Scalability analysis of aggregation web services for smart grid fast automated demand response

In this paper, we modeled stochastic wide-area communication delays in a fast automated demand response (FastADR) system using an M/M/1 queuing system. By considering a very large number of communication gateways in buildings spread over a wide area, the scalability of the aggregation communication performance was estimated by the M/M/1 transient analysis. The validity of our analysis model was confirmed in a laboratory experiment with realistic wide-area communication emulation equipment. Using the parameters from the experiment, expected aggregation service communication times were analyzed theoretically, including a large-scale FastADR system consisting of 1,000 buildings. Our scalability analysis has shown that it is necessary to divide the total system into 25 aggregation subsystems with each 40 building gateways to realize the expected aggregation Web service delay of less than 30 seconds.