Grid stability and supply security need to be maintained when generation and consumption mismatches occur. A potential solution to this problem could be using Energy Storage Technologies (EST). Since many alternatives exist, appropriate technology selection becomes a key challenge. Current research focuses on ranking and selecting the most suitable technology, regardless of the grid services to be provided. In this study, a multi-criteria decision making (MCDM) problem is formulated considering fifteen selection criteria and the opinions of five energy storage experts groups. Literature and expert consultation data have been converted to triangular fuzzy (TF) numbers to cope with ambiguity and heterogeneity and eighteen technologies have been ranked applying the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method. The proposed method has been implemented on a software tool and assessed in four representative microgrid services of interest for the ENERISLA Project. The results show that pump hydro storage is the most suitable EST for frequency regulation, time shifting and seasonal storage applications, while flywheels best suit inertial response. It is concluded that the proposed methodology provides an intuitive framework for EST selection under multi-agent uncertainty and different grid application scenarios.

Due to a greater social and environmental awareness of citizens, advantageous regulations and a favourable economic return on investment, the presence of photovoltaic (PV) installations in distribution grids is increasing. In the future, not only a significant increase in photovoltaic generation is expected, but also in other of the so-called distributed energy resources (DER), such as wind generation, storage, electric vehicle charging points or manageable demands. Despite the benefits posed by these technologies, an uncontrolled spread could create important challenges for the power system, such as increase of energy losses or voltages out-of-limits along the grid, for example. These issues are expected to be more pronounced in low voltage (LV) distribution networks. This article has two main objectives: proposing a method to calculate the LV distributed photovoltaic generation hosting capacity (HC) that minimizes system losses and evaluating different management techniques for solar PV inverters and their effect on the hosting capacity. The HC calculation is based on a mixture of deterministic methods using time series data and statistical ones: using real smart meters data from customers and generating different combinations of solar PV facilities placements and power to evaluate its effect on the grid operation.

Vehicle-to-Grid chargers (V2Gs) are currently considered a key component for supporting future power systems in primary and especially secondary frequency regulation. Most of the research works conducted so far on this topic are based on a vehicle-centric perspective, whereas global approaches where the impact caused by fleets of V2Gs is studied from the perspective of an entire electric grid remain quite unexplored. In particular, the effects of aggregating different amounts of V2Gs from the HV, MV and LV subgrids to participate in frequency control represents a novel aspect to be investigated, which is expected to possess a strong potential for further improving the aggregation processes. To this end, this work presents a “global working framework” developed to evaluate the impact on an entire electric system of V2Gs participation in frequency regulation. A reality-based electric network is considered, where two HV, three MV and ten LV subgrids are interconnected. The effects of four different percentages of V2Gs aggregated from the HV, MV and LV subgrids are evaluated for two V2G installed capacities, 10 MW and 20 MW. Results are finally analyzed, including frequency vs time response, rate of change of frequency, grid losses, etc., and valuable knowledge, insights and guidelines are obtained for guiding future grid-level aggregation optimizations of V2Gs participation in frequency regulation.

This paper gathers experiences and results from several demonstration projects in the field of grid integration of electric vehicles. The analyzed research projects are selected among research institutes and universities that are part of the European Energy Research Alliance Joint Program on Smart Grids. The paper provides an overview of recent trends in the field of electric vehicles integration issues and then dives deeper into specific aspects of each project. Twelve research projects are presented in general terms, while detailed information can be retrieved from the references and the websites. Although each project has its focus, a common element that can be devised is that the charging process can be technically controlled based on different interests and algorithms, but its role in the market is still under development. Particular focus is always given to the behavior of the user, which ultimately determines the possible level of flexibility that the electric vehicle can provide to the grid.

In low-voltage grids with a wide spread of domestic and/or small commercial consumers, mostly single-phase, problems can appear due to unbalanced power consumption between the different phases. These problems are mainly caused due to voltage unbalances between phases and the increase in distribution losses. This phenomenon occurs more frequently at the end of highly radial grids and can be stressed by the installation of renewable generators next to the consumers. Amongst the various techniques that have been proposed to solve this problem, this article explores the use of a D-STATCOM, presenting and testing a new method for the optimal location of this type of D-FACT. The developed method starts from a detailed analysis of the existing voltage unbalances in a distribution network and identifies the optimal location of the D-STATCOM (i.e., the one that reduces these unbalances while reducing energy losses). The developed method has been successfully tested for one year at four real European locations with different characteristics and different kinds of users.