10
1949-3029 (c) 2018 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TSTE.2019.2895387, IEEE Transactions on Sustainable Energy 1 An Incentive-compatible Energy Trading Framework for Neighborhood Area Networks with Shared Energy Storage Chathurika P. Mediwaththe, Member, IEEE, Marnie Shaw, Saman Halgamuge, Fellow, IEEE, David B. Smith, Member, IEEE, and Paul Scott Abstract—Here, a novel energy trading system is proposed for demand-side management of a neighborhood area network (NAN) consisting of a shared energy storage (SES) provider, users with non-dispatchable energy generation, and an electricity retailer. In a leader-follower Stackelberg game, the SES provider first maximizes their revenue by setting a price signal and trading energy with the grid. Then, by following the SES provider’s actions, the retailer minimizes social cost for the users, i.e., the sum of the total users’ cost when they interact with the SES and the total cost for supplying grid energy to the users. A pricing strategy, which incorporates mechanism design, is proposed to make the system incentive-compatible by rewarding users who disclose true energy usage information. A unique Stackelberg equilibrium is achieved where the SES provider’s revenue is maximized and the user-level social cost is minimized, which also rewards the retailer. A case study with realistic energy demand and generation data demonstrates 28% - 45% peak demand reduction of the NAN, depending on the number of participating users, compared to a system without SES. Simulation results confirm that the retailer can also benefit financially, in addition to the SES provider and the users. Index Terms—Demand-side management, game theory, mech- anism design, neighborhood area network, non-dispatchable energy generation, shared energy storage. I. I NTRODUCTION Electricity demand-side management with distributed en- ergy resources helps accommodate peak electricity demand without the need for upgrading conventional power grid in- frastructure. In particular, shared energy storage (SES) systems such as community energy storages [1] can be effectively used to exploit user-owned non-dispatchable energy generation, for example, rooftop solar or wind energy generation, to regulate users’ peak electricity demand. With this capability, SESs would enable electricity retailers to effectively serve the energy needs of neighborhood area networks (NANs) that consist of small groups of residential buildings, for example, 50 house- holds. In addition, SESs can facilitate user-centric demand- side management solutions without end-users having to invest in personal energy storage devices. Increasing interest in SES systems has led to a range of projects worldwide exploring C. P. Mediwaththe, M. Shaw, S. Halgamuge, and P. Scott are with the Australian National University, Canberra, ACT 0200, Aus- tralia. e-mail: (chathurika.mediwaththe, marnie.shaw, saman.halgamuge, [email protected]). S. Halgamuge is also with the University of Melbourne, Parkville, VIC 3010, Australia. D. B. Smith is with Data61, CSIRO, Eveleigh, NSW 2015, Australia. e- mail: ([email protected]). their feasibility for utilizing user-owned non-dispatchable en- ergy generation for demand-side management [2]. User-centric demand-side management driven by electricity retailers requires the knowledge of true energy usage informa- tion of users, including their energy demand and generation, for robust operation. However, users might intentionally misre- port private information so as to gain personal cost benefits that would challenge achieving system-wide objectives in demand- side management [3]. Hence, smart pricing strategies capable of motivating users to reveal true private information are imperative for effective demand-side management [4], [5]. In this paper, a novel energy trading system is proposed for demand-side management of a NAN that consists of an SES provider, users with non-dispatchable energy generation, and an electricity retailer. The SES is used to store surplus energy from users’ non-dispatchable generation and discharged when electricity demand is high. The energy transactions between the SES and the users as well as the energy transactions between the power grid and both the users and the SES are coordinated by the retailer. The interplay between the SES provider and the retailer is formulated as a non-cooperative Stackelberg game where the SES provider (leader) moves first to maximize revenue by setting a price signal and trading energy with the grid through the retailer. Then, by following the SES provider’s actions, the retailer (follower) minimizes social cost for the users and determines energy amounts for the users to trade with the grid and the SES. Here, the social cost is defined as the sum of the total users’ cost when they interact with the SES and the cost incurred by the retailer in supplying grid energy to the users. Insights from the Vickrey- Clarke-Groves (VCG) mechanism are applied to the retailer’s social cost minimization problem to develop a pricing strategy that can motivate users to reveal true energy usage information to the retailer. This paper has the following contributions: The Stackelberg game has a unique pure strategy equilib- rium where the SES provider maximizes revenue and the retailer minimizes the social cost of participating users. The system is incentive-compatible as participating users can only minimize their personal energy costs by reveal- ing their true energy usage information. In addition to providing financial benefits to the SES provider and the participating users, our solution also enables the retailer to benefit financially by coordinating the energy transactions between the grid and the system.

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1949-3029 (c) 2018 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.

This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TSTE.2019.2895387, IEEETransactions on Sustainable Energy

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An Incentive-compatible Energy TradingFramework for Neighborhood Area Networks with

Shared Energy StorageChathurika P. Mediwaththe, Member, IEEE, Marnie Shaw, Saman Halgamuge, Fellow, IEEE, David B.

Smith, Member, IEEE, and Paul Scott

Abstract—Here, a novel energy trading system is proposedfor demand-side management of a neighborhood area network(NAN) consisting of a shared energy storage (SES) provider,users with non-dispatchable energy generation, and an electricityretailer. In a leader-follower Stackelberg game, the SES providerfirst maximizes their revenue by setting a price signal and tradingenergy with the grid. Then, by following the SES provider’sactions, the retailer minimizes social cost for the users, i.e., thesum of the total users’ cost when they interact with the SES andthe total cost for supplying grid energy to the users. A pricingstrategy, which incorporates mechanism design, is proposed tomake the system incentive-compatible by rewarding users whodisclose true energy usage information. A unique Stackelbergequilibrium is achieved where the SES provider’s revenue ismaximized and the user-level social cost is minimized, which alsorewards the retailer. A case study with realistic energy demandand generation data demonstrates 28% - 45% peak demandreduction of the NAN, depending on the number of participatingusers, compared to a system without SES. Simulation resultsconfirm that the retailer can also benefit financially, in additionto the SES provider and the users.

Index Terms—Demand-side management, game theory, mech-anism design, neighborhood area network, non-dispatchableenergy generation, shared energy storage.

I. INTRODUCTION

Electricity demand-side management with distributed en-ergy resources helps accommodate peak electricity demandwithout the need for upgrading conventional power grid in-frastructure. In particular, shared energy storage (SES) systemssuch as community energy storages [1] can be effectively usedto exploit user-owned non-dispatchable energy generation, forexample, rooftop solar or wind energy generation, to regulateusers’ peak electricity demand. With this capability, SESswould enable electricity retailers to effectively serve the energyneeds of neighborhood area networks (NANs) that consist ofsmall groups of residential buildings, for example, 50 house-holds. In addition, SESs can facilitate user-centric demand-side management solutions without end-users having to investin personal energy storage devices. Increasing interest in SESsystems has led to a range of projects worldwide exploring

C. P. Mediwaththe, M. Shaw, S. Halgamuge, and P. Scott arewith the Australian National University, Canberra, ACT 0200, Aus-tralia. e-mail: (chathurika.mediwaththe, marnie.shaw, saman.halgamuge,[email protected]).

S. Halgamuge is also with the University of Melbourne, Parkville, VIC3010, Australia.

D. B. Smith is with Data61, CSIRO, Eveleigh, NSW 2015, Australia. e-mail: ([email protected]).

their feasibility for utilizing user-owned non-dispatchable en-ergy generation for demand-side management [2].

User-centric demand-side management driven by electricityretailers requires the knowledge of true energy usage informa-tion of users, including their energy demand and generation,for robust operation. However, users might intentionally misre-port private information so as to gain personal cost benefits thatwould challenge achieving system-wide objectives in demand-side management [3]. Hence, smart pricing strategies capableof motivating users to reveal true private information areimperative for effective demand-side management [4], [5].

In this paper, a novel energy trading system is proposed fordemand-side management of a NAN that consists of an SESprovider, users with non-dispatchable energy generation, andan electricity retailer. The SES is used to store surplus energyfrom users’ non-dispatchable generation and discharged whenelectricity demand is high. The energy transactions betweenthe SES and the users as well as the energy transactionsbetween the power grid and both the users and the SES arecoordinated by the retailer. The interplay between the SESprovider and the retailer is formulated as a non-cooperativeStackelberg game where the SES provider (leader) moves firstto maximize revenue by setting a price signal and tradingenergy with the grid through the retailer. Then, by followingthe SES provider’s actions, the retailer (follower) minimizessocial cost for the users and determines energy amounts forthe users to trade with the grid and the SES. Here, the socialcost is defined as the sum of the total users’ cost when theyinteract with the SES and the cost incurred by the retailer insupplying grid energy to the users. Insights from the Vickrey-Clarke-Groves (VCG) mechanism are applied to the retailer’ssocial cost minimization problem to develop a pricing strategythat can motivate users to reveal true energy usage informationto the retailer. This paper has the following contributions:

• The Stackelberg game has a unique pure strategy equilib-rium where the SES provider maximizes revenue and theretailer minimizes the social cost of participating users.

• The system is incentive-compatible as participating userscan only minimize their personal energy costs by reveal-ing their true energy usage information.

• In addition to providing financial benefits to the SESprovider and the participating users, our solution alsoenables the retailer to benefit financially by coordinatingthe energy transactions between the grid and the system.

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Mechanism design has been widely applied to exploredemand-side management that achieves socially desirable out-comes while ensuring incentive-compatibility for users. Forinstance, mechanism design has been utilized in [6] to developa pricing strategy that rewards users who reveal true privateinformation in a load curtailment scheme that minimizesaggregate user inconvenience due to load curtailment. In[4], mechanism design has been used to develop a demand-scheduling program that minimizes the aggregate user costand provides benefits to users who reveal true energy usageinformation. To the best of our knowledge, this paper is thefirst to leverage mechanism design with Stackelberg game the-ory to study the feasibility of integrating an SES system withuser-owned non-dispatchable energy generation for demand-side management of a NAN by minimizing social energy costand assuring incentive-compatibility for the users.

This work has three key differences to our previous work[7]. First, in contrast to allowing users to minimize personalcosts selfishly, the proposed system minimizes total users’energy costs from a social planner’s perspective. Second, theusers in the proposed system interact with the SES providerthrough the retailer as a result of minimizing the social costwhereas users in the system in [7] directly interact with theSES provider. In addition, the solution here is capable ofbenefiting the retailer for coordinating grid energy with theusers and the SES unlike the solution presented in [7].

The rest of the paper is organized as follows. SectionII presents related work, and Section III describes systemmodels of the energy trading system. Section IV explainsthe formulation of the energy trading system, and Section Vpresents simulation results. Section VI concludes the paper.

II. RELATED WORK

The concept of sharing energy storage systems for demand-side management has gained attention in both industry andresearch communities [2], [8]–[12]. For instance, sharinghousehold-distributed energy storages through joint-ownershipbetween domestic users and network operators has beenexplored in [8] to facilitate demand response. Sharing user-owned energy storages for demand response has been studiedin [10] while demonstrating an optimal policy to determinethe shareable energy storage capacity to network operators.Various algorithms based on mixed-integer linear program-ming have been proposed for optimal scheduling of electricappliances of users using SES systems [9], [11].

Mechanism design and game theory have been widelyused to investigate energy management problems, includingdemand-side management, with strategic user behavior [5],[13]–[18]. Utilizing auction mechanisms with block-chaintechnology has gained growing interest in peer-to-peer en-ergy trading markets, including energy trading among electricvehicles, to elicit true local information from users [19]. Aneconomically efficient pricing strategy for wholesale electricitymarkets is proposed in [15] using the VCG mechanism.Mechanism design has been used to develop a pricing strategyin [5] that effectively motivates users to report true energyinformation to the electricity retailer in an energy consump-tion scheduling game among users. In contrast, this paper

applies insights of mechanism design in a different demand-side management setting where users with non-dispatchableenergy generation trade energy with an SES. In the literature,combining incentive compatibility for users in social costminimization generally results in bi-level structures whereusers, at the second level, react to the decisions taken bythe social planner [4], [5], [14], [15]. However, in this paper,combining incentive compatibility for users and a Stackelberggame between the retailer and the SES provider leads to a tri-level structure where users, at the third level, implicitly reactto the decisions taken in the Stackelberg game.

III. SYSTEM MODELS

The energy trading system consists of energy users, anelectricity retailer, and an SES owned by a third-party thatprovides storage services [1], referred to as the SES provider,as depicted in Fig. 1. This section explains the role of eachentity and the energy cost models used in the system. Thedefinitions of notations in this paper are summarized in Table I.

A. Demand-side Model

The set of all users in the NAN, A, is divided into twosets, participating users P and non-participating users N .Thus, A = P ∪ N . The users P have non-dispatchableenergy generation systems, for example, rooftop solar panels,without local energy storage facilities. The users P participatein the system by trading energy with the grid and the SESthrough the electricity retailer. The retailer coordinates theenergy transactions between the grid and both the users Aand the SES in addition to the energy transactions betweenthe SES and the users P . The SES is shared among the usersP to store surplus energy from their local energy generation.The users N may have non-dispatchable energy generationsystems without storage and do not participate in the energytrading optimization framework. They are considered as thetraditional energy users of the grid. If a user in N owns alocal energy generation system, they sell the excess energygenerated directly to the grid through the retailer.

The time period T , typically one day, is divided into Hequal time steps and the control time t = 1, 2, · · · , H . Theusers P are divided into two time-dependent sets; P+(t) andP−(t). Surplus energy at user n ∈ P at time t is given by

sn(t) = gn(t)− dn(t). (1)

Electricity retailer

Non-participating users(N)

Participating users(P)

Shared energy storage provider

Energy flow

!!(!) ! !!(!)!"!

! !!(!)!"#

!!(!) !!(!)

!(!)

Power grid

Fig. 1. Configuration of the energy trading system.

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TABLE ITABLE OF NOTATION.

Variable/parameter Definition Variable/parameter Definition

A Set of all users in the NAN. P+(t) Set of surplus energy users at time t.P Set of participating users. P−(t) Set of deficit energy users at time t.N Set of non-participating users en(t) Energy traded by user n with the grid at time t.T Entire time period of analysis. sn(t) Surplus energy of user n at time t.

H Total number of time steps in T . es(t)Energy exchanged between the grid and the SES attime t.

I Total number of users in P . b(t) The charge level of the SES at the end of time t.η+, η− Charging and discharging inefficiencies of the SES. E(t) Total energy load on the grid at time t.α Leakage rate of the SES; (0 < α ≤ 1). EA(t) Total grid load of the users A at time t.QM Maximum energy capacity of the SES. EP (t) Total grid load of the users P at time t.

EmaxMaximum load that the grid can support withoutoverloading it. EN (t) Total grid load of the users N at time t.

R Revenue of the SES provider. En(t) Feasible strategy set of user n at time t.Q Feasible strategy set of the SES provider. kn(t) Payment made by user n to the retailer at time t.

G Stackelberg game between the SES provider and theretailer. Cn(t) Personal energy cost of user n at time t.

τ Small positive value. s(t)Declared surplus energy profile by the users P to theretailer at time t.

r Iteration number. s−n(t)Declared surplus energy profile by all other usersP\n to the retailer at time t.

L SES provider. U(t) Net payoff of the retailer at time t.

F Retailer. pg(t)Unit energy price paid by the retailer to the grid attime t.

dn(t) Electricity demand of user n at time t. ps(t) Unit energy price of the SES at time t.gn(t) Energy generation of user n at time t. δt, φt Positive time-of-use tariff constants at time t.xn(t) Energy traded with the SES by user n at time t. Ct Social cost at time t.

If gn(t) > dn(t), i.e., when sn(t) > 0, then user n ∈ P+(t).If gn(t) < dn(t), i.e., when sn(t) < 0, then user n ∈ P−(t).

For each user n ∈ P , it is assumed that there is alocal energy controlling device. All these controlling devicescommunicate with a central controlling device at the retailerthat performs the energy cost optimization on behalf of theusers P . In doing so, the retailer determines users’ optimalenergy amounts that are traded with the SES and the grid.

For each user n ∈ P , en(t) > 0 if they buy energy from thegrid, and en(t) < 0 if they sell energy to the grid. Additionally,xn(t) > 0 if the user sells energy to the SES, and xn(t) < 0if they buy energy from the SES. Then, the energy balance atuser n gives en(t) = xn(t) + dn(t)− gn(t). Hence, with (1),

en(t) = xn(t)− sn(t). (2)

The optimal values for en(t) and xn(t) are determined day-ahead by the retailer using the reported information of sn(t) bythe users P . The users P generate information of sn(t) usingtheir next day’s energy generation and demand forecasts, andwe assume the users P have accurate energy forecasts 1. Sincethe surplus energy levels of the users P are private informationand unknown to the retailer, the reported surplus energy levelby user n ∈ P is denoted by sn(t) to highlight that the usercan misreport this information to the retailer. Then we usexn(t) and en(t) to denote the SES and grid energy transactionsdetermined by the retailer for user n at time t, respectively.It is considered that 0 ≤ xi(t) ≤ si(t), ∀i ∈ P+(t) and

1To make the game-theoretic analysis tractable, we assume accurate energyforecasts in this paper. On that note, as an interesting future work, to handleenergy generation and demand forecast errors, the game-theoretic frameworkintroduced in Section IV can be combined with stochastic game theory withimperfect information [20].

sj(t) ≤ xj(t) ≤ 0, ∀j ∈ P−(t). Therefore, with (2),

−si(t) ≤ ei(t) ≤ 0, ∀i ∈ P+(t), t ∈ T ,0 ≤ ej(t) ≤ −sj(t), ∀j ∈ P−(t), t ∈ T .

(3)

B. Shared Energy Storage Model

Here, the storage model is similar to that in [17]. In additionto being charged/discharged with the users P , the SES mayexchange energy es(t) with the grid at time t through theretailer. In this paper, es(t) > 0 if the SES charges from thegrid, and es(t) < 0 if it discharges energy to the grid.

Consider separating xn(t) and es(t) such that xn(t) =x+n (t) − x−n (t) and es(t) = e+s (t) − e−s (t). Here,x+n (t), e+s (t) ≥ 0 are the charging energy profiles, andx−n (t), e−s (t) ≥ 0 are the discharging energy profiles attime t. Given that, all optimal SES energy strategies satisfyx+n (t)x

−n (t) = 0 and e+s (t)e

−s (t) = 0 at each time t to prevent

simultaneous charging and discharging of the SES [7]. Weintroduce η+ and η− such that 0 < η+ ≤ 1 and η− ≥ 1to consider conversion losses of the SES. For example, ifx+ energy is transferred to the SES, only η+x+ energy iseffectively stored. Conversely, to get x− energy, the SES hasto be discharged by η−x−. If the charge level of the SES atthe beginning of time t is b(t− 1), then b(t) is given by

b(t) = αb(t− 1) + η+(e+s (t) +

∑n∈P

x+n (t))

− η−(e−s (t) +

∑n∈P

x−n (t)). (4)

At each time t, b(t) is bounded above by QM and belowby 0 [17]. Therefore,

0 ≤ b(t) ≤ QM , ∀t ∈ T (5)

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where b(t) is calculated using (4). To ensure the continuousoperation of the SES for the next day and to prevent over-charging or over-discharging of the SES, it is specified [21]

b(H) = b(0) (6)

where b(0) is the initial charge level of the SES that isconsidered to be within the safe operating region of the SES.

C. Energy Cost Models

The retailer buys electricity from the grid at cost Dt at timet. If the retailer buys E(t) amount of energy from the grid attime t, then Dt is calculated by

Dt = φtE(t)2 + δtE(t) (7)

where φt and δt are determined according to a day-aheadmarket clearing process [17]. The cost function in (7) canapproximate piecewise linear pricing models used in currentelectricity markets [22] and is widely used in the smart grid lit-erature [16], [22]. In the system, E(t) = es(t)+EN (t)+EP(t)where EP(t) =

∑n∈P en(t). Note that it is possible to exist

either EN (t) ≥ 0 or EN (t) ≤ 0 at time t. EN (t) < 0 occursif some or all users in N have local energy generation systemsthat produce more energy than the total energy demand of theusers N at time t. Using (7), the unit energy price paid by theretailer to the grid at time t is given by

pg(t) = φtE(t) + δt. (8)

It is considered that E(t) > 0 for non-negative pricing in (8)and assumed E(t) < Emax. Additionally, energy transmissionlosses are neglected within the NAN due to the short proximitybetween its elements [23]. The SES provider sets a price ps(t)for the traded energy amount xn(t) by each user n ∈ P andtrades es(t) with the retailer at the price pg(t).

IV. ENERGY TRADING SYSTEM

This section explains the energy trading interaction betweenthe SES provider and the retailer by using a non-cooperativeStackelberg game. Stackelberg games are used to exploremulti-level decision-making processes. Generally, in a Stack-elberg game, one player acts as a leader and moves first toselect their strategies. The rest of the players are followersand react to the decisions made by the leader to maximizetheir profits [24]. In this paper, the SES provider acts asthe leader by moving first to make energy trading decisions,(ps(t), es(t)), ∀t ∈ T , and maximizes revenue. By followingthe SES provider’s decisions, the retailer determines the gridenergy allocations, en(t), ∀n ∈ P, ∀t ∈ T . The solutions tothe Stackelberg game are derived by using backward induction[20]. Thus, the actions of the retailer are derived first based onthe knowledge of the SES provider’s actions. Then the analysisproceeds backwards to find the SES provider’s actions.

A. Objective of the Electricity Retailer

To determine en(t), ∀n ∈ P, ∀t ∈ T , the retailerminimizes the social cost that is the sum of the total costfor the users P when they interact with the SES and the costfor the retailer for supplying grid energy to the users P . Thesocial cost at time t is given by

Ct =∑n∈P

(−ps(t)xn(t) + pg(t)en(t)

). (9)

By using (2) and (8), (9) can be written as a function of EP(t)such that

Ct(EP(t)) = φtEP(t)2 +

(φt(EN (t) + es(t)) + δt

− ps(t))EP(t)− ps(t)

∑n∈P

sn(t). (10)

In response to suitable (ps(t), es(t)), ∀t ∈ T of the SESprovider, the retailer minimizes (10) at each time t as

minEP(t) ∈ E

Ct(EP(t)) (11)

where E =∏I

n=1 En(t), and En(t) subjects to constraints (3).The objective function in (11) is strictly convex with respectto EP(t). Also, its feasible strategy set E is convex, closed,and non-empty because it is only subject to linear constraints.Hence, (11) has a unique solution with respect to EP(t) [25].

The unique optimal solution EP(t) in (11) for given(ps(t), es(t)) is found by using ∂Ct(EP(t))

∂EP(t) = 0 that gives

EP(t) =1

2

(φ−1t (ps(t)− δt)− EN (t)− es(t)

). (12)

Since EP(t) =∑

n∈P en(t), there can be multiple combi-nations for the grid energy allocation of the users P , e(t) =(e1(t), · · · , eI(t)), that satisfy (12). However, the elements ine(t) should satisfy (3). Hence, any tuple of e(t) that satisfiesboth (12) and (3) forms the optimal solution for (11). OnceEP(t) is found by using (12), the corresponding grid energyallocation of the users P at time t, ˜e(t), is found by

˜en(t) =

{EP(t)sn(t)∑

n∈Psn(t)

, if all P are either surplus or deficit,

0, if P has both types of users.(13)

Once ˜en(t) is found, the corresponding ˜xn(t) can be foundusing (2). Clearly, (12) is a function of ps(t) and es(t) andhence, it does not guarantee that any values for (ps(t), es(t))would result in ˜en(t) satisfying (3). Therefore, constraints areconsidered in the SES provider’s revenue maximization so thatits selection of (ps(t), es(t)) ensures ˜en(t) in (13) satisfiesconstraints (3). The details are given in Section IV-C.

The users P may not disclose true surplus energy levels, andthis may lead to inefficient results in the above optimization[26]. Hence, we are interested in a mechanism that motivatesthe users P to report their true information about sn(t) to theretailer or, in other words, an incentive-compatible mechanism.In game theory context, a mechanism is said to be incentive-compatible if each user can achieve minimized personal costby being truthful in their actions [26]. To this end, we areinterested in utilizing the VCG mechanism that can induce

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reporting true sn(t), ∀t ∈ T to the retailer as the dominantstrategy for user n ∈ P . A dominant strategy refers to astrategy where a self-interested user minimizes their personalcost regardless of other users’ strategies [26].

B. Vickrey-Clarke-Groves Mechanism for Energy Trading

The VCG mechanism is a well-known solution for obtaininglocal information from users in resource allocation settings[26]. In a VCG mechanism-based energy allocation setting,users are asked to reveal their energy usage information, e.g.,surplus energy levels of the users P , to determine energy pricescharged to users. In particular, the payments are designed suchthat users are motivated to reveal local information truthfully.

At time t, user n ∈ P pays kn(t) to the retailer for theirgrid energy transaction en(t). Then, for each user n ∈ P ,

Cn(t) = −ps(t)xn(t) + kn(t) (14)

where −ps(t)xn(t) is the cost paid to the SES provider.We take s∗(t) = (s1(t), · · · , sn(t), · · · , sI(t)) to denote the

case when user n reports their true surplus energy level. Inresponse to any tuple s(t) = (s1(t), . . . , sI(t)), the retailer, byusing the VCG mechanism, selects the grid energy allocatione(s(t)) ≡ e(t) by solving (11) as described in Section IV-Aand structures the payments kn(s(t)) ≡ kn(t) as

kn(s(t)) = pg(s(t))en(s(t)) +∑

m∈P\n

(−ps(t)xm(s(t))

+ pg(s(t))em(s(t)))− hn(s−n(t)). (15)

Here, hn(s−n(t)) is a function that depends onthe declared surplus energy profile by all otherusers P\n to the retailer at time t given bys−n(t) = (s1(t), . . . , sn−1(t), sn+1(t), . . . , sI(t)). Todetermine hn(s−n(t)), we use the popular choice referred toas Clarke tax [26]. Then we take

hn(s−n(t)) =∑

m∈P\n

(− ps(t)xm(s−n(t))

+ pg(s−n(t))em(s−n(t))). (16)

Here, em(s−n(t)) and xm(s−n(t)) denote the grid and SESenergy transactions of user m ∈ P\n at time t, respectively,after solving (11) without user n in the system. Similarly,pg(s−n(t)) denotes the grid price paid by the retailer, as per(8), after solving (11) without user n in the system. The casewithout user n in the system refers to when user n is neithera participating user nor a non-participating user, i.e., whenn /∈ A. Thus, (16) implies hn(s−n(t)) is the social cost ofthe other users P\n in (11) without user n in the system. Bydirectly following this argument, we can rewrite (15) as

kn(s(t)) = pg(s(t))en(s(t)) + hn(s(t))− hn(s−n(t)) (17)

where hn(s(t)) =∑

m∈P\n

(−ps(t)xm(s(t)) +

pg(s(t))em(s(t)))

is the social cost of the other usersP\n in (11) with user n in the system. Hence, kn(s(t)) isthe difference between the social costs of the other users

P\n in (11) with and without user n in the system plus theretailer’s cost for supplying en(s(t)).

It is important that when user n ∈ P+(t), they receive anincome for selling energy (i.e., kn(t) < 0), and when user n ∈P−(t), they incur an expense for buying energy (i.e., kn(t) >0). Proposition 1 demonstrates the proposed mechanism yieldsthis property.

Proposition 1. The payment structure in (15) results in anincome for user n (kn(t) < 0) when n ∈ P+(t) and anexpense (kn(t) > 0) when n ∈ P−(t).

Proof. Using (2), the last two terms of (17) can be derived as

hn(s(t))−hn(s−n(t)) = ps(t)(EP\n(s−n(t))−EP\n(s(t))

)−(pg(s−n(t))EP\n(s−n(t))− pg(s(t))EP\n(s(t))

)(18)

where EP\n(s(t)) =∑

m∈P\n em(s(t)) andEP\n(s−n(t)) =

∑m∈P\n em(s−n(t)) are the total grid load

of all other users P\n at time t with and without user n inthe system, respectively. If we denote the total grid load ofall participating users at time t in (11) without user n in thesystem by EP(s−n(t)), then EP(s−n(t)) = EP\n(s−n(t))because, in this case, user n is not in the system, i.e., n /∈ A.If we denote the total grid load of all participating users attime t in (11) with user n in the system by EP(s(t)), thenEP(s(t)) = EP\n(s(t)) + en(s(t)) since n ∈ P .

At optimality in (11), the total grid load of the participatingusers only depends on φt, δt, EN (t), ps(t), and es(t) (see(12)) that are considered to be given and hence, fixed at timet. Hence, EP(s(t)) = EP(s−n(t)). Then, E(t) remains thesame at optimality of (11) in both cases with and withoutuser n in the system. Therefore, (8) reflects pg(s−n(t)) =pg(sn(t)). Thus, from (17) and (18),

kn(s(t)) = ps(t)en(s(t)). (19)

Since the SES price ps(t) > 0, (19) implies that kn(t) < 0when user n ∈ P+(t) with en(t) < 0, and kn(t) > 0 whenuser n ∈ P−(t) with en(t) > 0.

Clearly, (19) implies that the retailer adopts the same priceas the SES provider for unit grid energy traded by user n ∈ P .It is assumed that the users N pay the same unit energy priceas the users P for their grid energy transactions.

By using a similar explanation to Theorem 10.4.2 in [26],we confirm, by Proposition 2, that the VCG payment structureensures the disclosure of true surplus energy levels to the re-tailer is a dominant strategy for each user in P that minimizestheir personal cost in the system.

Proposition 2. Revealing true surplus energy levels is adominant-strategy for each user n ∈ P when solving (11) withthe payment structure (15) for given feasible (ps(t), es(t)).

Proof. Consider user n’s problem is to choose the best strategyfor sn(t) that minimizes their personal cost, Cn(s(t)) ≡Cn(t), given in (14). As a shorthand, denote s(t) =(sn(t), s−n(t)) and s∗(t) = (sn(t), s−n(t)). The beststrategy for user n is the one that solves

minsn(t)

Cn(s(t)) ≡ minsn(t)

(− ps(t)xn(s(t)) + kn(s(t))

). (20)

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where kn(s(t)) is given by (15). Since hn(s−n(t)) does notdepend on sn(t), it is sufficient for user n to solve

minsn(t)

(− ps(t)xn(s(t)) + pg(s(t))en(s(t))

+∑

m∈P\n

(−ps(t)xm(s(t)) + pg(s(t))em(s(t))

))(21)

by excluding hn(s−n(t)) from (20).Given s(t), the retailer picks a grid energy allocation e(t) ∈E for the users P by minimizing the social cost in (9). Hence,by disaggregating the cost of user n and the cost of other usersP\n in (9), we can rewrite the retailer’s problem as

mine(t)

(− ps(t)xn(s(t)) + pg(s(t))en(s(t))

+∑

m∈P\n

(−ps(t)xm(s(t)) + pg(s(t))em(s(t))

)). (22)

Clearly, from (21) and (22), user n and the retailer try tominimize the same objective function however, with respect tosn(t) and e(t), respectively. Hence, the best way for user n tominimize their personal cost is by influencing the retailer topick an e(t) ∈ E that minimizes the cost in (21). This impliesuser n would like to disclose sn(t) that leads the retailer topick an e(t) ∈ E which solves

mine(t)

(− ps(t)xn(s∗(t)) + pg(s

∗(t))en(s∗(t))

+∑

m∈P\n

(−ps(t)xm(s∗(t)) + pg(s

∗(t))em(s∗(t)))).

(23)

Hence, user n ∈ P leads the retailer to select the choice thatthey most prefer by reporting true surplus energy level, i.e.,sn(t) = sn(t), regardless of the reported surplus energy levelsby the other users. Hence, revealing true surplus energy at eachtime t is a dominant strategy for user n ∈ P .

In the system, the retailer coordinates the energy trans-actions between the grid and the NAN to maintain the en-ergy balance. Therefore, a mechanism wherein the retailersimultaneously benefits, in addition to the SES provider andthe users P , leads to a better operating and economicallyviable environment. The conditions in Proposition 3 assurethe proposed VCG mechanism can achieve this in the system.

Proposition 3. The payment (15) produces a non-negativepayoff for the retailer across T given that at time t ∈ T

ps(t) ≤M(t), if EA(t) < 0,

ps(t) ≥M(t), otherwise.

}(24)

where M(t) = φt(es(t) + EN (t)) + δt.

Proof. At time t ∈ T , the set P can have either only surplususers, only deficit users, or both types of users. Hence, weconsider all these three different cases in the proof. At time t,the retailer buys energy from the grid at pg(t) in (8), and theusers A trade grid energy with the retailer at ps(t) as shownwith Proposition 1. However, the SES provider trades es(t)at the same grid price pg(t) and hence, the retailer receives

zero payoffs from the SES provider’s grid energy transactions.Therefore, the retailer’s net payoff at time t is given by

U(t) = (ps(t)− pg(t))EA(t). (25)

Note that, here, we focus on the temporal change of sign, i.e.,plus or minus, of EP(t) due to different types of users in P .

First, assume time t has only surplus users in P . Then,en(t) ≤ 0, ∀n ∈ P and hence, EP(t) ≤ 0. Thus, in this case,it is possible to exist either EA(t) < 0 or EA(t) > 0 becauseEA(t) = EP(t) + EN (t) and EN (t) ≥ 0 or EN (t) ≤ 0. IfEA(t) < 0, then ps(t) ≤ pg(t) results in a non-negative payoffin (25). If EA(t) > 0, then ps(t) ≥ pg(t) gives a non-negativepayoff in (25). Given pg(t) = φt(EP(t)+EN (t)+es(t))+δtwhere EP(t) is given by (12), ps(t) ≤ pg(t) gives ps(t) ≤M(t). Similarly, ps(t) ≥ pg(t) results in ps(t) ≥M(t).

Now, assume time t has only deficit users in P . Then,en(t) ≥ 0, ∀n ∈ P and hence, EP(t) ≥ 0. Hence, withsimilar arguments to the previous case, it is possible to existeither EA(t) < 0 or EA(t) > 0. If EA(t) > 0, thenps(t) ≥ pg(t) (or ps(t) ≥ M(t)) gives a non-negativepayoff in (25), and if EA(t) < 0, then ps(t) ≤ pg(t) (orps(t) ≤M(t)) gives a non-negative payoff in (25).

Finally, assume time t has both surplus and deficit usersin P . According to (13), en(t) = 0, ∀n ∈ P that implies thepayoff in (25) is equal to (ps(t)−pg(t))EN (t). If EN (t) ≥ 0,then ps(t) ≥ pg(t) (or ps(t) ≥ M(t)) gives a non-negativepayoff in (25), and if EN (t) ≤ 0, then ps(t) ≤ pg(t) (orps(t) ≤M(t)) gives a non-negative payoff in (25).

Under these conditions, the sum of U(t) across T leads toa non-negative payoff for the retailer.

Therefore, to obtain a non-negative payoff for the retailer,the SES provider’s selection of es(t) and ps(t) can be adjustedsuch that the conditions in (24) are satisfied.

C. Objective of the Shared Energy Storage ProviderThe SES provider maximizes revenue R by trading energy

with the users P and the grid through the retailer. Then

R =H∑t=1

(−ps(t)

∑n∈P

xn(t)− pg(t)es(t)

). (26)

As per backward induction, by substituting the retailer’s strat-egy (12) in (26), the SES provider’s revenue maximization isgiven by

maxρ∈Q

H∑t=1

(λps(t)2 + µps(t) + νes(t)

2 + ξes(t)) (27)

where ρ = (ps, es) with ps = (ps(1), · · · , ps(H))T andes = (es(1), · · · , es(H))T . Additionally, λ = − 1

2φ−1t , µ =

( 12 (EN (t) + φ−1t δt) −∑

n∈P sn(t)), ν = − 12φt, and ξ =

− 12 (φtEN (t)+ δt). As recognized in Section IV-A, to ensure

˜en(t) in (13) satisfies (3), the SES provider selects ps(t) andes(t) at time t such that∑

n∈P −sn(t) ≤ EP(t) ≤ 0, if all P are surplus,

0 ≤ EP(t) ≤∑

n∈P −sn(t), if all P are deficit,

EP(t) = 0, if P has both types of users

(28)

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where EP(t) is given by (12). Thus, the SES provider’sfeasible strategy set Q is subject to (5), (6), (24), and (28).Note that (27) is a convex optimization problem that can besolved by using optimization algorithms such as the interiorpoint algorithm [25]. It also has a unique solution because theobjective function is strictly convex with respect to ρ, and Q isnon-empty, closed, and convex due to linear constraints [25].

D. Non-cooperative Stackelberg Game

In this system, the Stackelberg game between the SESprovider and the retailer can be given by the strategic formof G ≡ 〈{L,F}, {Q, E}, {R,Ct}〉 where the SES provider Lis the leader and the retailer F is the follower.

Proposition 4. The game G has a unique pure strategyStackelberg equilibrium.

Proof. In the system, the energy cost minimization (11) hasa unique solution for given (ps(t), es(t)) and that is givenby EP(t) (Section IV-A). Given EP(t), the optimizationproblem of the SES provider in (27) also has a unique solution(Section IV-C). Therefore, according to backward induction,the game G has a unique pure strategy Stackelberg equilibrium(ρ∗, E∗P) where E∗P = (E∗P(1), · · · , E∗P(H)), and E∗P(t) isfound by substituting the tth element of the optimal solutionof (27), i.e., ρ∗(t) = (p∗s(t), e

∗s(t)), in (12) [20].

The equilibrium (ρ∗, E∗P) of the game G satisfies

Ct(E∗P(t),ρ

∗) ≤ Ct(EP(t),ρ∗), ∀EP(t) ∈ E , ∀t ∈ T ,

(29)

R(E∗P ,ρ∗) ≥ R(E∗P ,ρ), ∀ρ ∈ Q. (30)

As shown in Algorithm 1, a two-step iterative algorithm,similar to the one in [7] that was shown to converge, wasdeveloped to obtain the Stackelberg equilibrium.

Algorithm 1 Algorithm to obtain the Stackelberg equilibriumStep 1:

1: r ← 1.2: if r = 13: The SES provider selects a feasible starting point for ρ

and communicates it to the retailer.4: else5: The SES provider maximizes (26) subject to (5), (6),

(24), and (28) using EP(t),∑

n∈P˜xn(t), ∀t ∈ T and

communicates ρ to the retailer.6: end if

Step 2:7: The retailer determines (˜en(t), ˜xn(t)), ∀n ∈ P, ∀t ∈T using ρ, (12), (13), and (2) and announcesEP(t),

∑n∈P

˜xn(t), ∀t ∈ T back to the SES provider.8: r ← r + 1.9: Repeat from 2 until ‖ρ(r) − ρ(r−1)‖2/‖ρ(r)‖2 ≤ τ . Here,ρ(r) refers to ρ calculated at iteration r.

10: Return EP(t), ∀t ∈ T and ρ as the equilibrium.

V. RESULTS AND DISCUSSION

To numerically analyze the performance of the proposedsystem, a residential community of 40 users with photovoltaic(PV) power generation is considered. The demand profiles ofthe users P are varied among the users such that their averagedemand profile is equal to the average daily domestic electric-ity demand profile in the Western Power Network in Australiaon a typical spring day [27]. For example, when there are 10participating users, demand profiles of 5 users are generated byscaling down the demand profile in [27] with scaling factorschanging from 0.84 to 0.92 in 0.02 steps. For the other 5 users,the demand profiles are generated by scaling up the demandprofile in [27] with scaling factors changing from 1.08 to 1.16in 0.02 steps. For each user in N , the same demand profileas the one in [27] is assigned. For each user in P , PV powergeneration profile is the same as the average domestic PVpower generation profile in the Western Power Network ona typical spring day [27]. The users N are considered to beenergy users without PV power generation capabilities. Weselected H = 48, QM = 80 kWh, α = 0.9(1/48), η+ = 0.9,η− = 1.1 [17], and b(0) = 0.25QM . In simulations, φ isselected such that φpeak = 1.5× φoff-peak, and peak period forthe energy demand is taken as 16 : 00 − 23 : 00. Here, φpeakis selected such that the range of the predicted price signal,(pg(1), · · · , pg(H)), that the retailer pays to the grid is thesame as the range of the time-of-use price signal in [28]. δtis set as a constant across T such that the average predictedgrid price is the same as the average reference price signal.

A. Preliminary Study of the Proposed System

Here, the behavior of the proposed system is compared witha baseline system without an SES where the users P tradeenergy only with the grid through the retailer. In the baseline,each user in P is charged with a price pg(t), calculated as per(8), for their unit grid energy consumption.

In Fig. 2, the price signal of the SES provider is equal tothat of the retailer used to trade grid energy with the users P(see (19)). At midday, when there is excess PV energy, theSES provider and the retailer in the proposed system pay ahigher price to purchase energy from the users P than in thebaseline. During peak demand hours, when there is insufficientPV energy to supply users’ energy demand, participation in theproposed system helps to decrease the energy buying price forthe users, and the users P transfer some of their peak energydemand to the SES. In this way, the proposed system reducesthe peak energy demand on the grid as illustrated in Fig. 3, andthe peak-to-average load ratio is reduced by 30.74% comparedto the baseline. Moreover, the proposed system can delivernearly 10% social cost reduction compared to the baseline.

As per Fig. 2, when the users P have little PV energy(before 09:00 and after 16:00), the retailer sells grid energy tothe users at a higher price than the grid price. At other times,the retailer buys energy from the users with a lower price thanthe grid price. Hence, with 25% participating users, the systemprovides a cumulative payoff of 520 AU cents to the retailer.

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8

0 4 8 12 16 20 240

10

20

30

Time (Hours)

Pric

e (A

U c

ents

kWh−

1 )

SES provider/Electricity retailerPower gridBaseline system

Fig. 2. Variation of the grid and SES electricity prices in the proposed systemcompared to the baseline with 25% participating users (i.e.,10).

0 4 8 12 16 20 240

5

10

15

20

Time (Hours)

Agg

rega

te L

oad

on

the

Grid

(kW

h)

Proposed systemBaseline system

Fig. 3. Load variation on the grid with 25% participating users.

B. Participating Users versus Non-participating Users

The primary incentive for a user to become a participatinguser is a reduction in their energy cost. Fig. 4 depicts thevariation of average daily energy costs for the users P and Nas the number of users in P increases. The figure shows thatthe users P benefit more than the users N for all percentagesof the users P . When the number of users P increases, thegreater demand on the SES leads to a greater price of the SESprovider. Concurrently, the grid energy price for the users Aincreases because the SES price is equal to the price usedby the retailer to trade grid energy with the users A (seeSection IV-B). Hence, the average costs for the users P andN increase when the number of users P increases. However,users in N who pay 127 AU cents on average when thereare 10% participating users in the system only have to pay121 AU cents on average by participating in the system whenthere are 90% participating users. Hence, it is beneficial for auser in N to become a user in P in the proposed system.

C. Proposed System versus Competitive System

Here, the performance of the proposed system is comparedto the competitive energy trading system proposed in [7] wherethe objective is to minimize individual energy costs of theusers P and maximize the revenue for the SES provider.The solution in [7] is incapable of producing a payoff toan intermediary electricity retailer because there is no pricedifferentiation for grid energy traded by the participating users.In contrast, the proposed system produces a non-negativepayoff to a retailer due to the price difference between thegrid and the users A (see (25)) while minimizing the socialcost in (11) and maximizing the revenue for the SES provider.

In Fig. 5, the community cost is the sum of the energy costsof the three entities: the SES provider, the users P , and the

10 20 30 40 50 60 70 80 900

50

100

150

Participating Users (%)

Ave

rage

Dai

ly E

nerg

y Co

st (A

U c

ents)

Participating usersNon−participating users

Fig. 4. Average daily energy costs of participating and non-participating usersin the proposed system with different fractions of participating users.

Community cost, PS Community cost, CS SES provider revenue, PS SES provider revenue, CS

Retailer revenue, PS Retailer revenue, CS

5000

4000

3000

2000

1000

0

20 40 60 80 100 Participating Users (%)

Mon

etar

y V

alue

(A

U c

ents

)

Fig. 5. Energy cost and revenue comparison with different fractions ofparticipating users. Proposed system (PS), competitive system (CS).

retailer. Since part of the cost incurred by the SES provideris a profit to the users P and part of the cost incurred by theusers P produces a payoff to the retailer (see (14), (25), and(26)), the community cost in the proposed system is given by∑

t∈T pg(t)(es(t) + EA(t)

)− ps(t)EN (t). Note that when

there are 20% participating users, energy discharged by theSES to the grid during peak hours leads to a lower totalgrid energy load,

(es(t) + EA(t)

), than that of the users

N , EN (t), during peak hours. As a result, community costbecomes negative with 20% participating users. In each casein Fig. 5, the proposed system has a lower community costthan in the competitive system. The retailer can also benefitin the proposed system whereas the retailer in the competitivesystem does not receive a positive payoff. Hence, the proposedsystem provides a more economically viable solution for theenergy trading scenario by creating a better trade-off of costbenefits among the SES provider, the users P , and the retailer.Similar to [7], simulation experiments revealed that, in theproposed system, users with more surplus energy in P pay alower energy cost compared to users with less surplus energy.

In general, a higher peak-to-average load ratio reduction ispreferable as it indicates a flattened load profile on the grid[16]. Fig. 6 depicts when the fraction of participating users inthe proposed system increases from 5% to 100%, the peak-to-average load ratio reduction on the grid compared to thebaseline improves from 28% to 45%. The competitive systemdisplays a similar trend because the equilibrium energy tradingtransactions (the SES and grid energy transactions of the usersP) of the two systems present a similar behavior.

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9

10 20 30 40 50 60 70 80 90 10025

30

35

40

45

50

Participating Users (%)

Peak−T

o−A

vera

ge

Ratio

Red

uctio

n (%

)

Proposed systemCompetitive system

Fig. 6. Peak-to-average ratio reductions compared to the baseline system withdifferent fractions of participating users.

D. Imperfect Energy Forecasts and the Proposed System

As a preliminary study in exploring the effects of imperfectenergy forecasts on the system performance, proportionalvariance white noise errors were introduced to PV powergeneration and energy demand forecasts. When averaged overa large number of simulations, the mean absolute percentageerror (MAPE) of energy forecasts is equal to half of percentagewhite noise variance [7]. With 60% participating users in thesystem, as MAPE increases from 0% to 50%, community costincreased from 1020 AU cents to 1319 AU cents, and for each5% increase of MAPE, community cost increased by nearly15 AU cents. This is mainly because the retailer’s revenuegenerated from the non-participating users’ energy transactionsreduced as MAPE increases. However, as MAPE changesfrom 0% to 50%, the average daily costs for the users Premained nearly unchanged, at 108 AU cents, with a varianceless than 0.0002 AU cents2. This demonstrates participatinguser costs are unaffected by the forecast errors. Similar trendswere observed when changing the percentage of participatingusers from 20% to 100% in 10% steps.

VI. CONCLUSION

The energy trading interaction between a shared energystorage (SES) system and users with non-dispatchable energygeneration for demand-side management of a neighborhoodarea network (NAN) can be studied by minimizing energycosts of users from a social planners perspective. Here, wehave investigated an energy trading system among an SESprovider, users with non-dispatchable energy generation, andan electricity retailer for demand-side management of a NAN.By exploiting the insights of the Vickrey-Clarke-Groves mech-anism and Stackelberg game theory, we have developed thesystem to minimize social energy cost for the users andmaximize revenue for the SES provider. It has been shownthat the proposed system possesses incentive-compatibility forthe users by rewarding them in return for disclosing trueenergy usage information and provides benefits to the retailerin addition to the SES provider and the users.

Future research directions include investigating a stochasticmodel to incorporate energy forecast errors with the pro-posed system, extending the system to accommodate addi-tional constraints including secure grid voltage levels withenergy generation and demand fluctuations, and exploring a

price differentiation strategy between participating and non-participating users to encourage participation in the system.

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PLACEPHOTOHERE

Chathurika P. Mediwaththe (S’12-M’17) receivedthe B.Sc. degree (Hons.) in electrical and electronicengineering from the University of Peradeniya, SriLanka. She completed the PhD degree in electricalengineering at the University of New South Wales,Sydney, NSW, Australia in 2017. From 2013-2017,she was a research student with Data61-CSIRO(previously NICTA), Sydney, NSW, Australia. Sheis currently a research fellow with the ResearchSchool of Electrical, Energy and Materials Engineer-ing (RSEEME) and the Battery Storage and Grid

Integration Program, Australian National University, Australia. Her currentresearch interests include electricity demand-side management, renewableenergy integration into distribution power networks, game theory and opti-mization for resource allocation in distributed networks, and machine learning.

PLACEPHOTOHERE

Marnie Shaw received the B.Sc. (Hons.) and PhDdegrees, both from the School of Physics, Universityof Melbourne, Australia (2003). Her research inter-ests lie in applying data analytics and machine learn-ing to a range of data-rich problems, including theintegration of renewable energy into the electricitygrid. She has held postdoctoral research positions atHarvard University and the University of Heidelbergin Germany. She is currently Research Leader in theBattery Storage and Grid Integration Program, at theAustralian National University, and convenor of the

Energy Efficiency research cluster at the ANUs Energy Change Institute.

PLACEPHOTOHERE

Saman Halgamuge (F’17) is a Professor in theDepartment of Mechanical Engineering, School ofElectrical, Mechanical and Infrastructure Engineer-ing at the University of Melbourne, an honoraryProfessor of Australian National University (ANU)and an honorary member of ANU Energy ChangeInstitute. He was previously the Director of theResearch School of Engineering at the AustralianNational University (2016-18), Professor, AssociateDean International, Associate Professor and Readerand Senior Lecturer at University of Melbourne

(1997-2016). He graduated with Dipl.-Ing and PhD degrees in Data Engineer-ing from Technical University of Darmstadt, Germany and B.Sc. Engineeringfrom University of Moratuwa, Sri Lanka. His research interests are in MachineLearning including Deep Learning, Big Data Analytics and Optimizationand their applications in Energy, Mechatronics, Bioinformatics and Neuro-Engineering. His fundamental research contributions are in Big Data Analyticswith Unsupervised and Near Unsupervised type learning as well as inTransparent Deep Learning and Bioinspired Optimization.

PLACEPHOTOHERE

David B. Smith - (S01M04) received the B.E.degree in electrical engineering from the Universityof New South Wales, Sydney, NSW, Australia, in1997, and the M.E. (research) and Ph.D. degrees intelecommunications engineering from the Universityof Technology, Sydney, NSW, Australia, in 2001and 2004, respectively. Since 2004, he was withNational Information and Communications Technol-ogy Australia (NICTA, incorporated into Data61of CSIRO in 2016), and the Australian NationalUniversity (ANU), Canberra, ACT, Australia, where

he is currently a Principal Research Scientist with CSIRO Data61, and anAdjunct Fellow with ANU. He has a variety of industry experience in electricaland telecommunications engineering. His current research interests includewireless body area networks, game theory for distributed signal processing,disaster tolerant networks, 5G networks, IoT, distributed optimization forsmart grid and privacy for networks. He has published over 100 technicalrefereed papers. He has made various contributions to IEEE standardisationactivity. He is an area editor for IET Smart Grid and has served on thetechnical program committees of several leading international conferences inthe fields of communications and networks. Dr. Smith was the recipient offour conference Best Paper Awards.

PLACEPHOTOHERE

Paul Scott received BEng and BSc degree in 2010at the ANU, and a PhD in Computer Science in2016 at the ANU. He is now a research fellow inthe Research School of Computer Science at theANU, researching how optimisation and intelligentsystems can enable the integration of distributedenergy resources and renewable energy into ourelectricity networks.