Energies

Research

23263 KiB

Open AccessArticle

Progress of the Plasma Centerpost for the PROTO-SPHERA Spherical Tokamak

by Alessandro Lampasi, Giuseppe Maffia, Franco Alladio, Luca Boncagni, Federica Causa, Edmondo Giovannozzi, Luigi Andrea Grosso, Alessandro Mancuso, Paolo Micozzi, Valerio Piergotti, Giuliano Rocchi, Alessandro Sibio, Benedetto Tilia and Vincenzo Zanza

Energies 2016, 9(7), 508; https://doi.org/10.3390/en9070508 - 30 Jun 2016

Cited by 13 | Viewed by 9280

Abstract

Plasma properties can be useful in a wide spectrum of applications. Experimental projects on controlled nuclear fusion are the most challenging of these applications and, at the same time, the best way to approach plasma science. Since nuclear fusion reactors can ensure a [...] Read more.

Plasma properties can be useful in a wide spectrum of applications. Experimental projects on controlled nuclear fusion are the most challenging of these applications and, at the same time, the best way to approach plasma science. Since nuclear fusion reactors can ensure a large-scale, safe, environmentally-friendly and virtually inexhaustible source of energy, several fusion-oriented megaprojects and innovative companies are appearing all over the world. PROTO-SPHERA (Spherical Plasma for HElicity Relaxation Assessment) is the first plasma project with a simply connected configuration, namely not requiring additional objects inside the plasma volume. This is obtained by a plasma arc, shaped as a screw pinch, acting as the centerpost of a spherical torus with minimal aspect ratio. Due to its intrinsic physical, engineering and economic advantages, this new approach is attractive also on an industrial scale and with several developments that still needs to be explored. This paper presents the PROTO-SPHERA basic principles, its first encouraging results and its expected and potential evolutions. Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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3052 KiB

Open AccessArticle

Distributed Measuring System for Predictive Diagnosis of Uninterruptible Power Supplies in Safety-Critical Applications

by Sergio Saponara

Energies 2016, 9(5), 327; https://doi.org/10.3390/en9050327 - 28 Apr 2016

Cited by 16 | Viewed by 6376

Abstract

This work proposes a scalable architecture of an Uninterruptible Power Supply (UPS) system, with predictive diagnosis capabilities, for safety critical applications. A Failure Mode and Effect Analysis (FMEA) has identified the faults occurring in the energy storage unit, based on Valve Regulated Lead-Acid [...] Read more.

This work proposes a scalable architecture of an Uninterruptible Power Supply (UPS) system, with predictive diagnosis capabilities, for safety critical applications. A Failure Mode and Effect Analysis (FMEA) has identified the faults occurring in the energy storage unit, based on Valve Regulated Lead-Acid batteries, and in the 3-phase high power transformers, used in switching converters and for power isolation, as the main bottlenecks for power system reliability. To address these issues, a distributed network of measuring nodes is proposed, where vibration-based mechanical stress diagnosis is implemented together with electrical (voltage, current, impedance) and thermal degradation analysis. Power system degradation is tracked through multi-channel measuring nodes with integrated digital signal processing in the transformed frequency domain, from 0.1 Hz to 1 kHz. Experimental measurements on real power systems for safety-critical applications validate the diagnostic unit. Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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2840 KiB

Open AccessArticle

A Complete and Simplified Datasheet-Based Model of PV Cells in Variable Environmental Conditions for Circuit Simulation

by Silvano Vergura

Energies 2016, 9(5), 326; https://doi.org/10.3390/en9050326 - 28 Apr 2016

Cited by 74 | Viewed by 7211

Abstract

The paper proposes two mathematical models of a photo-voltaic (PV) cell—the complete model and the simplified model—which can be used also for modeling a PV module or a PV string under any environmental condition. Both of them are based on the well-known five-parameters [...] Read more.

The paper proposes two mathematical models of a photo-voltaic (PV) cell—the complete model and the simplified model—which can be used also for modeling a PV module or a PV string under any environmental condition. Both of them are based on the well-known five-parameters model, while the approach allows to write a new descriptive equation, whose terms are functions of the information always available in the modern datasheet of a PV module’s manufacturer. This implies that no pre-processing of the datasheet parameters is needed to use the proposed model, whichever the solar irradiance and the cell/module temperature are. Moreover, these models are interpreted from a circuital point of view, providing the electrical circuits constituted only by basic electrical components. Particularly, in order to take into account the variability of the environment parameters, several variable resistors and voltage-controlled sources are used. The proposed models are tested with the datasheet parameters of commercial PV modules. Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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3976 KiB

Open AccessArticle

Extracting Steady State Components from Synchrophasor Data Using Kalman Filters

by Farhan Mahmood, Hossein Hooshyar and Luigi Vanfretti

Energies 2016, 9(5), 315; https://doi.org/10.3390/en9050315 - 25 Apr 2016

Cited by 11 | Viewed by 6577

Abstract

Data from phasor measurement units (PMUs) may be exploited to provide steady state information to the applications which require it. As PMU measurements may contain errors and missing data, the paper presents the application of a Kalman Filter technique for real-time data processing. [...] Read more.

Data from phasor measurement units (PMUs) may be exploited to provide steady state information to the applications which require it. As PMU measurements may contain errors and missing data, the paper presents the application of a Kalman Filter technique for real-time data processing. PMU data captures the power system’s response at different time-scales, which are generated by different types of power system events; the presented Kalman Filter methods have been applied to extract the steady state components of PMU measurements that can be fed to steady state applications. Two KF-based methods have been proposed, i.e., a windowing-based KF method and “the modified KF”. Both methods are capable of reducing noise, compensating for missing data and filtering outliers from input PMU signals. A comparison of proposed methods has been carried out using the PMU data generated from a hardware-in-the-loop (HIL) experimental setup. In addition, a performance analysis of the proposed methods is performed using an evaluation metric. Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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5260 KiB

Open AccessArticle

Power Quality Improvement and LVRT Capability Enhancement of Wind Farms by Means of an Inductive Filtering Method

by Yanjian Peng, Yong Li, Zhisheng Xu, Ming Wen, Longfu Luo, Yijia Cao and Zbigniew Leonowicz

Energies 2016, 9(4), 302; https://doi.org/10.3390/en9040302 - 20 Apr 2016

Cited by 6 | Viewed by 5236

Abstract

Unlike the traditional method for power quality improvement and low-voltage ride through (LVRT) capability enhancement of wind farms, this paper proposes a new wind power integrated system by means of an inductive filtering method, especially if it contains a grid-connected transformer, a static [...] Read more.

Unlike the traditional method for power quality improvement and low-voltage ride through (LVRT) capability enhancement of wind farms, this paper proposes a new wind power integrated system by means of an inductive filtering method, especially if it contains a grid-connected transformer, a static synchronous compensator (STATCOM) and fully-tuned (FT) branches. First, the main circuit topology of the new wind power integrated system is presented. Then, the mathematical model is established to reveal the mechanism of harmonic suppression and the reactive compensation of the proposed wind power integrated system, and then the realization conditions of the inductive filtering method is obtained. Further, the control strategy of STATCOM is introduced. Based on the measured data for a real wind farm, the simulation studies are carried out to illustrate the performance of the proposed new wind power integrated system. The results indicate that the new system can not only enhance the LVRT capability of wind farms, but also prevent harmonic components flowing into the primary (grid) winding of the grid-connected transformer. Moreover, since the new method can compensate for reactive power in a wind farm, the power factor at the grid side can be improved effectively. Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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5807 KiB

Open AccessArticle

A Model for the Assessment of Different Net-Metering Policies

by Georgios C. Christoforidis, Ioannis P. Panapakidis, Theofilos A. Papadopoulos, Grigoris K. Papagiannis, Ioannis Koumparou, Maria Hadjipanayi and George E. Georghiou

Energies 2016, 9(4), 262; https://doi.org/10.3390/en9040262 - 1 Apr 2016

Cited by 48 | Viewed by 6706

Abstract

The photovoltaic market has recently experienced an enormous expansion, mainly due to the generous Feed-in-Tariffs (FiTs) adopted by many countries. However, in the recent years FiTs have been considerably reduced or even disappeared as their role in the PV deployment has ended. One [...] Read more.

The photovoltaic market has recently experienced an enormous expansion, mainly due to the generous Feed-in-Tariffs (FiTs) adopted by many countries. However, in the recent years FiTs have been considerably reduced or even disappeared as their role in the PV deployment has ended. One of the alternatives is the Net-Metering (NEM) policy, which has attracted the interest of stakeholders as it provides a basis for the efficient collaboration between generation and the consumption profiles of the consumer. Currently, there is a lack of a universal policy harmonizing the respective legislations of the E.U. member countries. This paper proposes a novel generalized methodology for the techno-economic assessment of different NEM policies in terms of profitability for the prosumer. The methodology is tested in a formulated case study based on the current NEM policy in Greece. The method proposed uses as inputs the averaged load profiles constructed from real measurements collected from 31 consumers in the Thessaloniki area and evaluated PV production. The current NEM policy and four alternatives are examined, using as additional input the average system marginal prices of the year 2013. The results show that the proposed methodology is capable of evaluating a wide variety of NEM policies and can lead to suggestions for policy adaptation in order to establish a win-win contract between all interested stakeholders. Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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3030 KiB

Open AccessArticle

Lightweight Borohydrides Electro-Activity in Lithium Cells

by Daniele Meggiolaro, Luca Farina, Laura Silvestri, Stefania Panero, Sergio Brutti and Priscilla Reale

Energies 2016, 9(4), 238; https://doi.org/10.3390/en9040238 - 25 Mar 2016

Cited by 13 | Viewed by 4952

Abstract

As a substitute for graphite, the negative electrode material commonly used in Li-ion batteries, hydrides have the theoretical potential to overcome performance limits of the current state-of-the-art Li-ion cells. Hydrides can operate through a conversion process proved for some interstitial hydrides like MgH [...] Read more.

As a substitute for graphite, the negative electrode material commonly used in Li-ion batteries, hydrides have the theoretical potential to overcome performance limits of the current state-of-the-art Li-ion cells. Hydrides can operate through a conversion process proved for some interstitial hydrides like MgH₂: M_xA_y + n Li = x M + y Li_mA, where m = n/y. Even if far from optimization, outstanding performances were observed, drawing the attention to the whole hydride family. Looking for high capacity systems, lightweight complex metal hydrides, such as borohydrides, deserve consideration. Capacities in the order of 2000–4000 mAh/g can be theoretically expected thanks to the very low formula unit weight. Although the potential technological impact of these materials can lead to major breakthroughs in Li-ion batteries, this new research field requires the tackling of fundamental issues that are completely unexplored. Here, our recent findings on the incorporation of borohydrides are presented and discussed. Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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2124 KiB

Open AccessArticle

On Variable Reverse Power Flow-Part II: An Electricity Market Model Considering Wind Station Size and Location

by Aouss Gabash and Pu Li

Energies 2016, 9(4), 235; https://doi.org/10.3390/en9040235 - 25 Mar 2016

Cited by 22 | Viewed by 7150

Abstract

This is the second part of a companion paper on variable reverse power flow (VRPF) in active distribution networks (ADNs) with wind stations (WSs). Here, we propose an electricity market model considering agreements between the operator of a medium-voltage active distribution network (MV-ADN) [...] Read more.

This is the second part of a companion paper on variable reverse power flow (VRPF) in active distribution networks (ADNs) with wind stations (WSs). Here, we propose an electricity market model considering agreements between the operator of a medium-voltage active distribution network (MV-ADN) and the operator of a high-voltage transmission network (HV-TN) under different scenarios. The proposed model takes, simultaneously, active and reactive energy prices into consideration. The results from applying this model on a real MV-ADN reveal many interesting facts. For instance, we demonstrate that the reactive power capability of WSs will be never utilized during days with zero wind power and varying limits on power factors (PFs). In contrast, more than 10% of the costs of active energy losses, 15% of the costs of reactive energy losses, and 100% of the costs of reactive energy imported from the HV-TN, respectively, can be reduced if WSs are operated as capacitor banks with no limits on PFs. It is also found that allocating WSs near possible exporting points at the HV-TN can significantly reduce wind power curtailments if the operator of the HV-TN accepts unlimited amount of reverse energy from the MV-ADN. Furthermore, the relationships between the size of WSs, VRPF and demand level are also uncovered based on active-reactive optimal power flow (A-R-OPF). Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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4340 KiB

Open AccessArticle

Experiment on Bidirectional Single Phase Converter Applying Model Predictive Current Controller

by Gabriele D’Antona, Roberto Faranda, Hossein Hafezi and Marco Bugliesi

Energies 2016, 9(4), 233; https://doi.org/10.3390/en9040233 - 24 Mar 2016

Cited by 12 | Viewed by 4567

Abstract

A bidirectional converter able to manage storage is a basic power electronics device, and it is a major component of renewable energy sources, micro grid and also the smart grid concept. In this paper, single-phase bidirectional converter topology is discussed. The state space [...] Read more.

A bidirectional converter able to manage storage is a basic power electronics device, and it is a major component of renewable energy sources, micro grid and also the smart grid concept. In this paper, single-phase bidirectional converter topology is discussed. The state space model has been derived, and a simple model based predictive current controller has been utilized to control the inverter. Control block diagrams have been designed with MATLAB and simulation results are presented and compared with experimental ones, giving credibility to the derived model and the designed control method. Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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3105 KiB

Open AccessArticle

An Actuator Control Unit for Safety-Critical Mechatronic Applications with Embedded Energy Storage Backup

by Sergio Saponara

Energies 2016, 9(3), 213; https://doi.org/10.3390/en9030213 - 17 Mar 2016

Cited by 4 | Viewed by 6391

Abstract

This paper presents an actuator control unit (ACU) with a 450-J embedded energy storage backup to face safety critical mechatronic applications. The idea is to ensure full operation of electric actuators, even in the case of battery failure, by using supercapacitors as a [...] Read more.

This paper presents an actuator control unit (ACU) with a 450-J embedded energy storage backup to face safety critical mechatronic applications. The idea is to ensure full operation of electric actuators, even in the case of battery failure, by using supercapacitors as a local energy tank. Thanks to integrated switching converter circuitry, the supercapacitors provide the required voltage and current levels for the required time to guarantee actuator operation until the system enters into safety mode. Experimental results are presented for a target application related to the control of servomotors for a robotized prosthetic arm. Mechatronic devices for rehabilitation or assisted living of injured and/or elderly people are available today. In most cases, they are battery powered with lithium-based cells, providing high energy density and low weight, but at the expense of a reduced robustness compared to lead-acid- or nickel-based battery cells. The ACU of this work ensures full operation of the wearable robotized arm, controlled through acceleration and electromyography (EMG) sensor signals, even in the case of battery failure, thanks to the embedded energy backup unit. To prove the configurability and scalability of the proposed solution, experimental results related to the electric actuation of the car door latch and of a robotized gearbox in vehicles are also shown. The reliability of the energy backup device has been assessed in a wide temperature range, from −40 to 130 °C, and in a durability test campaign of more than 10,000 cycles. Achieved results prove the suitability of the proposed approach for ACUs requiring a burst of power of hundreds of watts for only a few seconds in safety-critical applications. Alternatively, the aging and temperature characterizations of energy backup units is limited to supercapacitors of thousands of farads for high power applications (e.g., electric/hybrid propulsion) and with a temperature range limited to 70 °C. Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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4184 KiB

Open AccessArticle

Indices to Study the Electrical Power Signals in Active and Passive Distribution Lines: A Combined Analysis with Empirical Mode Decomposition

by Silvano Vergura, Roberto Zivieri and Mario Carpentieri

Energies 2016, 9(3), 211; https://doi.org/10.3390/en9030211 - 17 Mar 2016

Cited by 10 | Viewed by 4757

Abstract

The broad diffusion of renewable energy-based technologies has introduced several open issues in the design and operation of smart grids (SGs) when distributed generators (DGs) inject a large amount of power into the grid. In this paper, a theoretical investigation on active and [...] Read more.

The broad diffusion of renewable energy-based technologies has introduced several open issues in the design and operation of smart grids (SGs) when distributed generators (DGs) inject a large amount of power into the grid. In this paper, a theoretical investigation on active and reactive power data is performed for one active line characterized by several photovoltaic (PV) plants with a great amount of injectable power and two passive lines, one of them having a small peak power PV plant and the other one having no PV power. The frequencies calculated via the empirical mode decomposition (EMD) method based on the Hilbert-Huang transform (HHT) are compared to the ones obtained via the fast Fourier transform (FFT) and the wavelet transform (WT), showing a wider spectrum of significant modes mainly due to the non-periodical behavior of the power signals. The results obtained according to the HHT-EMD analysis are corroborated by the calculation of three new indices that are computed starting from the electrical signal itself and not from the Hilbert spectrum. These indices give the quantitative deviation from the periodicity and the coherence degree of the power signals, which typically deviate from the stationary regime and have a nonlinear behavior in terms of amplitude and phase. This information allows to extract intrinsic features of power lines belonging to SGs and this is useful for their optimal operation and planning. Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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5937 KiB

Open AccessArticle

Data Distribution Service-Based Interoperability Framework for Smart Grid Testbed Infrastructure

by Tarek A. Youssef, Ahmed T. Elsayed and Osama A. Mohammed

Energies 2016, 9(3), 150; https://doi.org/10.3390/en9030150 - 2 Mar 2016

Cited by 19 | Viewed by 8486

Abstract

This paper presents the design and implementation of a communication and control infrastructure for smart grid operation. The proposed infrastructure enhances the reliability of the measurements and control network. The advantages of utilizing the data-centric over message-centric communication approach are discussed in the [...] Read more.

This paper presents the design and implementation of a communication and control infrastructure for smart grid operation. The proposed infrastructure enhances the reliability of the measurements and control network. The advantages of utilizing the data-centric over message-centric communication approach are discussed in the context of smart grid applications. The data distribution service (DDS) is used to implement a data-centric common data bus for the smart grid. This common data bus improves the communication reliability, enabling distributed control and smart load management. These enhancements are achieved by avoiding a single point of failure while enabling peer-to-peer communication and an automatic discovery feature for dynamic participating nodes. The infrastructure and ideas presented in this paper were implemented and tested on the smart grid testbed. A toolbox and application programing interface for the testbed infrastructure are developed in order to facilitate interoperability and remote access to the testbed. This interface allows control, monitoring, and performing of experiments remotely. Furthermore, it could be used to integrate multidisciplinary testbeds to study complex cyber-physical systems (CPS). Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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2009 KiB

Open AccessArticle

Monte Carlo Evaluation of the Impact of Subsequent Strokes on Backflashover Rate

by Fabio Massimo Gatta, Alberto Geri, Stefano Lauria and Marco Maccioni

Energies 2016, 9(3), 139; https://doi.org/10.3390/en9030139 - 26 Feb 2016

Cited by 7 | Viewed by 4913

Abstract

The paper deals with the impact of subsequent strokes on the backflashover rate (BFR) of HV overhead transmission lines (OHLs), assessed by means of an ATP-EMTP Monte Carlo procedure. The application to a typical 150 kV Italian OHL is discussed, simulating several tower [...] Read more.

The paper deals with the impact of subsequent strokes on the backflashover rate (BFR) of HV overhead transmission lines (OHLs), assessed by means of an ATP-EMTP Monte Carlo procedure. The application to a typical 150 kV Italian OHL is discussed, simulating several tower grounding system arrangements. Subsequent strokes parameters are added to the statistical simulation variables: peak current, front time, time-to-half value, lightning polarity, line insulation withstand, lightning location and phase angle of the power frequency voltage. The input data are fed to an ATP-EMTP complete circuit model of the OHL, including line insulation, lightning representation and tower grounding system, the latter simulated by a pi-circuit model able to simulate the effects due to propagation and soil ionization, at modest computational costs. Numerical results evidence a non-negligible BFR increase (in relative terms) due to subsequent strokes: for spatially concentrated grounding systems the BFR increase approximatively vary in inverse proportion with the low frequency grounding resistance, whereas for spatially extended grounding systems the BFR increase depends on the grounding system behavior at high frequencies. Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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5064 KiB

Open AccessArticle

Shielding Effectiveness Simulation of Small Perforated Shielding Enclosures Using FEM

by Zdeněk Kubík and Jiří Skála

Energies 2016, 9(3), 129; https://doi.org/10.3390/en9030129 - 25 Feb 2016

Cited by 19 | Viewed by 6283

Abstract

Numerical simulation of shielding effectiveness (SE) of a perforated shielding enclosure is carried out, using the finite element method (FEM). Possibilities of model definitions and differences between 2D and 3D models are discussed. An important part of any simulation is verification of the [...] Read more.

Numerical simulation of shielding effectiveness (SE) of a perforated shielding enclosure is carried out, using the finite element method (FEM). Possibilities of model definitions and differences between 2D and 3D models are discussed. An important part of any simulation is verification of the model results—here the simulation result are verified in terms of convergence of the model in dependence on the degrees of freedom (DOF) and by measurements. The experimental method is based on measurement of electric field inside the enclosure using an electric field probe with small dimensions is described in the paper. Solution of an illustrative example of SE by FEM is shown and simulation results are verified by experiments. Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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1988 KiB

Open AccessArticle

On Variable Reverse Power Flow-Part I: Active-Reactive Optimal Power Flow with Reactive Power of Wind Stations

by Aouss Gabash and Pu Li

Energies 2016, 9(3), 121; https://doi.org/10.3390/en9030121 - 23 Feb 2016

Cited by 39 | Viewed by 9587

Abstract

It has recently been shown that using battery storage systems (BSSs) to provide reactive power provision in a medium-voltage (MV) active distribution network (ADN) with embedded wind stations (WSs) can lead to a huge amount of reverse power to an upstream transmission network [...] Read more.

It has recently been shown that using battery storage systems (BSSs) to provide reactive power provision in a medium-voltage (MV) active distribution network (ADN) with embedded wind stations (WSs) can lead to a huge amount of reverse power to an upstream transmission network (TN). However, unity power factors (PFs) of WSs were assumed in those studies to analyze the potential of BSSs. Therefore, in this paper (Part-I), we aim to further explore the pure reactive power potential of WSs (i.e., without BSSs) by investigating the issue of variable reverse power flow under different limits on PFs in an electricity market model. The main contributions of this work are summarized as follows: (1) Introducing the reactive power capability of WSs in the optimization model of the active-reactive optimal power flow (A-R-OPF) and highlighting the benefits/impacts under different limits on PFs. (2) Investigating the impacts of different agreements for variable reverse power flow on the operation of an ADN under different demand scenarios. (3) Derivation of the function of reactive energy losses in the grid with an equivalent-π circuit and comparing its value with active energy losses. (4) Balancing the energy curtailment of wind generation, active-reactive energy losses in the grid and active-reactive energy import-export by a meter-based method. In Part-II, the potential of the developed model is studied through analyzing an electricity market model and a 41-bus network with different locations of WSs. Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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3827 KiB

Open AccessArticle

Heuristic Optimization of Consumer Electricity Costs Using a Generic Cost Model

by Chris Ogwumike, Michael Short and Fathi Abugchem

Energies 2016, 9(1), 6; https://doi.org/10.3390/en9010006 - 23 Dec 2015

Cited by 30 | Viewed by 6638

Abstract

Many new demand response strategies are emerging for energy management in smart grids. Real-Time Energy Pricing (RTP) is one important aspect of consumer Demand Side Management (DSM), which encourages consumers to participate in load scheduling. This can help reduce peak demand and improve [...] Read more.

Many new demand response strategies are emerging for energy management in smart grids. Real-Time Energy Pricing (RTP) is one important aspect of consumer Demand Side Management (DSM), which encourages consumers to participate in load scheduling. This can help reduce peak demand and improve power system efficiency. The use of Intelligent Decision Support Systems (IDSSs) for load scheduling has become necessary in order to enable consumers to respond to the changing economic value of energy across different hours of the day. The type of scheduling problem encountered by a consumer IDSS is typically NP-hard, which warrants the search for good heuristics with efficient computational performance and ease of implementation. This paper presents an extensive evaluation of a heuristic scheduling algorithm for use in a consumer IDSS. A generic cost model for hourly pricing is utilized, which can be configured for traditional on/off peak pricing, RTP, Time of Use Pricing (TOUP), Two-Tier Pricing (2TP) and combinations thereof. The heuristic greedily schedules controllable appliances to minimize smart appliance energy costs and has a polynomial worst-case computation time. Extensive computational experiments demonstrate the effectiveness of the algorithm and the obtained results indicate the gaps between the optimal achievable costs are negligible. Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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4089 KiB

Open AccessArticle

A New Fast Peak Current Controller for Transient Voltage Faults for Power Converters

by Jesús Muñoz-Cruzado-Alba, Javier Villegas-Núñez, José Alberto Vite-Frías and Juan Manuel Carrasco Solís

Energies 2016, 9(1), 1; https://doi.org/10.3390/en9010001 - 22 Dec 2015

Cited by 11 | Viewed by 5549

Abstract

Power converters are the basic unit for the transient voltage fault ride through capability for most renewable distributed generators (DGs). When a transient fault happens, the grid voltage will drop suddenly and probably will also suffer a phase-jump event as well. State-of-the-art voltage [...] Read more.

Power converters are the basic unit for the transient voltage fault ride through capability for most renewable distributed generators (DGs). When a transient fault happens, the grid voltage will drop suddenly and probably will also suffer a phase-jump event as well. State-of-the-art voltage fault control techniques regulate the current injected during the grid fault. However, the beginning of the fault could be too fast for the inner current control loops of the inverter, and transient over-current would be expected. In order to avoid the excessive peak current of the methods presented in the literature, a new fast peak current control (FPCC) technique is proposed. Controlling the peak current magnitude avoids undesirable disconnection of the distributed generator in a fault state and improves the life expectancy of the converter. Experimental and simulation tests with high power converters provide the detailed behaviour of the method with excellent results. Full article

(This article belongs to the Special Issue Selected Papers from 15 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2015))

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