Research

13 pages, 4881 KiB

Open AccessArticle

Characterization of Storage Sizing for an Off-Grid House in the US and the Netherlands

by Diego Fernando Quintero Pulido, Gerwin Hoogsteen, Marnix V. Ten Kortenaar, Johann L. Hurink, Robert E. Hebner and Gerard J. M. Smit

Energies 2018, 11(2), 265; https://doi.org/10.3390/en11020265 - 23 Jan 2018

Cited by 14 | Viewed by 11333

Abstract

This work uses experimental data to estimate the size of storage needed for an isolated off-grid household in two different regions (Austin, Texas, US, and Nunspeet, NL). In our study, an off-grid house is considered to be supplied with 100% renewable energy during [...] Read more.

This work uses experimental data to estimate the size of storage needed for an isolated off-grid household in two different regions (Austin, Texas, US, and Nunspeet, NL). In our study, an off-grid house is considered to be supplied with 100% renewable energy during the summer period, in which cooling demand is neglected, and a solar photovoltaic (PV) system and batteries are the main electrical energy providers. Based on results achieved with the DEMkit simulation package we can conclude that, in both cases, using a solar PV system and a Sea-Salt battery would have been sufficient to provide the necessary electricity without showing a blackout during the summer of 2016. The Austin household needs a solar PV system of 38 kWp and storage of 452 kWh; in the case of Nunspeet, a solar PV system of 11.5 kWp and storage of 90 kWh is sufficient. Furthermore, using the DEMkit model, it is possible to determine an optimal value for the size of storage to half of the initial battery capacity (226 kWh for Austin and 45 kWh for Nunspeet) and still be able to provide enough power to cover the load demand of the households during the summer. In a second part, data of the solar PV system and load from Austin for one specific week was used to create data of a ‘typical’ but downscaled day. This day was used to determine the fluctuation of electricity for a real Sea-Salt battery for the considered off-grid scenario in Austin. The downscaling of the data was needed in order to have load values that fit to the size of the real battery. The tests show that the Sea-Salt battery under real electricity fluctuations is possibly adequate for off-grid scenarios. Full article

(This article belongs to the Special Issue Selected Papers from International Workshop of Energy-Open)

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29 pages, 5393 KiB

Open AccessFeature PaperArticle

Energy Flexibility from Large Prosumers to Support Distribution System Operation—A Technical and Legal Case Study on the Amsterdam ArenA Stadium

by Dirk Kuiken, Heyd F. Más, Maryam Haji Ghasemi, Niels Blaauwbroek, Thai H. Vo, Thijs Van der Klauw and Phuong H. Nguyen

Energies 2018, 11(1), 122; https://doi.org/10.3390/en11010122 - 04 Jan 2018

Cited by 10 | Viewed by 10948

Abstract

To deal with the rising integration of stochastic renewables and energy intensive distributed energy resources (DER) to the electricity network, alternatives to expensive network reinforcements are increasingly needed. An alternative solution often under consideration is integrating flexibility from the consumer side to system [...] Read more.

To deal with the rising integration of stochastic renewables and energy intensive distributed energy resources (DER) to the electricity network, alternatives to expensive network reinforcements are increasingly needed. An alternative solution often under consideration is integrating flexibility from the consumer side to system management. However, such a solution needs to be contemplated from different angles before it can be implemented in practice. To this end, this article considers a case study of the Amsterdam ArenA stadium and its surrounding network where flexibility is expected to be available to support the network in the future. The article studies the technical aspects of using this flexibility to determine to what extent, despite the different, orthogonal goals, the available flexibility can be used by various stakeholders in scenarios with a large load from electric vehicle charging points. Furthermore, a legal study is performed to determine the feasibility of the technical solutions proposed by analysing current European Union (EU) and Dutch law and focusing on the current agreements existing between the parties involved. The article shows that flexibility in the network provided by Amsterdam ArenA is able to significantly increase the number of charging points the network can accommodate. Nonetheless, while several uses of flexibility are feasible under current law, the use of flexibility provided by electric vehicles specifically faces several legal challenges in current arrangements. Full article

(This article belongs to the Special Issue Selected Papers from International Workshop of Energy-Open)

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979 KiB

Open AccessArticle

Improving an Integer Linear Programming Model of an Ecovat Buffer by Adding Long-Term Planning

by Gijs J. H. de Goeijen, Gerard J. M. Smit and Johann L. Hurink

Energies 2017, 10(12), 2039; https://doi.org/10.3390/en10122039 - 03 Dec 2017

Cited by 7 | Viewed by 10108

Abstract

The Ecovat is a seasonal thermal storage solution consisting of a large underground water tank divided into a number of virtual segments that can be individually charged and discharged. The goal of the Ecovat is to supply heat demand to a neighborhood throughout [...] Read more.

The Ecovat is a seasonal thermal storage solution consisting of a large underground water tank divided into a number of virtual segments that can be individually charged and discharged. The goal of the Ecovat is to supply heat demand to a neighborhood throughout the entire year. In this work, we extend an integer linear programming model to describe the charging and discharging of such an Ecovat buffer by adding a long-term (yearly) planning step to the model. We compare the results from the model using this extension to previously obtained results and show significant improvements when looking at the combination of costs and the energy content of the buffer at the end of the optimization. Furthermore, we show that the model is very robust against prediction errors. For this, we compare two different cases: one case in which we assume perfect predictions are available and one case in which we assume no predictions are available. The largest observed difference in costs between these two cases is less than 2%. Full article

(This article belongs to the Special Issue Selected Papers from International Workshop of Energy-Open)

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1240 KiB

Open AccessArticle

Impact of DC Voltage Enhancement on Partial Discharges in Medium Voltage Cables—An Empirical Study with Defects at Semicon-Dielectric Interface

by Aditya Shekhar, Xianyong Feng, Angelo Gattozzi, Robert Hebner, Douglas Wardell, Shannon Strank, Armando Rodrigo-Mor, Laura Ramírez-Elizondo and Pavol Bauer

Energies 2017, 10(12), 1968; https://doi.org/10.3390/en10121968 - 26 Nov 2017

Cited by 16 | Viewed by 6019

Abstract

A scientific consensus is emerging on the benefits of direct current (DC) distribution in medium voltage (MV) power systems of ships and cities. At least 50% space savings and increased power transfer capacity are estimated with enhanced voltage DC operation of electric cables. [...] Read more.

A scientific consensus is emerging on the benefits of direct current (DC) distribution in medium voltage (MV) power systems of ships and cities. At least 50% space savings and increased power transfer capacity are estimated with enhanced voltage DC operation of electric cables. The goal of this research is to contribute to developing the empirical knowledge on the insulation performance in order to validate the feasibility of such anticipated gains of DC versus alternating current (AC), and to determine the comparative impact of different operational conditions from a component engineering point of view. The partial discharge (PD) activity in cables is measured under AC and DC conditions as an indicator of insulation performance. Specifically, PDs in defects at the semicon-insulation interface are studied in terms of inception voltage, repetition rate and discharge magnitude. Empirical understanding is drawn for operating voltage and frequency dependence of the discharge behavior in such voids in the range of 10 to 20 kV and 0 to 0.1 Hz, respectively. The change in PD activity with void evolution post temperature-induced ageing process is explored. Full article

(This article belongs to the Special Issue Selected Papers from International Workshop of Energy-Open)

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1076 KiB

Open AccessArticle

Battery Energy Management in a Microgrid Using Batch Reinforcement Learning

by Brida V. Mbuwir, Frederik Ruelens, Fred Spiessens and Geert Deconinck

Energies 2017, 10(11), 1846; https://doi.org/10.3390/en10111846 - 12 Nov 2017

Cited by 131 | Viewed by 7885

Abstract

Motivated by recent developments in batch Reinforcement Learning (RL), this paper contributes to the application of batch RL in energy management in microgrids. We tackle the challenge of finding a closed-loop control policy to optimally schedule the operation of a storage device, in [...] Read more.

Motivated by recent developments in batch Reinforcement Learning (RL), this paper contributes to the application of batch RL in energy management in microgrids. We tackle the challenge of finding a closed-loop control policy to optimally schedule the operation of a storage device, in order to maximize self-consumption of local photovoltaic production in a microgrid. In this work, the fitted Q-iteration algorithm, a standard batch RL technique, is used by an RL agent to construct a control policy. The proposed method is data-driven and uses a state-action value function to find an optimal scheduling plan for a battery. The battery’s charge and discharge efficiencies, and the nonlinearity in the microgrid due to the inverter’s efficiency are taken into account. The proposed approach has been tested by simulation in a residential setting using data from Belgian residential consumers. The developed framework is benchmarked with a model-based technique, and the simulation results show a performance gap of 19%. The simulation results provide insight for developing optimal policies in more realistically-scaled and interconnected microgrids and for including uncertainties in generation and consumption for which white-box models become inaccurate and/or infeasible. Full article

(This article belongs to the Special Issue Selected Papers from International Workshop of Energy-Open)

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528 KiB

Open AccessArticle

Rethinking Participation in Smart Energy System Planning

by Imke Lammers and Maarten J. Arentsen

Energies 2017, 10(11), 1711; https://doi.org/10.3390/en10111711 - 26 Oct 2017

Cited by 1 | Viewed by 3363

Abstract

While the technical layout of smart energy systems is well advanced, the implementation of these systems is slowed down by the current decision-making practice regarding such energy infrastructures. We call for a reorganisation of the decision-making process on local energy planning and address [...] Read more.

While the technical layout of smart energy systems is well advanced, the implementation of these systems is slowed down by the current decision-making practice regarding such energy infrastructures. We call for a reorganisation of the decision-making process on local energy planning and address the question ‘how can decision-making on the design and implementation of Smart Energy Systems be accelerated?’ Inspired by engineering design thinking and based on two workshop sessions, we identify five design phases and an implementation phase, and distinguish between a design component and a participation component. This allows for the effective participation of external stakeholders at four specific moments in the decision-making process. This way, efficiency and effectiveness in smart energy system planning can be increased, without compromising on participation. When applied to the Dutch context of energy planning, the developed decision-making model is useful for project participants as well as policy-makers in a wide variety of settings. Full article

(This article belongs to the Special Issue Selected Papers from International Workshop of Energy-Open)

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1177 KiB

Open AccessArticle

Performance Assessment of Black Box Capacity Forecasting for Multi-Market Trade Application

by Pamela MacDougall, Bob Ran, George B. Huitema and Geert Deconinck

Energies 2017, 10(10), 1673; https://doi.org/10.3390/en10101673 - 23 Oct 2017

Cited by 8 | Viewed by 3836

Abstract

With the growth of renewable generated electricity in the energy mix, large energy storage and flexible demand, particularly aggregated demand response is becoming a front runner as a new participant in the wholesale energy markets. One of the biggest barriers for the integration [...] Read more.

With the growth of renewable generated electricity in the energy mix, large energy storage and flexible demand, particularly aggregated demand response is becoming a front runner as a new participant in the wholesale energy markets. One of the biggest barriers for the integration of aggregator services into market participation is knowledge of the current and future flexible capacity. To calculate the available flexibility, the current aggregator pilot and simulation implementations use lower level measurements and device specifications. This type of implementation is not scalable due to computational constraints, as well as it could conflict with end user privacy rights. Black box machine learning approaches have been proven to accurately estimate the available capacity of a cluster of heating devices using only aggregated data. This study will investigate the accuracy of this approach when applied to a heterogeneous virtual power plant (VPP). Firstly, a sensitivity analysis of the machine learning model is performed when varying the underlying device makeup of the VPP. Further, the forecasted flexible capacity of a heterogeneous residential VPP was applied to a trade strategy, which maintains a day ahead schedule, as well as offers flexibility to the imbalance market. This performance is then compared when using the same strategy with no capacity forecasting, as well as perfect knowledge. It was shown that at most, the highest average error, regardless of the VPP makeup, was still less than 9%. Further, when applying the forecasted capacity to a trading strategy, 89% of the optimal performance can be met. This resulted in a reduction of monthly costs by approximately 20%. Full article

(This article belongs to the Special Issue Selected Papers from International Workshop of Energy-Open)

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1117 KiB

Open AccessArticle

Newton Power Flow Methods for Unbalanced Three-Phase Distribution Networks

by Baljinnyam Sereeter, Kees Vuik and Cees Witteveen

Energies 2017, 10(10), 1658; https://doi.org/10.3390/en10101658 - 20 Oct 2017

Cited by 58 | Viewed by 7826

Abstract

Two mismatch functions (power or current) and three coordinates (polar, Cartesian and complex form) result in six versions of the Newton–Raphson method for the solution of power flow problems. In this paper, five new versions of the Newton power flow method developed for [...] Read more.

Two mismatch functions (power or current) and three coordinates (polar, Cartesian and complex form) result in six versions of the Newton–Raphson method for the solution of power flow problems. In this paper, five new versions of the Newton power flow method developed for single-phase problems in our previous paper are extended to three-phase power flow problems. Mathematical models of the load, load connection, transformer, and distributed generation (DG) are presented. A three-phase power flow formulation is described for both power and current mismatch functions. Extended versions of the Newton power flow method are compared with the backward-forward sweep-based algorithm. Furthermore, the convergence behavior for different loading conditions,

R / X

ratios, and load models, is investigated by numerical experiments on balanced and unbalanced distribution networks. On the basis of these experiments, we conclude that two versions using the current mismatch function in polar and Cartesian coordinates perform the best for both balanced and unbalanced distribution networks. Full article

(This article belongs to the Special Issue Selected Papers from International Workshop of Energy-Open)

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