Energies

Research

19 pages, 5213 KiB

Open AccessArticle

Study on Selecting the Optimal Algorithm and the Effective Methodology to ANN-Based Short-Term Load Forecasting Model for the Southern Power Company in Vietnam

by Manh-Hai Pham, T-A-Tho Vu, Duc-Quang Nguyen, Viet-Hung Dang, Ngoc-Trung Nguyen, Thu-Huyen Dang and The Vinh Nguyen

Energies 2019, 12(12), 2283; https://doi.org/10.3390/en12122283 - 14 Jun 2019

Cited by 3 | Viewed by 3156

Abstract

Recently, power companies apply optimal algorithms for short-term load forecasting, especially the daily load. However, in Vietnam, the load forecasting of the power system has not focused on this solution. Optimal algorithms and can help experts improve forecasting results including accuracy and the [...] Read more.

Recently, power companies apply optimal algorithms for short-term load forecasting, especially the daily load. However, in Vietnam, the load forecasting of the power system has not focused on this solution. Optimal algorithms and can help experts improve forecasting results including accuracy and the time required for forecasting. To achieve both goals, the combinations of different algorithms are still being studied. This article describes research using a new combination of two optimal algorithms: Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). This combination limits the weakness of the convergence speed of GA as well as the weakness of PSO that it easily falls into local optima (thereby reducing accuracy). This new hybrid algorithm was applied to the Southern Power Corporation’s (SPC—a large Power company in Vietnam) daily load forecasting. The results show the algorithm’s potential to provide a solution. The most accurate result was for the forecasting of a normal working day with an average error of 1.15% while the largest error was 3.74% and the smallest was 0.02%. For holidays and weekends, the average error always approximated the allowable limit of 3%. On the other hand, some poor results also provide an opportunity to re-check the real data provided by SPC. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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27 pages, 18411 KiB

Open AccessArticle

A SGAM-Based Test Platform to Develop a Scheme for Wide Area Measurement-Free Monitoring of Smart Grids under High PV Penetration

by Abouzar Estebsari, Luca Barbierato, Alireza Bahmanyar, Lorenzo Bottaccioli, Enrico Macii and Edoardo Patti

Energies 2019, 12(8), 1417; https://doi.org/10.3390/en12081417 - 12 Apr 2019

Cited by 14 | Viewed by 4567

Abstract

In order to systematically shift existing control and management paradigms in distribution systems to new interoperable communication supported schemes in smart grids, we need to map newly developed use cases to standard reference models like Smart Grid Architecture Model (SGAM). From the other [...] Read more.

In order to systematically shift existing control and management paradigms in distribution systems to new interoperable communication supported schemes in smart grids, we need to map newly developed use cases to standard reference models like Smart Grid Architecture Model (SGAM). From the other side, any new use cases should be tested and validated ex-ante before being deployed in the real-world system. Considering various types of actors in smart grids, use cases are usually tested using co-simulation platforms. Currently, there is no efficient co-simulation platform which supports interoperability analysis based on SGAM. In this paper, we present our developed test platform which offers a support to design new use cases based on SGAM. We used this platform to develop a new scheme for wide area monitoring of existing distribution systems under growing penetration of Photovoltaic production. Off-the-shelf solutions of state estimation for wide area monitoring are either used for passive distribution grids or applied to the active networks with wide measurement of distributed generators. Our proposed distribution state estimation algorithm does not require wide area measurements and relies on the data provided by a PV simulator we developed. This practical scheme is tested experimentally on a realistic urban distribution grid. The monitoring results shows a very low error rate of about

1 %

by using our PV simulator under high penetration of PV with about

30 %

error of load forecast. Using our SGAM-based platform, we could propose and examine an Internet-of-Things-based infrastructure to deploy the use case. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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11 pages, 6131 KiB

Open AccessArticle

Thin Conductor Modelling Combined with a Hybrid Numerical Method to Evaluate the Transferred Potential from Isolated Grounding System

by Giovanni Aiello, Salvatore Alfonzetti, Santi Agatino Rizzo and Nunzio Salerno

Energies 2019, 12(7), 1210; https://doi.org/10.3390/en12071210 - 28 Mar 2019

Cited by 2 | Viewed by 2477

Abstract

Grounding systems are essential parts of substations and power generation stations. The evaluation of transferred potentials from an active grounding system to other passive ones or to any near conductors is an important aspect to be considered, because transferred potentials may cause serious [...] Read more.

Grounding systems are essential parts of substations and power generation stations. The evaluation of transferred potentials from an active grounding system to other passive ones or to any near conductors is an important aspect to be considered, because transferred potentials may cause serious and fatal events. Moreover, it is an intrinsic issue of the Smart Grid where the ground systems of the power and ICT systems could be close to each other. Therefore, the estimation of the transferred potential is necessary at grounding system design stage for people safety and electric components safeguard. Numerical methods are the best choice to perform a truthful estimation, especially when large and complex grounding systems have to be designed. However, this task is complicated by the “unbounded” nature of the electromagnetic field and by the presence of components of extremely different size in the analysis domain. In this paper, an efficient hybrid finite element method is applied for the accurate and fast computation of transferred earth potentials from grounding systems. Moreover, the small dimensions of the components in the analysis domain are taken into account by the use of one-dimensional finite elements inserted in the tetrahedral mesh. It is worth mentioning the additional advantage of obtaining the electric potential on the earth surface without any post-processing operation. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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18 pages, 3350 KiB

Open AccessArticle

A Driving Technique for AC-AC Direct Matrix Converters Based on Sigma-Delta Modulation

by Simone Orcioni, Giorgio Biagetti, Paolo Crippa and Laura Falaschetti

Energies 2019, 12(6), 1103; https://doi.org/10.3390/en12061103 - 21 Mar 2019

Cited by 6 | Viewed by 2739

Abstract

Direct conversion of AC power between three-phase systems operating at different frequencies can be achieved using solid-state circuits known as matrix converters. These converters do not need energy storage elements, but they require sophisticated control algorithms to operate the switches. In this work [...] Read more.

Direct conversion of AC power between three-phase systems operating at different frequencies can be achieved using solid-state circuits known as matrix converters. These converters do not need energy storage elements, but they require sophisticated control algorithms to operate the switches. In this work we propose and evaluate the use of a sigma-delta modulation approach to control the operation of a direct matrix converter, together with a revised line filter topology suited to better handle the peculiarities of the switching noise produced by the sigma-delta modulation. Simulation results show the feasibility of such an approach, which is able to generate arbitrary output waveforms and adjust its input reactive power. Comparison with a space vector modulation implementation shows also better performance about total harmonic distortion, i.e., less harmonics in the input and output. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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20 pages, 1485 KiB

Open AccessArticle

A Microforecasting Module for Energy Management in Residential and Tertiary Buildings ^†

by Sergio Bruno, Gabriella Dellino, Massimo La Scala and Carlo Meloni

Energies 2019, 12(6), 1006; https://doi.org/10.3390/en12061006 - 15 Mar 2019

Cited by 27 | Viewed by 2782

Abstract

The paper describes the methodology used for developing an electric load microforecasting module to be integrated in the Energy Management System (EMS) architecture designed and tested within the “Energy Router” (ER) project. This Italian R&D project is aimed at providing non-industrial active customers [...] Read more.

The paper describes the methodology used for developing an electric load microforecasting module to be integrated in the Energy Management System (EMS) architecture designed and tested within the “Energy Router” (ER) project. This Italian R&D project is aimed at providing non-industrial active customers and prosumers with a monitoring and control device that would enable demand response through optimization of their own distributed energy resources (DERs). The optimal control of resources is organized with a hierarchical control structure and performed in two stages. A cloud-based computation platform provides global control functions based on model predictive control whereas a closed-loop local device manages actual monitoring and control of field components. In this architecture, load forecasts on a small scale (a single residential or tertiary building) are needed as inputs of the predictive control problem. The microforecasting module aimed at providing such inputs was designed to be flexible, adaptive, and able to treat data with low time resolution. The module includes alternative forecasting techniques, such as autoregressive integrated moving average (ARIMA), neural networks, and exponential smoothing, allowing the application of the right forecasting strategy each time. The presented test results are based on a dataset acquired during a monitoring campaign in two pilot systems, installed during the ER Project in public buildings. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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28 pages, 3149 KiB

Open AccessArticle

Ageing and Efficiency Aware Battery Dispatch for Arbitrage Markets Using Mixed Integer Linear Programming ^†

by Holger C. Hesse, Volkan Kumtepeli, Michael Schimpe, Jorn Reniers, David A. Howey, Anshuman Tripathi, Youyi Wang and Andreas Jossen

Energies 2019, 12(6), 999; https://doi.org/10.3390/en12060999 - 14 Mar 2019

Cited by 38 | Viewed by 5994

Abstract

To achieve maximum profit by dispatching a battery storage system in an arbitrage operation, multiple factors must be considered. While revenue from the application is determined by the time variability of the electricity cost, the profit will be lowered by costs resulting from [...] Read more.

To achieve maximum profit by dispatching a battery storage system in an arbitrage operation, multiple factors must be considered. While revenue from the application is determined by the time variability of the electricity cost, the profit will be lowered by costs resulting from energy efficiency losses, as well as by battery degradation. In this paper, an optimal dispatch strategy is proposed for storage systems trading on energy arbitrage markets. The dispatch is based on a computationally-efficient implementation of a mixed-integer linear programming method, with a cost function that includes variable-energy conversion losses and a cycle-induced battery capacity fade. The parametrisation of these non-linear functions is backed by in-house laboratory tests. A detailed analysis of the proposed methods is given through case studies of different cost-inclusion scenarios, as well as battery investment-cost scenarios. An evaluation with a sample intraday market data set, collected throughout 2017 in Germany, offers a potential monthly revenue of up to 8762 EUR/MWh

_{cap}

installed capacity, without accounting for the costs attributed to energy losses and battery degradation. While this is slightly above the revenue attainable in a reference application—namely, primary frequency regulation for the same sample month (7716 EUR/MWh

_{cap}

installed capacity)—the situation changes if costs are considered: The optimisation reveals that losses in battery ageing and efficiency reduce the attainable profit by up to 36% for the most profitable arbitrage use case considered herein. The findings underline the significance of considering both ageing and efficiency in battery system dispatch optimisation. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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25 pages, 6022 KiB

Open AccessArticle

Daily Operation Optimization of a Hybrid Energy System Considering a Short-Term Electricity Price Forecast Scheme

by Pedro Bento, Hugo Nunes, José Pombo, Maria do Rosário Calado and Sílvio Mariano

Energies 2019, 12(5), 924; https://doi.org/10.3390/en12050924 - 10 Mar 2019

Cited by 14 | Viewed by 4582

Abstract

The scenario where the renewable generation penetration is steadily on the rise in an increasingly atomized system, with much of the installed capacity “sitting” on a distribution level, is in clear contrast with the “old paradigm” of a natural oligopoly formed by vertical [...] Read more.

The scenario where the renewable generation penetration is steadily on the rise in an increasingly atomized system, with much of the installed capacity “sitting” on a distribution level, is in clear contrast with the “old paradigm” of a natural oligopoly formed by vertical structures. Thereby, the fading of the classical producer–consumer division to a broader prosumer “concept” is fostered. This crucial transition will tackle environmental harms associated with conventional energy sources, especially in this age where a greater concern regarding sustainability and environmental protection exists. The “smoothness” of this transition from a reliable conventional generation mix to a more volatile and “parti-colored" one will be particularly challenging, given escalating electricity demands arising from transportation electrification and proliferation of demand-response mechanisms. In this foreseeable framework, proper Hybrid Energy Systems sizing, and operation strategies will be crucial to dictate the electric power system’s contribution to the “green” agenda. This paper presents an optimal power dispatch strategy for grid-connected/off-grid hybrid energy systems with storage capabilities. The Short-Term Price Forecast information as an important decision-making tool for market players will guide the cost side dispatch strategy, alongside with the storage availability. Different scenarios were examined to highlight the effectiveness of the proposed approach. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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24 pages, 17803 KiB

Open AccessArticle

Power Management Control Strategy Based on Artificial Neural Networks for Standalone PV Applications with a Hybrid Energy Storage System

by João Faria, José Pombo, Maria do Rosário Calado and Sílvio Mariano

Energies 2019, 12(5), 902; https://doi.org/10.3390/en12050902 - 8 Mar 2019

Cited by 48 | Viewed by 5896

Abstract

Standalone microgrids with photovoltaic (PV) solutions could be a promising solution for powering up off-grid communities. However, this type of application requires the use of energy storage systems (ESS) to manage the intermittency of PV production. The most commonly used ESSs are lithium-ion [...] Read more.

Standalone microgrids with photovoltaic (PV) solutions could be a promising solution for powering up off-grid communities. However, this type of application requires the use of energy storage systems (ESS) to manage the intermittency of PV production. The most commonly used ESSs are lithium-ion batteries (Li-ion), but this technology has a low lifespan, mostly caused by the imposed stress. To reduce the stress on Li-ion batteries and extend their lifespan, hybrid energy storage systems (HESS) began to emerge. Although the utilization of HESSs has demonstrated great potential to make up for the limitations of Li-ion batteries, a proper power management strategy is key to achieving the HESS objectives and ensuring a harmonized system operation. This paper proposes a novel power management strategy based on an artificial neural network for a standalone PV system with Li-ion batteries and super-capacitors (SC) HESS. A typical standalone PV system is used to demonstrate and validate the performance of the proposed power management strategy. To demonstrate its effectiveness, computational simulations with short and long duration were performed. The results show a minimization in Li-ion battery dynamic stress and peak current, leading to an increased lifespan of Li-ion batteries. Moreover, the proposed power management strategy increases the level of SC utilization in comparison with other well-established strategies in the literature. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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18 pages, 3937 KiB

Open AccessArticle

Transformation of an Office Building into a Nearly Zero Energy Building (nZEB): Implications for Thermal and Visual Comfort and Energy Performance

by Ilaria Ballarini, Giovanna De Luca, Argun Paragamyan, Anna Pellegrino and Vincenzo Corrado

Energies 2019, 12(5), 895; https://doi.org/10.3390/en12050895 - 7 Mar 2019

Cited by 50 | Viewed by 5555

Abstract

Directive 2010/31/EU promotes the refurbishment of existing buildings to change them into nearly zero-energy buildings (nZEBs). Within this framework, it is of crucial importance to guarantee the best trade-off between energy performance and indoor environmental quality (IEQ). The implications of a global refurbishment [...] Read more.

Directive 2010/31/EU promotes the refurbishment of existing buildings to change them into nearly zero-energy buildings (nZEBs). Within this framework, it is of crucial importance to guarantee the best trade-off between energy performance and indoor environmental quality (IEQ). The implications of a global refurbishment scenario on thermal and visual comfort are assessed in this paper pertaining to an existing office building. The retrofit actions applied to achieve the nZEB target consist of a combination of envelope and technical building systems refurbishment measures, involving both HVAC and lighting. Energy and comfort calculations were carried out through dynamic simulation using Energy Plus and DIVA, for the thermal and visual performance assessments, respectively. The results point out that energy retrofit actions on the building envelope would lead to significant improvements in the thermal performance, regarding both energy savings (−37% of the annual primary energy for heating) and thermal comfort. However, a daylighting reduction would occur with a consequent higher electricity demand for lighting (36%). The research presents a detailed approach applicable to further analyses aimed at optimizing the energy efficiency measures in order to reduce the imbalance between visual and thermal comfort and to ensure the best performance in both domains. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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17 pages, 3323 KiB

Open AccessArticle

Analysis of Numerical Methods to Include Dynamic Constraints in an Optimal Power Flow Model

by Francisco Arredondo, Edgardo Daniel Castronuovo, Pablo Ledesma and Zbigniew Leonowicz

Energies 2019, 12(5), 885; https://doi.org/10.3390/en12050885 - 7 Mar 2019

Cited by 6 | Viewed by 4117

Abstract

The optimization of the operation of power systems including steady state and dynamic constraints is efficiently solved by Transient Stability Constrained Optimal Power Flow (TSCOPF) models. TSCOPF studies extend well-known optimal power flow models by introducing the electromechanical oscillations of synchronous machines. One [...] Read more.

The optimization of the operation of power systems including steady state and dynamic constraints is efficiently solved by Transient Stability Constrained Optimal Power Flow (TSCOPF) models. TSCOPF studies extend well-known optimal power flow models by introducing the electromechanical oscillations of synchronous machines. One of the main approaches in TSCOPF studies includes the discretized differential equations that represent the dynamics of the system in the optimization model. This paper analyzes the impact of different implicit and explicit numerical integration methods on the solution of a TSCOPF model and the effect of the integration time step. In particular, it studies the effect on the power dispatch, the total cost of generation, the accuracy of the calculation of electromechanical oscillations between machines, the size of the optimization problem and the computational time. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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26 pages, 5325 KiB

Open AccessArticle

The Regulatory Framework for Market Transparency in Future Power Systems under the Web-of-Cells Concept

by Viktorija Bobinaite, Marialaura Di Somma, Giorgio Graditi and Irina Oleinikova

Energies 2019, 12(5), 880; https://doi.org/10.3390/en12050880 - 6 Mar 2019

Cited by 4 | Viewed by 3828

Abstract

This paper investigates the regulatory rules of market transparency which could be applied within the wholesale electricity market and market for frequency and voltage control in the Web-of-Cells (WoC) decentralized power control architecture, which has been developed in the ELECTRA Project to respond [...] Read more.

This paper investigates the regulatory rules of market transparency which could be applied within the wholesale electricity market and market for frequency and voltage control in the Web-of-Cells (WoC) decentralized power control architecture, which has been developed in the ELECTRA Project to respond the challenges and needs of the future power system (2030+). In this decentralized functional architecture for frequency and voltage control, the European Union (EU) power grid is divided into grid control areas, i.e., cells, which are defined as portions of the grid having adequate monitoring infrastructure and local reserves capacity, allowing voltage and balancing (frequency) problems to be solved at cell level, under the responsibility of a Cell System Operator (CSO) (present Distribution System Operator (DSO)/Transmission System Operator (TSO)). In order to foster the practical realization of the WoC-based architecture, the related wholesale electricity market and market for frequency and voltage control are proposed considering the competitive market principles, including transparency. The critical review of the existing EU regulations dealing with this issue suggests respecting the valid provisions on market transparency while tailoring them into the WoC-based architecture. Moreover, in order to take into account the WoC peculiarities, a set of integrations to the current regulatory rules is also proposed, addressing: (1) disclosure of information in respect to attributes of emerging technologies such as renewable energy sources (RES), distributed energy resources (DER), storage; (2) provision of generation and load forecast information; (3) process of procurement of flexibilities; (4) retail market transparency; (5) disclosure of privacy-sensitive household attributes; and (6) disclosure of information on market for frequency and voltage control. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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14 pages, 2114 KiB

Open AccessArticle

A Study of Fuel Cell Scheduling Effect on Local Energy Markets with Heterogeneous Renewable Sources

by Borislava Spasova, Daisuke Kawamoto and Yoshiyasu Takefuji

Energies 2019, 12(5), 854; https://doi.org/10.3390/en12050854 - 5 Mar 2019

Cited by 4 | Viewed by 2587

Abstract

The study presented in this paper aims to show the impact of introducing a priority-based internal power flow management system on the local energy market of prosumers with solar panels, fuels cells and batteries. The community used for the study is based on [...] Read more.

The study presented in this paper aims to show the impact of introducing a priority-based internal power flow management system on the local energy market of prosumers with solar panels, fuels cells and batteries. The community used for the study is based on the Open Energy Systems (OES), in which 19 autonomous subsystems, equipped with batteries, solar panels and AC grid connection are interconnected via a DC power bus. For the simulation purposes, fuel cell, modeled after Ene-Farm, is added to the original configuration. Each standalone system has internal, priority-based, agent, capable of scheduling the operating hours of the fuels cell to maximize the utilization of the generation and minimize curtailment. The energy market is based on a simplified version of the Zaraba, a continuous double auction algorithm used by the Japanese Stock Exchange, in which prosumer can submit a bid for a future timeslot. The preliminary numerical evaluation is based on the results from several simulations using different versions of the internal management system. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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26 pages, 6498 KiB

Open AccessArticle

Evaluation Study of Potential Use of Advanced Conductors in Transmission Line Projects

by Svetlana Beryozkina

Energies 2019, 12(5), 822; https://doi.org/10.3390/en12050822 - 1 Mar 2019

Cited by 13 | Viewed by 4776

Abstract

Transmission networks recently faced new technical and economic challenges. The direct use of advanced technologies and modern methods could solve these issues. This paper discusses the potential application of straightforward technology such as high-temperature low-sag conductors (HTLScs) as an additional measure for the [...] Read more.

Transmission networks recently faced new technical and economic challenges. The direct use of advanced technologies and modern methods could solve these issues. This paper discusses the potential application of straightforward technology such as high-temperature low-sag conductors (HTLScs) as an additional measure for the protection and effective operation of overhead power lines. An evaluation was conducted to determine an approach for selecting the cross-sectional area and type of conductor with respect to a fault current limitation. It showed the potential benefits of using HTLScs based on an assessment of the throughput capacity and up-front capital costs. A case study considered two scenarios: the construction of a new power line and reconductoring of the existing one. The data for a real project with two overhead power lines were used. The obtained results are analyzed and discussed in detail in this paper. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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Graphical abstract

17 pages, 4957 KiB

Open AccessArticle

Dynamic Emulation of a PEM Electrolyzer by Time Constant Based Exponential Model

by Damien Guilbert and Gianpaolo Vitale

Energies 2019, 12(4), 750; https://doi.org/10.3390/en12040750 - 24 Feb 2019

Cited by 76 | Viewed by 9859

Abstract

The main objective of this paper is to develop a dynamic emulator of a proton exchange membrane (PEM) electrolyzer (EL) through an equivalent electrical model. Experimental investigations have highlighted the capacitive effect of EL when subjecting to dynamic current profiles, which so far [...] Read more.

The main objective of this paper is to develop a dynamic emulator of a proton exchange membrane (PEM) electrolyzer (EL) through an equivalent electrical model. Experimental investigations have highlighted the capacitive effect of EL when subjecting to dynamic current profiles, which so far has not been reported in the literature. Thanks to a thorough experimental study, the electrical domain of a PEM EL composed of 3 cells has been modeled under dynamic operating conditions. The dynamic emulator is based on an equivalent electrical scheme that takes into consideration the dynamic behavior of the EL in cases of sudden variation in the supply current. The model parameters were identified for a suitable current interval to consider them as constant and then tested with experimental data. The obtained results through the developed dynamic emulator have demonstrated its ability to accurately replicate the dynamic behavior of a PEM EL. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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25 pages, 3329 KiB

Open AccessFeature PaperArticle

Feasible Islanding Operation of Electric Networks with Large Penetration of Renewable Energy Sources considering Security Constraints

by Seyed Arash Alavi, Valentin Ilea, Alireza Saffarian, Cristian Bovo, Alberto Berizzi and Seyed Ghodratollah Seifossadat

Energies 2019, 12(3), 537; https://doi.org/10.3390/en12030537 - 8 Feb 2019

Cited by 5 | Viewed by 2991

Abstract

The high penetration of Renewable Energy Sources into electric networks shows new perspectives for the network’s management: among others, exploiting them as resources for network’s security in emergency situations. The paper focuses on the frequency stability of a portion of the grid when [...] Read more.

The high penetration of Renewable Energy Sources into electric networks shows new perspectives for the network’s management: among others, exploiting them as resources for network’s security in emergency situations. The paper focuses on the frequency stability of a portion of the grid when it remains islanded following a major fault. It proposes an optimization algorithm that considers the frequency reaction of the relevant components and minimizes the total costs of their shedding. The algorithm predicts the final frequency of the island and the active power profiles of the remaining generators and demands. It is formulated as a Mixed-Integer Non-Linear Programming problem and the high computation time due to a large-size problem is mitigated through a simplified linear version of the model that filters the integer variables. The algorithm is designed to operate on-line and preventively compute the optimal shedding actions to be engaged when islanding occurs. The algorithm is validated for a typical distribution grid: the minimum amount of shedding actions is obtained while the most frequency reactive resources are maintained in operation to assure a feasible frequency. Finally, time-domain simulations show that the optimal solution corresponds to the one at the end of the network’s transients following the islanding. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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24 pages, 5051 KiB

Open AccessArticle

Reliability Enhancement in Power Networks under Uncertainty from Distributed Energy Resources

by Mike Brian Ndawula, Sasa Z. Djokic and Ignacio Hernando-Gil

Energies 2019, 12(3), 531; https://doi.org/10.3390/en12030531 - 7 Feb 2019

Cited by 40 | Viewed by 4883

Abstract

This paper presents an integrated approach for assessing the impact that distributed energy resources (DERs), including intermittent photovoltaic (PV) generation, might have on the reliability performance of power networks. A test distribution system, based on a typical urban MV and LV networks in [...] Read more.

This paper presents an integrated approach for assessing the impact that distributed energy resources (DERs), including intermittent photovoltaic (PV) generation, might have on the reliability performance of power networks. A test distribution system, based on a typical urban MV and LV networks in the UK, is modelled and used to investigate potential benefits of the local renewable generation, demand-manageable loads and coordinated energy storage. The conventional Monte Carlo method is modified to include time-variation of electricity demand profiles and failure rates of network components. Additionally, a theoretical interruption model is employed to assess more accurately the moment in time when interruptions to electricity customers are likely to occur. Accordingly, the impact of the spatio-temporal variation of DERs on reliability performance is quantified in terms of the effect of network outages. The potential benefits from smart grid functionalities are assessed through both system- and customer-oriented reliability indices, with special attention to energy not supplied to customers, as well as frequency and duration of supply interruptions. The paper also discusses deployment of an intelligent energy management system to control local energy generation-storage-demand resources that can resolve uncertainties in renewable-based generation and ensure highly reliable and continuous supply to all connected customers. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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20 pages, 653 KiB

Open AccessFeature PaperArticle

Ignition of Welding Arc and UV Actinic Hazard Evaluation

by Andrzej Rybczyński, Agnieszka Wolska, Mariusz Wisełka, Jolanta Matusiak and Tomasz Pfeifer

Energies 2019, 12(3), 512; https://doi.org/10.3390/en12030512 - 6 Feb 2019

Cited by 7 | Viewed by 4302

Abstract

Welding arcs emit strong ultraviolet (UV) radiation, which could pose serious health risks for skin and eyes. According to Directive 2006/25/EC, UV hazard evaluation has to be performed in the working environment. The measurement of welding arc ignition radiation is a difficult task. [...] Read more.

Welding arcs emit strong ultraviolet (UV) radiation, which could pose serious health risks for skin and eyes. According to Directive 2006/25/EC, UV hazard evaluation has to be performed in the working environment. The measurement of welding arc ignition radiation is a difficult task. This article describes the effort made to determine actinic radiant exposure levels during welding arc ignition in the controlled environment of a welding laboratory. A new method of UV actinic hazard evaluation from welding arc ignition radiation using a CCD spectroradiometer combined with a photometer is presented. The hazard of UV emitted in pulsed metal active gas welding (MAG-P) of construction steel is described. The duration of ignition peak in the study was in the range of 9–15 ms. The actinic radiant exposure during arc ignition over aversion response time was in the range of 0.26–1.12 J/m². The daily exposure time can easily exceed the permissible exposure time obtained in our study, i.e., 13–34 s, which means that UV radiation form MAG-P arc welding is hazardous for workers in the vicinity of the welding arc. The measurement method presented in the article enables determination of radiant exposure of arc ignition radiation. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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20 pages, 9550 KiB

Open AccessArticle

Dynamic Simulation Model of Trans-Critical Carbon Dioxide Heat Pump Application for Boosting Low Temperature Distribution Networks in Dwellings

by Livio de Santoli, Gianluigi Lo Basso, Davide Astiaso Garcia, Giuseppe Piras and Giulia Spiridigliozzi

Energies 2019, 12(3), 484; https://doi.org/10.3390/en12030484 - 2 Feb 2019

Cited by 16 | Viewed by 5064

Abstract

This research investigates the role of new hybrid energy system applications for developing a new plant refurbishment strategy to deploy small scale smart energy systems. This work deals with a dynamic simulation of trans-critical carbon dioxide heat pump application for boosting low temperature [...] Read more.

This research investigates the role of new hybrid energy system applications for developing a new plant refurbishment strategy to deploy small scale smart energy systems. This work deals with a dynamic simulation of trans-critical carbon dioxide heat pump application for boosting low temperature distribution networks to share heat for dwellings. Heat pumps provide high temperature heat to use the traditional emission systems. The new plant layout consists of an air source heat pump, four trans-critical carbon dioxide heat pumps (CO₂-HPs), photovoltaic arrays, and a combined heat and power (CHP) for both domestic hot water production and electricity to partially drive the heat pumps. Furthermore, electric storage devices adoption has been evaluated. That layout has been compared to the traditional one based on separated generation systems using several energy performance indicators. Additionally, a sensitivity analysis on the primary energy saving, primary fossil energy consumptions, renewable energy fraction and renewable heat, with changes in building power to heat ratios, has been carried out. Obtained results highlighted that using the hybrid system with storage device it is possible to get a saving of 50% approximately. Consequently, CO₂-HPs and hybrid systems adoption could be a viable option to achieve Near Zero Energy Building (NZEB) qualification. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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19 pages, 4508 KiB

Open AccessArticle

Analysis of the Sensitivity of Extended Kalman Filter-Based Inertia Estimation Method to the Assumed Time of Disturbance

by Davide del Giudice and Samuele Grillo

Energies 2019, 12(3), 483; https://doi.org/10.3390/en12030483 - 2 Feb 2019

Cited by 24 | Viewed by 4245

Abstract

The frequency behavior of an electric power system right after a power imbalance is determined by its inertia constant. The current shift in generation mix towards renewable energy sources is leading to a smaller and more variable inertia, thereby compromising the frequency stability [...] Read more.

The frequency behavior of an electric power system right after a power imbalance is determined by its inertia constant. The current shift in generation mix towards renewable energy sources is leading to a smaller and more variable inertia, thereby compromising the frequency stability of modern grids. Therefore, real-time inertia estimation methods would be beneficial for grid operators, as their situational awareness would be enhanced. This paper focuses on an inertia estimation method specifically tailored for synchronous generators, based on the extended Kalman filter (EKF). Such a method should be started at the time of disturbance, which must be estimated accurately, otherwise additional errors could be introduced in the inertia estimation process. In this paper, the sensitivity of the EKF-based inertia estimation method to the assumed time of disturbance is analyzed. It is shown that such sensitivity is influenced by the initially assumed inertia constant, the use time of the filter and by the time required for primary frequency regulation to be activated. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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22 pages, 5718 KiB

Open AccessArticle

A Single Intersection Cooperative-Competitive Paradigm in Real Time Traffic Signal Settings Based on Floating Car Data

by Vittorio Astarita, Vincenzo Pasquale Giofrè, Giuseppe Guido and Alessandro Vitale

Energies 2019, 12(3), 409; https://doi.org/10.3390/en12030409 - 28 Jan 2019

Cited by 27 | Viewed by 4780

Abstract

New technologies such as “connected” and “autonomous” vehicles are going to change the future of traffic signal control and management and possibly will introduce new traffic signal systems that will be based on floating car data (FCD). The use of floating car data [...] Read more.

New technologies such as “connected” and “autonomous” vehicles are going to change the future of traffic signal control and management and possibly will introduce new traffic signal systems that will be based on floating car data (FCD). The use of floating car data to regulate traffic signal systems, in real time, has the potential for an increased sustainability of transportation in terms of energy efficiency, traffic safety and environmental issues. However, research has never explored how not “connected” vehicles would benefit by the implementation of such systems. This paper explores the use of floating car data to regulate traffic signal systems in real-time in a single intersection and in terms of cooperative-competitive paradigm between “connected” vehicles and conventional vehicles. In a dedicated laboratory, developed for testing regulation algorithms, results show that “invisible vehicles” for the system (which are not “connected”) in most simulated cases also benefit when real time traffic signal settings based on floating car data are introduced. Moreover, the study estimates the energy and air quality impacts of a single intersection signal regulation by evaluating fuel consumption and pollutant emissions. Specifically, the study demonstrates that significant improvements in air quality are possible with the introduction of FCD regulated traffic signals. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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18 pages, 3811 KiB

Open AccessArticle

Renewable Energy Sources and Battery Forecasting Effects in Smart Power System Performance

by Mehdi Bagheri, Venera Nurmanova, Oveis Abedinia, Mohammad Salay Naderi, Noradin Ghadimi and Mehdi Salay Naderi

Energies 2019, 12(3), 373; https://doi.org/10.3390/en12030373 - 24 Jan 2019

Cited by 23 | Viewed by 3289

Abstract

In this study, the influence of using acid batteries as part of green energy sources, such as wind and solar electric power generators, is investigated. First, the power system is simulated in the presence of a lead–acid battery, with an independent solar system [...] Read more.

In this study, the influence of using acid batteries as part of green energy sources, such as wind and solar electric power generators, is investigated. First, the power system is simulated in the presence of a lead–acid battery, with an independent solar system and wind power generator. In the next step, in order to estimate the output power of the solar and wind resources, a novel forecast model is proposed. Then, the forecasting task is carried out considering the conditions related to the state of charge (SOC) of the batteries. The optimization algorithm used in this model is honey bee mating optimization (HBMO), which operates based on selecting the best candidates and optimization of the prediction problem. Using this algorithm, the SOC of the batteries will be in an appropriate range, and the number of on-or-off switching’s of the wind turbines and photovoltaic (PV) modules will be reduced. In the proposed method, the appropriate capacity for the SOC of the batteries is chosen, and the number of battery on/off switches connected to the renewable energy sources is reduced. Finally, in order to validate the proposed method, the results are compared with several other methods. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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16 pages, 1009 KiB

Open AccessArticle

Risk Data Analysis Based Anomaly Detection of Ship Information System

by Bowen Xing, Yafeng Jiang, Yuqing Liu and Shouqi Cao

Energies 2018, 11(12), 3403; https://doi.org/10.3390/en11123403 - 4 Dec 2018

Cited by 3 | Viewed by 2757

Abstract

Due to the vulnerability and high risk of the ship environment, the Ship Information System (SIS) should provide 24 hours of uninterrupted protection against network attacks. Therefore, the corresponding intrusion detection mechanism is proposed for this situation. Based on the collaborative control structure [...] Read more.

Due to the vulnerability and high risk of the ship environment, the Ship Information System (SIS) should provide 24 hours of uninterrupted protection against network attacks. Therefore, the corresponding intrusion detection mechanism is proposed for this situation. Based on the collaborative control structure of SIS, this paper proposes an anomaly detection pattern based on risk data analysis. An intrusion detection method based on the critical state is proposed, and the corresponding analysis algorithm is given. In the Industrial State Modeling Language (ISML), risk data are determined by all relevant data, even in different subsystems. In order to verify the attack recognition effect of the intrusion detection mechanism, this paper takes the course/roll collaborative control task as an example to carry out simulation verification of the effectiveness of the intrusion detection mechanism. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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14 pages, 4674 KiB

Open AccessArticle

Suppression of Electron Avalanches in Ultra-Dilute SF₆-N₂ Mixtures Subjected to Time-Invariant Crossed Fields

by Mustafa Sezai Dincer, Suleyman Sungur Tezcan and Hidir Duzkaya

Energies 2018, 11(12), 3247; https://doi.org/10.3390/en11123247 - 22 Nov 2018

Cited by 8 | Viewed by 2694

Abstract

Ultra-dilute SF₆ + N₂ mixtures are subjected to crossed fields with the applied magnetic field normal to the electric field in order to investigate critical magnetic field values for suppression of electron avalanche growth resulting in increased dielectric strength. Electron avalanche [...] Read more.

Ultra-dilute SF₆ + N₂ mixtures are subjected to crossed fields with the applied magnetic field normal to the electric field in order to investigate critical magnetic field values for suppression of electron avalanche growth resulting in increased dielectric strength. Electron avalanche growth inhibition together with the related electron mean energy variation and electron energy distribution functions are reported in the binary mixtures subjected to the combined fields. Even if a very small amount of greenhouse gas (SF₆) is used, high dielectric strength can be achieved in the binary mixtures with 0.25%, 0.50%, 0.75%, 3%, and 7% SF₆ contents subjected to the evaluated combined fields. The magnitude of the crossed magnetic field, which results in avalanche growth inhibition, decreases as the electronegativity of the mixture is increased. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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10 pages, 4623 KiB

Open AccessArticle

Effect of Saturation on Field Oriented Control of the New Designed Reluctance Synchronous Motor

by Pavol Rafajdus, Valeria Hrabovcova, Pavel Lehocky, Pavol Makys and Filip Holub

Energies 2018, 11(11), 3223; https://doi.org/10.3390/en11113223 - 21 Nov 2018

Cited by 8 | Viewed by 4231

Abstract

In this paper the effect of saturation on torque production of a reluctance synchronous motor (RSM), which was originally built as an induction motor (IM), is investigated. The rotor was replaced with new one, designed as synchronous reluctance cageless rotor with barriers, the [...] Read more.

In this paper the effect of saturation on torque production of a reluctance synchronous motor (RSM), which was originally built as an induction motor (IM), is investigated. The rotor was replaced with new one, designed as synchronous reluctance cageless rotor with barriers, the shape and number of which were optimized to maximize the reluctance ratio. The torque measurement was done while the RSM was fed by frequency converter controlled by a microcontroller with closed loop field oriented control strategy to find out how saturation effects the developed torque at various values of the currents and speeds. It is shown how the load angle at which the maximum torque was achieved is changed. It was found out that the load angle was shifted to higher values depending on the speed of operation. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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20 pages, 8912 KiB

Open AccessArticle

Electrical Modelling of a DC Railway System with Multiple Trains

by Hammad Alnuman, Daniel Gladwin and Martin Foster

Energies 2018, 11(11), 3211; https://doi.org/10.3390/en11113211 - 19 Nov 2018

Cited by 41 | Viewed by 10397

Abstract

Electrical modelling of rail tracks with multiple running trains is complex due to the difficulties in solving the power flow. The train positions, speed and acceleration are constantly varying resulting in a nonlinear system. In this work, a method is proposed for modelling [...] Read more.

Electrical modelling of rail tracks with multiple running trains is complex due to the difficulties in solving the power flow. The train positions, speed and acceleration are constantly varying resulting in a nonlinear system. In this work, a method is proposed for modelling DC electric railways to support power flow analysis of a simulated metro train service. The method exploits the MathWorks simulation tool Simscape, using it to model the mechanical and electrical characteristics of the rail track system. The model can be simulated to provide voltages at any position in the track and additionally, the voltages seen by any train. The model includes regenerative braking on trains, this is demonstrated to cause overvoltage in the feeding line if it is higher than the power demand of the other trains at that time. Braking resistors are used to protect the network from overvoltage by burning the excess energy. Through the implementation of Energy Storage Systems (ESSs), it will be possible to improve the energy efficiency and remove timetabling restrictions of electric railways by effectively controlling the rail track voltage. The paper proposes several methods to validate the model. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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25 pages, 1693 KiB

Open AccessArticle

A Passenger-Oriented Optimization Model for Implementing Energy-Saving Strategies in Railway Contexts

by Luca D’Acierno and Marilisa Botte

Energies 2018, 11(11), 2946; https://doi.org/10.3390/en11112946 - 29 Oct 2018

Cited by 30 | Viewed by 3336

Abstract

Rail and metro systems are characterized by high-performing and environmentally friendly features that make them a crucial factor for driving modal split towards public transport modes, thus reducing private car use and related externalities (such as air and noise pollution, traffic congestion and [...] Read more.

Rail and metro systems are characterized by high-performing and environmentally friendly features that make them a crucial factor for driving modal split towards public transport modes, thus reducing private car use and related externalities (such as air and noise pollution, traffic congestion and accidents). Within this framework, the implementation of suitable energy-saving policies, allowing to reduce energy consumption, but, at the same time, preserving timetable stability and passengers’ satisfaction, may turn out to be imperative. In particular, this study aims to develop an analytical framework for properly supporting the implementation of eco-driving strategies in a passenger-oriented perspective. An application to a rail line in southern Italy is performed so as to demonstrate the usefulness of the proposed approach in determining the optimal compromise between energy reductions and travel time increases. Full article

(This article belongs to the Special Issue Selected Papers from EEEIC 2018—18th International Conference on Environment and Electrical Engineering)

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