The paper presents a unified control framework which allows the responsive end-user devices (REDs) such as inverter-based photovoltaic systems (PVs), plug-in hybrid electric vehicles (PHEVs), and domestic controllable loads at residential level to effectively participate in the voltage and frequency control of the smart grid. The presented control framework basically relies on extracting information from active and reactive power sensitivities at different buses. In this framework, for voltage control, two support groups namely the active support group and the reactive support group are dedicated to each transmission bus. However, for frequency control, only one active support group is defined for the entire system. The REDs used for voltage and frequency control are classified based on their controllability degree. The idea of selecting the most effective buses is also presented to minimize the burden of communication commands. Following the detection of voltage or frequency violation in the system, the targeted buses are identified and receive corrective control signals to accordingly change their active and/or reactive powers. To minimize the manipulated active and reactive powers, the whole process is formulated as a multiobjective problem solved by the particle swarm optimization. The control procedure involves a series of commands for which the incident command system is used as a secure communication structure.
