Based on the concept of cyber physical system (CPS), a novel hierarchical control strategy for islanded microgrids is proposed in this paper. The control structure consists of physical and cyber layers. It’s used to improve the control effect on the output voltages and frequency by droop control of distributed energy resources (DERs), share the reactive power among DERs more reasonably and solve the problem of circumfluence in microgrids. The specific designs are as follows: to improve the control effect on voltages and frequency of DERs, an event-trigger mechanism is designed in the physical layer. When the trigger conditions in the mechanism aren’t met, only the droop control (i.e., primary control) is used in the controlled system. Otherwise, a virtual leader-following consensus control method is used in the cyber layer to accomplish the secondary control on DERs; to share the reactive power reasonably, a method of double virtual impedance is designed in the physical layer to adjust the output reactive power of DERs; to suppress circumfluence, a method combined with consensus control without leader and sliding mode control (SMC) is used in the cyber layer. Finally, the effectiveness of the proposed hierarchical control strategy is confirmed by simulation results.
To solve the problem of track failure in railway system, integrative design of an emergency resource forecasting-scheduling-repairing method is proposed in this paper. In the current railway repair process, resource dispatching centers dispatch transport resources to the fault point for the repair work. In order to optimize this process, a hybrid prediction method consisting of radial basis function neuron network (RBFNN) and expert prediction method to rationally predict repair resources is proposed. In order to optimize the resource transportation path and reduce the transportation cost, a bi-objective resource scheduling method is presented in this paper. A fuzzy evaluation method combining with the prospect theory to optimally select the repairing for the repair work is formulated. Finally, experiment studies are carried out and the results illustrate the effectiveness of the proposed method.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.