Smart-grid technologies seek to enhance the electri cal grid's efficiency by introducing bi-directional communication and dynamic adaptive control between energy suppliers and consumers. We develop a large-scale network simulation model for evaluating such a hierarchical transactive control system that is part of our work on the Pacific Northwest Smart Grid Demonstration Project. The transactive control system communicates local supply conditions using incentive signals and load adjustment responses using feedback signals in a distributed fashion in order to match the consumer-desired load to the utility desired supply scenario. We study the system protocol and a dynamic control mechanism that is implied by the design under a reasonable collection of models that capture load variation, stochastic signal losses, consumer fatigue to demand response and certain 'stickiness' criterion on the control signals that arise out of physical constraints. Our results indicate that the control mechanism can perform adequately in adjusting the aggregate supply-demand mismatch, and is robust to steady transactive signal losses.Index Terms-smart grid, demand response, transactive con trol, discrete-event network simulator