Integrated voltage control and line congestion management in Active Distribution Networks by means of smart transformers

Within the context of Active Distribution Networks (ADNs), smart transformers represent very powerful devices able to provide fast and efficient control actions with respect to different ADNs ancillary services. This paper discusses the benefits, in terms of ADNs voltage and line flows controls, achieved by interfacing distributed generators with the power grid by means of a smart transformer. Among several benefits, these devices allow for a phase-per-phase control of the generators active and reactive power injections. This peculiarity enables to deploy new control schemes that are analyzed and discussed in the paper with reference to a case study based on a modified IEEE 34 node test distribution feeder

Embedded intelligence for electrical network operation and control

Integrating multiple types of intelligent, mulitagent data analysis within a smart grid can pave the way for flexible, extensible, and robust solutions to power network management

Active congestion quantification and reliability improvement considering aging failure in modern distribution networks

The enormous concerns of climate change and traditional resource crises lead to the increased use of distributed generations (DGs) and electric vehicles (EVs) in distribution networks. This leads to significant challenges in maintaining safe and reliable network operations due to the complexity and uncertainties in active distribution networks, e.g., congestion and reliability problems. Effective congestion management (CM) policies require appropriate indices to quantify the seriousness and customer contributions to congested areas. Developing an accurate model to identify the residual life of aged equipment is also essential in long-term CM procedures. The assessment of network reliability and equipment end-of-life failure also plays a critical role in network planning and regulation. The main contributions of this thesis include a) outlining the specific characteristics of congestion events and introducing the typical metrics to assess the effectiveness of CM approaches; b) proposing spatial, temporal and aggregate indices for rapidly recognizing the seriousness of congestion in terms of thermal and voltage violations, and proposing indices for quantifying the customer contributions to congested areas; c) proposing an improved method to estimate the end-of-life failure probabilities of transformers and cables lines taking real-time relative aging speed and loss-of-life into consideration; d) quantifying the impact of different levels of EV penetration on the network reliability considering end-of-life failure on equipment and post-fault network reconfiguration; and e) proposing an EV smart charging optimization model to improve network reliability and reduce the cost of customers and power utilities. Simulation results illustrate the feasibility of the proposed indices in rapidly recognizing the congestion level, geographic location, and customer contributions in balanced and unbalanced systems. Voltage congestion can be significantly relieved by network reconfiguration and the utilization of the proposed indices by utility operators in CM procedures is also explained. The numerical studies also verify that the improved Arrhenius-Weibull can better indicate the aging process and demonstrate the superior accuracy of the proposed method in identifying residual lives and end-of-life failure probabilities of transformers and conductors. The integration of EV has a great impact on equipment aging failure probability and loss-of-life, thus resulting in lower network reliability and higher cost for managing aging failure. Finally, the proposed piecewise linear optimization model of the EV smart charging framework can significantly improve network reliability by 90% and reduce the total cost by 83.8% for customers and power utilities

Ancillary Services in Hybrid AC/DC Low Voltage Distribution Networks

In the last decade, distribution systems are experiencing a drastic transformation with the advent of new technologies. In fact, distribution networks are no longer passive systems, considering the current integration rates of new agents such as distributed generation, electrical vehicles and energy storage, which are greatly influencing the way these systems are operated. In addition, the intrinsic DC nature of these components, interfaced to the AC system through power electronics converters, is unlocking the possibility for new distribution topologies based on AC/DC networks. This paper analyzes the evolution of AC distribution systems, the advantages of AC/DC hybrid arrangements and the active role that the new distributed agents may play in the upcoming decarbonized paradigm by providing different ancillary services.Ministerio de Economía y Competitividad ENE2017-84813-RUnión Europea (Programa Horizonte 2020) 76409

Pregled različitih tehnologija upravljanja naprednim mrežama za povećanje fleksibilnosti elektroenergetskih sustava i omogućavanje masovne integracije obnovljivih izvora energije

Over the last 15 years, major changes have taken place in the electricity sector. A significant increase in the share of renewable energy sources (RES) with variable generation, followed by the decommissioning of conventional power plants based on fossil fuels, has dramatically changed the way of the power system (EPS) operation. During this time, there has been inadequate and untimely investment in the transmission infrastructure. This occurred partly due to the lack of funding, and partly due to the climate change and the rising environmental awareness, as well as the influence of green activists making it difficult to obtain permits to build electrical grid facilities. Additionally, electricity consumption is steadily increasing due to population growth in the undeveloped and developing countries, and due to the rising living standard in the developed countries. Therefore, global electricity consumption is expected to triple by 2050. To meet the new demands, Transmission System Operators (TSOs) are deploying advanced transmission technologies based on a comprehensive application of information and communication solutions. These technologies increase the capacity, efficiency, and reliability of both the existing and new elements of the transmission system. These solutions applied vary from system to system and depend on many influencing factors. The application of these advanced technologies is particularly important for congestion management, as the power system operates closer and closer to stability limits, increasing the risk of collapse. The paper describes the technologies that transform the existing network into smart grids, primarily from the point of view of increasing the capacity of the existing infrastructure through different smart grid investments.U posljednjih 15 godina u elektroenergetskom sektoru dogodile su se velike promjene. Značajno povećanje udjela obnovljivih izvora energije (OIE) s varijabilnom proizvodnjom, praćeno gašenjem konvencionalnih elektrana na fosilna goriva, dramatično je promijenilo način rada elektroenergetskog sustava (EES). Tijekom tog vremena bilo je neodgovarajućih i nepravovremenih ulaganja u prijenosnu infrastrukturu. To se dogodilo dijelom zbog nedostatka financijskih sredstava, a dijelom zbog klimatskih promjena i porasta ekološke svijesti, kao i utjecaja zelenih aktivista koji su otežali dobivanje dozvola za izgradnju energetskih objekata. Osim toga, potrošnja električne energije u stalnom je porastu zbog rasta stanovništva u nerazvijenim zemljama i zemljama u razvoju te zbog povećanja životnog standarda u razvijenim zemljama. Stoga se očekuje da će se globalna potrošnja električne energije utrostručiti do 2050. Kako bi zadovoljili nove zahtjeve, operatori prijenosnih sustava (TSO) uvode napredne tehnologije prijenosa temeljene na sveobuhvatnoj primjeni informacijskih i komunikacijskih rješenja. Ove tehnologije povećavaju kapacitet, učinkovitost i pouzdanost postojećih i novih elemenata prijenosnog sustava. Ova primijenjena rješenja razlikuju se od sustava do sustava i ovise o mnogim utjecajnim čimbenicima. Primjena ovih naprednih tehnologija posebno je važna za upravljanje zagušenjima jer elektroenergetski sustav radi sve bliže i bliže granicama stabilnosti, povećavajući rizik od njegovog sloma. U radu su opisane tehnologije koje transformiraju postojeću mrežu u napredne elektroenergetske mreže, prvenstveno sa stajališta povećanja kapaciteta postojeće infrastrukture kroz različite investicije u napredne tehnologije

Review on distribution network optimization under uncertainty

With the increase of renewable energy in electricity generation and increased engagement from demand sides, distribution network planning and operation face great challenges in the provision of stable, secure and dedicated service under a high level of uncertainty in network behaviors. Distribution network planning and operation, at the same time, also benefit from the changes of current and future distribution networks in terms of the availability of increased resources, diversity, smartness, controllability and flexibility of the distribution networks. This paper reviews the critical optimization problems faced by distribution planning and operation, including how to cope with these changes, how to integrate an optimization process in a problem-solving framework to efficiently search for optimal strategy and how to optimize sources and flexibilities properly in order to achieve cost-effective operation and provide quality of services as required, among other factors. This paper also discusses the approaches to reduce the heavy computation load when solving large-scale network optimization problems, for instance by integrating the prior knowledge of network configuration in optimization search space. A number of optimization techniques have been reviewed and discussed in the paper. This paper also discusses the changes, challenges and opportunities in future distribution networks, analyzes the possible problems that will be faced by future network planning and operations and discusses the potential strategies to solve these optimization problems

A unified control strategy for active distribution networks via demand response and distributed energy storage systems

AbstractAs part of the transition to a future power grid, distribution systems are undergoing profound changes evolving into Active Distribution Networks (ADNs). The presence of dispersed generation, local storage systems and responsive loads in these systems incurs severe impacts on planning and operational procedures. This paper focuses on the compelling problem of optimal operation and control of ADNs, with particular reference to voltage regulation and lines congestion management. We identify the main challenges and opportunities related to ADNs control and we discuss recent advances in this area. Finally, we describe a broadcast-based unified control algorithm designed to provide ancillary services to the grid by a seamless control of heterogeneous energy resources such as distributed storage systems and demand-responsive loads

ESTABLISHMENT OF THE SECOND LIST OF UNION PROJECTS OF COMMON INTEREST: EVALUATION OF CANDIDATE PROJECTS OF COMMON INTEREST IN THE FIELD OF SMART GRIDS

The document presents the outcome of the evaluation process of candidate Projects of Common Interest in the area of Smart Grids, under the trans-European energy infrastructure regulation. The evaluation follows the guidelines of the assessment framework for Smart Grid projects, developed by the JRC within the EC Smart Grid Task Force.JRC.F.3-Energy Security, Systems and Marke