Earth Fault Research Articles

Analiza delovanja zaštite struje zemljospoja na izvodu 10 kV

For the normal functioning of the power system, it is necessary to ensure adequate protection of each elements. Part of the electric power system are electric networks, the term of which will primarily mean lines (air and cable). In the paper, the operation of basic line protections was analyzed by mathematical calculations and field measurements. The earth fault protection was caused in the field in order to compare it with the mathematical calculation and draw conclusions about the correct setting and full functionality of the relay protection. Power grid protection is a key aspect for the safety and normal operation of power systems. This analysis includes tests of protection equipment through simulations of earth fault event. The testing is of great importance for new power system maintenance strategies.

Single-Phase Isolated PT Based Novel Structure for Power Distribution System and New Theoretical/Practical Judgement Criteria in Detecting High Impedance Earth Faults

Single-Phase Isolated PT Based Novel Structure for Power Distribution System and New Theoretical/Practical Judgement Criteria in Detecting High Impedance Earth Faults

РАЗРАБОТКА КОМПЛЕКСНОЙ МЕТОДИКИ ОПРЕДЕЛЕНИЯ ТОКОВ ОДНОФАЗНЫХ ЗАМЫКАНИЙ НА ЗЕМЛЮ В РАСПРЕДЕЛИТЕЛЬНОЙ СЕТИ КАРЬЕРА

The paper discusses methods for determining single-phase ground fault currents in the quarry's electrical distribution network. The appearance of these short circuits in an electrical network with an isolated or compensated neutral leads to the appearance of significant overvoltages of undamaged phases at the time of the circuit and a decrease in the stability of the functioning of protection devices against single-phase ground faults. It has been established that oscillography is carried out to study the components of higher harmonics in the groundfault current, the network voltage, the neutral bias voltage, as well as to determine the time required to restore the voltage on the grounded phase to a normal value after disconnecting the ground fault. Methods for determining the current of single-phase earth faults by indirect methods are presented, corresponding measurement schemes are presented in the absence of natural unbalance voltage, without a voltage transformer, as well as at a certain value of natural unbalance voltage...

Principles of protection against single phase earth faults in networks with capacitive current compensation

Principles of protection against single phase earth faults in networks with capacitive current compensation

Medium voltage digital instrument transformer

Instrument transformers with digital output provides significant advantages, including those related to increased reliability of power system operation. With the appearance of digital instrument transformers, the topology of the measurement channel and the functional purpose of its components change. This paper considers some function migration examples from protection devices to the primary converter (digital current and voltage transformer). Combined digital transformers expand the application area of distance protection principles, increase the fault location accuracy, as well as improve sensitivity and speed of single-phase earth fault (SPF) protection in 6-35 kV networks.

Influence of Ultra-High-Voltage hybrid reactive power compensation on interruption performance of circuit breakers under different faults

For extremely large ultra-high-voltage (UHV) power transmission and distribution lines with typical project using hybrid reactive power compensation (HRPC), single-phase earth fault (1LG), three-phase ground fault (3LG), phase-to-phase fault (2LS), and two-phase grounding fault (2LG) often occurs. Circuit breaker is one of the most critical equipment of UHV transmission system. And the interruption performance is crucial to circuit breakers’ breaking capability. In this study, formal expressions of the indicators for the interruption performance of the circuit breaker are deduced in case of different faults based on the equivalent-valued parameter circuit based on the structure a UHV demonstration project. The simulations are used to validate the accuracy of formal expressions. Then, the influence of such factors as the location of the fault and the degree of HRPC on the interruption performance of the 1LG, 2LG, 3LG, and 2LS is analyzed. Finally, the interruption performance of circuit breakers under different faults are compared. A quantitative evaluation of the influence of changes in the relevant indicators on the interruption performance of circuit breakers can provide a technical basis for choosing the appropriate design of the circuit breaker in light of the application as well as equipment development and assessment.© 2017 Elsevier Inc. All rights reserved.

Method of Reducing the Effects of Repeated Ignition during Earth Faults in Compensated Medium Voltage Networks

The article presents the results of research in the field of limiting the effects of overvoltages and improving the conditions for the self-extinguishing of transient faults in medium voltage networks with earth fault current compensation. The aim of the research was to estimate the level of overvoltages generated by an earth fault during re-ignition of the electric arc and to assess the possibility of reducing them by increasing the attenuation of the earth fault circuit. The results of the conducted tests show that to increase the attenuation, which ensures a significant effect of limiting such overvoltages, it is enough to change the way of operation of the devices forcing an additional active component of the earth fault current (AWSCz/ACFA). In Poland, such devices are commonly used to improve the effectiveness of earth fault protection. It was also found that the proposed solution enables accurate tuning of the Petersen coil in networks with natural asymmetry of earth capacitances. Therefore, changes in the operation of AWSCz/ACFA devices may have a beneficial effect on the limiting the effects of repeated ignitions during earth faults and, at the same time, enable the accurate tuning of the Petersen coil and increase its ability to extinguish arc-fed faults. Research and theoretical analysis of the issue were carried out on the basis of data characterizing the parameters of the earth fault circuits of the real 15 kV network.

Implementation and laboratory verification of method utilizing phase and neutral quantities for detection and location of low‐current earth faults in resonant grounded networks

AbstractEarth faults is a challenging fault type to locate in resonant grounded networks due to their naturally low fault current, and the problem increases with an increased fault impedance. This paper describes the detailed implementation and laboratory testing of a method for detection, location and clearing of earth faults with very small fault currents. The method consists of two indicators used in the fault detection stage, where their simultaneous operation ensures selective fault detection and faulty feeder selection. One of these indicators also enables continuous fault indication throughout a sectionalizing process. The laboratory tests demonstrate that both indicators function as intended, and it is the current sensors which ultimately limit the attainable sensitivity. Faults up to 15 kΩ were detected successfully in the laboratory network based on phase current measurements, while the sectionalizing indicator showed much higher sensitivity and functioned as intended in a 50 kΩ fault. Measurements from one field test in a 22 kV network corroborate the laboratory results and demonstrate the expected earth fault indicator response.

The Research on the Improvement of the Zero-Sequence Relay for the Low Resistance Grounded Power Grid

In the low resistance grounded power grid, when a high-impedance grounding fault occurs at a distribution line, the zero-sequence fault current is not big enough to make the zero-sequence over-current relays trip because of the setting limitations, and thus the earth fault would exist for a long time with no alarm signal. As a result, there would be a hidden danger that the grounding fault might cause further faults or cause harm to personal safety. To solve the problem, in the paper, the characteristics of zero-sequence components when the high-impedance grounding fault occurs are analyzed, and the practicability and the deficiency of the directional zero-sequence over-current relay are pointed out. Based on the analysis, an improved zero-sequence relay with the resistance-capacitance ratio restriction is raised. The resistance-capacitance ratio restriction condition is based on the different structures of the resistant part and the capacitive part of zero-sequence currents, and the faulted line can be identified with the resistance-capacitance ratio criterion. The resistance-capacitance ratio criterion is not influenced by the polarity of the voltage transformer (VT) and current transformer (TA) and can avoid the influence caused by the reversed polarity of the exclusive zero-sequence TA. With the improved zero-sequence over-current relay with the resistance-capacitance ratio restriction, the ability to identify high-impedance grounding faults can be improved, and the fault area can be isolated quickly, to guarantee the reliability and safety of the operation in power grids.

Research on Phase-to-phase Fault Location Method of Active Distribution Network

Due to the weak feed characteristic of active distribution networks, the sensitivity of the original fault phase selection method and the accuracy of fault location are decreased. Most of the existing fault section location methods focus on the phase selection and location of the earth fault, and there is a lack of relevant research on the location of the fault section to the phase-to-phase fault. Moreover, most of the methods need to install the signal measuring device in the system as large as possible, which is not economical. The operation condition of active distribution networks is complicated, the fault characteristics are weak, and the location result is easily affected by non-fault disturbances such as DG access capacity and location. In this paper, the phase-to-phase fault of active distribution networks is taken as the research object. Firstly, phase current and zero-sequence current combined criterion is used for fault phase selection, and then combined with the phase-frequency characteristics of mode impedance of distribution line and photovoltaic power line, a fault section location method based on transient characteristic frequency band is proposed, which is not affected by non-fault disturbance such as photovoltaic control strategy and DG access capacity and location. Simulation results show that the method is effective.

Including Shield Wires in the Analysis of Transient Processes Occurring in HVAC Transmission Lines

The article presents an analysis of electromagnetic transient processes in long ultra-high voltage transmission lines, taking into account shield wires. It was shown that EMTP and Matlab/Simulink software are currently widely used in the study of transient processes in power lines. The EMTP software package uses the finite element method when integrating the equation that mathematically models the distributed parameter transmission line. The Matlab/Simulink software uses the d’Alembert method. In both cases, it is not known how the boundary conditions for the partial differential equation that mathematically models the transmission line are determined. The power line is analyzed as a distributed parameter system, described by a second-order partial differential equation. The advantage of the proposed method of calculating the boundary conditions for the abovementioned equation is the use of boundary conditions of the second and third types of Neumann and Poincaré, which allowed us to take into account the mutual influence of shield wires and phase conductors of the line in one power system. On this basis, the methodology for obtaining time domain graphs, spatial distributions, and traveling wave distributions of voltages and currents for phase conductors and line shielding wires is presented. The results of a computer simulation of transient processes when switching on the power line, taking into account controlled phase commutation and under single-phase earth fault conditions, are presented. All calculation results of transient processes presented in the article were obtained exclusively using numerical methods.

Development of a method for selective determination of the outgoing line and the distance to the place of occurrence of a single-phase earth fault

Subject of research: algorithms for selective determination of the outgoing line in the event of a single-phase earth fault; algorithms for determining the distance to the fault location.
 Purpose of research: development of an industrial frequency overlay method for determining the outgoing line with a single-phase earth fault. Development of an algorithm for determining the distance to the place of a single-phase earth fault by the method of standing waves.
 Object of research: electrical networks 6-35 kV.
 Methods of research: theory of electrical circuits, mathematical analysis and modeling; resonant modes; standing wave method.
 Main results of research: An algorithm for the selective determination of the outgoing line with a single-phase earth fault has been developed. An algorithm for determining the distance to the closure site by the standing wave method has been developed.

Development of an arc extinguishing reactor control system

Subject of research: the system of automatic control of the arc-extinguishing reactor.
 Purpose of research: development of an automatic control system of an arc-extinguishing reactor to improve the efficiency of the electrical network.
 Object of research: 6-35 kV electric networks with compensated neutral through an arc-extinguishing reactor.
 Methods of research: the main provisions of the theory of electrical circuits, mathematical analysis and modeling, numerical programming.
 Main results of research: The article proposes the idea of using the wavelet transform to organize software The article proposes a refined mathematical model of a distribution network with an arc-extinguishing reactor, which allows to increase the accuracy of determining network parameters, including the neutral offset voltage. The algorithm of the reactor settings according to the extreme method in the absence of a single-phase earth fault in a distribution network with a high natural asymmetry.

The application of fault diagnosis techniques and monitoring methods in building electrical systems – based on ELM algorithm

The reliability of modern building electrical systems are receiving increasing attention as they become more intelligent and complex. As the majority of building electrical systems use neutral point grounding, earth faults or short circuits can get worse over time and damage both the distribution system and the electrical equipment. To this end, the corresponding three phases and four categories, namely three-phase voltage, three-phase current after fault, three-phase voltage distortion rate, three-phase current distortion rate, a total of 12 dimensional fault feature vectors and 10 fault simulation types, were summarised and extracted in conjunction with the actual operating conditions of the system. Using traditional fault identification ideas and neural network algorithm as reference, a 12-dimensional fault feature vector is used as the model input to construct a building electrical fault diagnosis and detection model based on ELM algorithm. Results showed that the ELM-based model’s classification accuracy for this experimental sample was 97.56 %, its AUC was 0.92, and its RMSE was 0.3521. These figures were higher than the classification accuracy and performance of the BP algorithm and GA-BP algorithm fault diagnosis models, and they also demonstrate better robustness and generalizability. The model also has a 97.27 % correct rate in fault discrimination, while the computation time is only 0.201 s, and its fault identification and diagnosis speed is faster than other algorithmic models. At the same time, this research model has a good fault monitoring accuracy of up to 98.6 % for building electrical systems. The research can provide a more sensitive, accurate and rapid fault monitoring method for the current building electrical system. It also improves the reliability of the building electrical system in a complex environment and achieves better protection of the system. This has a certain significance for the development of the building electrical industry.

Simultaneous series and shunt earth fault detection and classification using the Clarke transform for power transmission systems under different fault scenarios

For high-voltage (symmetric and non-symmetric) transmission networks, detecting simultaneous faults utilizing a single-end-based scheme is complex. In this regard, this paper suggests novel schemes for detecting simultaneous faults. The proposed schemes comprise two different stages: fault detection and identification and fault classification. The first proposed scheme needs communication links among both ends (sending and receiving) to detect and identify the fault. This communication link between both ends is used to send and receive three-phase current magnitudes for sending and receiving ends in the proposed fault detection (PFD) unit at both ends. The second proposed scheme starts with proposed fault classification (PFC) units at both ends. The proposed classification technique applies the Clarke transform on local current signals to classify the open conductor and simultaneous faults. The sign of all current Clarke components is the primary key for distinguishing between all types of simultaneous low-impedance and high-impedance faults. The fault detection time of the proposed schemes reaches 20 ms. The alternative transient program (ATP) package simulates a 500 kV–150-mile transmission line. The simulation studies are carried out to assess the suggested fault detection and identification and fault classification scheme performance under various OCFs and simultaneous earth faults in un-transposed and transposed TLs. The behavior of the proposed schemes is tested and validated by considering different fault scenarios with varying locations of fault, inception angles, fault resistance, and noise. A comparative study of the proposed schemes and other techniques is presented. Furthermore, the proposed schemes are extended to another transmission line, such as the 400 kV–144 km line. The obtained results demonstrated the effectiveness and reliability of the proposed scheme in correctly detecting simultaneous faults, low-impedance faults, and high-impedance faults.

Estimating distance to transient and restriking earth faults in high-impedance grounded, ring-operated distribution networks using current ratios

Earth faults occur frequently in distribution networks, and in resonant grounded networks they are challenging to locate precisely due to their naturally low fault current. Transient and restriking faults are more challenging still due to the short time available for the fault location logic, as well as the absence of steady-state conditions. This paper investigates the performance of three fault location methods utilizing the ratios of various current components in a network operated in a closed-ring configuration. A frequency dependent model of a distribution network is used to simulate transient and restriking faults, and both isolated grounding and resonance grounding are considered. The results show that fault location based on negative-sequence currents is able to locate transient faults, and its accuracy of a few hundred metres is comparable to what has been observed during permanent faults. A zero-sequence method is observed to be less accurate, particularly in resonant grounded networks. A transient method is also proposed, and while it is fast, it is ultimately limited by the presence of loads and branches in the network. It is concluded that the negative sequence method is best suited for transient and restriking faults.

Techno-Economic analysis of distributed generation for power system reliability and loss reduction

ABSTRACT This paper presents a techno-economic analysis of the impact of distributed generation (DG) integration for power loss reduction and reliability of two 33 kV radial outgoing feeders at the Motta distribution substation in Ethiopia. Transient earth faults and permanent short-circuits were identified to be the most common causes of interruptions. The substation's system average interruption frequency index (SAIFI) is 806 and its system average interruption duration index (SAIDI) is 1394.145 for planned outages. This necessitates the pursuit of effective methods to increase the reliability of the distribution system. The results show that the distribution system is more reliable with the SAIFI and customer average interruption frequency index (CAIFI) reduced by 97.8%, SAIDI reduced by 76%, average service availability index (ASAI) increased by 14.38%, and average service unavailability index (ASUI) reduced by 76%, resulting in a total power loss reduction of 0.32 MW. The cost analysis was performed using the Monte Carlo (MC) reliability analysis and the DG net present cost analysis results in a payback period of less than five years indicating that the system is profitable.

Three‐phase isolated power transformer based novel structure for power distribution system and new theoretical/practical judgement criteria in detecting high‐impedance earth faults

AbstractSingle phase‐earth faults are the most frequent faults likely to occur but hard to identify in distribution system, especially in a neutral un‐effectively grounded system. To address this issue, this paper innovatively proposes a typical distribution system structure, in which it only introduces one three‐phase isolated power transformer (PT)‐based subnetwork division mode that can effectively limit the zero‐sequence current flow from other sound lines. Second, following the qualitative discussions about the effect of the proposed structures on power supply reliability and probability of bushfires caused by high impedance earth faults (HIEFs), a novel detecting judgement criterion merely using vector‐based variation via pre‐fault and post‐fault zero‐sequence voltage is mathematically formulated. In general, the proposed structure takes into account the the fault current suppression while manifesting fault feature at the same time, and in contrast with current detecting methods, vectorized form can present a wider exploring space and a higher identifying sensitivity, especially in detecting HIEFs. Numerical simulations and field tests validate the effectiveness and adaptability of the proposed detecting approach towards single phase‐earth fault identification field.

ANALYSE STATISTIQUE DE LIMPACT DES PANNES DU RESEAU ELECTRIQUE SUR LES SOURCES ET LA CHARGE: ETUDE DE CAS DU RESEAU ELECTRIQUE DE LA COMMUNAUTE ELECTRIQUE DU BENIN

Breakdowns in the electricity network contribute to economic losses and upset populations who are increasingly dependent on this source of energy in their daily lives. The Benin Electric Community (CEB) is in charge of the electricity transmission network for Togo and Benin. It is responsible for dispatching the national sources of electrical energy production in the two countries and the import sources to the distribution networks of the two nations. Minimizing breakdowns and blackouts of this network will make it possible to contribute effectively to the economic and technical development of the company on the one hand and the socio-political development of the two countries on the other. This study aims to analyze the impact of breakdowns of the CEB network on the socio-economic level of the two countries on the one hand and on the electrical quantities of the operation of the network (sources or loads) with the aim of proposing a digital failure prediction solution. To achieve this objective, an analysis based on descriptive statistics and statistical linear regression was used. The results showed that more than 55.68% of breakdowns are caused by distribution networks. Earth faults are the most represented among the failures inherent in network control and management systems. There is an impact of blackouts on the social level. The populations of Parakou in Benin are the most affected with cumulative service unavailability of 75 days 19 hours 52 minutes. The economic impacts on the CEB were also recorded. For the correlative study, it appears that there is a weak negative correlation between the number of triggers and the sum of the sources of the CEB. This indicates a possibility of predictive detection of network failures using data from CEB sources. In the rest of this work, a stochastic statistical analysis of the data would be made to determine a mathematical model in order to design the CEB network failure prediction tool.

Post-seismic deformation of the 2008 Wenchuan earthquake reveals a misaligned rheological boundary in the lower crust along the eastern Tibetan Plateau margin

SUMMARY Along the margins of orogenic plateaus, the viscous Earth structure and fault geometries play a primary role in controlling the tectonic evolution and earthquake generation. After the 2008 Mw 7.9 Wenchuan earthquake, the long-standing debate regarding the tectonics producing and maintaining prominent topography across the Longmen Shan reignited. Post-seismic deformation, representing the surface strain history in response to lithospheric stress perturbations, provides important insights into the lithospheric rheology and active structures. Here, we construct a new 3-D post-seismic deformation model for the Wenchuan earthquake, invoking viscoelastic relaxation and afterslip. Our best-fitting model indicates that the steady-state viscosities of the lower crust in the region to the immediately west of the Songpan-Ganzi terrane and beneath the Songpan-Ganzi terrane are estimated to be 4.0 × 1018 and 1.0 × 1018 Pa s, respectively. Our results, combining geophysical and geodetic observations and model analyses, highlight the prevalent parallelism between the rheological and structural boundaries of the lower crust, which diverge northward away from the trend of the Longmen Shan fault at ∼20°. This diverging rheological structure and the partially coupled upper and lower crust have broad implications for the stress build-up, strain partitioning and deformation styles along the eastern Tibetan Plateau margin.