Thermal energy systems (TES) contribute to the on-going process that leads to higher integration among different energy systems, with the aim of reaching a cleaner, more flexible and sustainable use of the energy resources. This paper reviews the current literature that refers to the development and exploitation of TES-based solutions in systems connected to the electrical grid. These solutions facilitate the energy system integration to get additional flexibility for energy management, enable better use of variable renewable energy sources (RES), and contribute to the modernisation of the energy system infrastructures, the enhancement of the grid operation practices that include energy shifting, and the provision of cost-effective grid services. This paper offers a complementary view with respect to other reviews that deal with energy storage technologies, materials for TES applications, TES for buildings, and contributions of electrical energy storage for grid applications. The main aspects addressed are the characteristics, parameters and models of the TES systems, the deployment of TES in systems with variable RES, microgrids, and multi-energy networks, and the emerging trends for TES applications.

Load pattern clustering based on the shape of the electricity consumption is a key tool to provide enhanced knowledge on the nature of the consumption and assist meaningful customer partitioning. This paper presents new developments to group the load patterns using an initial set of centroids specified according to a user-defined centroid model. The original Electrical Pattern Ant Colony Clustering (EPACC) algorithm is illustrated, highlighting its characteristics and parameters, with centroids evolution during the iterative process until stabilization. The EPACC results are compared with those obtained from the classical k-means algorithm to group the representative load patterns taken from a set of non-residential customers in typical weekdays.

In this paper, the notion of reliability assessment for distribution system applications is revisited to include a number of practices emerging in the smart grid context. The information on the variations in time of generation and demand is taken into account to establish a reference network configuration that considers the definition of an intraday reconfiguration strategy based on conventional load profiles for different categories of demand (residential, industrial, and commercial). After a fault, the service restoration process is aided by the formation of autonomous islanded subsystems (microgrids). During the restoration period, each subsystem is able to serve the local demand in a given portion of the network and to reconnect to the main network through proper synchronization. Dedicated solutions for mobile generation and storage are exploited to reach the nodes needing additional supply. A sequential Monte Carlo method is used to carry out reliability assessment. The use of this method incorporates the effects of interfering near-coincident faults and time-varying load and local generation patterns. The application on a real distribution network is presented, showing the probability distributions of the reliability indicators (power and energy not supplied), as well as the breakdown of these indicators for different demand categories.

With the increase in the electrical load and the progressive introduction of power generation from intermittent renewable energy sources, the power line operating conditions are approaching the thermal limits. The definition of thermal limits variable in time has been addressed under the concept of dynamic thermal rating (DTR), with which it is possible to provide a more detailed assessment of the line rating and exploit the electrical system more flexibly. Most of the literature on DTR has addressed overhead lines exposed to different weather conditions. The interest in the dynamic thermal rating of power cables is increasing, considering the evolution of computational methods and advanced systems for cable monitoring. This paper contains an overview of the concepts and methods referring to dynamic cable rating (DCR). Starting from the analytical formulations developed many years ago for determining the power cable rating in steady-state conditions, also reported in International Standards, this paper considers the improvements of these formulations proposed during the years. These improvements are leading to include more specific details in the models used for DCR analysis and the computational methods used to assess the power cable’s thermal conditions buried in soil. This paper is focused on highlighting the path from the initial theories and models to the latest literature contributions. Attention is paid to thermal modelling with different levels of detail, applications of 2D and 3D solvers and simplified models, and their validation based on experimental measurements. A salient point of the overview is considering the DCR impact on reliability aspects, risk estimation, real-time calculations, forecasting, and planning with different time horizons.

The paper’s main objective is to demonstrate the trading and flexibility of services amongst TSOs, DSOs, and Prosumers in a transparent, secure, and cost-effective manner using Blockchain-based TSO-DSO flexibility marketplace (EFLEX). The aim is to look for ways to help DSOs/TSOs be more flexible and more directly engaged in managing energy flows on the network. EFLEX will streamline the needs of both TSO and DSO on the same platform. Based on the paper’s proposed services, the pilot service demonstration will be carried out in Bulgaria and Romania, and the main focus will be on congestion management, TSO-DSO Coordination, and Marketplace. The proposed objective is achieved by using Blockchain-based smart contracts and distributed ledger technology.

Unbalance of the three-phase currents in photovoltaic (PV) systems may depend on structural aspects of the installation, the effect of partial shading, or both. In this paper, a number of unbalance indicators are calculated starting from data that are measured during experimental analyses on a real building-integrated PV system that represents different types of unbalance. Detailed information is obtained from indices that identify the balance and unbalance components that are also in the presence of waveform distortion. These indices extend the current definitions of unbalance given in the power quality standards. The results show that the unbalance cannot be considered negligible, even with no single-phase inverters and is more significant if nonlinear loads add a contribution to both harmonic distortion and unbalance seen from the distribution transformer.