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Electricity, Volume 2, Issue 4 (December 2021) – 12 articles

Cover Story (view full-size image): The growing global electricity demand and the upcoming integration of charging options for electric vehicles is creating challenges for power grids. With continuously falling costs for lithium-ion batteries, storage systems represent an alternative to conventional grid reinforcement. This paper proposes a novel operation strategy for battery energy storage systems to achieve both an improvement in the distribution grid and savings for the industrial consumer. Information on the additional stress on the storage system is derived from a detailed analysis based on six key characteristics. The results show that, with the combined approach, both the local peak load and the global peak load can be reduced, while the stress on the energy storage is not significantly increased. View this paper
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39 pages, 52160 KiB  
Article
Development of Planning and Operation Guidelines for Strategic Grid Planning of Urban Low-Voltage Grids with a New Supply Task
by Patrick Wintzek, Shawki Alsayed Ali, Markus Zdrallek, Julian Monscheidt, Ben Gemsjäger and Adam Slupinski
Electricity 2021, 2(4), 614-652; https://doi.org/10.3390/electricity2040035 - 16 Dec 2021
Cited by 10 | Viewed by 3677
Abstract
In contrast to rural distribution grids, which are mostly “feed-in oriented” in terms of electrical power, urban distribution grids are “load oriented”, as the number of customer connections and density of loads in urban areas is significantly higher than in rural areas. Taking [...] Read more.
In contrast to rural distribution grids, which are mostly “feed-in oriented” in terms of electrical power, urban distribution grids are “load oriented”, as the number of customer connections and density of loads in urban areas is significantly higher than in rural areas. Taking into account the progressive electrification of the transport and heating sector, it is necessary to assess the required grid optimization or expansion measures from a conventional, as well as an innovative point of view. This is necessary in order to be able to contain the enormous investment volumes needed for transforming the energy system and aligning the infrastructures to their future requirements in time. Therefore, this article first explains the methodological approach of allocating scenarios of the development of electric mobility and heat pumps to analyzed grids. The article continues with describing which power values need to be applied and which conventional and innovative planning measures are available for avoiding voltage band violations and equipment overloads within the framework of strategic grid planning. Subsequently, the results of grid planning studies are outlined and evaluated with an assessment model that evaluates capital as well as operational costs. On this basis, planning and operation guidelines for urban low-voltage grids are derived. The main result is that low-voltage grids can accommodate charging infrastructure for electric mobility, as well as heat pumps to a certain degree. In addition, it is concluded that conventional planning measures are not completely avoidable, but can be partially avoided or deferred through dynamic load management. Full article
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24 pages, 9010 KiB  
Article
Parameterized 2D Field Model of a Switched Reluctance Motor
by Krzysztof Bieńkowski, Michał Szulborski, Sebastian Łapczyński, Łukasz Kolimas and Hubert Cichecki
Electricity 2021, 2(4), 590-613; https://doi.org/10.3390/electricity2040034 - 3 Dec 2021
Cited by 1 | Viewed by 3199
Abstract
This work aimed to develop a parameterized, two-dimensional field model of a switched reluctance motor (SRM). The main task of the developed model was to calculate the value of the electromagnetic torque for various positions of the rotor. Based on these calculations, the [...] Read more.
This work aimed to develop a parameterized, two-dimensional field model of a switched reluctance motor (SRM). The main task of the developed model was to calculate the value of the electromagnetic torque for various positions of the rotor. Based on these calculations, the characteristics of the electromagnetic torque were determined depending on the position of the rotor angle φ for the current function I (T = f (φ, I)). Using the model, it was possible to additionally observe the phenomena occurring in the motor winding, e.g., distributions, isolines of magnetic potential, induction, and to calculate the values of the temperature. The parameterized structural elements that made up the entire model can be freely changed and, thus, the results for various structures can be obtained. Thanks to this, it was possible to evaluate and compare motor of different designs. To validate the model, measurements were conducted on real-scale reluctance motors, and families of electromagnetic torque characteristics were obtained for various design cases. The results received from the tested motors were juxtaposed with simulation results procured via the model. Based on this comparison, it was possible to determine the accuracy of the model’s operation. Full article
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17 pages, 800 KiB  
Article
Peak Shaving with Battery Energy Storage Systems in Distribution Grids: A Novel Approach to Reduce Local and Global Peak Loads
by Daniel Kucevic, Leo Semmelmann, Nils Collath, Andreas Jossen and Holger Hesse
Electricity 2021, 2(4), 573-589; https://doi.org/10.3390/electricity2040033 - 15 Nov 2021
Cited by 10 | Viewed by 5880
Abstract
The growing global electricity demand and the upcoming integration of charging options for electric vehicles is creating challenges for power grids, such as line over loading. With continuously falling costs for lithium-ion batteries, storage systems represent an alternative to conventional grid reinforcement. This [...] Read more.
The growing global electricity demand and the upcoming integration of charging options for electric vehicles is creating challenges for power grids, such as line over loading. With continuously falling costs for lithium-ion batteries, storage systems represent an alternative to conventional grid reinforcement. This paper proposes an operation strategy for battery energy storage systems, targeted at industrial consumers to achieve both an improvement in the distribution grid and electricity bill savings for the industrial consumer. The objective is to reduce the peak power at the point of common coupling in existing distribution grids by adapting the control of the battery energy storage system at individual industrial consumer sites. An open-source simulation tool, which enables a realistic simulation of the effects of storage systems in different operating modes on the distribution grid, has been adapted as part of this work. Further information on the additional stress on the storage system is derived from a detailed analysis based on six key characteristics. The results show that, with the combined approach, both the local peak load and the global peak load can be reduced, while the stress on the energy storage is not significantly increased. The peak load at the point of common coupling is reduced by 5.6 kVA to 56.7 kVA and the additional stress for the storage system is, on average, for a six month simulation, period only 1.2 full equivalent cycles higher. Full article
(This article belongs to the Special Issue Recent Advances in Energy Storage Systems)
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19 pages, 3688 KiB  
Article
Voltage Unbalance, Power Factor and Losses Optimization in Electrified Railways Using an Electronic Balancer
by António P. Martins, Pedro Rodrigues, Mahmoud Hassan and Vítor A. Morais
Electricity 2021, 2(4), 554-572; https://doi.org/10.3390/electricity2040032 - 12 Nov 2021
Cited by 5 | Viewed by 3695
Abstract
Unbalanced currents, low power factor and high losses contribute to increasing the bill infrastructure managers must pay to the TSO/DSO operator that supplies electric energy to the railway system. Additionally, if regenerative energy coming from braking regimes is not allowed to be injected [...] Read more.
Unbalanced currents, low power factor and high losses contribute to increasing the bill infrastructure managers must pay to the TSO/DSO operator that supplies electric energy to the railway system. Additionally, if regenerative energy coming from braking regimes is not allowed to be injected into the grid or even is penalized when it occurs, then the optimization of those parameters must be pursued. One of the possible measures that can be taken to counteract those phenomena is the installation of electronic balancers in heavy loaded substations in order to optimize the interface to the three-phase electric grid. This paper shows the benefit of such use taking examples from real conditions and realistic simulations assumed equivalent to field measurements. Full article
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30 pages, 5034 KiB  
Article
Microgrid Protection through Adaptive Overcurrent Relay Coordination
by Haneen Bawayan and Mohamed Younis
Electricity 2021, 2(4), 524-553; https://doi.org/10.3390/electricity2040031 - 5 Nov 2021
Cited by 5 | Viewed by 4194
Abstract
The inclusion of distributed energy resources (DER) in Microgrids (MGs) comes at the expense of increased changes in current direction and magnitude. In the autonomous mode of MG operation, the penetration of synchronous distributed generators (DGs) induces lower short circuit current than when [...] Read more.
The inclusion of distributed energy resources (DER) in Microgrids (MGs) comes at the expense of increased changes in current direction and magnitude. In the autonomous mode of MG operation, the penetration of synchronous distributed generators (DGs) induces lower short circuit current than when the MG operates in the grid-connected mode. Such behavior impacts the overcurrent relays and makes the protection coordination difficult. This paper introduces a novel adaptive protection system that includes two phases to handle the influence of fault current variations and enable the MG to sustain its operation. The first phase optimizes the power flow by minimizing the generators’ active power loss while considering tolerable disturbances. For intolerable cases, the second phase opts to contain the effect of disturbance within a specific area, whose boundary is determined through correlation between primary/backup relay pairs. A directional overcurrent relay (DOCR) coordination optimization is formulated as a nonlinear program for minimizing the operating time of the relays within the contained area. Validation is carried out through the simulation of the IEEE 9, IEEE 14, and IEEE 15 bus systems as an autonomous MG. The simulation results demonstrate the effectiveness of our proposed protection system and its superiority to a competing approach in the literature. Full article
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21 pages, 130281 KiB  
Article
Optimization of 1D/3D Electro-Thermal Model for Liquid-Cooled Lithium-Ion Capacitor Module in High Power Applications
by Danial Karimi, Hamidreza Behi, Mohsen Akbarzadeh, Sahar Khaleghi, Joeri Van Mierlo and Maitane Berecibar
Electricity 2021, 2(4), 503-523; https://doi.org/10.3390/electricity2040030 - 4 Nov 2021
Cited by 10 | Viewed by 3599
Abstract
Lithium-ion capacitor technology (LiC) is well known for its higher power density compared to electric double-layer capacitors (EDLCs) and higher energy density compared to lithium-ion batteries (LiBs). However, the LiC technology is affected by a high heat generation problem in high-power applications when [...] Read more.
Lithium-ion capacitor technology (LiC) is well known for its higher power density compared to electric double-layer capacitors (EDLCs) and higher energy density compared to lithium-ion batteries (LiBs). However, the LiC technology is affected by a high heat generation problem in high-power applications when it is continuously being charged/discharged with high current rates. Such a problem is associated with safety and reliability issues that affect the lifetime of the cell. Therefore, for high-power applications, a robust thermal management system (TMS) is essential to control the temperature evolution of LiCs to ensure safe operation. In this regard, developing accurate electrical and thermal models is vital to design a proper TMS. This work presents a detailed 1D/3D electro-thermal model at module level employing MATLAB/SIMULINK® coupled to the COMSOL Multiphysics® software package. The effect of the inlet coolant flow rate, inlet coolant temperature, inlet and outlet positions, and the number of arcs are examined under the cycling profile of a continuous 150 A current rate without a rest period for 1400 s. The results prove that the optimal scenario for the LCTMS would be the inlet coolant flow rate of 500 mL/min, the inlet temperature of 30 °C, three inlets, three outlets, and three arcs in the coolant path. This scenario decreases the module’s maximum temperature (Tmax) and temperature difference by 11.5% and 79.1%, respectively. Moreover, the electro-thermal model shows ±5% and ±4% errors for the electrical and thermal models, respectively. Full article
(This article belongs to the Special Issue Recent Advances in Energy Storage Systems)
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16 pages, 4088 KiB  
Article
Repowering Feasibility Study of a Current Hybrid Renewable System. Case Study, Galapagos Islands
by Paul Arévalo, Marcos Tostado-Véliz and Francisco Jurado
Electricity 2021, 2(4), 487-502; https://doi.org/10.3390/electricity2040029 - 28 Oct 2021
Cited by 6 | Viewed by 2875
Abstract
Renewable sources on islands seem to be the most attractive option to decarbonize and lower the price of electricity; currently, most islands do so by replacing their diesel generators with wind or solar sources, along with energy storage. The Galapagos Islands are no [...] Read more.
Renewable sources on islands seem to be the most attractive option to decarbonize and lower the price of electricity; currently, most islands do so by replacing their diesel generators with wind or solar sources, along with energy storage. The Galapagos Islands are no exception. This study presents a techno-economic analysis of hybrid renewable systems in the Galapagos Islands, considering the repowering of its renewable sources and reduction in the penetration of diesel generators. This study uses EnergyPlan software, where the best option is chosen based on technical, economic, and environmental indicators. Finally, several sensitivity analyses are done. The results show that by increasing the capacity of current wind and photovoltaic systems, the total annual cost reduces by 20% and 10.31%, respectively; this is a specific result of this study. Moreover, there is a reduction in CO2 emissions produced by diesel generators, up to 38.96%. Full article
(This article belongs to the Special Issue Recent Advances toward Carbon-Neutral Power System)
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16 pages, 765 KiB  
Article
Participative Renewable Energy Community—How Blockchain-Based Governance Enables a German Interpretation of RED II
by Stefan P. M. Chantrel, Arne Surmann, Thomas Erge and Jessica Thomsen
Electricity 2021, 2(4), 471-486; https://doi.org/10.3390/electricity2040028 - 27 Oct 2021
Cited by 9 | Viewed by 2790
Abstract
Distributed solar photovoltaic generation is less expensive than the retail price of electricity from the grid in most parts of Europe. Growing shares of variable generation place a focus on Renewable Energy Communities (REC) to increase the economic benefits of local energy systems. [...] Read more.
Distributed solar photovoltaic generation is less expensive than the retail price of electricity from the grid in most parts of Europe. Growing shares of variable generation place a focus on Renewable Energy Communities (REC) to increase the economic benefits of local energy systems. Civil society could play an influential and necessary role in the development of such communities, the expansion of renewable energy capacity and the provision of flexibility. However, current RECs models still confine tenants to their role as non-participating consumers. This article provides a concept to enable participative RECs within the German regulatory framework through collective self-consumption by including consumers for a fair allocation of renewable electricity using the blockchain technology. Full article
(This article belongs to the Special Issue Recent Advances in Grid Connected Photovoltaic Systems)
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12 pages, 5917 KiB  
Article
Minimizing the Cost of PHEV Usage with Price Sensitive Charging Strategies
by Dimitra Zarbouti, Elisavet Koutsi, Georgia Athanasiadou and George Tsoulos
Electricity 2021, 2(4), 459-470; https://doi.org/10.3390/electricity2040027 - 25 Oct 2021
Cited by 1 | Viewed by 2801
Abstract
Electric cars sales have been rising almost steadily over the past decade. Uncontrolled charging has recently emerged as the main detrimental factor to this otherwise environmentally friendly and paradigm shifting technology due to the incurred impact on the energy grid. In addition, people [...] Read more.
Electric cars sales have been rising almost steadily over the past decade. Uncontrolled charging has recently emerged as the main detrimental factor to this otherwise environmentally friendly and paradigm shifting technology due to the incurred impact on the energy grid. In addition, people are usually hesitant in allowing their vehicles to be controlled by external units; therefore, controlled charging strategies that offer users the option to have some control over their vehicles seems to be a sensible choice moving towards a gasoline-free vehicles market. This work investigated two price-sensitive charging strategies that allowed users to control the charging of their vehicle in order to receive cost benefits. These strategies were of a parametric nature; thus, the analysis focused on providing useful rules of thumb to guide users in choosing the most suitable strategy and the relevant parameters according to their driving profiles. The results show that when driving less than 40 km/h on average and employing a price-sensitive charging strategy with the proposed optimized parameters, electric car users may obtain 30–40% of the running cost reduction. Full article
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20 pages, 8829 KiB  
Article
Design, Analysis and Experimental Verification of the Self-Resonant Inverter for Induction Heating Crucible Melting Furnace Based on IGBTs Connected in Parallel
by Borislav Dimitrov, Khaled Hayatleh, Steve Barker and Gordana Collier
Electricity 2021, 2(4), 439-458; https://doi.org/10.3390/electricity2040026 - 11 Oct 2021
Cited by 1 | Viewed by 4439
Abstract
The object of this research was a self-resonated inverter, based on paralleled Insulated-Gate Bipolar Transistors (IGBTs), for high-frequency induction heating equipment, operating in a wide range of output powers, applicable for research and industrial purposes. For the nominal installed capacity for these types [...] Read more.
The object of this research was a self-resonated inverter, based on paralleled Insulated-Gate Bipolar Transistors (IGBTs), for high-frequency induction heating equipment, operating in a wide range of output powers, applicable for research and industrial purposes. For the nominal installed capacity for these types of invertors to be improved, the presented inverter with a modified circuit comprising IGBT transistors connected in parallel was explored. The suggested topology required several engineering problems to be solved: minimisation of the current mismatch amongst the paralleled transistors; a precise analysis of the dynamic and static transistors’ parameters; determination of the derating and mismatch factors necessary for a reliable design; experimental verification confirming the applicability of the suggested topology in the investigated inverter. This paper presents the design and analysis of IGBT transistors based on datasheet parameters and mathematical apparatus application. The expected current mismatch and the necessary derating factor, based on the expected mismatch in transistor parameters in a production lot, were determined. The suggested design was experimentally tested and investigated using a self-resonant inverter model in a melting crucible induction laboratory furnace. Full article
(This article belongs to the Topic Application of Innovative Power Electronic Technologies)
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16 pages, 2026 KiB  
Article
μPMU-Based Temporal Decoupling of Parameter and Measurement Gross Error Processing in DSSE
by Rodrigo D. Trevizan, Cody Ruben, Aquiles Rossoni, Surya C. Dhulipala, Arturo Bretas and Newton G. Bretas
Electricity 2021, 2(4), 423-438; https://doi.org/10.3390/electricity2040025 - 2 Oct 2021
Cited by 4 | Viewed by 2852
Abstract
Simultaneous real-time monitoring of measurement and parameter gross errors poses a great challenge to distribution system state estimation due to usually low measurement redundancy. This paper presents a gross error analysis framework, employing μPMUs to decouple the error analysis of measurements and [...] Read more.
Simultaneous real-time monitoring of measurement and parameter gross errors poses a great challenge to distribution system state estimation due to usually low measurement redundancy. This paper presents a gross error analysis framework, employing μPMUs to decouple the error analysis of measurements and parameters. When a recent measurement scan from SCADA RTUs and smart meters is available, gross error analysis of measurements is performed as a post-processing step of non-linear DSSE (NLSE). In between scans of SCADA and AMI measurements, a linear state estimator (LSE) using μPMU measurements and linearized SCADA and AMI measurements is used to detect parameter data changes caused by the operation of Volt/Var controls. For every execution of the LSE, the variance of the unsynchronized measurements is updated according to the uncertainty introduced by load dynamics, which are modeled as an Ornstein–Uhlenbeck random process. The update of variance of unsynchronized measurements can avoid the wrong detection of errors and can model the trustworthiness of outdated or obsolete data. When new SCADA and AMI measurements arrive, the LSE provides added redundancy to the NLSE through synthetic measurements. The presented framework was tested on a 13-bus test system. Test results highlight that the LSE and NLSE processes successfully work together to analyze bad data for both measurements and parameters. Full article
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20 pages, 2440 KiB  
Article
Least-Cost Non-RES Thermal Power Plants Mix in Power Systems with Majority Penetrations of Renewable Energy
by Hugo Algarvio
Electricity 2021, 2(4), 403-422; https://doi.org/10.3390/electricity2040024 - 24 Sep 2021
Cited by 2 | Viewed by 2750
Abstract
The ambitious targets of the European Union (EU) for a greater penetration of renewable energy sources (RES) in all areas of activity have led to power systems with growing levels of variable RES (VRES) all over the EU. Considering these targets, the EU [...] Read more.
The ambitious targets of the European Union (EU) for a greater penetration of renewable energy sources (RES) in all areas of activity have led to power systems with growing levels of variable RES (VRES) all over the EU. Considering these targets, the EU countries presented their National Energy and Climate Plans (NECP) with their expected capacity until 2030. The NECPs considered a relevant increase in the VRES capacity and in some cases a decrease in the capacity of dispatchable power plants. VRES have near-zero marginal costs and increase the volatility of the net-load due to the stochastic profile of their production. These characteristics increase the need to maintain fast-response dispatchable power plants to guarantee the security of supply and also decrease market prices. Thus, governments promote externalities, as capacity mechanisms and other incentives to these players, guaranteeing their economic sustainability. This study presents the optimization of the non-RES thermal capacity of the Iberian power system by 2030, considering the least-cost algorithm. Considering a cooperative scenario between Portugal and Spain, it is possible to reduce the system costs by 17.40%, the curtailments quantity by 21.93%, the number of market-splitting hours by 43.26% and the dioxide carbon emissions by 4.76%. Full article
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