The energy blockchain is a distributed Internet protocol for energy transactions between nodes of a power system. Recent applications of the energy blockchain in microgrids only consider the energy transactions between peers without considering the technical issues that can arise, especially when the system is islanded. One contribution of the paper is, thus, to depict a comprehensive framework of the technical and economic management of microgrids in the blockchain era, considering, for the first time, the provision of ancillary services and, in particular, of the voltage regulation service. When more PV nodes are operating in the grid, large reactive power flows may appear in the branches. In order to limit such flows, a reactive optimal power flow (R-OPF) is solved, setting the voltage at the PV buses as variables within prescribed limits. Each PV generator will thus contribute to voltage regulation, receiving a remuneration included in the transaction and certified by the blockchain technology. For showing how this system can work, a test microgrid, where some energy transactions take place, has been considered. For each transaction, the R-OPF assigns the reactive power to the PV buses. The R-OPF is solved by a Glow-worm Swarm Optimizer. Finally, the paper proposes a method for remuneration of reactive power provision; this method, integrated into the blockchain, allows evaluating the contribution to voltage regulation and increases the transparency and cost traceability in the transactions. The application section shows the implementation of a Tendermint-based Energy transaction platform integrating R-OPF and the above cited technical assessments.

The oscillatory behaviour of the power system is an aspect that is significantly affected by the increasing integration of converter-based generation sources. Several works address the impact of non-synchronous generation on the operation of the system from different points of view, but only a few studies focus on power-frequency oscillations with a prevalence of generation sources interfaced through power electronics. A lack of research can be found in particular in the comparative analysis of the two main control strategies for power converters, namely grid-following and grid-forming. The article aims to contribute to this direction, starting from a theoretical analysis of the two control structures and then examining the case study of an existing transmission system. The research provides a specific insight into the fundamental aspects related to synchronisation mechanism and inertial capabilities of both grid-following with synthetic inertia and grid-forming controls. The difference in the relationship between synchronisation unit and inertial capability is recognised as the fundamental aspect determining the different impacts on the oscillatory characteristics of the system. The observation derived in the theoretical analysis is then applied to an actual power system with a high predominance of converter-based generation, considering the Colombian interconnected national system as a case study.

The design of multi-carrier energy systems (MESs) has become increasingly important in the last decades, due to the need to move towards more efficient, flexible, and reliable power systems. In a MES, electricity, heating, cooling, water, and other resources interact at various levels, in order to get optimized operation. The aim of this study is to identify the optimal combination of components, their optimal sizes, and operating schedule allowing minimizing the annual cost for meeting the energy demand of Pantelleria, a Mediterranean island. Starting from the existing energy system (comprising diesel generators, desalination plant, freshwater storage, heat pumps, and domestic hot water storages) the installation of solar resources (photovoltaic and solar thermal) and electrical storage were considered. In this way, the optimal scheduling of storage units injections, water desalination operation, and domestic hot water production was deduced. An energy hub model was implemented using MATLAB to represent the problem. All equations in the model are linear functions, and variables are real or integer. Thus, a mixed integer linear programming algorithm was used for the solution of the optimization problem. Results prove that the method allows a strong reduction of operating costs of diesel generators also in the existing configuration.

The occurrence of system separations in the power system of Continental Europe has been observed in recent decades as a critical event which might cause power imbalances higher than the reference incident specified per system design, representing an actual challenge for the stability and safe operation of the system. This work presents an analysis and simulations of the primary frequency control in the Continental Europe synchronous area in conditions of system separation. The adopted approach is based on fundamental aspects of the frequency-containment reserve process. The analysis takes an actual event into consideration, which determined the separation of the system in January 2021. The main purpose of the work is the development of specific models and simulations able to reproduce the actual split event. Due to specific arrangements discussed in detail, it is possible to obtain a substantial match between the simulations and the frequencies registered after the system split. The work also provides insight into the importance of the temporal sequence of power imbalances and defensive actions in the primary frequency control process. The models developed in the work are finally used to investigate the separation event under different operating conditions, such as missing defensive actions and low inertia scenarios.

The operation of a power system with 100% converter-interfaced generation poses several questions and challenges regarding various aspects of the design and the control of the system. Existing literature on the integration of renewable energy sources in isolated systems mainly focuses on energy aspects or steady-state issues, and only a few studies examine the dynamic issues of autonomous networks operated with fully non-synchronous generation. A lack of research can be found in particular in the determination of the required amount of grid-forming power, the selection of the number and rated power of the units which should implement the grid-forming controls, and the relative locations of the grid-forming converters. The paper aims to address those research gaps starting from a theoretical point of view and then by examining the actual electrical network of an existing island as a case study. The results obtained from the investigations indicate specific observations and design opportunities, which are essential for securing the synchronization and the stability of the grid. Possible solutions for a fully non-synchronous operation of autonomous systems, in terms of dynamic characteristics and frequency stability, are presented and discussed.