Conventional Protection Research Articles

Detection and experimental investigation of open conductor and single-phase earth return faults in distribution systems

This paper presents a new and reliable detection approach for different crucial faults in distribution systems. These faults are one-open conductor faults at the far side of the feeder or simultaneous faults that are an open conductor followed by an earth fault at either the source side or load side (downed conductor-return faults). Under downed conductor-return faults, there is no zero-sequence current at the conventional protection point. Furthermore, the negative-sequence component is less than the normal unbalance component of the conventional protection point under one-open conductor faults at the far side of the feeder. Therefore, the presented detection approach is based on the measurements at the low voltage side of the load transformers. The proposed method detects such faults by monitoring only the magnitude of the measured three-phase voltage at the load side without installing voltage transformers. A robust threshold value is proposed to guarantee dependability against all fault conditions and security against the normal unbalance. Also, the security of the proposed approach against external faults (at the low voltage side) is verified by monitoring the magnitude of the three-phase current. Fortunately, the proposed system identifies the faulted section. The faulted feeder isolation and the faulted section isolation are accomplished by a proposed autonomous control method with the aid of the infrastructure of smart grids (available communication system). Extensive investigations are done based on a detailed simulation of the selected distribution feeder using the ATP-EMTP program. For verification purposes, recorded faulted cases are experimentally applied on a real distribution feeder to visualize such fault conditions and confirm the detection impossibility of earth-return faults by conventional protection, significantly if the fault faraway the substation. On the other hand, all applied test results corroborate the efficacy of the proposed detection method under the considered faults.

Active Cable Sheath Current-Based Protection Scheme for an Offshore HVAC Wind Transmission System

Due to the complex sending terminal structure of offshore wind transmission systems, conventional on-line monitoring-based protection cannot work well. The electromagnetic transient faults are also difficult to locate due to a short time span with fast characteristics that are affected by various power electronic devices and control algorithms. To solve the aforementioned problems, a new offshore wind transmission line protection scheme based on active detection of submarine cable sheath current is proposed. This method uses a normalized coding cooperation to realize the risk levels and failure locations of the transient defects, and then the sheath currents become a characteristic input data source, which can build a clear system protection boundary. Case studies using MATLAB and ATP simulations are carried out, where three types of transient faults represented by sheath currents are studied, i.e., loss of electrical continuity of grounding device, short circuit of segmented metal sheath of cable joint, and water immersion of junction box. Testing results illustrated that the proposed method could achieve fast fault detection and precise fault location of the electromagnetic transients. Moreover, compared with conventional wind farm protection techniques, it only needs to add few signal injection modules with high sampling frequency into the submarine optical fibers.

Superconducting fault current limiter (SFCL) for fail-safe DC-DC conversion: From power electronic device to micro grid protection

In DC micro grids and networks, DC-DC power converters having a large number of semiconductor-based power electronic devices are usually adopted to interconnect the renewable sources and flexible loads. Most of the semiconductor-based devices suffer from poor fault withstanding abilities, but conventional power electronic protection schemes have the bottlenecks of the time-delay, self-malfunction and mis-judgement. This paper presents a novel solution using the superconducting fault current limiter (SFCL) to protect a power electronic device and extend the usage to a micro grid. This SFCL is actually a self-triggering, recoverable, and passive current limiter, which does not involve any additional circuit hardware and software. Experimental investigations and simulation analyses clarify the feasibility of using this superconductor-based protection scheme to implement the self-acting fail-safe protection of DC-DC converters. Further system-level simulations explore the SFCL to suppress the over-current and stabilize the bus voltage of a photovoltaic based DC micro grid, particularly facing millisecond-level transients and faults. Our experimental and theoretical investigations lay some technical bases to establish a superconductor-semiconductor-coupled interdisciplinary application from the view from the applied superconductivity, to power electronics, and to micro grids.

An Adaptive Overcurrent Protection Scheme for Dual-Setting Directional Recloser and Fuse Coordination in Unbalanced Distribution Networks With Distributed Generation

The recloser–fuse coordination of the distribution networks (DNs) equipped with distributed generators may be jeopardized by using the conventional overcurrent protection strategies thus degrading the network reliability. This article focuses on the design of a protection coordination strategy based on the dual-setting directional recloser (DSDR) for the effective implementation of a fuse-saving scheme in DNs. The proposed DSDR-based protection strategy will assist the network operators by providing a flexible coordination range along with more accurate protection settings to meet the protection coordination requirements. The performance of the proposed protection scheme has been validated through its implementation on IEEE standardized test systems and a comparative analysis has been drawn to demonstrate its effectiveness. Furthermore, this article concentrates on the economical design of the protection strategy for DNs by utilizing fewer numbers of protective devices. The results show that the proposed strategy will considerably reduce the number of temporary and sustained interruptions experienced by the consumers of large DNs thus improving the network reliability indices.

Transparent and electrically tunable electromagnetic wave absorbing metamaterial

Electromagnetic protection materials are widely used in both military and civilian fields. However, the limited wave-absorbing band and low transparency of conventional electromagnetic protection materials are the impediment for extensive applications. Here, a transparent and electrically tunable wave-absorbing metamaterial for stealth technology and electromagnetic protection has been theoretically and experimentally realized. The trend of the absorption feature change in simulation is consistent with that of the experiment results. The main part of this material adopts a sandwich structure consisting of two layers of indium tin oxide (ITO) and one layer of glass in between. The upper ITO layer is periodically patterned and combined with varactor diodes, which function as a frequency-selective surface. The effective operating frequency range is in the S-band, which covers the common frequency band of WiFi and many other electronic devices. The wave absorbing performance of this material can be electronically tunable by changing the applied voltage. The main absorption peak can be up to 90% with a tunable amplitude range of 30% and a tunable frequency band range of 1 GHz, and the transmittance of the sample in the visible is 80.23%. The metamaterial has high performance on electromagnetic shielding, whose effectiveness is larger than 30 dB in the range of 2.6–3.95 GHz. This transparent and tunable metamaterial has great potential for the applications in electromagnetic protection and stealth.

Influence of Biopesticides and Natural Preparations on the Regulation of Diseases and Pests in the Ecological Protection of Tomatoes (Lycopersicon esculentum L.) and Cucumbers (Cucumis sativus L.)

Organic agriculture is increasingly present on farms in response to environmental pollution and food safety. However, organic farmers have a big production risk due to frequent plant diseases. This research was conducted to compare the influence of preparations for plant protection allowed in organic agriculture and phytopharmaceutical preparations which are used in conventional agriculture and observe their effect in regulation of pests and diseases in tomato and cucumber production in an open field. The research included the tomato variety „Oxheart“, and the cucumber variety „Long green“. The time of research was four months from planting to harvest (period: May 2020. – August 2020.) until more than 70% of vegetation was completed. The tests were performed at a location in the rural part of the town of Živinice (Tupković) in an open field with an altitude of 250 m, during the vegetation period of 2020. The tests were performed on two separate plots. The plot where phytopharmaceutical (conventional) preparations were used, was physically separated from the plot where preparations allowed in organic agriculture were used. Temperature measurement was performed using a TFA Dostmann thermometer (-25ºC to + 50ºC) and it was set at a height of 2 meters in the open field. The amount of rainfall was monitored with the TFA Dostmann rain gauge. In the tests with organic plant protection, the nettle solution and preparation with active substance Bacillus thuringiensis for pests was used, and for plant diseases, the milk+soda solution and copper-oxide were used. In the tests with conventional protection, preparations with active substances acetamiprid and imidacloprid for pests were used, and the diseases were treated with mancozeb+copper and metalaxyl-M+mancozeb. After treatments, the onset of diseases was monitored. To conclude, the conventional insecticides gave better results in the regulation of pests in comparison to organic preparations, and in the case of organic preparations, the nettle solution had a better effect. Plant protection with copper-oxide gave the same results as using conventional preparations in disease regulation. This shows that plant protection is possible in organic production, but preparations must be applied more often and in a timely manner.

Long term control of corrosion of steel reinforcement by a two-stage cathodic protection method

It has been shown experimentally that corrosion of steel reinforcement can be arrested if sufficient cathodic charge at a current density higher than 20 mA/m2 is applied over a period of weeks. Once corrosion is arrested, a cathodic prevention current density, which requires a current density an order of magnitude lower than for conventional cathodic protection, can be applied for long-term prevention of re-initiation of corrosion. Self-contained products were developed in the laboratory according to the Two-Stage principle, each single product containing a battery-operated ICCP element which produces a high initial current output of between 20 mA/m2 and 50 mA/m2 of steel area during an initial polarisation corrosion arrest phase and a galvanic anode component which delivers the lower cathodic prevention current long-term. Diodes ensure that the current from the battery is delivered to the steel reinforcement and not dumped onto the galvanic anode and allow the galvanic current to flow only when the ICCP element becomes inoperable. This paper describes the principles of the technique, illustrates products developed and presents medium-term field studies to demonstrate the success of the Two-Stage CP technique.

Staff Knowledge and Attitudes Towards COVID-19 New Biosafety Practices at a Brazilian Dental School

Objective To evaluate knowledge and attitudes towards biosafety recommendations during the COVID-19 pandemic at a Brazilian dental school. Material and Methods A cross-sectional study was performed in 2020 with the clinical staff of a Brazilian dental school. The whole clinical staff was sent pre-tested self-administered online questionnaires about knowledge and attitudes towards the recommendations for biosafety in dental settings in the context of the COVID-19 pandemic. Descriptive statistical analyses were carried out for proportion calculation. Results Disposable head covering caps, isolation gowns, and gloves were the most frequently reported personal protective equipment (PPE). The rates ranged from 52.9% to 88.5% for N95 respirators, from 68.6% to 92.6% for face shields, from 47.4% to 67.5% for conventional eye protection shields, and 45.1% to 77.4% for eye protection with solid side shields. Chlorhexidine gluconate was the most frequent mouthwash indicated before clinical dental care. The percentage of agreement to provide clinical care to patients with suspected COVID-19 varied from 23.5% to 50.0%. The percentage of respondents who agreed that bioaerosol-generating procedures should be avoided was higher than 74.5%. Less than 50% knew the correct sequence for doffing of PPE. Conclusion This study revealed important gaps in knowledge and attitudes towards prevention and control measures against infection in dental environments in the context of COVID-19, indicating the need for improvements.

Results of "Shin-Etsu" pheromone application on immune cultivars in the apple protection system to control of codling moth

Codling moth is a very dangerous pest in apple orchards: the pest could damage up to 70-90% of pome fruits in the years of mass reproduction. The climate change increased the harmfulness of the pest during the last years. The aim of our study was the determination of “Shin-Etsu” dispenser application efficiency for codling moth disorientation comparing with conventional apple protection system. The experiment was done in apple orchards of JSC “Dubovoye” (Tambov oblast) in 2020-2021. The objects of the study were the scab immune cultivars Venyaminovskoye and Flagman grafted on B396 rootstock. Codling moth damaged 9.4-12.1% fruits in the control treatment after the first generation and 11.6-15.2% by the second generation. The application of the experimental protection system with dispensers decreased the fruit damage rate after the first generation up to 0.5-0.8% and second generation—0.9-1.1%. The biological efficiency of the experimental system in both cultivars was higher and reached 92.2-96.7% after the first generation and 90.5-94.0% after the second. The average yield in the “Shin-Etsu” protection system was 9.7-12.5 kg tree-1 where 87-90% fruits were premium quality.

Performance Evaluation of Open-Source Endpoint Detection and Response Combining Google Rapid Response and Osquery for Threat Detection

Detecting the latest advanced persistent threats (APTs) using conventional information protection systems is a challenging task. Although various systems have been employed to detect such attacks, they are limited by their respective operating systems. Furthermore, they are developed as closed platforms and cannot be customized to meet user environments. To overcome these limitations, open-source endpoint detection and response (EDR) techniques are needed. In this study, we construct one that integrates open-source security frameworks combining GRR (Google Rapid Response) and osquery. A threat-detecting case study is conducted to validate the feasibility of the proposed open-source EDR system. Additionally, APT coverage for the proposed EDR system is analyzed using MITRE’s Adversarial Tactics, Techniques, and Common Knowledge model. The assessment result shows that APT tactics having high levels of threat detection using non-customized osquery configurations comprise 28.5 % of all detections, which is lower than the other response levels. The performance of open-source EDR can be increased by customizing osquery for specific purposes and environments. Open-source EDR combining GRR and osquery has the potential to provide the detection-coverage efficient threat detection system and has the advantage of flexible integration with other applications; it can also be developed for evolving system environments such as cloud and internet of things.

Integrated Thermal Protection System Design for Hypersonic Vehicle Based on New Thermal–Mechanical Method

With the development of hypersonic vehicles, considerable attention has been paid to thermal protection systems (TPSs). Among the different types of TPS, integrated TPS (ITPS) has attracted extensive interest because of its light weight, cost effectiveness, bearing capacity, and easy maintenance. However, ITPS, with its complex structure and reusable requirement, is facing challenges and it is worth devoting much effort to this. In an effort to overcome these challenges, we develop a novel approximate analytical method based on separation of variables and orthogonal expansion technique, which is presented for the prediction of heat transfer. The approximate analytical method has the ability to consider the effects of temperature-dependent thermal material properties, convection and radiation. Moreover, a C0 higher-order layer-wise finite-element model combined with homogenization techniques and a simplified three-dimensional (3D) finite-element model based on the periodic structure characteristic are proposed to estimate the thermal–mechanical response and stability of ITPS effectively. In addition, an optimization procedure based on the proposed methods for ITPS is developed. Implementation of the optimization is demonstrated by applying it to design the ITPS of space shuttles and hypersonic vehicles. By comparing with conventional thermal protection systems (CTPSs), ITPS exhibits an outstanding advantage in weight and an acceptable disadvantage in size. The objective of this paper is to establish an accurate and efficient design method aiming at determination of the optimal performance of ITPS, and puts forward the foundation for the development of a hypersonic vehicle.

Leveraging a micro synchrophasor for fault detection in a renewable based smart grid—A machine learned sustainable solution with cyber-attack resiliency

The advent of renewable distributed generation has led to the rethinking of the conventional protection systems, especially during fault. A sustainable fault detection algorithm is needed to enhance the distribution system's resiliency and safety. Keeping this point of view, the paper presents a micro synchrophasor or µPMU-based fault detection algorithm with fewer probabilities of cyber-attack. In the µPMU, after obtaining the current signals, the three-phase sequence components are evaluated and the angular sum of the positive and zero sequences is recorded. The maximum angular sum is fed to a trained machine learning (random forest) classifier for fault detection. The algorithm has a high resistance to cyber-attacks and is strongly immune to noise. The method has 98.91% accuracy, 99.89% precision and exhibits a detection time of 8.5 ms. The method is cost effective as it leverages a µPMU for fault detection algorithm, reducing the need of additional hardware and software. The method also proves to be superior than other fault detection methods in terms of accuracy, precision, detection time and the capability to handle noise and cyber-attacks. All the simulations are done in MATLAB/SIMULINK for a renewable based IEEE 13 node distribution test feeder.

A Robust Fault Detection and Location Prediction Module Using Support Vector Machine and Gaussian Process Regression for AC Microgrid

Better reliability of power supply is assured with the inculcation of distributed generators (DGs) in a distribution network. Smart sensors and latest grid communication protocols have played a crucial role in the development of intelligent microgrids (MGs). Conventional protection schemes do not provide reliable performance when implemented in MGs. This article proposes an approach which requires root mean square value of one cycle three -phase voltage and current measurements during fault. These data are treated as inputs for developing a fault isolation and locator module. This module is supposed to be available at central protection system, and is designed using machine learning (ML) based techniques viz. Gaussian process regression for fault location prediction and support vector machine for fault identification. Effectiveness of the proposed methodology is evaluated by considering practical grid scenarios with load variation and different DG penetration level. Furthermore, the robustness of the proposed model is assessed by performing sensitivity analysis with consideration of variation in line parameters and load as well as effect of DG correlation. A 7-bus meshed ac MG test system consisting of three DGs and two grid sources is modeled in SIMULINK platform, and is used to demonstrate the proposed module. Data analytics tools of MATLAB 2020a has been explored to develop an ML-based fault isolation and location module for MGs. The proposed scheme has also been validated with real-time MG data obtained from OPAL Real time (OPAL-RT) real-time simulator OP-4510. The accuracy in predicted results proves that the proposed scheme is pertinent for real-time practical applications.

A combined experimental and theoretical study of green corrosion inhibition of bronze B66 in 3% NaCl solution by Aloe saponaria (syn. Aloe maculata) tannin extract

Since antiquity, bronzes have been one of the main cultural heritage metallic artifacts. Currently, they continue to have many applications in various industrial fields. Nevertheless, bronzes are subject to the corrosion process in aggressive environments containing chlorides. To overcome this destructive phenomenon, various conventional protection inhibitors have been developed. Unfortunately, these prevention inhibitors have serious drawbacks are expensive and harmful to human health and the environment. Plant extracts are one of the alternatives that can be used as an ecological, cost-effective and efficient alternative. In this context, Aloe saponaria tannin (AST) extract has been tested as green corrosion inhibitor for bronze B66 in 3% NaCl. The experimental study was conducted by gravimetric and electrochemical measurements, supplemented by surface analysis scanning electron microscopy (SEM) coupled to energy dispersive X-ray spectroscopy (EDX). Which allowed us to highlight the protective effect of our inhibitor. In addition, to investigate the adsorption action of AST compounds over the bronze surface, the theoretical simulations based on the MD (molecular dynamics) and DFT (density functional theory) were done. The electrochemical measurements confirmed the results obtained from the gravimetric measurements and noted that the effect of our inhibitors alters the mechanism of the electrochemical process at the metal/solution interface. The experimental results obtained allowed to note that the AST compounds act as a cathodic type inhibitor. Then, the maximal inhibition efficiency reaches 90% at 150 ​ppm of AST extract. Moreover, the results of theoretical modeling studies supported the adsorption of AST molecules on the target metal substrate.

Design and protection of microgrid clusters: A comprehensive review

<abstract> <p>A microgrid is a concept that has been developed with the increasing penetration of distributed generators. With the increasing penetration of distributed energy resources in the microgrids, along with advanced control and communication technologies, the traditional microgrid concept is being transited towards the concept of microgrid clustering. It decomposes the distribution system into several interconnected microgrids, effectively reducing problems such as voltage rise, harmonics, poor power factor, reverse power flow and failure of the conventional protection schemes. Microgrid clusters effectively coordinate power sharing among microgrids and the main grid, improving the stability, reliability and efficiency of the distribution network at the consumption premises. Despite the evident benefits of microgrid clusters to the consumers and the electrical utility, there are challenges to overcome before adopting the microgrid cluster concept. This paper is aimed at critically reviewing the challenges in design aspects of microgrid clustering. Categorization of multi-microgrids into different architectures based on the layout of the interconnections, evaluation of reported control techniques in microgrid clustering and multi-microgrid protection aspects are presented, highlighting the possible areas of future research that would improve the operational aspects of microgrid clusters.</p> </abstract>

Concise Silicon Carbide DC Circuit Breaker Module for Satellite Electrical Systems

Fault protection and real-time monitoring of Satellite Electrical Power Systems (SEPS) are of importance for the advancement of modern satellite systems of high power, compact sizing and long lifespan. Conventional protection methods could handle the overcurrent faults but lack flexibility in fault clearance time. With these important considerations, a compact and programable Silicon Carbide (SiC) power MOSFET based DC circuit breaker module is developed to not only handle multiple levels of overcurrent faults with suitable time-delay protection scheme, but also provide the real-time monitoring of circuit breaker status by using the Long Range (LoRa) and Internet of Things (IoT) Technology. The proposed module has been implemented and its effectiveness was tested and confirmed in laboratory under various overcurrent fault conditions.

Comparison study among the different existing loss of excitation protection schemes in synchronous generator

Synchronous generator is the most important element of a power system and its fast and reliable protection is crucial. One of the most abnormal conditions in a generator is loss of excitation (LOE) which is harmful to both the generator and the power system. This condition should be detected and the generator isolated from the system to avoid generator damage as well as power system instability.
 This work presents an experimental study and comparison of the two conventional LOE protection schemes, negative-offset and positive-offset mho element under different conditions. The results show that the two schemes can detect LOE fault under total or partial LOE conditions, however in terms of speed (fault detection time) the positive offset scheme is faster than the negative offset scheme under all loading conditions. Besides, the two LOE protection schemes are reliable and do not operate under power swing disturbances caused by any type of external faults.

Line Voltage Based Distance Relay Using a Multistage Convolutional Neural Network Classifier

This paper presents a novel proposed method for the fault diagnosis in distance protection of transmission line, by which the real time voltage signal is the only required relay input. Unlike conventional protection schemes, the current signal is excepted without influencing the basic functions of the relay as a protecting and a monitoring device to detect and locate the fault. The new method is based on a pre-trained Convolutional Neural Network (CNN) with a combination of the higher order spectral estimations, which performs a deep learning classification with a very high accuracy. This research has succeeded in proposing an efficient 2D CNN model that takes the Short-Time Fourier Transform (STFT) of the signal for high accuracy fault detecting, locating, and classifying. The performance of the proposed models is tested using a new large dataset prepared using Simulink/ Matlab. The results show a high numerical performance evaluation that validates the consistency of the proposed methods.

Blockchain jako niestandardowa odpowiedź na ograniczenia prawa stanowionego w środowisku social mediów

Nowadays, most people use the Internet and social media. However, the Internet is a space in which there are various types of violations that are difficult to counteract with the use of legal institutions and tools, which are often not compatible with the fast-developing environment. The COVID-19 pandemic, which forced people to rearrange their lives in all fields and often move a significant part of their activities to the network, intensified negative phenomena including spreading false and socially harmful information. This article is an original reflection on the effectiveness of Polish legislation against the backdrop of the current activities of European Union bodies aimed at increasing the security of Internet users on the example of counteracting the dissemination of misinformation. In the author’s opinion, both national and EU authorities do not seem to be interested in searching for alternatives based on technological solutions that could foster prevention of such infringements on the Internet, but rather focus on improving conventional protection models, whose effectiveness seems to be questionable. The article aims to start an interdisciplinary debate on the possibility to reduce the number of negative phenomena in the social media environment using blockchain technology, including the discussion on the possibility of developing appropriate regulations in this regard.

An improved desaturation short-circuit protection method for SiC power modules

Silicon Carbide (SiC) MOSFET devices have smaller chip size and higher current density than Si counterparts, which results in the limited short-circuit capability of SiC power modules. The presently used protection circuit is actually conventional desaturation protection method, which is very suitable for IGBT modules. But this conventional protection circuit has relatively slow response, and cannot be directly used in SiC modules due to its higher di/dt and weaker ruggedness compared to IGBT modules. So we propose an improved desaturation protection method. We first analyse the short-circuit process to obtain the short circuit characteristics of SiC MOSFET. Then, we give the principle of the improved desaturation protection method, and present the comparison between the conventional protection circuit and the improved one. At last, short-circuit protection tests under HSF and FUL faults have been conducted to verify the improved desaturation protection circuit. The experimental results show that the improved desaturation protection circuit has a faster response than the traditional one, and can make SiC modules work reliably.