Demand dynamics aggregation using hybrid systems

Modeling the dynamical behavior of a large population of responsive loads is especially important to evaluate the effectiveness of various demand response programs. Existing works on aggregated load modeling mainly focus on Thermostatically Controlled Loads (TCLs) described by first-order linear ordinary differential equations. In this paper, we propose a unified hybrid system model with general nonlinear subsystem dynamics to describe individual load dynamics. Such a model can be used to represent both TCLs and deferrable loads such as washers, dryers and plug-in hybrid electric vehicles (PHEVs). An aggregate model is also developed based on the proposed hybrid system load model. Realistic simulations show that the aggregate model can accurately capture the collective dynamics for TCLs and deferrable loads. The results presented in this paper can be used as a general aggregate load modeling framework for the analysis and design of various demand response strategies.