Enabling reliable data center demand response via aggregation

Although data centers are recognized as promising resources for demand response (DR), it is not easy for them to participate into DR programs due to their unreliable DR capacities. The unreliability mainly comes from their random workload arrivals. In this paper, we study how to enable reliable data center DR. We focus on the scenario that independent data centers participate into capacity bidding program (CBP) in which they need to sign forward contracts to commit the amount of power reduction during the DR event. We show that due to the uncertainty of DR capacity in real time, it is risky for the data centers to sign contracts in advance. Such risky behaviors are adverse to the profitability of data centers when providing DR resources. Inspired by the intuition that aggregation can reduce uncertainty, we propose that data centers cooperate with others and sign the forward contract collectively based on their aggregated DR capacity to mitigate the uncertainty of DR capacity. A coalitional game is used to model the cooperation among the data centers. We further design a payoff allocation to split the profit generated via cooperation fairly, guaranteeing that no coalition has the incentive to deviate. In addition, we show that the proposed payoff allocation captures the marginal contribution of each data center and is efficient. Finally, trace driven simulation results are presented to demonstrate the effectiveness of the proposed approach. The results show that participating into CBP collaboratively leads to a win-win situation where the data centers obtain higher profits and the utility company gets more reliable DR resources from data centers.