Search

In order to solve the problem of power deviation caused by voltage drop of line impedance, a control strategy of interlinking converter (IC) in hybrid microgrid based on line impedance compensation is proposed. In this method, one specified harmonic signal whose frequency is closely related to the voltage of point of common coupling (PCC) is injected into IC. The harmonic frequency is obtained by the usage of a filter and phase-locked loop at the ac side of IC, and the line impedance is obtained consequently. Compensating the voltage drop with the estimated line impedance, and the accurate power transmission can be realized. Finally, simulation results verify the effectiveness of the proposed method.

In order to improve the AC/DC sub-grid voltage accuracy of the traditional normalized droop control, an adaptive droop control strategy for AC/DC hybrid micro-grid interlinking interface is proposed. The proposed control strategy can not only reduce unnecessary power exchange while ensuring the bidirectional flow of power between AC and DC sub-grids, but also improve power transmission accuracy to realize a better compensation of the voltage deviation. As for the island mode of low-voltage hybrid AC/DC microgrid, the relationship between droop coefficient and transmitted power is deduced first. Then, the voltage variation is introduced to construct the operating criterion that characterizes the system load condition. Based on the above analysis, a control strategy whose droop coefficient is changing adaptively is designed. Moreover, considering the variation of line impendence, a control strategy is proposed to realize power distribution properly and suppress circulating current between parallel ICs. Finally, a simulation model of hybrid AC/DC microgrid is built on the Matlab/Simulink, and the effectiveness and superiority of the proposed control strategy are verified by simulation results.

Delay Tolerant Networks are a special kind of ad hoc networks that consist of a number of mobile devices. In DTNs, network topology frequently changes and source-to-destination communication paths can hardly be sustained. However, some social features have been observed in DTNs by analyzing the real mobile trajectories of DTNs. To utilize these social features to facilitate data routing, we present a community-based routing protocol that efficiently detects the community structure by using proposed time-varying community partitioning algorithm. For intracommunity routing, according to the remaining time-to-live of the message, the minimum number of message copies necessary to achieve a given delivery probability is calculated, which is the number of message copies utilized to spray in the current community. To facilitate intercommunity routing, we choose the gateway node that connects the next community frequently as relay. The evaluation of our strategy is conducted by extensive traced-driven simulations. The results of simulations confirm the effectiveness of our routing strategy.