Shepherd: sharing energy for privacy preserving in hybrid AC-DC microgrids

Renewable energy becomes increasingly popular due to its zero carbon dioxide emissions and increasing energy demand. To better utilize renewable energy, hybrid Alternative Current (AC)-Direct Current (DC) microgrids have been proposed because the most common renewable energy that can be harvested in residential homes is solar energy, which provides DC power. However, a major issue in a hybrid AC-DC microgrid is privacy leakage because power consumption information of each home can be exposed through the power lines or compromised neighbors in the microgrid. Power consumption data then can be used to reveal precise information about appliances' activities with non-intrusive load monitoring algorithms. To mitigate leakage of human behaviors in homes, battery-based load hiding (BLH) is widely studied. In this approach, a battery is used to store and supply energy to appliances to hide the actual power consumption. However, BLH requires to deploy large and expensive batteries at each home. In this paper, instead of using batteries, we propose to leverage the unique features of hybrid AC-DC microgrids to hide power consumption information. Specifically, we design Shepherd, a privacy protection framework to hide power consumption information from different types of power consumption detection techniques. To minimize energy transmission among neighboring homes, we provide an optimal offline solution and an efficient heuristic online solution. We conducted extensive system evaluations with 40 homes. Results indicate that our proposed approach can i) significantly reduce the detection ratio from 33% to 13% compared to BLH, and ii) effectively hide consumption information even with 25% compromised neighbors.