Conventional Protection Devices Research Articles

A multilayer integrative approach for diagnosis, classification and severity detection of electrical faults in photovoltaic arrays

Early detection of faults in photovoltaic (PV) systems is crucial for improving their lifespan and reliability. Conventional protection devices may not be able to detect electrical faults under critical conditions. This usually occurs due to (i) the current-limiting nature and non-linear output characteristics of PV arrays, (ii) the changing environmental conditions (such as irradiance and temperature variations), and (iii) the influence of the maximum power point tracker (MPPT), particularly in the presence of critical fault impedance values or mismatch levels. Therefore, modern data-driven methods are required for fault detection and classification in PV arrays. However, careful investigation in previous studies reveals the existing gaps and limitations, such as poor accuracy, and incomprehensive models which have not considered various electrical faults, low mismatch levels, and critical fault impedance values. To this end, in this study, a comprehensive multilayer model is proposed which consists of six layers for diagnosis, classification and severity identification of electrical faults in PV arrays. Each layer adopts a weighted ensemble learning (WEL) algorithm consisting of three classifiers namely Support Vector Machine (SVM), Naïve Bayes (NB) and Logistic Regression (LR). Besides, a genetic algorithm (GA) is employed in each layer to find the optimal weights for each classifier (i.e., SVM, NB and LR). The initial dataset is acquired through an investigation into the PV array current–voltage (I-V) characteristic curve and extraction of several features under various faulty and normal conditions. To reduce the dataset dimensionality thus computationally simplifying the training process, the sequential floating forward selection (SFFS) algorithm is utilized in each layer as a powerful feature selection technique. The results show a highly accurate performance in fault diagnosis, classification, and severity assessment, with an average simulation and experimental accuracies of 98.9% and 98.37%, respectively.

Enhancing hearing protection in complex noise environments with extended-wear hearing aids

Conventional hearing protection devices (HPDs) work well in predictable noise environments where it is practical to put them on prior to exposure and remove them after. However, some noise environments are characterized by long periods of relative quiet that are unpredictably interrupted by brief periods of hazardous noise. These environments make it difficult to ensure that HPDs are worn when exposure to hazardous levels occurs. One possible solution is the extended-wear hearing aid (EWHA), a hearing aid that completely blocks the ear canal and can remain in the ear for months at a time. Previous research has shown that the EWHA can provide protection from impulse noise without significantly interfering with detection and localization of environmental sounds. At that time, the major drawback of the EWHA was that once it was removed it could only be re-inserted by an audiologist. This limitation has been addressed by the development of a self-insertion tool that allows users to remove and re-insert the EWHA as desired. We will discuss the potential advantages of using the EWHA as an HPD, with an emphasis on situations where the EWHA could be used to reduce noise exposure without modifying the current commercially available device.

On the Assessment of Sampling Rate Impacts on Responses of Digital Protective Relays

Power systems (including industrial and commercial power systems) widely utilize digital protective relays for component and system protection. These protective devices have shown numerous operational advantages over conventional electromagnetic protective devices. Such operational advantages include the accuracy, reliability, response speed, interoperability, weight, and size. Performance and operational advantages of digital protective relays are typically dependent on the resolution of their input data, as well as their algorithms for fault detection and identification. This paper assesses the performance of time-based, frequency-based, and time-frequency-based digital protective relays, when operated at different sampling rates. Tested sampling rates include low, medium, and high sampling rates that range from 16 to 288 samples per cycle. In this paper, the three digital protective relays are tested when deployed as the digital 87 T transformer digital protection. Performance of the time-based, frequency-based, and time-frequency-based digital protective relays is assessed in terms of their accuracy and response speed. Test results show that low sampling rates can deteriorate the accuracy and response speed of the three tested digital protective relays. Obtained performance results also reveal that medium and high sampling rates can effectively improve the accuracy and response speed of the time-based, frequency-based, and time-frequency-based digital protective relays.

Effects of Conventional and Musician-Specific Hearing Protection Devices on Speech Intelligibility

(1) Background: To assess and compare speech intelligibility with conventional and universal musician-specific hearing protection devices (HPD); (2) Methods: The sample comprised 15 normal-hearing musicians of both sexes who had been professionals for more than 5 years. They underwent thorough audiological assessment and free-field audiometry to measure the attenuation levels of three HPD models (musician-specific, silicone, and foam devices). The sentence recognition thresholds in quiet (SRTQ) and noise (SRTN) were assessed with the Lists of Sentences in Portuguese. User satisfaction with musician HPD was assessed after 2 months; (3) Results: Conventional HPD had higher pure-tone mean attenuation levels than musician HPD. No statistically significant differences were found in SRTQ and SRTN between the three HPD types. However, the musician HPD had higher mean signal-to-noise ratios and percentages of correct words from sentences presented in noise than the other HPD. The answers also indicated a positive trend toward satisfaction with the musician-specific HPD; (4) Conclusions: Despite the lack of significant differences in speech intelligibility while wearing the three HPD models in either quiet or noise, the musician-specific HPD provided greater musical sound quality. This reinforces the possibility of an effective and adequate use of protection to preserve musicians’ hearing.

Novel Approach for the Monitoring of Single Phase-to-Ground Fault Associated with Power Arc

This paper presents a general theoretical overview of a novel approach for the monitoring of the single phase-to-ground fault associated with power arc. Although several existing fault protection methods have been employed in order to resolve the power arcing faults associated with the single phase-to-ground faults, still ongoing research is trying to develop efficient methods that could help to suppress completely these dangerous power arcs from the systems. The operation of the protective relays and fuse systems is quite often questionable during recurrent failures in detecting the electric arcs as expected, especially during these arcs earlier events of formation. The most relevant reason causing these traditional faults protective switchgears seldom failures, limitations and drawbacks include essentially the varying amounts of resistance associated with these previously mentioned power arcs. Subsequently, the electric arcs related impedance and that of the power system tend to limit the arcing fault currents and voltages quantities at very low rates. Hence preventing the existing fault protective devices and switchgears to detect these arcs hazards, as long as the arcing fault related currents and voltages quantities are kept for a relatively long period of time below the nominal setting values of both the relays and the fuses systems. Subsequently, the entire power distribution system experiences the devastating effects of theses dangerous parasitic electric arcs hazards. However, in order to overcome the limitations, the disadvantages and the drawbacks of the above mentioned conventional fault protective devices, this paper divorces completely with the traditional practices in order to propose a radio measurement method.

Prevention of Noise-Induced Hearing Loss In Vivo: Continuous Application of Insulin-like Growth Factor 1 and Its Effect on Inner Ear Synapses, Auditory Function and Perilymph Proteins.

As noise-induced hearing loss (NIHL) is a leading cause of occupational diseases, there is an urgent need for the development of preventive and therapeutic interventions. To avoid user-compliance-based problems occurring with conventional protection devices, the pharmacological prevention is currently in the focus of hearing research. Noise exposure leads to an increase in reactive oxygen species (ROS) in the cochlea. This way antioxidant agents are a promising option for pharmacological interventions. Previous animal studies reported preventive as well as therapeutic effects of Insulin-like growth factor 1 (IGF-1) in the context of NIHL. Unfortunately, in patients the time point of the noise trauma cannot always be predicted, and additive effects may occur. Therefore, continuous prevention seems to be beneficial. The present study aimed to investigate the preventive potential of continuous administration of low concentrations of IGF-1 to the inner ear in an animal model of NIHL. Guinea pigs were unilaterally implanted with an osmotic minipump. One week after surgery they received noise trauma, inducing a temporary threshold shift. Continuous IGF-1 delivery lasted for seven more days. It did not lead to significantly improved hearing thresholds compared to control animals. Quite the contrary, there is a hint for a higher noise susceptibility. Nevertheless, changes in the perilymph proteome indicate a reduced damage and better repair mechanisms through the IGF-1 treatment. Thus, future studies should investigate delivery methods enabling continuous prevention but reducing the risk of an overdosage.

Review of Methods for Addressing Challenging Issues in the Operation of Protection Devices in Microgrids with Voltages of up to 1 kV That Integrates Distributed Energy Resources

With the large-scale integration of distributed energy resources (DER) into passive distribution networks with voltages of up to 1 kV, these networks are being converted into microgrids. When the topology and operating conditions change, several challenging issues arise related to the functioning of the protection devices (PD) that are in operation. Most DERs, including renewable generators, are integrated into microgrids by means of inverters. In the event of short circuits (SC) in microgrids, these DERs provide a fault current contribution of no more than 1.2–2.0 Irated at the fault location. This makes it difficult to identify the fault location and to carry out the selective disconnection of the faulty element by means of conventional PDs. This article provides an overview of engineering solutions for improving conventional protection schemes that have been historically used in passive distribution networks, as well as for creating modern protection schemes based on innovative principles and new methods. The use of adaptive protections built on decentralized and centralized principles in most cases ensures the reliable protection of microgrids. Modern intelligent electronic devices (IEDs), where protection functions are implemented, rank higher with respect to their technical perfection in terms of reliability, sensitivity, selectivity, and speed performance. The use of multi-agent systems in the implementation of modern protection schemes requires the availability of broadband communication channels, which hinders their use because of the high cost. The combined use of fault current limiters (FCL) and energy storage systems (ESS) allows for the reliable operation of microgrid protections. The use of modern PDs ensures the reliable operation of DERs and power supply to consumers in microgrids, both in the case of grid-connected and islanded operation modes. Since there is no unified concept of designing protection schemes for microgrids with DERs, the choice of specific approaches to the design of protection schemes should be based on the results of a comparative technical and economic analysis of different options.

A weighted ensemble learning-based autonomous fault diagnosis method for photovoltaic systems using genetic algorithm

Conventional protection devices may not be able to diagnose the faults in Photovoltaic (PV) systems due to the nonlinear behavior of PV characteristics, its dependency on the operating environment, and operation of Maximum Power Point Tracking (MPPT) algorithms. To date, numerous studies have been carried out to overcome this challenge through Artificial Intelligence (AI) techniques. However, most of the AI-based techniques require a large dataset and also suffer overfitting problem. In this study, we propose an intelligent and automatic fault diagnosis method using less dataset for the training process through feature extraction and selection algorithms, as well as using an ensemble learning algorithm to classify open-circuit (OC) and line-line (LL) faults in PV systems. For this purpose, the proposed model firstly extracts the key features of the operating current and voltage of the PV arrays. Secondly, the Lasso penalty as an embedded feature selection technique is applied to determine the best subset of features. Thirdly, an ensemble learning algorithm consisting of three individual learning algorithms namely Logistic Regression (LR), Support Vector Machine (SVM), and k-Nearest Neighbors (KNN) is used in the classification stage to predict conditions of PV systems based on a weighted voting approach. Moreover, we apply a genetic algorithm to optimize the weights assigned to the algorithms in order to detect electrical faults in PV systems with higher accuracy. The experimental results demonstrate the proposed model is very efficient and reliable to diagnose open-circuit (OC) and line-line (LL) faults in PV arrays under any challenging conditions with an accuracy of 99%.

A multi-scale dual-stage model for PV array fault detection, classification, and monitoring technique

The output generated by photovoltaic arrays is influenced mainly by the irradiance, which has non-uniform distribution in a day. This has resulted in the current-limiting nature and nonlinear output characteristics, and conventional protection devices cannot detect and clean faults appropriately. This paper proposes a low-cost model for a multi-scale dual-stage photovoltaic fault detection, classification, and monitoring technique developed through MATLAB/Simulink. The main contribution of this paper is that it can detect multiple common faults, be applied on multi-scale photovoltaic arrays regardless of environmental conditions, and be beneficial for photovoltaic system maintenance work. The experimental results show that the developed algorithm using supervised learning algorithms mutual with k-fold cross-validation has produced good performances in identifying six common faults of photovoltaic arrays, achieved 100% accuracy in fault detection, and achieved good accuracy in fault classification. Challenges and suggestions for future research direction are also suggested in this paper. Overall, this study shall provide researchers and policymakers with a valuable reference for developing photovoltaic system fault detection and monitoring techniques for better feasibility, safety, and energy sustainability.

Protection Coordination Method Using Symmetrical Components in Loop Distribution System

Power utilities worldwide commonly use the radial distribution system because of its advantages of being simple in structure and having relatively inexpensive installation costs. It has a disadvantage in that its power supply reliability is low because the load side of the fault section will suffer from an outage in the event of a fault in the system. However, recently, with ICT (Information and Communication Technologies) development, system reliability is required to be high as the outage-susceptible loads increase. In addition, the increase in the connection of distributed resources such as renewable energy and electric vehicles is making it impossible to predict the power flow and reducing line utilization. Therefore, a loop power distribution system is proposed as a measure to solve this problem. Because all buses (nodes) in a loop distribution system have two or more power supply routes, they are more reliable than the radial system. It allows them to improve line utilization by connecting lines with different load peak times. However, in the case of a fault in the loop distribution system, the fault current is supplied from both directions, making it impossible to properly isolate the fault section with the protection method of the conventional distribution system. The permissive overreach transfer trip (POTT) method using communication to compensate for the limitations of conventional protection devices, and the other method using directional distance relay, is proposed. However, these methods operate by determining the direction of the fault current but have a disadvantage. It is difficult to detect a fault due to the effects of ground faults and distributed generation (DG) occurring in other lines. Therefore, in this paper, we propose a protection coordination algorithm that uses the negative-sequence component of voltage and current that occur when an unbalanced fault occurs, rather than the determination of the directionality and use of communication. To validate this, we configured a system using PSCAD/EMTDC (Manitoba Hydro International Ltd., Winnipeg, Manitoba, Canada), a system analysis program package and verified the results depending on the type of faults with the proposed algorithm.

An Enhanced Algorithm for Conventional Protection Devices of Transmission Lines With DTLR

As the installed capacity of renewable generation continues to increase nowadays to satisfy both emissions and economic requirements, the nature of intermittent generation results in a need to further increase transmission capacity. Dynamic thermal line rating may be used to increase the capacity of transmission lines without upgrading infrastructure. However, existing transmission line protection devices may mal-operate due to the increased capacity. So, it is required to evaluate the performance of existing protection devices. This paper proposes an algorithm that enhances the performance of existing conventional relays such as distance and overcurrent relays. The proposed algorithm is based on a combination of dynamic thermal rating, current ratio of negative and positive sequences and voltage criterion to detect faults whether symmetrical or asymmetrical and unsafe overload. In addition, it aims at restraining the existing relays during safe overloads. A model of a system under investigation is simulated, with studies are performed in MATLAB/Simulink environment. The results demonstrate the ability of the proposed scheme to detect all types of faults and unsafe overload dependably and restrain the conventional relays securely during safe overloads.

DC Arc-Fault Detection Based on Empirical Mode Decomposition of Arc Signatures and Support Vector Machine

Protection devices are extensively utilized in direct current (DC) systems to ensure their normal operation and safety. However, series arc faults that establish current paths in the air between conductors introduce arc impedance to the system. Consequently, they can result in a decrease of current, and thus conventional protection devices may not be triggered. Undetected series arc faults can cause malfunctions and even lead to fire hazards. Therefore, a series arc-fault detection system is essential to DC systems to operate reliably and efficiently. In this paper, a series arc-fault detection system based on arc time-frequency signatures extracted by a modified empirical mode decomposition (EMD) technique and using a support vector machine (SVM) algorithm in decision making is proposed for DC systems. The oscillatory frequencies from the arc current are decomposed by the EMD with an analysis of the Hurst exponent ( ${H}$ ) to reject interference from the power electronics noise. ${H}$ analyzes the trend of a signal and the intrinsic oscillations of the signal are those with values of ${H}$ larger than 1/2. Comparing to traditional filters or wavelet transforms, this method does not require knowledge of the frequency range of the interference which varies from system to system. The capability and applicability of the proposed technique are validated in a photovoltaic system. The effectiveness of arc-fault detection is significantly improved by this technique because it can acquire sufficient and accurate arc signatures and it does not need to predefine various thresholds.

Protection philosophy in low short‐circuit capacity distribution grids with high penetration of converter‐interfaced distributed renewable energy sources

The ever-growing penetration of converter-interfaced distributed renewable energy sources (CI-DRES) in distribution networks, despite the undoubted advantages, has a profound impact on the traditional protection systems. The protection problem becomes even more complicated as the increase in the CI-DRES penetration level leads to the decommissioning of conventional power plants. Due to the limited current capability of CI-DRES, decommissioning of conventional units will lead to a transmission grid of significantly lower short-circuit level. This study proposes a novel protection philosophy for distribution grids of low short-circuit capacity and high CI-DRES penetration. According to the proposed approach, CI-DRES are controlled to actively participate in the fault-clearing procedure, supporting the short-circuit capacity, in an aggregated form, through the injection of controllable currents. Therefore, conventional overcurrent protection devices can be used, without any additional investments for a protection system upgrade. The CI-DRES fault contribution is based on their relative position to the fault, respecting technical and protection-malfunction constraints. In addition to the short-circuit level, the effect of the feeder parameters and the power factor of the injected fault current on the voltage recovery is also investigated. The proposed protection philosophy is validated via detailed simulations in DIgSILENT PowerFactory.

Comparative Analysis of Fuzzy Inference System (FIS) And Adaptive Neuro-Fuzzy Inference System (ANFIS) Methods in the Classification and Location of High Impedance Faults on Distribution System

Unlike low impedance faults, which involve relatively large magnitude of fault currents and are easily detected by conventional over-current protection devices, high impedance faults pose a serious challenge to protection engineers because they can remain on the system without the protective relays being able to detect them. This paper presents an improved method for detection and location of high impedance fault using ANFIS model. The study was conducted on the 33 kV Uyo-Ikot Ekpene power distribution line. The case study power distribution system was modeled using MATLAB software. HIFs were introduced at various locations along the distribution line. The data obtained from the MATLAB/Simulink simulated fault using discrete wavelet transform (DWT) were used to train the ANFIS for the location of HIF points along the distribution system as well as for prediction of the distance of the fault location to the nearest injection substation. The results show that ANFIS model gives 52.5 percentage reduction in error compared with FIS in the location of fault points on the case study power distribution system.

Comparative Analysis of Fuzzy Inference System (FIS) And Adaptive Neuro-Fuzzy Inference System (ANFIS) Methods in the Classification and Location of High Impedance Faults on Distribution System

Unlike low impedance faults, which involve relatively large magnitude of fault currents and are easily detected by conventional over-current protection devices, high impedance faults pose a serious challenge to protection engineers because they can remain on the system without the protective relays being able to detect them. This paper presents an improved method for detection and location of high impedance fault using ANFIS model. The study was conducted on the 33 kV Uyo-Ikot Ekpene power distribution line. The case study power distribution system was modeled using MATLAB software. HIFs were introduced at various locations along the distribution line. The data obtained from the MATLAB/Simulink simulated fault using discrete wavelet transform (DWT) were used to train the ANFIS for the location of HIF points along the distribution system as well as for prediction of the distance of the fault location to the nearest injection substation. The results show that ANFIS model gives 52.5 percentage reduction in error compared with FIS in the location of fault points on the case study power distribution system.

Engineering model development using Fuzzy Logic for wireless protective devices

Operationally, the distribution of electricity faces various technical limitations and environmental conditions during operations, on the other hand, it also bears the increasing need for electrical energy. Therefore, the system is required to provide high service by considering various disturbances that occur. Thus, an electric power system requires a protection system that is reliable and sensitive to various types of disturbances, and it has a fast response. In this work, the study is aimed to develop conventional protection devices by implementing intelligent systems based on fuzzy logic. The use of fuzzy is intended to support decision making by considering the voltage, current and temperature of the cable. The results show that the device developed can react quickly and cut off electricity. In addition, it can also respond to the types of interruptions that exist. Moreover, it also avoids damage devices installed on the network.

\xb5PMU-based smart adaptive protection scheme for microgrids

The concepts of microgrids (MGs) and smart grid represent the recent targeted revolution towards fully smart electrical network integrated with high penetration of renewable energy sources (RESs). The protection system of MGs becomes a challenge due to variable characteristics of its currents, bidirectional power flow and output power fluctuations of RES, causing selectivity and sensitivity issues for conventional protective devices (PDs) with fixed setting. In this paper, a smart protection scheme (SPS) is proposed using micro-phasor measurement units (µPMUs) to obtain the continuous rapid synchronized phasor measurement data. And it is communicated with a microgrid central controller (MGCC) through highly reliable communication architecture to carry out online smart adaptive protection scheme. Fault index coefficients and abnormality coefficients are calculated for each feeder to detect the fault location and the abnormality case. Detailed modeling of an MG including 10-bus connected distribution system with integrated distributed generation (DG) is simulated using ETAP software. The proposed protection algorithm is modeled and evaluated using MATLAB software. The proposed fault detector and abnormality detector can enable quick and accurate fault identification and isolation.

Optimal Placement of Remote-Controlled Switches in Distribution Networks in the Presence of Distributed Generators

A two-level optimization method is presented to find the optimal number and location of conventional protective devices to be upgraded to remote-controlled switches (RCSs) for an existing distribution network (DN). The effect of distributed generation (DG) on this problem is considered. In the first level, a nonlinear binary program is proposed to maximize the restored customers subject to technical and topological constraints. All feasible interchanges between protective devices and ties involved in the restoration, when a fault occurs at all possible locations are found considering switching dependencies. In the second level, a nonlinear cost function, combining the expected cost of interruptions (ECOST) and the switch cost, is minimized with respect to the location of RCSs. The expected cost function is computed based on the optimum restoration policies obtained from the first level. The optimum placement of RCSs using the proposed algorithm is tested on a 4-feeder 1069-node test system and compared to the solution obtained with a genetic algorithm (GA) on the same system.

Application of Superconducting Fault Current Limiter (SFCL) in Power Systems: A Review

The fault current levels of an interconnected power network have witnessed a general rise due to increase in power demand. This rise in fault current if not properly mitigated may exceed the maximum ratings of the switchgear. Many conventional protective devices such as series reactors, fuses, high impedance transformers, etc. have high cost, increased power loss and loss of power system stability, which may ultimately cause lower reliability and reduced operational flexibility. Superconducting Fault Current Limiter (SFCL) is a flexible alternative to the use of conventional protective devices, due to its effective ways of reducing fault current within the first cycle of fault current, reduced weight and zero impedance during normal operation. This paper reviews various concepts of SFCLs and its applications in power systems.

Application of Superconducting Fault Current Limiter (SFCL) in Power Systems: A Review

The fault current levels of an interconnected power network have witnessed a general rise due to increase in power demand. This rise in fault current if not properly mitigated may exceed the maximum ratings of the switchgear. Many conventional protective devices such as series reactors, fuses, high impedance transformers, etc. have high cost, increased power loss and loss of power system stability, which may ultimately cause lower reliability and reduced operational flexibility. Superconducting Fault Current Limiter (SFCL) is a flexible alternative to the use of conventional protective devices, due to its effective ways of reducing fault current within the first cycle of fault current, reduced weight and zero impedance during normal operation. This paper reviews various concepts of SFCLs and its applications in power systems.