The development of power systems and the move to smart grid have increased the need for new technologies. In this regard, solid-state transformers have been proposed as a suitable alternative to conventional transformers. Solid-state transformers are among the equipment based on power electronic converters that in addition to better performance than conventional transformers provide a variety of other services. In this article, the concept and types of solid-state transformer topologies and configurations and their applications, especially in smart grid, are investigated. Studies show that the various characteristics of solid-state transformers have led to much consideration as potential transformers in smart grid applications, the integration of distributed generation sources, modern traction systems, and so on.

This study aims to provide a comprehensive review of various superconducting fault current limiters (SFCLs) configurations. Regarding the applied technology, the different types of SFCLs are classified into three groups including quench‐type SFCL, non‐quench‐type SFCL, and composite‐type SFCL. Resistive‐type SFCL, hybrid‐type SFCL, magnetic‐shielded iron‐core‐type SFCL, superconducting fault current limiting transformer, transformer‐type SFCL, flux‐lock‐type SFCL, saturated iron‐core‐type SFCL, and resonance‐type SFCL are some of the investigated structures. The structures are fully surveyed in terms of operating principle, technical feasibility, and recent advancements. The study is performed based on published information in papers, reports, and other available online documents. It is expected that this study provides a fundamental foundation for researchers and companies to become familiar with different types of SFCLs. It would be useful to help further studies about the development and the implementation of SFCL for real power systems.

This study presents a model for the activities of the price‐maker microgrid aggregator (MGA). In this model, an MGA is considered to aggregate several microgrids (MGs) and be in charge of obtaining an optimal bidding strategy for MGs as well as scheduling their resources and demand. Two price‐maker strategies (the marginal and non‐marginal strategies for players) are proposed and the robust scheduling and optimal transactions of a price‐taker MGA are also obtained in order to analyse different bidding behaviour of MGA. A robust optimisation is used in this model in order to capture uncertainties associated with renewable generation in the worst‐case situation. Accordingly, the robust solution is obtained for the optimal scheduling of an MGA participating in the pool‐based day‐ahead electricity market. The proposed robust bidding strategies and scheduling of a price‐maker MGA are obtained considering a hypothetical test system and the results are compared with the bidding strategy and robust scheduling of a price‐taker MGA. The results show that the robust scheduling and also the market prices are completely changed for different strategies of the MGA. Also, using the proposed model for the price‐maker MGA increases the profits of MGs.

According to the increasing penetration of microgrids (MGs) in power systems, the design and implementation of these new emerged structures are under the question of planners, operators, and investors of electrical energy sector. This paper aims at finding a response for this question to present a game based model under a competitive market for long-term multiperiod planning of a distribution network containing several MGs, such that it can model the impact of decision making of the distribution system operator (DSO) on the MG investor and vice versa, also improve MG allocation algorithms. To achieve this, a mixed-integer nonlinear bilevel programming (MINBLP) is employed, where in the external level, DSOs objectives and in the internal level, MGs objectives are optimized based on the dictation by DSO. Since solving this type of problems by employing the conventional tools is almost impossible, so a mathematical method is utilized to convert this problem to a standard form. In the proposed method, using the reformulation and linearization, the available binary variables are transformed to a continuous form and then are linearized.