  This paper considers a real-time electricity market involving an independent
system operator (ISO) and a group of strategic generators. The ISO operates a
market where generators bid prices at which there are willing to provide power.
The ISO makes power generation assignments with the goal of solving the
economic dispatch problem and regulating the network frequency. We propose a
multi-rate hybrid algorithm for bidding and market clearing that combines the
discrete nature of iterative bidding with the continuous nature of the
frequency evolution in the power network. We establish sufficient upper bounds
on the inter-event times that guarantee that the proposed algorithm
asymptotically converges to an equilibrium corresponding to an efficient Nash
equilibrium and zero frequency deviation. Our technical analysis builds on the
characterization of the robustness properties of the continuous-time version of
the bidding update process interconnected with the power network dynamics via
the identification of a novel LISS-Lyapunov function. Simulations on the IEEE
14-bus system illustrate our results.
