• Energy Research

The rapid increase of electric vehicles (EVs) penetration represents an important challenge for the distribution system operator (DSO). The main issues arise not only from an optimal grid expansion planning point of view but also for managing the system in the near future. The paper focuses on a short-term period EV penetration scenario and proposes a mechanism of EV charging sessions rescheduling in order to mitigate grid congestions. The collaboration between three actors, namely the DSO, the fleet manager and the end user, allows the DSO to identify rescheduling programs in order to face overload events, that represent the most important issue for the grid caused by the widespread penetration of EVs. The IEEE 33-bus test system is used to check the potential of the proposed mechanism. Load flow simulations show that more than 50% of congestions are avoided by means of this approach. The promising results constitute a base case for a future work in which the optimal rescheduling program would be investigated.

Many private and public companies are moving towards fleet electrification; this new trend is significantly fostered by public strategies about decarbonization, market conditions and companies' policies for reducing their carbon footprint. Nevertheless, the impact of the electrical fleet on logistics and electrical consumptions has not been extensively evaluated in the literature. This paper aims to assess these impacts considering the data of an existing traditional fleet. The presented model takes into account several parameters and conditions and it validates different policies and design solutions. The results show that the proposed solutions would enable company managers painlessly adopting electric vehicles in their fleets.

Hydrogen aroused a great interest in the last decades as a promising energy vector for the energy transition as well as renewable energy storage. This article investigates the technical feasibility of a hydrogen-powered fleet, in the context of a microgrid with renewable generation. The hydrogen demand is satisfied through the electrolyser powered by local RES and periodical external refueling of a local hydrogen storage system. The model of the microgrid is implemented in the open-source GNU Octave environment and is exploited to size the local storage capacity. Different types of vehicles were considered and hydrogen pressure levels were distinguished among the system components. The model was applied to the waste collection fleet and the headquarters of ASM S.p.A., a utility located in the center of Italy, chosen as a case study. The dataset of 143 vehicles was used to model the hydrogen-powered fleet. Three scenarios were evaluated: hydrogen production using i) Reverse Power Flow, ii) PV production and iii) electricity drown from the grid. The storage capacity depends on the scenarios and in the case study it ranges from about 35 to 47 m 3 , in comparison with 13.6 m 3 of current diesel refueling system, assuming the same frequency of external refueling.

The penetration of e-mobility is growing thanks to the European guidelines on climate preservation regarding the reduction in CO2 emission. Governments are adapting their economic policies with the aim to incentivize e-mobility. At the same time, with a view to equality and accessibility, countries are working to introduce e-mobility services also for people with disabilities in order to improve the quality of their lives. The paper reports the deployment of an e-mobility service for persons with disabilities carried out in a project financed by Sapienza University of Rome. The project includes a feasibility study and a cost–benefit analysis in order to identify the optimal solution from a technical and environmental point of view for a sustainable e-mobility service for people with reduced mobility. A methodology to design a service based on optimal routes and electric vehicles with respect to energy consumption, time travel, energy and vehicle costs and quality of service is proposed. The 5-step methodology calculates the most energy-efficient routes and defines the optimal charging schedule, taking into account charging points dislocated along the routes and choosing vehicle typologies with the best performance based on economic evaluations. A software was developed to automatize the methodology.

The paper suggests a 3-steps methodology, integrated in a unique-procedure, to optimally design a hybrid RPP (Renewable Power Plant) to be installed in the available areas of railway's power plants. The procedure takes into account power profiles and time schedule of trains, traction line's features, sizing and siting of TPSSs (Traction Power Substations) and features of renewable sources as PV (Photovoltaic) and wind turbines for optimizing the siting of the RPP, considering the investment convenience. The optimal sizing of a hybrid power plant is based on mixed-integer linear programming (MILP) taking into account the energy absorbed by TPSSs, the physical and geometric constraints and the operating and maintenance costs of RPP. The integrated procedure has been tested on a real case study regarding a new 3 kV DC railway located in the South of Italy. The main results show that a hybrid RPP with 4980 PV panels and 3 wind turbines installed in a TPSS area, adopting a capital cost of 645,000 /MW for PV panels and 3000 /kW for wind farms, ensures an annual revenue of 227,439 , with a total investment of 897,400 . Results show that the available areas in TPSS should be the target of relevant investments to support a new sustainable and green power traction supply system.

Sustainable Energy, Grids and Networks Volume 32, December 2022, 100899 Sardinia as a 100% renewable power system: A frequency stability study Author links open overlay panelFedericoCarereLudovicoNati https://doi.org/10.1016/j.segan.2022.100899 Get rights and content Abstract This paper investigates a real complex power system supplied by a 100% renewable generation, focusing on the primary frequency regulation. The grid and the power production park are represented by means of an electro-mechanical model in a free open-source environment. The lack of synchronous generators in the grid, due to the conventional power plants shutdowns, requires higher performances from renewable power plants (RPPs) in terms of synchronization and inertial response. Doubly fed induction generators (DFIGs) are identified as the promising power plants able to lessen inertial issues. DFIG system control is investigated in the present paper, according to the recent studies in the literature, implementing a new strategy of control in case of avoiding maximum power point tracker (MPPT) operation. The 100% renewable 112-bus Sardinia islanded power system is the case study of this paper. Four scenarios were selected to show the primary frequency response in the most critical under and upper frequency events among the year. The simulations revealed that the most severe frequency nadir in the simulation reached a decrease of 0.37 Hz. DFIGs control system appeared robust in terms of inertial response and capability of reaching new stable operating point.

During an extraordinary event, like the COVID19 pandemic, very rapid changes in consumption profiles and customers behaviors were recorded. This paper investigates the impact of the lockdown on load and production in the distribution system of Terni. From a DSO point of view, no relevant issues were encountered to be faced. The distributed power generation from renewable resources did not affect relevant issues, maintaining the typical annual generation profiles. A domestic consumption increase was replaced by more relevant decrease of industrial processes and commercial activities absorptions. More than 25,000 domestic users increased their consumptions in April 2020 and the overall consumption of domestic customers in March was 1,05 times higher than the 2015 respectively consumption. The power flows at primary substations reveal a relevant electric demand reduction for each point of connection with the high voltage transmission system; especially bar 1 and 2 of the most relevant Terni primary substation, recorded a 15.3% decrease with respect to March 2019, and a 24.25% decrease with respect to April 2019.

Large-scale deployment of renewable energy sources brings new challenges for smart grid management requiring the development of decentralized solutions and active participation of prosumer and non-grid-owned assets. Local energy flexibility markets can help in monitoring energy flows, motivate changes in prosumers’ energy supply and demand, achieving local energy balance, and optimization of electricity flows. In this paper, we propose a blockchain-based decentralized energy flexibility market enabling small-scale prosumers to trade in a peer-to-peer fashion their flexibility in terms of load modulation concerning the baseline energy profiles. We have defined an energy flexibility token for digitizing the flexibility of prosumers allowing to be traded on the market as an asset and self-enforcing smart contracts for decentralized market operation including functions such as the placement of flexibility bids/offers, trading session management, or energy and financial settlement of energy flexibility transactions. For matching the flexibility bids and offers, a solution based on a greedy heuristic and a bipartite graph is proposed for minimizing the number of flexibility transactions and reducing the blockchain-associated costs, while Oracles are used to assure its secure integration with the blockchain. The blockchain-based flexibility market was validated with the help of the Terni city Distribution System Operator, showing promising results in enabling the self-consumption of renewable energy generated in a small scale urban micro-grid considering live energy monitoring data, and in assuring the local balancing of the demand side in a simulated environment considering many market participants and historical energy data.