Line Protection Research Articles

A Fast and Sensitive Current Differential Protection for MMC-HVDC Lines

A Fast and Sensitive Current Differential Protection for MMC-HVDC Lines

Enhanced Kullback–Leibler Divergence Based Pilot Protection for Lines Connecting Battery Energy Storage Stations

In light of the challenges faced by existing protection methods when battery energy storage station (BESS) and various nonideal conditions emerge, enhanced Kullback–Leibler divergence-based time-domain pilot protection is put forward in this article. Given the discrepancy in current waveforms between internal and external faults, KLD is employed to quantify the degree of similarity between two current waveforms, enabling the accurate distinction between internal and external faults. To eliminate the asymmetry of KLD, improved KLD(IKLD) is introduced. Whereafter, a technique is proposed to convert the current sampling sequence into a probability distribution that can be utilized by IKLD. To counteract the negative influence of current transformer(CT) saturation on IKLD-based protection, the time-domain waveform features of summation current are adequately employed to develop an enhanced KLD(EKLD). Further, high and low thresholds are legitimately designed to ensure both dependability and security. The flowchart of EKLD-based pilot protection is described, and its effectiveness is extensively validated by variation in fault resistance, location, type and operating mode of BESS using PSCAD and a hardware-in-the-loop(HIL) testing platform. Additionally, proposed protection outclasses power frequency component-based current differential protection and some up-to-date presented time-domain protection methods.

Engineering and design of a last mile novel helmet concept

Modern society witnessed a remarkable surge in urban mobility with the proliferation of micro-mobility sharing services. However, this transformation has also led to a worrisome increase in severe accidents and injured users. In addition, conventional helmets are significantly lacking in sustainability. This research investigates the feasibility and safety aspects of a novel bicycle helmet concept using cork as a protective liner. In comparison to traditional synthetic foams, cork offers eco-friendly advantages, such as recyclability and superior protection against multiple impacts. The newly proposed helmet is designed to provide enhanced sustainability and convenience, maintaining compliance with the EN 1078:2012+A1 standard whilst offering the capability to flatten for easy storage and transportation. Numerical simulations were conducted to optimise the design concept, and impact tests, in accordance with the European standard, were performed using physical prototypes categorised into three types of design configuration. The results from the standard impact test were outstanding, with the best performing configuration demonstrating a performance 36.8% below the standard’s threshold. This falls within the average performance range of a regular bicycle helmet made entirely of petrol-derived materials. Furthermore, it exhibited safe head injury criterion levels, indicating a minimal risk of severe head injury.

Аксиологические рубежи обороны системы национальной безопасности: функциональное предназначение

The aim of this study is to substantiate the strategically significant functional role of the axiological defense lines of the national security system. This formulation of the question proceeds from the consideration of this system as a citadel, a unified defensive complex comprised of six defensive lines, the names of which correspond to the generalized means of managing social systems: methodological (gnoseological), historical-algorithmic, factual (ideological), economic, demographic, and military. Among the six mentioned defense lines, the first three are in the plane of sciences belonging to the humanitarian cycle and closely related to the value system, components of the country’s cultural code. In the context of hybrid warfare, the state is forced to use the military arsenal when it has conceded to the enemy on all previous defense lines, primarily on axiological lines. Neglecting the issues of protection of axiological defense lines of the national security system leads to the fact that the country suffers significant and often irreparable damage to subsequent lines: economic, demographic, military. It is recommended that axiological defense lines be defended and reinforced no less intensively than economic and other defense lines of the national security system. Without prompt resolution of these issues, the full-fledged implementation of Russia’s national projects and the achievement of technological sovereignty will be significantly hampered.

Role of artificial intelligence in transmission line protection: A review of three decades of research

The optimal functioning of the power system is crucially dependent upon the sound protection of its major stakeholder, i.e., the transmission line, as it is prone to fault. To maintain the integrity of the power system and protect costly power system equipment, protective relaying is necessary to provide a steady and affordable supply of electricity. Relays recognize, classify, and identify transmission line faults using input signals of voltage and current. Many artificial intelligent methods based on Expert Systems, Artificial Neural Networks, Fuzzy Logic, Support Vector Machines, Wavelet-based systems, and deep learning techniques are being investigated to improve modern digital relays’ consistency, speed, and accuracy. This paper is a comprehensive and all-inclusive survey that reviews and incorporates Phasor Measurement Unit (PMU) and Global Positioning System (GPS) approaches together with all of these intelligent transmission line safety strategies and concepts. Initial investigators will benefit from this study by being able to examine, evaluate, and analyze a variety of approaches with references for all relevant contributions.

Effect of DG penetration on hybrid relay coordination using user-defined dual-setting directional overcurrent relays and distance relays

ABSTRACT The efficient coordination of the distance and directional overcurrent relays (DOCRs) is jeopardized by the massive deployment of renewable distributed generation (DG) into electrical power networks. The two key aspects influencing the relay coordination are the bidirectional flow of current and increased short-circuit currents due to DG integration. This study investigates the consequences of variable DG penetration on the distance and dual-setting DOCRs (DS-DOCRs) coordination. As a result, common optimal relay settings have been obtained that can be utilized for variable DG penetration levels in modified IEEE-14 bus test system. For the distance relays (DRs), a fixed zone 1 and variable zone 2 operation have been considered. The proposed combined protection scheme is tested on a modified IEEE-14 bus test system using DS-DOCRs and DRs. The relay coordination problem is formulated as a constrained non-linear optimization problem and solved by genetic algorithm (GA) and gray wolf optimization (GWO). In this paper, DS-DOCRs with user-defined relay characteristics have demonstrated superior performance in line protection compared to conventional DOCRs with normal inverse (NI) characteristics. In addition, a comprehensive comparative analysis of optimization algorithms has been performed between GA and GWO algorithms.

Application of FBG Sensing Technology for Real-Time Monitoring in High-Stress Tunnel Environments

In the process of tunnel construction, problems such as high-stress rockburst, large deformation of soft rock, water inrush and mud gushing, secondary cracking of linings, blasting interference, man-made damage, and mechanical damage are often encountered. These pose a great challenge to the installation of monitoring equipment and line protection. In order to solve these problems, the 2# inclined shaft of Muzhailing Tunnel in the Gansu Province of China, which exists under high stress, water bearing, and bias conditions, was taken as the research object in this paper. By assembling a string, drilling grouting and sealing, and introducing multiple modes of protection, new fiber grating sensor group installation and line protection methods were proposed. The automatic continuous monitoring of the deep deformation of surrounding rock and the automatic continuous monitoring of steel arch stress were realized. The field monitoring results showed that: (1) the fiber grating displacement sensor group could be used to verify the authenticity of the surface displacement results monitored by the total station; (2) the NPR anchor cable coupling support effectively limited the large deformation of soft rock and the expansion of surrounding rock in a loose circle, and the range of the loose circle was stable at about 1 m; and (3) the main influence range of blasting was at a depth of 0~5 m in surrounding rock, and about 25 m away from the working face. In addition, to secure weak links in the steel arch due to the hardening phenomenon, a locking tube was set at the arch foot. In the support design, the fatigue life of the steel was found to be useful as the selection index for the steel arch frame to ensure the stability of the surrounding rock and the long-term safety of the tunnel. The present research adopted a robust method and integrates a variety of sensor technologies to provide a multifaceted view of the stresses and deformations encountered during the tunneling process, and the effective application of the above results could have certain research and reference value for the design and monitoring of high stress, water-bearing, and surrounding rock supports in tunnels.

Features in the Operation of Starting Elements of Remote Protection and Directional Residual Overcurrent Protection of Power Lines with Saturated Current Transformers

Features in the Operation of Starting Elements of Remote Protection and Directional Residual Overcurrent Protection of Power Lines with Saturated Current Transformers

Flexible DC transmission line fault type identification scheme based on Pearson correlation coefficient

Abstract Faults occurring on the DC side of the line are very harmful to the MMC-MTDC system, and with the popularization of flexible DC transmission technology based on overhead lines, how to discriminate the type of fault is the difficulty of MTDC DC line protection. This paper gives a fault kind identification approach based totally on the Pearson correlation coefficient, which discriminates the fault kind with the aid of calculating the Pearson correlation coefficient of the line voltage at each pole after the fault.

Novel pilot protection for transmission lines with large-scale wind farms based on trajectory distance characteristics

In terms of integrating large-scale wind farms into power systems, the fault characteristics of power systems have undergone fundamental changes, potentially leading to the rejection and misoperation of traditional protections. To address these issues, a time-domain pilot protection based on trajectory distance characteristics is proposed. A novel trajectory distance calculation method is introduced to improve the one-way distance (OWD) algorithm, which is used as a metric to quantify the distance between current trajectories to identify internal and external faults. To overcome the adverse impact of nonideal conditions, a metric, namely the ratio of nonsimultaneous points is proposed. Faults are identified using two metrics. Validation results from PSCAD/EMTDC and hardware-in-the-loop platform demonstrate that the proposed protection can operate within 15 ms in most cases and has excellent robustness against diverse nonideal conditions, including tolerating noise with 10 dB signal-to-noise ratio. Moreover, it considerably outperforms traditional and new differential protection methods.

Determining Fault Location in Transmission Lines Using Differential Equation Algorithms

A transmission line, in the context of electrical engineering and power systems, is a high-voltage or high-tension line that is used to transmit electrical power over long distances from power generation sources (such as power plants) to substations, where the electricity is then distributed to homes, businesses, and industrial facilities. Transmission lines are the backbone of the electrical grid, serving as the highways for electricity delivery. Their efficient and reliable operation is essential for ensuring that electricity is generated, transmitted, and distributed effectively, meeting the needs of consumers while maintaining grid stability and resilience. Transmission line protection refers to a set of techniques and devices used in electrical power systems to detect and respond to faults or abnormal conditions that can occur in high-voltage transmission lines. These lines are a critical part of the electrical grid and are responsible for transporting electricity over long distances from power generation plants to distribution substations. This paper proposes a different differential equation algorithm to locate faulty section on transmission lines. As seen from performance curves, the proposed protection algorithm is able to distinguish normal and faulty conditions.

A hybrid intelligent system for protection of transmission lines connected to PV farms based on linear trends

Conventional relays face challenges for transmission lines connected to inverter-based resources (IBRs). In this article, a single-ended intelligent protection of the transmission line in the zone between the grid and the PV farm is suggested. The method employs a fuzzy logic and random forest (RF)-based hybrid system to detect faults based on combined linear trend attributes of the 3-phase currents. The fault location is determined and the faulty phase is detected. RF feature selection is used to obtain the optimal linear trend feature. The performance of the methodology is examined for abnormal events such as faults, capacitor and load-switching operations simulated in PSCAD/EMTDC on IEEE 9-bus system obtained by varying various fault and switching parameters. Additionally, when validating the suggested strategy, consideration is given to the effects of conditions such as the presence of double circuit lines, PV capacity, sampling rate, data window length, noise, high impedance faults, CT saturation, compensation devices, evolving and cross-country faults, and far-end and near-end faults. The findings indicate that the suggested strategy can be used to deal with a variety of system configurations and situations while still safeguarding such complex power transmission networks.

Backup protection method for half-wavelength transmission lines based on inverse-time characteristic

The advantages of ultra-high voltage (UHV) Half-wavelength AC transmission (HWACT) technology are achieving full-line reactive power self-balancing without the need for reactive power compensation equipment along the line and avoiding the Ferranti effect. Recently, this technology has gained considerable attention worldwide. While numerous main protection methods that were tailored to the unique operational characteristics of HWACT lines have been proposed, backup protection for HWACT has been overlooked relatively. As a transmission line requires both main and backup protection for safe and reliable operation, this paper analyzes the necessity of backup protection for HWACT lines and proposes a method based on inverse-time backup protection. This method relies on the rate of change of current (RCC), determines faults by calculating the initial value of the change rate of the fault current, and applies inverse-time characteristics to remove faults. This protection method demonstrates good quick-acting properties by adopting the RCC in the initial phase of a single-end fault without the need for dual-end communication. A large number of simulation results validated that this method was smaller affected by fault distance, initial fault phase angle, transition resistance and fault type, making it an effective protection approach for main protection failures.

Spatio-temporal forecasting of landslide hazard in Chongqing National Transmission Protection Regions, China

ABSTRACT Previous studies on landslide susceptibility (LS) and hazard (LH) assessments have overlooked a crucial measure for evaluating validation effectiveness, which involves the use of post-temporal landslide inventories instead of solely relying on historical data. Therefore, this study constructed a regional LH prediction and validation framework at different timescales using the landslide data from 2002 to 2021. Firstly, based on updated landslide data and conditioning factors, the datasets for susceptibility modelling were built for various periods. Then, the performances of traditional ma chine learning, ensemble and deep learning models were compared. Finally, the multi-period rainfall data and susceptibility results were used in innovative LH forecasting. Our study results show that the ensemble learning model (random forest) has stronger generalisation ability in different time periods, with all Area Under Curve (AUC) values exceeding 0.9. The hazard modelling framework based on rainfall erosion intensity and susceptibility can effectively forecast LH, and the shortened timescale for rainfall erosion intensity can improve the accuracy of LH forecasting. At the very high hazard level, the percentage of landslides forecast increased from 25.23% to 42.86%. This study comprehensively explores spatio-temporal dynamic changes in LH, accurately identifying areas posing threats to the National Transmission Line Protection Regions (NTLPR).

A single-ended high-impedance fault protection scheme for hybrid HVDC transmission lines based on coordination of control objective

Hybrid HVDC transmission technology advancement has led to significant progress. A reliable and effective DC line protection scheme is crucial for DC transmission systems. The traditional protection schemes suffer from insufficient sensitivity and reliability during high-impedance faults on DC lines. To address the issue, this study introduces a hybrid HVDC line single-ended protection scheme based on the coordination of converter control objectives. In the fault-ride-through(FRT) stage, different control strategies and objectives are applied to the converter based on the fault pole and fault direction identification results. Internal and external faults are discerned by calculating measured voltage with the coordination of the converter control objective. This approach maintains heightened sensitivity to high-impedance DC line faults. Moreover, it operates independently of double-ended communication and demands a low sampling rate. Extensive simulation results robustly substantiate the efficacy of the proposed protection scheme.

Research on new distributed distribution network hidden fault remote automatic recovery technology

Abstract To solve a series of chain reactions in which a fault in the distribution network triggers the shutdown of other components, a new distributed distribution network hidden fault remote automatic recovery technology research is proposed. The traditional chain fault model about line protection describes that when a fault occurs on one or some lines of the system, the line protection devices will operate with a certain probability, and the misoperation or inappropriate action of these line protection devices will lead to the expansion of the fault and ultimately form a wide range of power outages. This study quantitatively gives the interaction relationship between the components in the system. Firstly, the difference between the distribution network chained fault and the main network chained fault mechanism is analyzed; secondly, the topology of the distribution network is modeled; then, the fault transfer model of the distribution network and the chained fault model based on the line dynamics model are constructed based on this model; finally, the detailed distribution network chained fault algorithm process is given based on the proposed model.

Minocycline Inhibits Tick-Borne Encephalitis Virus and Protects Infected Cells via Multiple Pathways.

Tick-borne Encephalitis (TBE) is a zoonotic disease caused by the Tick-borne Encephalitis virus (TBEV), which affects the central nervous system of both humans and animals. Currently, there is no specific therapy for patients with TBE, with symptomatic treatment being the primary approach. In this study, the effects of minocycline (MIN), which is a kind of tetracycline antibiotic, on TBEV propagation and cellular protection in TBEV-infected cell lines were evaluated. Indirect immunofluorescence, virus titers, and RT-qPCR results showed that 48 h post-treatment with MIN, TBEV replication was significantly inhibited in a dose-dependent manner. In addition, the inhibitory effect of MIN on different TBEV multiplicities of infection (MOIs) in Vero cells was studied. Furthermore, the transcriptomic analysis and RT-qPCR results indicate that after incubation with MIN, the levels of TBEV and CALML4 were decreased, whereas the levels of calcium channel receptors, such as RYR2 and SNAP25, were significantly increased. MIN also regulated MAPK-ERK-related factors, including FGF2, PDGFRA, PLCB2, and p-ERK, and inhibited inflammatory responses. These data indicate that administering MIN to TBEV-infected cells can reduce the TBEV level, regulate calcium signaling pathway-associated proteins, and inhibit the MAPK-ERK signaling pathway and inflammatory responses. This research offers innovative strategies for the advancement of anti-TBEV therapy.

Complex plane based adaptive method for protection of series compensated transmission line using phasor measurement unit data

Though differential relays are preferred for the protection of series-compensated transmission line (SCTL), they may mal-operate during current inversion, high resistance internal faults and current infeed/outfeed situations. Therefore, a new protection scheme for SCTL using Phasor Measurement Unit data, that adaptively manages the operating region in the current ratio complex plane according to the percentage compensation level, is presented. Boundaries of the operating region are determined adaptively based on the estimated impedance value of the series compensation. Usefulness of the technique is confirmed by generating cases covering wide range of fault parameters, compensation level, and load angle on an existing 400 kV Indian SCTL using PSCAD software as well as through Hardware in Loop simulation employing the Real Time Digital Simulator. Reported outcomes reveal the ability of the suggested algorithm in sensing all types of internal faults. Its performance remains unaffected during current/voltage inversion, operation of MOV and/or airgap during high fault current conditions, current infeed/outfeed situation, and external fault with current transformer saturation condition. Impact of the presence of noise in the acquired signals is also analyzed. The suggested technique is applicable for SCTLs having different voltage levels and power flow conditions. The proposed method has higher responsiveness during high resistance internal faults up to 500 Ω and better steadiness during external faults compared to numerous prevailing methods.

Error analysis and improved method of time-domain distance protection for wind power transmission lines

Time-domain distance protection has a good transient performance and operation speed when applied to wind power transmission lines. In this paper, the error analysis and improved method of phase-to-phase time-domain distance protection are investigated. Firstly, based on the time-domain mathematical model, the location error caused by fault resistance is analyzed, and then the algorithmic convergence and accuracy of conventional phase-to-phase distance relay are evaluated. To solve the computational non-convergence problem, an improved phase-to-phase distance relay is proposed, in which the instantaneous negative-sequence current is used to improve the location accuracy, especially during the fault transient stage of wind farms. In order to avoid the protection overreach problem, the threshold selection method is designed based on the maximum allowable error of the calculated distance. According to the proposed method, the corresponding protection device is developed. And the hardware-in-the-loop (HIL) test system is built based on the real-time digital simulation (RTDS) platform. Extensive experimental tests are carried out, to verify the feasibility and superiority of the proposed time-domain distance protection.

An efficient setting calculation method for traveling wave protection of VSC-HVDC lines

To reduce the setting calculation workload of traveling wave protection for VSC-HVDC lines, this paper proposes an efficient setting calculation method. Firstly, the fault responses of four typical characteristic quantities (CQ) are analyzed, including the rate-of-change-of-voltage, the change-of-voltage, the rate-of-change-of-current, and the change-of-current. The setting principles of the protection criteria based on these CQs are then revealed, indicating that the extreme values of CQs (EVCQ) are required for setting calculation. A novel method is developed to efficiently obtain EVCQs. By exploring the influence of various operating conditions on CQs, the working conditions corresponding to each EVCQ are pre-selected so that EVCQs can be obtained through only several simulations. Finally, the proposed method is validated by a four-terminal VSC-HVDC grid in PSCAD/EMTDC. The setting results through the proposed method are consistent with those through the conventional enumerative method, but the workload of the former is less than one-fiftieth that of the latter. The results demonstrate that the proposed method can significantly improve the setting calculation efficiency while ensuring accuracy.