Research

20 pages, 1910 KiB

Open AccessArticle

Service Continuity of PV Synchronous Buck/Buck-Boost Converter with Energy Storage^†

by Saima Siouane, Slaviša Jovanović and Philippe Poure

Energies 2018, 11(6), 1369; https://doi.org/10.3390/en11061369 - 28 May 2018

Cited by 9 | Viewed by 4808

Numerous advantages offered by Photovoltaic (PV) generation systems coupled with the increasing power demands for clean energy put PV systems in the front of many research works. For stand-alone applications powered with PV systems, the reliability of the power conversion stage is essential [...] Read more.

Numerous advantages offered by Photovoltaic (PV) generation systems coupled with the increasing power demands for clean energy put PV systems in the front of many research works. For stand-alone applications powered with PV systems, the reliability of the power conversion stage is essential to ensure the continuous supply of energy. Therefore, in the case of any failure occurring in the power conversion stage, it is mandatory to provide remedial actions to guarantee the service continuity of the produced electrical power. This paper analyses the service continuity of a two-stage buck/buck-boost converter with energy storage, driven with synchronous control. The initial two-stage converter is made fault-tolerant and robust to failures of its two switches by adding only one additional switch associated with two diodes. In this study, only open-circuit switch faults are considered. The proposed fault-tolerant circuit and the initial one have the same electrical behavior when synchronous control is used. The applied synchronous control in both healthy conditions and post-fault operation ensures the same functionalities without degrading the system’s performances. The proposed two-stage synchronously-controlled circuit is validated through simulation in the cases of open circuit faults on the two switches of the initial converter. The obtained results show the feasibility of the proposed functional redundancy and the continuity of operation at full power after switch fault diagnosis. Full article

(This article belongs to the Special Issue 17TH International Conference on Environment and Electrical Engineering)

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17 pages, 10798 KiB

Open AccessArticle

A Multifunctional Dynamic Voltage Restorer for Power Quality Improvement

by Dung Vo Tien, Radomir Gono and Zbigniew Leonowicz

Energies 2018, 11(6), 1351; https://doi.org/10.3390/en11061351 - 25 May 2018

Cited by 37 | Viewed by 5138

Abstract

Power quality is a major concern in electrical power systems. The power quality disturbances such as sags, swells, harmonic distortion and other interruptions have an impact on the electrical devices and machines and in severe cases can cause serious damages. Therefore it is [...] Read more.

Power quality is a major concern in electrical power systems. The power quality disturbances such as sags, swells, harmonic distortion and other interruptions have an impact on the electrical devices and machines and in severe cases can cause serious damages. Therefore it is necessary to recognize and compensate all types of disturbances at an earliest time to ensure normal and efficient operation of the power system. To solve these problems, many types of power devices are used. At the present time, one of those devices, Dynamic Voltage Restorer (DVR) is the most efficient and effective device used in power distribution systems. In this paper, design and modeling of a new structure and a new control method of multifunctional DVRs for voltage quality correction are presented. The new control method was built in the stationary frame by combining Proportional Resonant controllers and Sequence-Decouple Resonant controllers. The performance of the device and this method under different conditions such as voltage swell, voltage sag due to symmetrical and unsymmetrical short circuit, starting of motors, and voltage distortion are described. Simulation result show the superior capability of the proposed DVR to improve power quality under different operating conditions and the effectiveness of the proposed method. The proposed new DVR controller is able to detect the voltage disturbances and control the converter to inject appropriate voltages independently for each phase and compensate to load voltage through three single-phase transformers. Full article

(This article belongs to the Special Issue 17TH International Conference on Environment and Electrical Engineering)

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21 pages, 6879 KiB

Open AccessArticle

Installation, Commissioning and Tests of Four Fast Switching Units of up to 20 kA for the JT-60SA Nuclear Fusion Experiment

by Alessandro Lampasi, Filippo Burini, Giuseppe Taddia, Sandro Tenconi, Makoto Matsukawa, Katsuhiro Shimada, Luca Novello, Antti Jokinen and Pietro Zito

Energies 2018, 11(4), 996; https://doi.org/10.3390/en11040996 - 20 Apr 2018

Cited by 6 | Viewed by 4621

Abstract

The nuclear fusion project JT-60SA is presently under construction in Naka (Japan) as a joint collaboration between Europe and Japan, within the framework of the Broader Approach Agreement. According to such agreement, the various JT-60SA systems are supplied by European and Japanese institutions. [...] Read more.

The nuclear fusion project JT-60SA is presently under construction in Naka (Japan) as a joint collaboration between Europe and Japan, within the framework of the Broader Approach Agreement. According to such agreement, the various JT-60SA systems are supplied by European and Japanese institutions. In particular, the Italian Agency ENEA was in charge for the procurement of the four Switching Network Units (SNUs) for the JT-60SA Central Solenoid (CS). The main SNU function is to interrupt a DC current up to 20 kA in a short time (less than 1 ms) in order to produce an overvoltage of up to 5 kV, crucial to generate and sustain the fusion plasma. The SNU design, manufacturing and factory test activities have been completed in 2016. After the delivery in Naka, the four SNUs have been installed and successfully commissioned in 2017. After an overview on the main technical characteristics of the SNUs and the key aspects of their design, this paper describes the activities performed on-site, highlighting the results obtained during the final acceptance tests and comparing them with the design simulation and the factory test results. Full article

(This article belongs to the Special Issue 17TH International Conference on Environment and Electrical Engineering)

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17 pages, 2005 KiB

Open AccessArticle

Impulsive Noise Characterization in Narrowband Power Line Communication

by Li Bai, Mauro Tucci, Sami Barmada, Marco Raugi and Tao Zheng

Energies 2018, 11(4), 863; https://doi.org/10.3390/en11040863 - 08 Apr 2018

Cited by 16 | Viewed by 4973

Abstract

Currently, narrowband Power line communication (PLC) is considered an attractive communication system in smart grid environments for applications such as advanced metering infrastructure (AMI). In this paper, we will present a comprehensive comparison and analysis in time and frequency domain of noise measured [...] Read more.

Currently, narrowband Power line communication (PLC) is considered an attractive communication system in smart grid environments for applications such as advanced metering infrastructure (AMI). In this paper, we will present a comprehensive comparison and analysis in time and frequency domain of noise measured in China and Italy. In addition, impulsive noise in these two countries are mainly analyzed and modeled using two probability based models, Middleton Class A (MCA) model and

α

stable distribution model. The results prove that noise measured in China is rich in impulsive noise, and can be modeled well by

α

stable distribution model, while noise measured in Italy has less impulsive noise, and can be better modeled by the MCA model. Full article

(This article belongs to the Special Issue 17TH International Conference on Environment and Electrical Engineering)

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16 pages, 7502 KiB

Open AccessArticle

On the Distribution of Lightning Current among Interconnected Grounding Systems in Medium Voltage Grids

by Guido Ala, Salvatore Favuzza, Elisa Francomano, Graziella Giglia and Gaetano Zizzo

Energies 2018, 11(4), 771; https://doi.org/10.3390/en11040771 - 28 Mar 2018

Cited by 19 | Viewed by 3979

Abstract

This paper presents the results of a first investigation on the effects of lightning stroke on medium voltage installations’ grounding systems, interconnected with the metal shields of the Medium Voltage (MV) distribution grid cables or with bare buried copper ropes. The study enables [...] Read more.

This paper presents the results of a first investigation on the effects of lightning stroke on medium voltage installations’ grounding systems, interconnected with the metal shields of the Medium Voltage (MV) distribution grid cables or with bare buried copper ropes. The study enables us to evaluate the distribution of the lightning current among interconnected ground electrodes in order to estimate if the interconnection, usually created to reduce ground potential rise during a single-line-to-ground fault, can give place to dangerous situations far from the installation hit by the lightning stroke. Four different case studies of direct lightning stroke are presented and discussed: (1) two secondary substations interconnected by the cables’ shields; (2) two secondary substations interconnected by a bare buried conductor; (3) a high voltage/medium voltage station connected with a secondary substation by the medium voltage cables’ shields; (4) a high voltage/medium voltage station connected with a secondary substation by a bare buried conductor. The results of the simulations show that a higher peak-lowering action on the lighting-stroke current occurs due to the use of bare conductors as interconnection elements in comparison to the cables’ shields. Full article

(This article belongs to the Special Issue 17TH International Conference on Environment and Electrical Engineering)

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17 pages, 3231 KiB

Open AccessArticle

Reliability Equivalence to Symmetrical UHVDC Transmission Systems Considering Redundant Structure Configuration

by Xing Jiang, Chengjin Ye, Yi Ding and Ruipeng Guo

Energies 2018, 11(4), 753; https://doi.org/10.3390/en11040753 - 26 Mar 2018

Cited by 4 | Viewed by 2872

Abstract

In recent years, the ultra-high voltage direct current (UHVDC) transmission system has been developed rapidly for its significant long-distance, high-capacity and low-loss properties. Equipment failures and overall outages of the UHVDC system have increasingly vital influence on the power supply of the receiving [...] Read more.

In recent years, the ultra-high voltage direct current (UHVDC) transmission system has been developed rapidly for its significant long-distance, high-capacity and low-loss properties. Equipment failures and overall outages of the UHVDC system have increasingly vital influence on the power supply of the receiving end grid. To improve the reliability level of UHVDC systems, a quantitative selection and configuration approach of redundant structures is proposed in this paper, which is based on multi-state reliability equivalence. Specifically, considering the symmetry characteristic of an UHVDC system, a state space model is established as a monopole rather than a bipole, which effectively reduces the state space dimensions to be considered by deducing the reliability merging operator of two poles. Considering the standby effect of AC filters and the recovery effect of converter units, the number of available converter units and corresponding probability are expressed with in universal generating function (UGF) form. Then, a sensitivity analysis is performed to quantify the impact of component reliability parameters on system reliability and determine the most specific devices that should be configured in the redundant structure. Finally, a cost-benefit analysis is utilized to help determine the optimal scheme of redundant devices. Case studies are conducted to demonstrate the effectiveness and accuracy of the proposed method. Based on the numerical results, configuring a set of redundant transformers is indicated to be of the greatest significance to improve the reliability level of UHVDC transmission systems. Full article

(This article belongs to the Special Issue 17TH International Conference on Environment and Electrical Engineering)

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21 pages, 6637 KiB

Open AccessArticle

Algorithm for Fast and Efficient Detection and Reaction to Angle Instability Conditions Using Phasor Measurement Unit Data

by Igor Ivanković, Igor Kuzle and Ninoslav Holjevac

Energies 2018, 11(3), 681; https://doi.org/10.3390/en11030681 - 17 Mar 2018

Cited by 11 | Viewed by 4576

Abstract

In wide area monitoring, protection, and control (WAMPAC) systems, angle stability of transmission network is monitored using data from phasor measurement units (PMU) placed on transmission lines. Based on this PMU data stream advanced algorithm for out-of-step condition detection and early warning issuing [...] Read more.

In wide area monitoring, protection, and control (WAMPAC) systems, angle stability of transmission network is monitored using data from phasor measurement units (PMU) placed on transmission lines. Based on this PMU data stream advanced algorithm for out-of-step condition detection and early warning issuing is developed. The algorithm based on theoretical background described in this paper is backed up by the data and results from corresponding simulations done in Matlab environment. Presented results aim to provide the insights of the potential benefits, such as fast and efficient detection and reaction to angle instability, this algorithm can have on the improvement of the power system protection. Accordingly, suggestion is given how the developed algorithm can be implemented in protection segments of the WAMPAC systems in the transmission system operator control centers. Full article

(This article belongs to the Special Issue 17TH International Conference on Environment and Electrical Engineering)

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13 pages, 1914 KiB

Open AccessArticle

Data Mining and Neural Networks Based Self-Adaptive Protection Strategies for Distribution Systems with DGs and FCLs

by Wen-Jun Tang and Hong-Tzer Yang

Energies 2018, 11(2), 426; https://doi.org/10.3390/en11020426 - 13 Feb 2018

Cited by 20 | Viewed by 3403

Abstract

In light of the development of renewable energy and concerns over environmental protection, distributed generations (DGs) have become a trend in distribution systems. In addition, fault current limiters (FCLs) may be installed in such systems to prevent the short-circuit current from exceeding the [...] Read more.

In light of the development of renewable energy and concerns over environmental protection, distributed generations (DGs) have become a trend in distribution systems. In addition, fault current limiters (FCLs) may be installed in such systems to prevent the short-circuit current from exceeding the capacity of the power apparatus. However, DGs and FCLs can lead to problems, the most critical of which is miscoordination in protection system. This paper proposes overcurrent protection strategies for distribution systems with DGs and FCLs. Through the proposed approach, relays with communication ability can determine their own operating states with the help of an operation setting decision tree and topology-adaptive neural network model based on data processed through continuous wavelet transform. The performance and effectiveness of the proposed protection strategies are verified by the simulation results obtained from various system topologies with or without DGs, FCLs, and load variations. Full article

(This article belongs to the Special Issue 17TH International Conference on Environment and Electrical Engineering)

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33 pages, 13088 KiB

Open AccessArticle

Impact of Optimum Allocation of Renewable Distributed Generations on Distribution Networks Based on Different Optimization Algorithms

by Mohamed A. Tolba, Hegazy Rezk, Vladimir Tulsky, Ahmed A. Zaki Diab, Almoataz Y. Abdelaziz and Artem Vanin

Energies 2018, 11(1), 245; https://doi.org/10.3390/en11010245 - 19 Jan 2018

Cited by 44 | Viewed by 4757

Abstract

Integration of Renewable Distributed Generations (RDGs) such as photovoltaic (PV) systems and wind turbines (WTs) in distribution networks can be considered a brilliant and efficient solution to the growing demand for energy. This article introduces new robust and effective techniques like hybrid Particle [...] Read more.

Integration of Renewable Distributed Generations (RDGs) such as photovoltaic (PV) systems and wind turbines (WTs) in distribution networks can be considered a brilliant and efficient solution to the growing demand for energy. This article introduces new robust and effective techniques like hybrid Particle Swarm Optimization in addition to a Gravitational Search Algorithm (PSOGSA) and Moth-Flame Optimization (MFO) that are proposed to deduce the optimum location with convenient capacity of RDGs units for minimizing system power losses and operating cost while improving voltage profile and voltage stability. This paper describes two stages. First, the Loss Sensitivity Factors (LSFs) are employed to select the most candidate buses for RDGs location. In the second stage, the PSOGSA and MFO are implemented to deduce the optimal location and capacity of RDGs from the elected buses. The proposed schemes have been applied on 33-bus and 69-bus IEEE standard radial distribution systems. To insure the suggested approaches validity, the numerical results have been compared with other techniques like Backtracking Search Optimization Algorithm (BSOA), Genetic Algorithm (GA), Particle Swarm Algorithm (PSO), Novel combined Genetic Algorithm and Particle Swarm Optimization (GA/PSO), Simulation Annealing Algorithm (SA), and Bacterial Foraging Optimization Algorithm (BFOA). The evaluated results have been confirmed the superiority with high performance of the proposed MFO technique to find the optimal solutions of RDGs units’ allocation. In this regard, the MFO is chosen to solve the problems of Egyptian Middle East distribution network as a practical case study with the optimal integration of RDGs. Full article

(This article belongs to the Special Issue 17TH International Conference on Environment and Electrical Engineering)

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