A review on economic and technical operation of active distribution systems

© 2019 Elsevier Ltd Along with the advent of restructuring in power systems, considerable integration of renewable energy resources has motivated the transition of traditional distribution networks (DNs) toward new active ones. In the meanwhile, rapid technology advances have provided great potentials for future bulk utilization of generation units as well as the energy storage (ES) systems in the distribution section. This paper aims to present a comprehensive review of recent advancements in the operation of active distribution systems (ADSs) from the viewpoint of operational time-hierarchy. To be more specific, this time-hierarchy consists of two stages, and at the first stage of this time-hierarchy, four major economic factors, by which the operation of traditional passive DNs is evolved to new active DNs, are described. Then the second stage of the time-hierarchy refers to technical management and power quality correction of ADSs in terms of static, dynamic and transient periods. In the end, some required modeling and control developments for the optimal operation of ADSs are discussed. As opposed to previous review papers, potential applications of devices in the ADS are investigated considering their operational time-intervals. Since some of the compensating devices, storage units and generating sources may have different applications regarding the time scale of their utilization, this paper considers real scenario system operations in which components of the network are firstly scheduled for the specified period ahead; then their deviations of operating status from reference points are modified during three time-intervals covering static, dynamic and transient periods

Analysis of measures to increment the share of renewable energy in distribution grids

The actual power system is undergoing a period of transformation. The introduction of renewable energy power parks in the grid started the transition from a high voltage connected generation model towards a model where part of the generation assets will be connected to medium and even low voltage grids. Furthermore, the fast-changing world of technology is starting to allow passive users to generate and manage electricity, and thus, take a new position towards the grid. This transformation entails new opportunities and challenges for a power system that was initially thought to be vertically integrated and with unidirectional power flows. Europe is already giving its directives to ease the transition towards a more decentralized power system; however, some member states are faster than others when transposing them. Taking advantage of the different speeds between member states, this thesis aims to analyse and compare those pioneering regulatory frameworks in terms of renewable energy sources connection to distribution grids. This should allow the thesis to identify which kind of measures are the best ones to increase the share of renewable energy sources. In order to carry out the research, a systematic review of technical and energy policy articles has been carried out consulting the ScienceDirect, the IEEE Xplore, and the ResearchGate databases, together with European directives and regulations in the field of energy policies and member states network codes for connection of generation assets. The core of the thesis is based on a few institutions and documents which we would like to highlight. To set the technical basis of the impact of renewable energy sources, the book Integration of Distributed Generation in the Power System has been used. In terms of conceptualizing the regulatory framework the Florence School of Regulation technical reports The EU Electricity Network Codes and the Clean Energy Package are essential to this thesis together with the European energy e-Directive and e-Regulation. The report The smartEn Map: European Balancing Markets Edition (2018) published by smartEn has been used as a reference point to study the state of the art of balancing markets. Finally, the network codes for Low Voltage Grid Connection of Generators from Italy, Germany and Denmark are the base for the development of the energy storage section. The European directives and regulations point towards a market-based approach to overcome the challenges and benefit from the opportunities that the transition towards a distributed power system will create. The thesis go from a holistic view, considering the new European guidelines, to a study of those member states that are already half-way on their transition towards a distributed power system based on renewable energy sources. This is will give an overview of the current regulatory framework and find the main outlines of the forthcoming one. Finally, comment that one of the outcomes of the research carried out during the thesis is the participation in the conference paper "RESOlvD: ICT services and energy storage for increasing renewable hosting capacity in LV distribution grids". The paper has been approved for publication, and it can be partially consulted in the Annex A of the thesis

Impact of Electrolysers on the Network

The “Impact of Electrolysers on the Distribution Network” project was commissioned to establish if it is possible to manage the production of hydrogen by electrolysis such that the need for network reinforcement is reduced, delayed or removed, and also to investigate the impact on renewable generation output where electrolysers are integrated with renewable technologies. Scottish and Southern Electricity Networks (SSEN) operated as a partner in the Aberdeen Hydrogen Bus Project which included the design, construction and operation of a Hydrogen Refuelling Station (HRS) located in the Kittybrewster area of Aberdeen.SSEN developed a control system to run trials on the Kittybrewster HRS. Through the trials a series of network scenarios were simulated including demand‐constrained and generation constrained networks. The capacity of the electrolysers to operate flexibly in response to network, generation, and economic signals was also investigated and the outcomes of these trials are contained in this report. Through the development and implementation of these trials it was important to recognise that as the HRS is a fully operational site, the key and overriding requirement was to ensure that enough hydrogen was available to meet the refuelling needs of the ten hydrogen fuel cell buses that were operating across Aberdeen as part of the Aberdeen Hydrogen Bus Project