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Celebrating Applied Sciences Reaching the 20,000 Article Milestone: Invited Papers in the Section Energy

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Energy Science and Technology".

Deadline for manuscript submissions: closed (20 August 2021) | Viewed by 12958

Special Issue Editors


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Guest Editor
Department of Energy Technology, Aalborg University, 9220 Aalborg, Denmark
Interests: power electronics and its applications in motor drives; wind turbines; PV systems; harmonics; reliability of power electronic systems
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Department of Energy Technology, Aalborg University, 9220 Aalborg, Denmark
Interests: cybersecurity in power electronics; cyber-physical power electronic systems; control and stability of microgrids; renewable energy

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Guest Editor
Department of Energy Technology, Aalborg University, 9220 Aalborg, Denmark
Interests: electrical power engineering; power systems; power electronics; reliability, control and stability; renewable energies

Special Issue Information

Dear Colleague,

Electrifying the world is one of the pragmatic solutions for reducing carbon footprints. Electric transportation, renewable energy generation, electric storage systems, smart- and microgrid technologies, and digitalization are essential parts of a sustainable green society. Thus, modern energy systems are becoming more and more interconnected. This makes them vulnerable. Therefore, the reliable and secure planning and operation of modern energy systems require advanced and smart solutions.

This Special Issue aims to cover state-of-the-art methodologies, models and technical contributions for improving the reliability and performance of modern energy systems characterized by a high penetration of renewable energy sources, electric transportation, energy storage systems, smart homes and digitalization.  To celebrate the recent publication of Applied Sciences’ 20,000th paper and mark this special occasion together with our readers, the journal’s Editorial Board invites researchers in all the areas of interest covered by Energy to submit high-quality original research or review articles. 

Prof. Dr. Frede Blaabjerg
Prof. Dr. Subham Sahoo
Prof. Dr. Saeed Peyghami
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • transportation electrification
  • smart homes
  • role of power electronics in future energy systems
  • energy storage systems
  • digitalization of energy sector
  • renewable energies
  • reliability and resilience of interconnected energy systems

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Published Papers (4 papers)

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Research

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14 pages, 4519 KiB  
Article
Adaptive Volt–Var Control in Smart PV Inverter for Mitigating Voltage Unbalance at PCC Using Multiagent Deep Reinforcement Learning
by Yoongun Jung, Changhee Han, Dongwon Lee, Sungyoon Song and Gilsoo Jang
Appl. Sci. 2021, 11(19), 8979; https://doi.org/10.3390/app11198979 - 26 Sep 2021
Cited by 11 | Viewed by 2859
Abstract
Modern distribution networks face an increasing number of challenges in maintaining balanced grid voltages because of the rapid increase in single-phase distributed generators. Because of the proliferation of inverter-based resources, such as photovoltaic (PV) resources, in distribution networks, a novel method is proposed [...] Read more.
Modern distribution networks face an increasing number of challenges in maintaining balanced grid voltages because of the rapid increase in single-phase distributed generators. Because of the proliferation of inverter-based resources, such as photovoltaic (PV) resources, in distribution networks, a novel method is proposed for mitigating voltage unbalance at the point of common coupling by tuning the volt–var curve of each PV inverter through a day-ahead deep reinforcement learning training platform with forecast data in a digital twin grid. The proposed strategy uses proximal policy optimization, which can effectively search for a global optimal solution. Deep reinforcement learning has a major advantage in that the calculation time required to derive an optimal action in the smart inverter can be significantly reduced. In the proposed framework, multiple agents with multiple inverters require information on the load consumption and active power output of each PV inverter. The results demonstrate the effectiveness of the proposed control strategy on the modified IEEE 13 standard bus systems with time-varying load and PV profiles. A comparison of the effect on voltage unbalance mitigation shows that the proposed inverter can address voltage unbalance issues more efficiently than a fixed droop inverter. Full article
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16 pages, 634 KiB  
Article
Compliance of Distribution System Reactive Flows with Transmission System Requirements
by Panagiotis Pediaditis, Katja Sirviö, Charalampos Ziras, Kimmo Kauhaniemi, Hannu Laaksonen and Nikos Hatziargyriou
Appl. Sci. 2021, 11(16), 7719; https://doi.org/10.3390/app11167719 - 22 Aug 2021
Cited by 2 | Viewed by 1735
Abstract
Transmission system operators (TSOs) often set requirements to distribution system operators (DSOs) regarding the exchange of reactive power on the interface between the two parts of the system they operate, typically High Voltage and Medium Voltage. The presence of increasing amounts of Distributed [...] Read more.
Transmission system operators (TSOs) often set requirements to distribution system operators (DSOs) regarding the exchange of reactive power on the interface between the two parts of the system they operate, typically High Voltage and Medium Voltage. The presence of increasing amounts of Distributed Energy Resources (DERs) at the distribution networks complicates the problem, but provides control opportunities in order to keep the exchange within the prescribed limits. Typical DER control methods, such as constant cosϕ or Q/V functions, cannot adequately address these limits, while power electronics interfaced DERs provide to DSOs reactive power control capabilities for complying more effectively with TSO requirements. This paper proposes an optimisation method to provide power set-points to DERs in order to control the hourly reactive power exchanges with the transmission network. The method is tested via simulations using real data from the distribution substation at the Sundom Smart Grid, in Finland, using the operating guidelines imposed by the Finnish TSO. Results show the advantages of the proposed method compared to traditional methods for reactive power compensation from DERs. The application of more advanced Model Predictive Control techniques is further explored. Full article
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19 pages, 2882 KiB  
Article
A Theoretical Concept of Decoupled Current Control Scheme for Grid-Connected Inverter with L-C-L Filter
by Mohamad Amin Ghasemi, Seyed Fariborz Zarei, Saeed Peyghami and Frede Blaabjerg
Appl. Sci. 2021, 11(14), 6256; https://doi.org/10.3390/app11146256 - 6 Jul 2021
Cited by 11 | Viewed by 3996
Abstract
This paper proposes a nonlinear decoupled current control scheme for a grid-connected inverter with LCL filter. Decoupling the active and reactive current control channels is one of the main demands in the control of inverters. For inverters with an L filter, the decoupling [...] Read more.
This paper proposes a nonlinear decoupled current control scheme for a grid-connected inverter with LCL filter. Decoupling the active and reactive current control channels is one of the main demands in the control of inverters. For inverters with an L filter, the decoupling can be achieved by a proper feed-forward of grid voltages. However, the coupling of channels is a complex issue for converters with LCL filters. The resonance mode of the LCL filter may cause instability, which adds more complexity to the analysis. In this paper, state equations of the system are provided, which highlight the coupling between active and reactive currents injected into the grid. Accordingly, a non-linear control scheme is proposed which effectively decouples the channels and dampens the resonant modes of the LCL filter. The stability of the proposed control method is verified by the Lyapunov criterion. Independency of the system stability to the grid-impedance is another feature of the proposed approach. Moreover, only grid-side currents are needed for implementation of the proposed scheme, avoiding the need for additional current sensors for the output capacitor and grid-side inductor. For accurate modelling of the inverter, the computation and PWM sampling delays are included in the controller design. Finally, various case studies are provided that verify the performance of the proposed approach and the stability of the system. Full article
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Review

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18 pages, 8268 KiB  
Review
Quo Vadis Solar Energy Research?
by Miguel Angel Reyes-Belmonte
Appl. Sci. 2021, 11(7), 3015; https://doi.org/10.3390/app11073015 - 28 Mar 2021
Cited by 19 | Viewed by 2992
Abstract
In this paper, solar energy research trends and their publishing evolution are presented in terms of bibliometric analysis tools applied to the existing publications within the Web of Science Core Collection. Publishing evolution shows a clear interest in solar energy topics, as 50% [...] Read more.
In this paper, solar energy research trends and their publishing evolution are presented in terms of bibliometric analysis tools applied to the existing publications within the Web of Science Core Collection. Publishing evolution shows a clear interest in solar energy topics, as 50% of the total number of publications have been published within the time period between 2015 and 2020; most of them at journals and conference proceedings. A results analysis shows that China, the United States and India were the most productive countries in terms of solar energy research publications, and the list of the 10 most productive countries accounted for 83% of total publications within 2019 and 2020. The study pointed out as well that the main thematic areas in solar energy research in 2019–2020 were related to particular topics such as solar cells and optical properties, nanoparticles and composites, TiO2 and photocatalysis, and more general topics such as performance, simulations optimization and renewable energy. Based on paper findings, the research future of solar energy is bright, with continued growth in the publications record and a wide variety of research topics. Full article
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