Plug-and-Play Model Predictive Control for Load Shaping and Voltage Control in Smart Grids

This paper presents a predictive controller for handling plug-and-play (P&P) charging requests of flexible loads in a distribution system. We define two types of flexible loads: (i) deferrable loads that have a fixed power profile but can be deferred in time and (ii) shapeable loads that have flexible power profiles but fixed energy requests, such as Plug-in Electric Vehicles (PEVs). The proposed method uses a hierarchical control scheme based on a model predictive control (MPC) formulation for minimizing the global system cost. The first stage computes a reachable reference that trades off deviation from the nominal voltage with the required generation control. The second stage uses a price-based objective to aggregate flexible loads and provide load shaping services, while satisfying system constraints and users’ preferences at all times. It is shown that the proposed controller is recursively feasible under specific conditions, i.e. the flexible load demands are satisfied and bus voltages remain within the desired limits. Finally, the proposed scheme is illustrated on a 55 bus radial distribution network. ∗This work was funded in part by the Siebel Energy Institute, the Swiss National Science Foundation and the National Science Foundation within the Division of Electrical, Communications and Cyber Systems under Grant 1408107. †aCivil and Environmental Engineering, University of California, Berkeley, United States, [email protected] ‡bElectrical Engineering and Computer Sciences, University of California, Berkeley, United States §cMechanical and Process Engineering, ETH Zurich, Switzerland