Conventional Protection Research Articles

Paper Information Recording and Security Protection Using Invisible Ink and Artificial Intelligence.

Conventional paper information protection mainly relies on stimuli-responsive functional materials that can display color or luminescence under external stimuli; however, this method is rather predictable and can be easily cracked. In this work, a paper information protection scheme combining fluorescent invisible ink and artificial intelligence was proposed. The ink was prepared by dissolving carbon nanoparticles in water, which has a high quantum yield and outstanding light stability and salt stability, thus ensuring the integrity of information in complex environments. A five-layer convolutional neural network (one of the two mainstream architectures in today's artificial intelligence fields) was specially trained based on ultraviolet light excited symbols printed by invisible ink. Using this scheme, the correct information could only be read with the specially trained neural network after ultraviolet (UV) irradiation. Without this trained neural network or UV irradiation, misleading messages will be presented. Moreover, it was possible to design unpredictable and highly complex password books to further increase information security. This smart strategy provides new opportunities for high-level paper information encryption and also proposes new ideas for the applications of carbon nanoparticles and artificial intelligence.

Data-Driven Fault Detection and Classification for MTDC Systems by Integrating HCTSA and Softmax Regression

The requirement of fast fault isolation poses a great challenge to the safe operation of multi-terminal direct current (MTDC) systems. In order to make a better tradeoff between the speed and reliability of the protection scheme, it is imperative to mine more valuable information from fault transient signals. This paper puts forward a data-driven framework capable of digging out and synthesizing multi-dimensional features to achieve fast and reliable DC fault detection and classification in MTDC systems. Highly comparative time-series analysis (HCTSA) is first adopted to extract extensive features with clear physical interpretations from fault current waveforms, and a few features valuable to fault identification are then selected utilizing the greedy forward search. Based on the reduced features, a softmax regression classifier (SRC) is further proposed to calculate the probability of each fault category with a relatively minor on-line computational burden. Numerical simulations carried out in PSCAD/EMTDC have demonstrated the proposed approach is effective under different fault conditions, robust against noise corruptions as well as abnormal samplings, and replicable in various DC grids. In addition, comprehensive comparison studies with conventional derivative-based protection methods and some typical artificial intelligence based (AI-based) methods have been conducted. It is verified that the proposed method has the advantages of higher fault identification accuracy over conventional protections and shallow structure AI-based methods, better interpretability as well as lower on-line computing complexity over the deep architecture AI-based approaches.

Estimation of VFTO caused by same frequency and phase withstand voltage test of GIS

The same frequency and phase withstand voltage test of GIS has been applied in the transition test of substation expansion. However, when the breakdown accident occurs in the test process, the VFTO will seriously threaten the safety of the tested equipment and operating equipment. Aiming at a same frequency and phase withstand voltage test of GIS, EMTP simulation model is established and the parameters are determined. The VFTO that may occur in the GIS under different operation modes and different test conditions are studied. The restraint effect of the test protection resistance on the VFTO is analyzed, and the corresponding measures for safety are given. The results demonstrate that different operation modes of the tested GIS system will produce different VFTO. When the single breakdown is changed to ground flashover, the over-voltage amplitude of the non-tested bus node will increase, and the over-current of the break will also increase. The conventional test protection resistance cannot restrain the VFTO. The test state sensing measures and other safety measures need to be implemented in the test.

Optimization-Based Formulations for Short-Circuit Studies with Inverter-Interfaced Generation in PowerModelsProtection.jl

Protecting inverter-interfaced microgrids is challenging as conventional time-overcurrent protection becomes unusable due to the lack of fault current. There is a great need for novel protective relaying methods that enable the application of protection coordination on microgrids, thereby allowing for microgrids with larger areas and numbers of loads while not compromising reliable power delivery. Tools for modeling and analyzing such microgrids under fault conditions are necessary in order to help design such protective relaying and operate microgrids in a configuration that can be protected, though there is currently a lack of tools applicable to inverter-interfaced microgrids. This paper introduces the concept of applying an optimization problem formulation to the topic of inverter-interfaced microgrid fault modeling, and discusses how it can be employed both for simulating short-circuits and as a set of constraints for optimal microgrid operation to ensure protective device coordination.

Cosine Similarity Based Line Protection for Large Scale Wind Farms Part II—The Industrial Application

With the integration of the large-scale wind farms, the conventional pilot protection is facing new challenges. It suffers from the performance degradation can even refuse operation for some extreme fault scenarios. To address this problem, this article continues the research of the novel pilot protection based on cosine similarity. The protection pickup setting and industrial application testing is investigated. The functional structure is described and the logic of the cosine similarity based protection is evaluated under different fault scenarios. Compared with the conventional differential protection, application of the proposed protection can greatly improve the relay performance. The proposed protection is embedded into an industry relay device, and the standard hardware-in-loop tests are carried out using the real time digital simulator before the industrial application. Now, the protection device based on cosine similarity is installed in the wind farms and put into operation in Inner Mongolia.

High-Impedance Fault Identification Using Cyclostationary Characteristic Analysis

Conventional overcurrent-based protection systems are generally not sensitive to high impedance faults (HIFs) since they have a low overcurrent amplitude. This type of fault causes damages to dealers and can provoke the deaths of people and animals. Therefore, different methods for identifying HIFs in electric power distribution systems have been proposed. However, besides the low fault overcurrent level be still a problem, the noise interference on signals is also a difficulty for non-conventional methods. Therefore, this work proposes a reliable method based on statistical characteristics for identifying HIFs regardless of the noise interference and the overcurrent level. Specifically, the method uses cyclostationary characteristic analysis to extract cyclic autocorrelation information from the signals of interest by calculating the cyclic spectral density function. From this information, HIFs can be properly identified among other power system disturbances. The performance of the method was assessed with actual HIF data and with realistic HIF simulations, presenting promising results.

Research on Differential Protection of Generator Based on New Braking Mode

In view of the difficulties in coordination between reliability and sensitivity of conventional generator differential protection, this paper presents a novel generator differential protection scheme based on a new braking method. On the basis of the mathematical model of the field-circuit coupling method and the electrical network cascade characteristics, the stator windings were combined and decoupled by the improved six-sequence component method to eliminate electromagnetic coupling between winding coils. In accordance with the basic characteristics of longitudinal impedance, the function of sub-item discrimination was realized. Numerous simulations and the up-to-date dynamic experiments showed that the proposed method has good state discrimination ability and can effectively resist the influence of current transformer saturation. Thus, it has an excellent prospect for engineering promotion.

A new artificial intelligence based supervision method for low-impedance REF relays

The restricted earth fault (REF) protection of power transformers are prone to maloperation during magnetizing inrush and severe external faults due to current transformer (CT) saturation. To tackle this issue, for the first time, an intelligent supervision method is designed in this paper which can significantly improve the immunity of this protection scheme. For this purpose, some decisive parameters used in some conventional methods are selected as distinguishing features. In the next step, a real power transformer is simulated under different operating conditions using PSCAD/EMTDC software. Then, three different intelligent classifiers are trained and tested using the simulation results and the most accurate and fast one is chosen to be used as the intelligent supervisory unit. Finally, a conventional relay performance is analyzed before/after being equipped with the new supervision unit. The obtained results show that by equipping the conventional REF protection scheme with it, a magnificent security against maloperation can be achieved while the imposed time delay is ignorable.

A q component‐based adaptive protection coordination optimisation using overcurrent relays in coordination with fuses for hybrid microgrid

In a hybrid microgrid, the overcurrent relays (OCRs) must sense the changes in the fault currents while the microgrid switches from the grid-connected to the islanded mode of operation. Further, for the different types of distributed generator (DG), such as photovoltaic (PV), wind turbines of types I, III, and IV, the variation in fault currents must also be detected by the relays. This leads to delay and inappropriate coordination in conventional protection schemes. To minimise the impact of inappropriate coordination in this study, an adaptive protection scheme with optimal settings is proposed for phase and earth faults detection. It also takes care of different nature of DGs, all feasible operating modes of hybrid microgrid with only quadrature (q) component of fault current while zero component is used to differentiate between earth and phase faults. Also, only q component-based proposed technique optimises the coordination time (CT) of fuses as a backup to primary and backup relays with newly proposed CT interval constraints. A differential evolutionary algorithm is proposed for determination of optimal settings for the directional OCRs.

Effects of Using Perineal Underwear on Discomfort and Shame in Angiography Patients.

The purpose of this study is to develop and apply a type of perineal underwear that protects the patient’s physical privacy and to examine its effects on perineal discomfort and shame. This study collected primary data from 44 patients who visited Kyung Hee University hospital in Seoul city and were admitted to the neurosurgery ward to undergo angiography between 7 August 2017, and 30 April 2018. In this quasi-experimental study with a nonequivalent control group posttest-only design, participants were divided into an experimental group (n = 22) and a control group (n = 22). The control group used conventional protection, which involved wearing padding around the perineum, while the experimental group wore the perineal underwear developed in this study. The underwear group showed a significantly lower degree of shame (Z = −5.39, p < 0.001) and perineal discomfort (Z = −5.88, p < 0.001) than the padding group. In the padding group, women felt significantly more shame than men did (Z = −2.48, p = 0.013). The use of the perineal underwear developed in this study significantly reduced the degree of shame and perineal discomfort in patients undergoing angiography. Such perineal underwear could also be useful for protecting patients’ privacy during perineal examinations.

A novel current amplitude differential protection for active distribution network considering the source-effect of IM-type unmeasurable load branches

The current amplitude differential protection is one of the effective means to overcome the deficiencies of the conventional over-current protection in the active distribution network. However, the existing criterions are rarely immune to the unmeasurable load branches especially the IM-type unmeasurable load branches. Therefore, this paper derives the positive-sequence equivalent model of the IM during fault occurrence. Then, the general variation law of the current amplitude difference between both terminals is revealed. For the passive unmeasurable load branch, the current amplitude difference is greater than its original value under internal faults while smaller under external faults. But for the IM-type unmeasurable load branch, such difference can exceed its original value temporarily under external low-resistance faults. To cover the maximum possible current amplitude difference during external fault occurrence, the adaptive operation characteristic curve is established. Accordingly, a novel protection scheme based on the pre-fault and post-fault current amplitude differences is proposed. The simulation results show that the proposed protection can avoid the risk of mal-operation in various external fault scenarios and identify internal faults sensitively.

A New Model of Numerical MHO Distance Relay Associated with Power Swing Detector

In conventional transmission line protection, a distance relay is used to provide the primary as well as backup protection. The voltage and current phasors measurement needed by the distance relay for determining the impedance may be affected by the power disturbances such as power swing. Consequently, this power swing may cause mal-operation of Zone three distance relays which in turn may affect on the reliability of the whole protective scheme. Many power swing blocking functions (PSB) have been developed to mitigate these effects. In this paper, a new model of Mho distance relay with dual-quadrilateral power swing detection characteristic has been developed and implemented first in PC using LabVIEW, then tested using Power System Simulink Model under different faults and power swing conditions. Finally, the relay prototype has been realized using acquisition card NI USB-6009, which acquires real-time signals of the currents and the voltages, processes them digitally and outputs tripping or blocking signal to the circuit breaker. The obtained results show that the relay provides good discrimination between a fault and power swing condition.

Concrete Incorporating Nanosilica Cured under Freezing Temperatures Using Conventional and Hybrid Protection Methods

Ultrafine nanosilica particles have the potential to produce concrete under low temperatures. In this study, nanomodified concrete was cured under freezing temperatures (−10°C and −20°C) using insulation blankets without or with phase change material as conventional and hybrid protection methods, respectively. Six mixtures, incorporating general use and high early strength cements, fly ash (20%), nanosilica (6%), and cold weather admixture system (antifreeze/accelerator), were tested. The mixtures were assessed based on setting times, compressive strength, fluid absorption, and resistance to frost damage in water and salt solution. Moreover, thermogravimetric and mercury intrusion porosimetry were conducted to assess the hydration and microstructural development of concrete under these freezing temperatures. The nanomodified concrete protected by the hybrid system, even with the presence of 20% Class F fly ash, indicated improved hardening, mechanical, and durability performance; thus, such a mix design and protection method might present a viable option for concrete applications in cold conditions down to −20°C.

Cyclam-Based Chelators Bearing Phosphonated Pyridine Pendants for 64Cu-PET Imaging: Synthesis, Physicochemical Studies, Radiolabeling, and Bioimaging.

Herein we present the preparation of two novel cyclam-based macrocycles (te1pyp and cb-te1pyp), bearing phosphonate-appended pyridine side arms for the coordination of copper(II) ions in the context of 64Cu PET imaging. The two ligands have been prepared through conventional protection-alkylation sequences on cyclam, and their coordination properties have been thoroughly investigated. The corresponding copper complexes have been fully characterized in the solid state (X-ray diffraction analysis) and in solution (EPR and UV-vis spectroscopies). Potentiometric studies combined with spectrometry have also allowed us to determine their thermodynamic stability constants, confirming their high affinity for copper(II) cations. The kinetic inertness of the complexes has been verified by acid-assisted dissociation experiments, enabling their use in 64Cu-PET imaging in mice for the first time. Indeed, the two ligands could be quantitatively radiolabeled under mild conditions, and the resulting 64Cu complexes have demonstrated excellent stability in serum. PET imaging demonstrated a set of features emerging from the combination of picolinates and phosphonate units: high stability in vivo, fast clearance from the body via renal elimination, and most interestingly, very low fixation in the liver. This is in contrast with what was observed for monopicolinate cyclam (te1pa), which had a non-negligible accumulation in the liver, owing probably to its different charge and lipophilicity. These results thus pave the way for the use of such phosphonated pyridine chelators for in vivo 64Cu-PET imaging.

Sesamol-based terpenoids as promising bio-sourced crop protection compounds against the wheat pathogen Zymoseptoria tritici.

Research into environmentally friendly alternatives to conventional plant protection products, to promote sustainable agriculture and healthy food, is strongly encouraged. In this context, 20 naturally occurring terpenoids and phenolic compounds were selected and evaluated in vitro as crop protection compounds against Zymoseptoria tritici, the causal agent of Septoria tritici blotch of wheat. After selection of the most active compounds, some hemisynthetic modifications were conducted to modify their lipophilicity. These modifications led to the discovery of sesamol esters as promising antifungal agents, with IC50 around 10 μg/mL and a total absence of cytotoxicity against human cells. These sesamol-based derivatives should be selected for further evaluations in planta to validate their use as wheat crop protection agents. Moreover, the importance of a balanced hydrophily/lipophilicity ratio should be further studied. © 2021 Society of Chemical Industry.

Online Monitoring and Early Warning of Subsynchronous Oscillation Using Levenberg–Marquardt and Backpropagation Algorithm Combined with Sensitivity Analysis and Principal Component Analysis

Over the past few years, with the access of large-scale new energy sources, the problem of subsynchronous oscillation (SSO) in power systems has presented a novel multisource and multitransformation form, which may be significantly threatening. Conventional control and protection methods primarily give rise to device protection actions in the presence of severe oscillation. On the whole, online monitoring only identifies the frequency and amplitude, whereas it cannot identify the attenuation factor. Moreover, the determination of the warning threshold is more dependent on human experience, so the reliability and rapidity of the early warning cannot be ensured. This study conducts an in-depth investigation of the wind-thermal power bundling and extreme high-voltage alternating current- (AC-) direct current (DC) hybrid transmission system. The major factors of SSO using this system are unclear, which brings difficulties to effective monitoring. Given the mentioned problems, a method combining Levenberg–Marquardt- (LM-) Backpropagation (BP) machine learning and Sensitivity Analysis (SA) and principal component analysis (PCA) is developed. First, the sensitivity analysis of each factor in the system is conducted to identify the major factors of SSO. Subsequently, the historical sample data are reduced with the principal component analysis to reduce the redundancy, which is adopted to train the regression model to determine the attenuation factor and frequency and then send them to the classifier for classification to complete the task of the assessment model. When a novel data signal is uploaded, the assessment model identifies the attenuation factor and frequency and subsequently determines the presence of SSO. Accordingly, an early warning is conducted. The system's refined simulation model and machine learning model verify the effectiveness of the method.

Adaptive optimum coordination of overcurrent relays for deregulated distribution system considering parallel feeders

This paper proposes an adaptive optimum overcurrent protection for deregulated distribution networks containing parallel feeders. The proposed adaptive coordination eliminates the maloperation of conventional overcurrent protection under different fault scenarios. These scenarios take place when faults occur close to the end of the parallel feeders specially when faults are associated with significant fault resistances. Under these faults, the current at the backup relay is almost double that at the corresponding primary. Thus, adaptive pickup setting is recommended. However, this problem is complicated remarkably when distributed generation units feed the upstream source side faults or under the removal of the power source due to the interruption of a source side breaker. Simultaneously, the proposed coordination approach enhances the sensitivity and keeps on the optimum speed by automatically identifying the faulted zone. The faulted zone is identified by monitoring both the status concerning a single feeder or two parallel feeders in service and the faulted phase current direction of each pair of relays. Thus, a new fault direction identification method is presented. This method is based on comparing the angle of the post-fault current and that of the pre-fault current. Three optimization algorithms (genetic, harmony search, and water cycle algorithms) have competed to find the optimal settings of the installed overcurrent relays for each faulted zone. The reliability of the proposed method is examined as compared to conventional coordination concepts based on a detailed simulation of an actual 11-kV cascaded parallel series distribution feeder in the Egyptian distribution network. Sample results are examined.

Dynamic lightning protection method of electric power systems based on the large data characteristics

In this paper, a new active dynamic lightning protection method is proposed based on the large data characteristics of electric power. This method mainly includes two parts: Part one, Neo4j framework model which is used to analyze large data of power system and dynamic regulation of power system, and Python software which is used to compare and analyze different framework models; Part two, the comparison between dynamic lightning and conventional protection methods. The results show that Neo4j traversal speed is 87.5% and 89.1% faster than Hadoop and Spark respectively, clustering effect is 12.5% and 17.8% higher than Hadoop and Spark respectively. As a result, Neo4j framework model is more suitable for the characteristics of large data in power system. After the lightning accident, the power-off time of dynamic lightning protection system is reduced by about 53.1%, and the recovery time of the system also decreased by about 42.8%. In the dynamic regulation of power system, the output of power supply is reduced by 35.1 MW and the load is cut out by 15.8 MW, which greatly reduce the impact of lightning strike on power supply and important load.

Fault Detection in DC Microgrid Based on the Resistance Estimation

Evaluation toward the line parameter-based fault detection technique is an attractive option due to the limitations associated with the conventional differential and overcurrent protection schemes, mostly during a high-resistance fault situation. The fault detection strategy based on the line parameter can be exploited using the resistance instead of directly taking the decision from voltage and current. In this article, the proposed technique is focused on estimating the resistance and detecting the fault even during high-resistance fault case. Resistance is estimated using the local measurements available at the bus. After that, the sign of the estimated resistance is compared at both ends of the line segment to detect the fault and the use of the sign of resistance eliminates the time synchronization issues. The proposed method is capable of detecting the fault in radial as well as ring configuration dc microgrid. A ring main dc microgrid system is simulated using the EMTDC software to validate the proposed technique. The performance of the proposed approach is also validated using a dc microgrid hardware setup and tested for numerous situations. The results obtained from simulation and experiment verify that the proposed method accurately detects the faults (close in fault, high-resistance fault) in the dc microgrid.

An adaptive fault-component-based current differential protection scheme for distribution networks with inverter-based distributed generators

The high penetration of inverter-based distributed generators (IBDGs) T-connected into distribution networks has changed their structure from single-source networks to multi-source multi-branch networks; therefore, conventional distribution network protection schemes are difficult to apply. To this end, a mathematical model of IBDG fault component current considering the control strategy of IBDG is established, and then, a method for estimating the IBDG fault component current using only electrical information at both terminals of the protected line is proposed. On this basis, an adaptive fault-component-based current differential protection scheme suitable for distribution networks with IBDGs is proposed. The proposed scheme only needs to exchange the electrical information at both terminals of the protected line; that is, it can adapt to multiple IBDGs that are T-connected into the distribution networks, reducing the requirements of multi-terminal protection for communication channels and thus lowering costs. Finally, the effectiveness of the proposed protection scheme is demonstrated in the PSCAD/EMTDC software. The results show that the proposed protection scheme is not affected by the location, capacity of the IBDGs, or the fault type and has a high sensitivity.