Renewable energy generations have been attracting sustained attentions in academic and industry. Current-fed isolated bidirectional DC/DC converters (CF-IBDCs) are widely adopted in low voltage high current applications such as solar photovoltaic, fuel cell and energy storage. This paper gives an overview and a comprehensive comparative evaluation of CF-IBDCs. The active clamped, dual half-bridge, L-L type dual active bridge, resonant type, naturally clamped and other type topologies of CF-IBDCs are investigated, analyzed and compared regarding their circuit topological structures, characteristics, modulation methods and soft-switching technologies. In addition, component cost models and loss models of converters are deduced and presented. On this basis, quantitative and comprehensive performance comparison of six typical CF-IBDC topologies selected from each type are conducted in terms of costs, losses, weight, volume and power density for the given system specifications and design constraints.

In this paper, the aggregation of electric vehicles (EVs) and fast charging station (FCS) is modeled as a leader-followers game to provide regulation reserves for power systems. The leader of the game is FCS operator, who manages local sources and sets energy/reserve prices for EVs to increase its revenue, with the consideration of uncertain renewable sources and reserves called by the independent system operator. On the other hand, EVs act as the followers to obtain a tradeoff between the benefits from energy consumption and reserves provision, by deciding their charging and reserve strategies. The proposed game is reformulated as a bi-level optimization problem, which is solved by a mathematical programming with equilibrium constraints method. Furthermore, the existence of Stackelberg equilibriums has been proved. Effectiveness of the proposed game is verified by both single-period and multiple-periods simulation study. Simulation results demonstrate that the proposed game can increase the benefits of FCS operator and EVs simultaneously, compared with the centralized management method.

High voltage gain DC-DC converter is a prime requirement for renewable applications, in particular for PV. Though numerous DC-DC converter is available for increasing the voltage gain, the passive elements requirement is higher which reduces the compactness, consequently, increases the cost of the system. To address this issue, a high gain DC-DC converter is reported recently. However, the number of passive elements is quite high which increases the size. To reduce the number of passive elements and maintain the same number of semiconductor devices, in this paper, a new switched inductor arrangement is proposed which is named as switched inductor double switch DC-DC converter (SL-DS-DC). Moreover, the proposed converter has a higher gain as compared to the recently reported converter. The proposed converter is analyzed in steady state and a comparative analysis is presented to prove the suitability. Finally, the proposed converter is validated experimentally.

To realize high efficient energy conversion among multiple energy carriers in market environment, the hybrid AC/DC microgrid (MG) is embedded as the electrical hub for energy hubs (EHs), and a stochastic day-ahead bidding strategy is proposed for the energy hub operators (EHOs). The electricity, heating and cooling are managed to balance the operational cost and thermal service quality, while participating into the dayahead market and real-time market. The uncertainties of prices, electrical loads and ambient temperature are depicted by scenario trees, and are managed by a two-stage stochastic optimization scheme to minimize the expected and conditional value at risk of operational cost. This stochastic optimization problem is reformulated to a linear programming (LP) problem under given conditions. In addition, a chance constraint is proposed to relax the quality of thermal services, and a two-stage chance constrained stochastic programming is formulated accordingly. It is further reformulated to a mixed integer LP problem. Simulations have been carried out on an EH with multiple types of energy generation, conversion and storage systems. Results have verified the effectiveness of proposed method, providing efficient bidding curves to the EH though the stochastic management. Sensitive analysis shows the proposed strategy can balance the operational cost and service quality via the adjustment of chance constraints.

This article proposes a new bidirectional isolated LLC resonant converter, which is suitable for ultra-wide voltage gain range applications, such as electric vehicle charging systems. The inverter and rectifier of proposed topology both have two modes by reconfiguring different modulation schemes during bidirectional operation. This results in three voltage-gain ranges, allowing ultrawide output voltage operation over narrow modulation frequency. The conversion ratio and resonant tank can be designed for only a quarter of the required output voltage range. Finally, the proposed topology and analysis are validated by experiments results obtained from the converter prototype built in the laboratory.

For several reasons, particularly due to the mismatch in the feeder impedance, accurate power sharing in islanded microgrids is a challenging task. To get around this problem, a distributed event-triggered power sharing control strategy is proposed in this article. The suggested technique adaptively regulates the virtual impedances at both fundamental positive/negative sequence and harmonic frequencies and, therefore, accurately share the reactive, unbalanced, and harmonics powers among distributed generation units. The proposed method requires no information of feeder impedance and involves exchanging information among units at only event-triggered times, which reduces the communication burden without affecting the system performance. The stability and interevent interval are analyzed in this article. Finally, experimental results are presented to validate the effectiveness of the proposed scheme.