17,186 research outputs found

    Local flexibility market design for aggregators providing multiple flexibility services at distribution network level

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    This paper presents a general description of local flexibility markets as a market-based management mechanism for aggregators. The high penetration of distributed energy resources introduces new flexibility services like prosumer or community self-balancing, congestion management and time-of-use optimization. This work is focused on the flexibility framework to enable multiple participants to compete for selling or buying flexibility. In this framework, the aggregator acts as a local market operator and supervises flexibility transactions of the local energy community. Local market participation is voluntary. Potential flexibility stakeholders are the distribution system operator, the balance responsible party and end-users themselves. Flexibility is sold by means of loads, generators, storage units and electric vehicles. Finally, this paper presents needed interactions between all local market stakeholders, the corresponding inputs and outputs of local market operation algorithms from participants and a case study to highlight the application of the local flexibility market in three scenarios. The local market framework could postpone grid upgrades, reduce energy costs and increase distribution grids’ hosting capacity.Postprint (published version

    Autonomous Multi-Chemistry Secondary-Use Battery Energy Storage

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    Battery energy storage is poised to play an increasingly important role in the modern electric grid. Not only does it provide the ability to change the time-of-day and magnitude of energy produced by renewable resources like wind and solar, it can also provide a host of other 3ancillary grid-stabilizing services. Cost remains a limiting factor in deploying energy storage systems large enough to provide these services on the scale required by an electric utility provider. Secondary-use electric vehicle batteries are a source of inexpensive energy storage materials that are not yet ready for the landfill but cannot operate in vehicles any longer. However, the wide range of manufacturers using different battery chemistries and configurations mean that integrating these batteries into a large-format system can be difficult. This work demonstrates methods for the autonomous integration and operation of a wide range of stationary energy storage battery chemistries. A fully autonomous battery characterization is paired with a novel system architecture and transactive optimization to create a system which can provide utility-scale energy services using a multitude of battery chemistries in the same system. These claims are verified using a combination of in-situ testing and a computer modelling testbed. Results are presented which demonstrate the ability of the system to combine a wide range of batteries into an effective single system

    Smart grid architecture for rural distribution networks: application to a Spanish pilot network

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    This paper presents a novel architecture for rural distribution grids. This architecture is designed to modernize traditional rural networks into new Smart Grid ones. The architecture tackles innovation actions on both the power plane and the management plane of the system. In the power plane, the architecture focuses on exploiting the synergies between telecommunications and innovative technologies based on power electronics managing low scale electrical storage. In the management plane, a decentralized management system is proposed based on the addition of two new agents assisting the typical Supervisory Control And Data Acquisition (SCADA) system of distribution system operators. Altogether, the proposed architecture enables operators to use more effectively—in an automated and decentralized way—weak rural distribution systems, increasing the capability to integrate new distributed energy resources. This architecture is being implemented in a real Pilot Network located in Spain, in the frame of the European Smart Rural Grid project. The paper also includes a study case showing one of the potentialities of one of the principal technologies developed in the project and underpinning the realization of the new architecture: the so-called Intelligent Distribution Power Router.Postprint (published version

    Integration of Large PV Power Plants and Batteries in the Electric Power System

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    The declining cost of renewables, the need for cleaner sources of energy, and environmental protection policies have led to the growing penetration of inverter-based resources such as solar photovoltaics (PV), wind, and battery energy storage systems (BESS) into the electric power system. The intermittent nature of these resources poses multiple challenges to the power grid and substantial changes in the conventional generation and electrical power delivery practices will be required to accommodate the large penetration of these renewable power plants. The impact of large solar PV penetration on both generation and transmission systems, and the use of BESS to mitigate some of the challenges due to solar PV penetration has been studied in this dissertation. One of the major challenges in evaluating the impact of inverter-based resources (IBR) such as solar PV systems is developing an equivalent model adequate to represent its operation. This work proposes a detailed solar PV model suitable for analyzing the configurations, design, and operation of multi-MW grid connected PV systems. This model which takes into account the contributions of the power electronics control and operation was used to evaluate the impact of transient changes in solar PV power on an example transmission system. The benefits of a battery system configuration connected to the grid through an independent inverter were analyzed and its operation during transient conditions was also evaluated. After developing a detailed solar PV and BESS modules for analyzing the effect of IBR on transmission systems, an innovative approach for evaluating the impact of solar PV plants on both generation and transmission system based on a practical minute-to-minute economic dispatch model was proposed. The study demonstrates that large solar PV penetration may lead to both over- and under-generation violations, and substantial changes to conventional generation dispatch and unit commitment will be required to accommodate the growing renewable solar PV penetration. The terminal voltage of a battery pack varies based on multiple parameters and cannot be modeled as a constant voltage source for a detailed analysis BESS operation. A novel approach for estimating the equivalent circuit parameters for utility-scale BESS using equipment typically available at the installation site was proposed in this dissertation. This approach can be employed by utilities for monitoring energy storage system operation, ensure safety and avoid lithium-ion battery thermal runaway . The new methods developed, configurations and modules proposed in this dissertation may be directly applicable or extended to a wide range of utility practices for evaluating the impact of renewable resources and estimating the maximum solar PV capacity a service area can accommodate without significant upgrades to existing infrastructures

    The Design and Analysis of Large Solar PV Farm Configurations with DC Connected Battery Systems

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    Typically, solar inverters curtail or “clip” the available power from the PV system when it exceeds the maximum ac capacity. This paper discusses a battery system connected to the dc-link of an inverter to recuperate this PV energy. Contrary to conventional approaches, which employ two dc-dc converters, one each for the battery and solar PV system, the proposed configuration utilizes a single dc-dc converter capable of simultaneously operating as a charge controller and a maximum power point tracking (MPPT) tracking device. In addition to improving the overall system capacity factor, increasing the conversion efficiencies and ensuring MPPT stability, the proposed configuration offers a simple solution for adding energy storage to existing PV installations. With this configuration, the excess power that will otherwise be curtailed due to inverter rating limitations is stored in the battery and supplied to the grid during periods of reduced irradiance. Moreover, a systematic methodology for sizing a dc-bus connected battery to minimize total PV energy curtailed was developed using an annual PV generation profile at the Louisville Gas and Electric and Kentucky Utilities (LG&E and KU) E.W. Brown solar facility at Kentucky. The detailed behavior of the proposed system and its power electronics controls and operations were validated with case studies developed in PSCADTM/EMTDCTM for variable power generation and PV output power smoothing

    Robotite halduri alamsüsteemi väljatöötamine tarkvararaamistikule TEMOTO

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    Robots provide an opportunity to spare humans from tasks that are repetitive, require high precision or involve hazardous environments. Robots are often composed of multiple robotic units, such as mobile manipulators that integrate object manipulation and traversal capabilities. Additionally, a group of robots, i.e., multi robot systems, can be utilized for solving a common goal. However, the more elements are added to the system, the more complicated it is to control it. TeMoto is a ROS package intended for developing human-robot collaboration and multi-robot applications where TeMoto Robot Manager (TRM), a subsystem of TeMoto, is designed to unify the control of main robotic components: manipulators, mobile bases and grippers. However the implementation of TRM was incomplete prior to this work, having no functionality for controlling mobile bases and grippers. This thesis extends the functionality of TeMoto Robot Manager by implementing the aforementioned missing features, thus facilitating the integration of compound robots and multi-robot systems. The outcome of this work is demonstrated in an object transportation scenario incorporating a heterogeneous multi-robot system that consists of two manipulators, two grippers, and a mobile base. In estonian: Robotid võimaldavad aidata inimesi ülesannetes mis on eluohtlikud, nõuavad suurt täpsust või on üksluised. Üks terviklik robot koosneb tihtipeale mitme eri funktsionaalsusega alamrobotist, millest näiteks mobiilne manipulaator on kombinatsioon mobiilsest platvormist ja objektide manipuleerimise võimekusega robotist. Roboteid saab rakendada ülesannete lahendamisel ka mitme roboti süsteemina, kuid robotite hulga suurenemisel suureneb ka nende haldamise keerukus. TeMoto on ROSi kimp, mis hõlbustab inimene-robot koostöö ja mitme roboti süsteemide arendamist. Robotite haldur on TeMoto alamsüsteem, mis aitab käsitleda mobiilseid platvorme, manipulaatoreid ja haaratseid ühtse tervikliku robotina. Käesolevale tööle eelnevalt puudus Robotite halduril mobiilsete platvormide ja haaratsite haldamise võimekused, mille väljatöötamine oli antud töö peamiseks eesmärgiks. Töö tulemusena valmis TeMoto Robotite halduri terviklik lahendus, mille funktsionaalsust demonstreeriti objekti transportimise ülesande lahendamisel, kaasates kahest manipulaatorist, kahest haaratsist ja mobiilsest platvormist koosnevat heterogeenset mitme roboti süsteemi
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