3,136 research outputs found
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 EconomĂa y Competitividad ENE2017-84813-RUniĂłn Europea (Programa Horizonte 2020) 76409
Impact of operation strategies of large scale battery systems on distribution grid planning in Germany
Due to the increasing penetration of fluctuating distributed generation electrical grids require reinforcement, in order to secure a grid operation in accordance with given technical specifications. This grid reinforcement often leads to over-dimensioning of the distribution grids. Therefore, traditional and recent advances in distribution grid planning are analysed and possible alternative applications with large scale battery storage systems are reviewed. The review starts with an examination of possible revenue streams along the value chain of the German electricity market. The resulting operation strategies of the two most promising business cases are discussed in detail, and a project overview in which these strategies are applied is presented. Finally, the impact of the operation strategies are assessed with regard to distribution grid planning.Postprint (author's final draft
Photovoltaic Power Converter Management in Unbalanced Low Voltage Networks with Ancillary Services Support
TEC2016-77632-C3-1-R (AEI/FEDER, UE)
Sem PDF conforme despacho.The proliferation of residential photovoltaic (PV) prosumers leads to detrimental impacts on the low-voltage (LV) distribution network operation such as reverse power flow, voltage fluctuations and voltage imbalances. This is due to the fact that the strategies for the PV inverters are usually designed to obtain the maximum energy from the panels. The most recent approach to these issues involves new inverter-based solutions. This paper proposes a novel comprehensive control strategy for the power electronic converters associated with PV installations to improve the operational performance of a four-wire LV distribution network. The objectives are to try to balance the currents demanded by consumers and to compensate the reactive power demanded by them at the expense of the remaining convertersâ capacity. The strategy is implemented in each consumer installation, constituting a decentralized or distributed control and allowing its practical implementation based on local measurements. The algorithms were tested, in a yearly simulation horizon, on a typical Portuguese LV network to verify the impact of the high integration of the renewable energy sources in the network and the effectiveness and applicability of the proposed approach.publishersversionpublishe
Planning Tools for the Integration of Renewable Energy Sources Into Low- and Medium-Voltage Distribution Grids
This chapter presents two probabilistic planning tools developed for the long-term analysis of distribution networks. The first one focuses on the low-voltage (LV) level and the second one addresses the issues occurring in the medium-voltage (MV) grid. Both tools use Monte Carlo algorithms in order to simulate the distribution network, taking into account the stochastic nature of the loading parameters at its nodes. Section 1 introduces the probabilistic framework that focuses on the analysis of LV feeders with distributed photovoltaic (PV) generation using quarter-hourly smart metering data of load and generation at each node of a feeder. This probabilistic framework is evaluated by simulating a real LV feeder in Belgium considering its actual loading parameters and components. In order to demonstrate the interest of the presented framework for the distribution system operators (DSOs), the same feeder is then simulated considering future scenarios of higher PV integration as well as the application of mitigation solutions (reactive power control, P/V droop control thanks to a local management of PV inverters, etc.) to actual LV network operational issues arising from the integration of distributed PV generation. Section 2 introduces the second planning tool designed to help the DSO, making the best investment for alleviating the MV-network stressed conditions. Practically, this tool aims at finding the optimal positioning and sizing of the devices designed to improve the operation of the distribution grid. Then a centralized control of these facilities is implemented in order to assess the effectiveness of the proposed approach. The simulation is carried out under various load and generation profiles, while the evaluation criteria of the methodology are the probabilities of voltage violation, the presence of congestions and the total line losses
PRZEGLÄD METOD REGULACJI NAPIÄCIA W SIECIACH ELEKTROENERGETYCZNYCH NISKIEGO NAPIÄCIA Z DUĆ»YM UDZIAĆEM GENERACJI ROZPROSZONEJ
Deterioration of voltage conditions is one of the frequent consequences of connecting an increasing number of photovoltaic sources to the low-voltage (LV) power grid. Under adverse conditions, i.e. low energy consumption and high insolation, microgeneration can cause voltage surges that violate acceptable limits. Research shows that the increase in voltage is the main limitation for connecting new energy microsources to the LV network and forces the reconstruction of the network. An alternative to costly modernizations can be the implementation of appropriate strategies for controlling network operation to maintain the voltage at the required level. The article presents an overview of the methods and concepts of voltage control in a low-voltage network developed so far to mitigate the undesirable phenomenon of voltage boosting. The focus was mainly on local methodsânot requiring communication infrastructureâas best suited to the conditions of Polish distribution networks. Gathering the results of many tests and simulations carried out in different conditions and on different models allowed for the formulation of general conclusions and can be a starting point for further research on a control method that can be widely used in the national power system.JednÄ
z czÄstych konsekwencji przyĆÄ
czania do sieci elektroenergetycznej niskiego napiÄcia (nn) coraz wiÄkszej liczby ĆșrĂłdeĆ fotowoltaicznych jest pogorszenie warunkĂłw napiÄciowych. W niesprzyjajÄ
cych warunkach â przy niskim poborze energii i wysokim nasĆonecznieniu â mikrogeneracja moĆŒe powodowaÄ podskoki napiÄcia przekraczajÄ
ce dopuszczalne granice. Badania pokazujÄ
, ĆŒe wzrost napiÄcia stanowi podstawowe ograniczenie dla przyĆÄ
czania nowych mikroĆșrĂłdeĆ energii do sieci nn i wymusza przebudowÄ sieci. AlternatywÄ
dla kosztownych modernizacji moĆŒe byÄ wdroĆŒenie odpowiednich strategii sterowania pracÄ
sieci pozwalajÄ
cych utrzymaÄ napiÄcie na wymaganym poziomie. W artykule zaprezentowano przeglÄ
d opracowanych dotychczas metod i koncepcji regulacji napiÄcia w sieci nn majÄ
cych na celu opanowanie niepoĆŒÄ
danego zjawiska podbicia napiÄcia. Skupiono siÄ gĆĂłwnie na metodach lokalnych â nie wymagajÄ
cych do prawidĆowego dziaĆania infrastruktury komunikacyjnej â jako najlepiej przystosowanych do warunkĂłw polskich sieci dystrybucyjnych. Zebranie wynikĂłw badaĆ i symulacji, przeprowadzonych przy rĂłĆŒnych zaĆoĆŒeniach i na rĂłĆŒnych modelach, pozwoliĆo na sformuĆowanie ogĂłlnych wnioskĂłw i moĆŒe stanowiÄ punkt wyjĆcia do dalszych badaĆ nad metodÄ
sterowania mogÄ
cÄ
znaleĆșÄ szerokie zastosowanie w krajowym systemie elektroenergetycznym
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