Dynamic reconfiguration preserving stability

We present a systematic design method for automatically controlling the reconfiguration of shipboard power systems, which is implemented primarily via switching actions. This method takes advantage of the hybrid system model of the power network, in which certain parameters may be varied discretely or continuously to control the system. Any given state of the discrete switches (relays) that are used to control the system is referred to as a configuration of the power network, and by reconfiguration we mean a control action that effects a change in the state of these relays. We develop control strategies to rapidly assess the stability of a control action, and to find a sequence of discrete control steps that steer the system to a target equilibrium state in a safe and stable fashion. The region of stability for each configuration can be calculated using Lyapunov energy functions, avoiding the necessity of individual trajectory simulations. A switching action is defined as safe if the equilibrium of the pre-switch configuration lies in the region of stability of the post-switch configuration. The concept behind our methodology is the notion of a safe and stable reachability graph whose nodes are the various configurations of the system, where a directed edge between a pair of nodes implies a safe transition from the predecessor node to the successor node. This reachability graph is the basis for a controlling automaton that guides reconfiguration steps.