need to pay for the power losses.

    “However, since the charging stations are located at different buses and the power transmissions in distribution network result in power losses, giving them the same price is unfair. Also in that case, the DSO may need to pay for the power losses.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisecitation
    § A. Modelling of Charging Station · p. 4

    The charging power dispatched by the charging station may be less than the upper boundary, which may lead to dissatisfaction of EVs or decrease their utility.

    “The charging power dispatched by the charging station may be less than the upper boundary, which may lead to dissatisfaction of EVs or decrease their utility [9].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [9] [9] N. Liu, X. Yu, C. Wang, and J. Wang, 'Energy sharing management for microgrids with PV prosumers: A stackelberg game approach,' IEEE Trans. Ind. Informat. , vol. 13, no. 3, pp. 1088-1098, Jun. 2017. - source
  • Classified as probably not a substantial claim.

    Premisenone given
    § I. INTRODUCTION · p. 2

    EV charging stations have constraints distinct from other resources, such as the limitation due to a finite number of chargers.

    “In particular, EV charging stations has some constraints distinct from other resources, such as the limitation due to a finite number of chargers.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisecitation
    § I. INTRODUCTION · p. 2

    Centralized methods for EV charging scheduling require the charging station to know the data of all EVs, which may violate the privacy of EV owners.

    “However, the above methods require the charging station to know the data of all EVs, which may violate the privacy of EV owners.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [24] [24] Q. Yan, B. Zhang, and M. Kezunovic, 'Optimized operational cost reduction for an EV charging station integrated with battery energy storage and PV generation,' IEEE Trans. Smart Grid , vol. 10, no. 2, pp. 2096-2106, Mar. 2019. -

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [25] [25] J. Qi, C. Lai, B. Xu, Y. Sun, and K.-S. Leung, 'Collaborative energy management optimization toward a green energy local area network,' IEEE Trans. Ind. Informat. , vol. 14, no. 12, pp. 5410-5418, 2018. - source
  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given
    § D. Distributed Coordination Mechanism · p. 6

    The data exchanged between the charging stations and the DSO consists solely of the energy trading schedule/profile and the trading prices.

    “The data exchanged between the charging stations and the DSO consists solely of the energy trading schedule/profile and the trading prices.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Premisecitation
    § I. INTRODUCTION · p. 1

    Various techniques such as intermittent renewable generation and distributed energy storage in the charging station and distribution network further complicate the operation of charging stations and threaten power system reliability.

    “Meanwhile, various techniques, such as intermittent renewable generation and distributed energy storage, begin to appear in the charging station and distribution network [4]. This further complicates the operation of charging stations and threatens the power system reliability.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [4] [4] K. Chaudhari, A. Ukil, K. N. Kumar, U. Manandhar, and S. K. Kollimalla, 'Hybrid optimization for economic deployment of ESS in PV-integrated EV charging stations,' IEEE Trans. Ind. Informat. , vol. 14, no. 1, pp. 106-116, Jan. 2018. - source
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationreasoning
    § D. Performance Evaluation · p. 8

    The trading prices of the four charging stations follow the same trend because they are located close to each other.

    “This is because they are located close to each other.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationown data
    § D. Performance Evaluation · p. 8

    The proposed mechanism benefits both the charging stations and the distribution network by reducing power losses and costs, resulting in a win-win situation.

    “In conclusion, the proposed mechanism can not only benefit the charging stations, but also the distribution network by reducing power losses and costs, resulting in a win-win situation.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationown data
    § B. Aggregate EV Power Flexibility · p. 8

    The convergence speed of the proposed distributed coordination mechanism is fast and acceptable.

    “It can be found that the number of iterations to reach convergence is about 42, which indicates that the convergence speed is fast and acceptable.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given
    § D. Performance Evaluation · p. 8

    Less power loss in these lines is beneficial to prolong the service life of transmission lines.

    “which is beneficial to prolong the service life of transmission lines.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationown data
    § D. Performance Evaluation · p. 8

    The proposed coordination mechanism can promote local transactions and reduce the power loss of the distribution network.

    “It can be concluded that the proposed coordination mechanism can promote local transactions and reduce the power loss of the distribution network.”
    • Also stated in: § VI. CONCLUSION · p. 10 · plain
      “The energy sharing of charging stations affects the local power flow of the distribution network and results in a lower power loss.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationnone given
    § VI. CONCLUSION · p. 10

    Using an aggregate EV power flexibility region instead of complete information about EVs can protect EV owners' privacy and be much easier for the charging station to dispatch.

    “In contrast to the existing approaches that assume the charging station has complete information about the EVs, we use an aggregate EV power flexibility region instead. This can protect EV owners' privacy and be much easier for the charging station to dispatch.”
    Quote in the paperSubstantial claim
21 of 21
  • The authors state this as an assumption.

    The DSO will help coordinate energy trading by announcing an energy trading price to each charging station that accounts for grid buying/selling prices, distance from the utility grid, and other charging stations.

    “To facilitate the energy trading, here we assume that the DSO will help to coordinate the trading by announcing an energy trading price λ p,i ( t ) to each charging station that takes into account multiple factors such as the grid buying/selling prices, the distance from the utility grid and other charging stations, etc.”
  • The authors state this as an assumption.

    Each charging station is equipped with renewables such as PV panels.

    “In addition, each charging station is assumed to be equipped with renewables such as PV panels for reducing the energy bought from the grid.”
  • The authors state this as an assumption.

    The utility electricity sale price is less than the utility electricity buy price.

    “Further, they should meet the requirement λ s g ( t ) < λ b g ( t ) to ensure that the distribution network won't arbitrage by buying from and selling back to the utility at the same time.”
  • The paper relies on this without support.

    The DSO is in charge of distribution network management and will regulate energy transactions among charging stations.

    “Generally, the DSO is in charge of the distribution network management and will regulate the energy transactions among charging stations.”
  • The paper relies on this without support.

    EV owners are not willing to reveal their private information to the CSO, distribution network constraints are only available to the DSO, and the DSO does not know the batteries and PV generations in the charging stations.

    “The EV owners are not willing to reveal their private information (such as the charging needs) to the CSO; the distribution network constraints is only available to DSO; the DSO does not know the batteries and PV generations in the charging stations.”
  • The paper relies on this without support.

    Both charging and discharging cause battery degradation.

    “Both charging and discharging can cause battery degradation and the degradation cost is described by:”
  • The paper relies on this without support.

    The charging station operator has some flexibility in charging EVs instead of a fixed load curve.

    “Instead of a fixed load curve, the charging station operator has some flexibility in charging the EVs.”
  • The paper relies on this without support.

    The number of EVs charging at a charging station reflects how busy the station is.

    “In general, the number of EVs charging at a charging station reflects how busy the station is.”
8 of 8

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Most mentioned studies overlook the potential benefits of an integrated DER environment, such as DERMS, where EVs could operate in coordination with other DERs to enhance overall grid stability and flexibility.

    “Second, most studies overlook the potential benefits of an integrated DER environment, such as DERMS, where EVs could operate in coordination with other DERs to enhance overall grid stability and flexibility.”

    From Improving distribution system flexibility using electric vehicles under the distributed energy resource management system framework (2026) · cites this paper as [10]

    The Introduction (p. 1) says some earlier energy-trading studies did not consider distribution-network constraints, and the Overview (p. 2) describes coordinating EVs with PV and battery storage for reliable operation. The Conclusion (p. 10) reports lower power loss from the proposed coordination scheme. But the paper does not establish that most studies overlook integrated DER coordination or discuss DERMS specifically. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

Cites

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Authors
Yan, D., Ma, C., & Chen, Y.
Affiliations
  • Chinese University of Hong Kong (HK)
  • Shanghai Jiao Tong University (CN)
Venue
IEEE Transactions on Sustainable Energy
Published
2023-01
Volume
14
Issue
1
Pages
356-370
ISSN
  • 1949-3029 (ISSN-L)
  • 1949-3037
OpenAlex
W4313536130
Cited by
96
References
36
Citations by year
2026: 27 · 2025: 34 · 2024: 25 · 2023: 9 · 2022: 1
FWCI
4.62
Type
journal article
Language
en
Open access
Locations
  • IEEE Transactions on Sustainable Energy (publishedVersion)
  • arXiv (Cornell University) (submittedVersion, cc-by-nc-nd)
  • arXiv (Cornell University)
Funders
Chinese University of Hong Kong Direct Grant for Research (4055169)
Topics
  • Physical Sciences › Engineering › Electrical and Electronic Engineering › Electric Vehicles and Infrastructure
  • Physical Sciences › Engineering › Electrical and Electronic Engineering › Smart Grid Energy Management
  • Physical Sciences › Engineering › Electrical and Electronic Engineering › Optimal Power Flow Distribution
Keywords
electric vehicle charging stations, distributed coordination, privacy preservation, AC power flow constraints, distribution network constraints, two-stage optimization

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