Safety-assured collaborative load management in smart grids

When a power grid is overloaded, load shedding is a conventional way to combat the imbalance between supply and demand that may jeopardize the grid's safety. However, disconnected customers may be excessively inconvenienced or even endangered. With the emergence of demand-response based on cyber-enabled smart meters and appliances, customers may participate in solving the imbalance by curtailing their demands collaboratively, such that no single customers will have to bear a disproportionate burden of reduced usage. However, compliance or commitment to curtailment requests by untrusted users is uncertain, which causes an important safety concern. This paper proposes a two-phase load management scheme that (i) gives customers a chance to curtail their demands and correct a grid's undersupply when there are no immediate safety concerns, but (ii) falls back to conventional load shedding to ensure safety once the grid enters a vulnerable state. Extensive simulations based on a 37-bus electrical grid and traces of real electrical load demonstrate the effectiveness of this scheme. In particular, if customers are, as expected, sufficiently committed to the load curtailment, overloads can be resolved in real time by collaborative and graceful usage degradation among them, thereby avoiding unpleasant blackouts in existing practice.