The CrocodileAgent 2012: Reaching Agreements in
      a Simulation of a Smart Grid Wholesale Market

                Ivo Buljevic, Ivana Pranjic, Marija Mijic, Jurica Babic,
                           Ana Petric and Vedran Podobnik

         University of Zagreb, Faculty of Electrical Engineering and Computing,
                            Unska 3, 10000 Zagreb, Croatia
     {ivo.buljevic, ivana.pranjic, marija.mijic, jurica.babic,
                  ana.petric, vedran.podobnik}@fer.hr



       Abstract. Over the last few years electricity markets are going through liberali-
       zation and modernization processes, which have resulted in introduction of
       smart grids. The Power Trading Agent Competition (Power TAC) is a simula-
       tion platform for evaluating trading strategies for the smart grid electricity mar-
       kets: the tariff and the wholesale market. This paper gives an outline of our pro-
       posed strategies for reaching agreements in the Power TAC wholesale market.

       Keywords: smart grid, electric energy wholesale, negotiating agreements, bid-
       ding strategies


With the advent of smart grids, a growing need to maintain real-time balance between
electric energy production and consumption emerges due to high cost of electric ener-
gy storage. Successful trading on the wholesale market is an important prerequisite
for achieving that balance. In this paper we describe the wholesale market bidding
strategies implemented in the intelligent software agent CrocodileAgent 2012 that
acts as a broker in the smart grid power market simulator Power Trading Agent Com-
petition (Power TAC) [1].
   The Power TAC Wholesale Market is modelled as a periodic double auction which
clears every simulated timeslot. In the Power TAC Wholesale Market brokers buy and
sell electric energy at the market clearing price (i.e., equilibrium price). Brokers can
simultaneously send orders (i.e., bids or asks) to 24 different markets, each represent-
ing one of the 24 upcoming simulated timeslots (i.e., day-ahead market). Broker’s
main goal is to ensure the sufficient amount of energy for customers in its portfolio by
buying energy on the Power TAC Wholesale Market from producers and other bro-
kers. In case of energy imbalance the broker must pay a balancing fee.
   Modules of the CrocodileAgent 2012 are shown in Figure 1. The Forecasting
Module uses historic data (e.g., past energy production/consumption, previous clear-
ing prices) to predict the amount of energy customers will need in the next 24
timeslots and to estimate clearing prices on the Power TAC Wholesale Market. For
calculating predictions we use the triple exponential smoothing technique better
known as the Holt-Winters Method [2]. The predicted values are defined as:



AT2012, 15-16 October 2012, Dubrovnik, Croatia. Copyright held by the author(s).
                                                                                      (1)
where            [0.0, 1.0] are parameters used to calculate the triple exponential
smoothing of past values consisted in the parameter (i.e., past clearing prices), the
parameter           is the periodicity of those values (e.g., daily periodicity – periodici-
ty of 24 timeslots) while is the number of values to be predicted.




                     Fig. 1. The architecture of the CrocodileAgent 2012

    The CrocodileAgent 2012 retrieves the information about the amount of energy it
needs to buy or sell for each of the 24 upcoming timeslots and computes the price
offered on the Power TAC Wholesale Market depending on the number of tries left
(e.g., if the current timeslot is and the broker wants to buy the energy needed for
the timeslot       , it can do so by biding in the current and 9 upcoming timeslots). As
the respective timeslot approaches, the CrocodileAgent 2012 increases the price it is
willing to pay in order to buy the needed amount of energy. If there is only one try left
(i.e., the current timeslot is      ), the broker offers a predefined maximum price.
More detailed description of the CrocodileAgent 2012 can be found in [3].

Acknowledgments. The authors acknowledge the support of research project “Con-
tent Delivery and Mobility of Users and Services in New Generation Networks”,
funded by the Ministry of Science, Education and Sports of the Republic of Croatia.


References
 1. W. Ketter, J. Collins, P. Reddy, C. Flath, and M.d. Weerdt, “The Power Trading Agent
    Competition,” ERIM Report Series Reference No. ERS-2011-027-LIS, 2011.
 2. C.C. Holt, “Forecasting seasonals and trends by exponentially weighted moving averages,”
    International Journal of Forecasting, vol. 20, no. 1, pp. 5-10, 2004.
 3. J. Babic, et al., “The CrocodileAgent 2012: Research for Efficient Agent-based Electricity
    Trading Mechanisms”, In Proceedings of the Special Session on Trading Agent Competi-
    tion @ KES-AMSTA 2012, Dubrovnik, Croatia, pp. 1-13, 2012.