Ground Fault Location Research Articles

Grounding Protection of flexible grounding systems Based on Polarization of Faulty Phase Voltage

At present, the grounding protection of flexible grounding systems mostly follows the common protection methods of the low-resistance grounding system, and there are problems of insufficient adaptability and utilization of fault information. In the paper, We analyze the fault characteristics of flexible grounding systems after grounding faults, find that when a high-impedance grounding fault happened, after the low-resistance is connected to the Petersen Coil, the phase characteristics between the zero-sequence of voltage and current of flexible grounding system is similar to that of low-resistance grounding system when grounding faults happened, at this time the faulty phase voltage amplitude is far more than the zero sequence voltage and the phases of the two are opposite. Based on this, a flexible grounding system grounding fault location method using the phase relation between zero sequence current of lines and faulty phase voltage is proposed. By taking advantage of the mature phase selection technology of the resonant grounding system, selecting the faulty phase in the compensation stage of the Petersen Coil. When the low-resistance is in parallel, the faulty phase voltage is used to compare the phase with the zero sequence current of lines, which solves the problem that the zero sequence voltage is weak and difficult to measure when the high impedance grounding fault occurs. Simulation experiments and field tests show that this method can improve the reliability of high-impedance grounding protection, and the method can be used as a backup protection for zero sequence overcurrent protection to meet field requirements.

마이크로그리드 지락고장 발생시 보호 계전요소 효과 분석

Microgrid is being reviewed in many power systems as a supplement that can compensate for the shortcomings of central power supply, such as a remote and an out-of-the-way power supply. Simulated verification is needed to establish an electrical protection cooperation system, such as protection of human/livestock and power facilities and prevention of ripple to nearby areas. In this paper, verification of the optimal protection cooperation system valid under all assumed on/off grid conditions was conducted by reviewing the possibility of the location of ground fault, installation location of protection device, and relay element.

New ground fault location approach for partially coupled transmission lines

The technical requirements and environmental limitations increase utilizing both the parallel and partially coupled transmission lines. However, it is very demanding to find the fault point of the single phase to ground faults owing to the mutual coupling which does exist between the two circuits in these transmission lines. Furthermore, in practice, most of the transmission lines are not transposed, which makes the fault location problem more challenging. In this paper, by presenting the simulation results of the fault location for a parallel line, it is revealed that for the untransposed lines, the two-ended fault location approach based on the zero sequence network has a better performance as compared to the negative sequence network based methods addressed in the technical literature. In this regard, this study deals with proposing a new ground fault location methodology for partially coupled transmission lines. Therefore, the fault location equations based on the zero sequence network are derived and presented for both operation modes, including 1) both lines are in service, and 2) one line is in service, and another one is disconnected and grounded at both sides. The proposed method can also be applicable for the parallel lines if the parameter associated with the mutual coupling is altered. This fault location approach employs the measured voltage and current phasors at both sides of the line. Furthermore, in order to assess the accuracy of the presented method, extensive simulation studies of untransposed partially coupled transmission lines are carried out in the PSCAD/EMTDC software. To this aim, the proposed method performance against different fault resistances, source impedances, measurement errors, arcing faults, compact towers, line length, and two-phase to ground faults is investigated. The simulation results demonstrate that the proposed method provides very good accuracy for fault location.

Faulty Branch Identification Method for DC Generation and Storage Systems With Multiple Series-Parallel Cells

Solar photovoltaic energy and electrochemical energy storage are key elements for the development of more sustainable and efficient electrical energy systems such as electric vehicles or microgrids. These systems require of multiple series-parallel cell connections that complicate enormously the location of possible ground faults. In this context, this article proposes a new method based on a low frequency periodical commutation of a grounding resistor placed in the midpoint of the DC source, that allows to discern the faulty branch by measuring the current at strategical positions of each string. The highest relative current variation when the system is grounded or ungrounded determines the faulty branch. The proposed method has been analyzed for three types of grounding connections by means of simulations and experimental tests using batteries, achieving successful results.

Phase Selection and Location Method of Generator Stator Winding Ground Fault Based on BP Neural Network

The phase selection and fault location methods of generator stator winding single-phase grounding fault are greatly affected by the transition resistance. A new phase selection and generator stator ground fault location approach based on the BP neural network is proposed in this research from a data-driven angle. This method uses a neural network to calculate the probability of three-phase fault occurrence to identify the fault phase and directly calculate the fault location that takes the amplitude and phase angle characteristics of zero-sequence voltage as input. The simulation results show that the stator ground fault phase selection and location algorithm based on the neural network can achieve correct phase selection and small positioning error, which has verified the effectiveness of the method.

Grounding electrode line fault location method based on simulation after test and deduction

• Fault characteristics of the grounding electrode line are weak. • Fault location by injecting signals into the line. • The initial pulse signal is eliminated after linear mode transformation. • Using simulation after test and deduction to obtain fault distance. • No need to calibrate the arrival time of the wave head. When a high-voltage direct current (HVDC) transmission system with the grounding electrode line (GEL) is in the balanced operation mode, the unbalanced current in the GEL and the neutral potential of the system are extremely small. In the GEL, after a fault incident, the additional fault component will be small, and fault characteristics will be weak. As the traditional passive fault location methods are challenging to apply, a GEL fault location method based on simulation after test and deduction (SATD) is proposed in this paper. Firstly, the pulse signal is injected into the GEL. Then, the mutation point of the pulse response signal is projected along the line to form a virtual fault point matrix. Based on the mentioned matrix, the fault location function is constructed, and the fault distance is obtained by the catastrophe point of the function. In this method, the bottleneck of precisely identifying the traveling wave (TW) arrival time in the time domain is broken, and the automated single-ended TW location of the GEL can easily be implemented. Many real time digital simulator (RTDS) tests validate the high accuracy and strong robustness of the method.

Grounding fault location method of overhead line based on dual-axis magnetic field trajectory

To address the challenges in fault location in distribution networks, the distribution of magnetic field under overhead line and its relationship with three-phase currents are explored in this paper. At the same time, considering the influence of sensor installation position, line sag and galloping on magnetic field, a grounding fault location method of an overhead line based on dual-axis magnetic field trajectory is proposed. The analytical expressions of the magnetic field on the x-axis and y-axis under the overhead line are obtained by least squares fitting. The Lissajous figure synthesized by dual-axis is then compared with the general equation of an ellipse, and the characteristic quantity expression characterizing the magnetic field trajectory structure is obtained. Finally, a fault location criterion is constructed using the difference of the characteristic quantities of the ellipses synthesized by x-axis and y-axis magnetic fields upstream and downstream of the fault point, i.e., the difference of the length of the major axis and the minor axis, and the sign for the ratio of the cosine value of the inclination angle. Compared with other location methods based on electrical quantity, the principle of this method is simpler and it can locate faults more quickly and accurately. A large number of simulation results show that the proposed method is suitable for different types of fault conditions.

High impedance grounding fault location method for power cables based on reflection coefficient spectrum

When a high impedance grounding fault occurs in the power cables, the current at the fault point is extremely low and the fault characteristics are too weak to be detected by the reflectometry. Interfered by the multiple reflections, the fault is hard to be located in the field. In order to solve the problem of conventional frequency domain reflectometry, a high impedance grounding fault location method for 10 kV distribution cables is proposed in this paper, which is based on the reflection coefficient spectrum. Firstly, the equivalent model of cable distributed parameters is established, and the reflection coefficient spectrum at the cable head is derived. Then, according to the theorem of integral transformation and generalized orthogonality, the diagnostic function is built in the spatial domain. Besides, the Kaiser window is introduced to improve the location sensitivity. Finally, the feasibility of the method is verified by simulated and experimental results. It is shown that this method can effectively eliminate the impact of multiple reflections, and precisely locate the single- and multi-point grounding faults. The fault location error is within 0.2%.

Evaluation of fault location algorithm in distribution power system lines using differential equation method with fault indicator approach

A malfunction in any electrical system network will eventually happen. Damage and minor problems are less likely to develop if a problem can be resolved quickly. As a general rule, fault location is a procedure of aiming the location fault at the maximum feasible accuracy. In order to locate faults in distribution lines for multi-ended power systems, this work provides a single line to ground (SLG) fault location algorithm employing a differential equation (DE) with a fault indication approach. The overall distribution lines model combines the generalized compact models of all homogenous line sections. Furthermore, this study approached fault indicator equipment as an indicator during every section fault. Hence, the ATP Draw has simulated the medium voltage distribution lines consisting of overhead lines (OHL) and multiple underground cable lines (UCL). The evaluation of the method considered the parameter of fault resistance, fault distance, and fault inception angle. The results show that the fault location algorithm using DE fault location algorithm with fault indicator information produced the most accurate result.

A method of grounding fault location in power system based on adaptive filtering

A method of grounding fault location in power system based on adaptive filtering

A method of grounding fault location in power system based on adaptive filtering

A method of grounding fault location in power system based on adaptive filtering

Determining Remote Ground Fault Location in a 6- to 10-kV Cable Line Using Its Models

Determining Remote Ground Fault Location in a 6- to 10-kV Cable Line Using Its Models

Fault Phase Selection Method Based on Single-Phase Flexible Arc Suppression Device for Asymmetric Distribution Networks

The phase-to-ground admittance in distribution networks is asymmetric. This asymmetry is aggravated by the arc suppression coil, resulting in zero-sequence overvoltage. The magnitude of zero-sequence overvoltage can exceed the line-to-ground voltage, endangering the operation of electrical equipment. Moreover, after the occurrence of a single-line-to-ground fault, the change law of the three-phase voltage is affected by the zero-sequence overvoltage, leading to misjudgment of the fault phase. Accordingly, this paper proposes a fault phase selection method based on active current injection that can adapt to asymmetric distribution networks. The fault phase is selected by injecting current and calculating the equivalent power supply voltage of the faulty line without increasing the ground-fault current. The high sensitivity of the proposed fault phase selection method was verified for high impedance faults through software simulations and prototype experiments. Moreover, the zero-sequence overvoltage can be suppressed by a single-phase flexible arc suppression device during the normal operation of distribution networks. The ground-fault current can be quickly suppressed at different ground-fault locations and resistance values, ensuring the extinguishment of the ground-fault arc.

A Precise Stator Ground Fault Location Method for Large Generators Based on Potential Analysis of Slot Conductors

The stator ground fault location of large generators can guide rapid maintenance. In this paper, a location criterion without fault transition resistance is constructed by using the fundamental potential and the third harmonic potential of the faulty winding simultaneously. The above potentials of the faulty winding are corresponding to the fault position. To precisely locate the grounding fault, it is necessary to clarify the analytical relationship between the faulty winding potential and the fault position. However, the existing methods often take the coil potential as the unit to analyze the winding potential, which has theoretical errors for the generators with short-pitch winding. Aiming at this problem, a more precise analysis method for winding potential is established by taking the slot conductor potential as the unit. To solve the location criterion, the optimization model for each slot conductor of the faulty phase is constructed. The slot conductor with the smallest optimal objective function value is judged as the faulty slot conductor, and the corresponding decision variable is judged as the fault position. Simulation and experiments verify the effectiveness of the proposed method, which can still meet the needs of engineering applications under multiple adverse conditions.

Single-phase Grounding Fault Location Technology Based on Edge Calculation of Fault Components of the Positive-sequence Current

In the one-phase-to-ground fault of the distribution network, due to the difference in the distribution of the positive sequence current constituents of each line, the information contained in the fault path and the non-fault path also has a certain difference. On this basis, the edge of the fault constituent in the positive sequence current is used to locate the one-phase grounding. The method first uses phase current subtraction to multiply the period difference before and after the fault, and then uses the inverse transformation before and after the fault to determine the positive and null sequence constituents of the fault. Symmetrical composition. By analysing the amplitudes of the positive sequence and null sequence currents of the three-phase fault constituents, and according to the corresponding relationship between the amplitudes and the adaptive threshold, the location of the fault section is realized. A specific fault point location criterion and steps are given in this paper, and it is verified by ATP simulation software.

Ground fault location research based on multidimensional scaling and density clustering algorithm

When a single line-to-ground fault occurs in a current distribution network containing distributed power sources, fault location is primarily performed by current-based directional protection. This implies using the switching information at the nodes; however, this does not sufficiently maximize the fault information. To address these issues, a single-phase grounding fault location methodology is planned for distribution networks supported by a combination of three-dimensional scaling (MDS) and density-based spatial clustering of applications with noise (DBSCAN). First, the network description matrix is made to support the network topology. Second, the zero-sequence and negative-sequence currents collected at the terminals square measure pre-processed to obtain two-dimensional fault data feature vectors. Third, the fault feature vectors square measure is subjected to DBSCAN bunch analysis to obtain the fault zones of the distribution network, thus compensating for the disadvantage that DBSCAN cannot efficiently replicate high-dimensional knowledge. The simulation results reveal that the planned methodology is not tormented by fault location, fault resistance, fault angle, or line sort; therefore, the fault location results in a correct square measure and might effectively utilize the fault data.

A Ground Fault Location Method for DC Systems Through Multiple Grounding Connections

Direct current (dc) systems have an increasingly important role in electrical systems, especially photovoltaic (PV) solar power plants and battery storage systems as they are essential for the development of more sustainable, efficient, and reliable electrical systems. PV panels and batteries are generally composed of multiple series-parallel cells. This fact makes their fault diagnosis challenging, especially against ground faults as these systems are generally ungrounded. In this article, a ground fault location method for dc sources with multiple series-parallel cells is proposed. It estimates the faulty branch, the faulty cell location inside this branch and its fault resistance. The method is based on the output current measurement of each branch and on the voltage measurement on a grounding resistor, which is switched between three positions: the positive, the midpoint and the negative terminals of the protected dc system. To validate it, several computer simulations and experimental tests on a battery pack have been carried out. The results obtained proves an excellent performance for faulty cell location and fault resistance estimation, although further investigations are required to better discern the faulty branch.

Single phase to ground fault location method of overhead line based on magnetic field detection and multi-criteria fusion

The distribution network has many branches and complex structure, and the existing protection is difficult to achieve accurate fault section location. Moreover, the monitoring device based on electrical quantity has some problems, such as high cost, power failure in installation and maintenance, and the information collected can not meet the requirements of distribution network for operation monitoring. Therefore, fault location is still a difficult problem in the existing distribution network. The magnetic field (MF) under the overhead line can reflect the change of line current, locate the fault position between two pole towers, and the magnetoresistive sensor has the advantages of low cost and uninterrupted installation and maintenance. Therefore, in recent years, the non-contact fault feeder detection and location method based on MF has begun to develop rapidly. Based on the similarity analysis of MF waveform under overhead line from different aspects by using five criteria: relative entropy, Frobenius norm, maximum mean discrepancy, cosine similarity and correlation coefficient, it proposed a multi criteria fusion fault location method based on D-S evidence theory, which makes full use of the advantages of each criterion and overcomes the limitations of single criterion. Simulation results show that the method is not affected by conductor sag, galloping and data window length, and it fit for the noise interference and high impedance fault (HIF). Compared with the other MF method, the method has stronger adaptability.

Monopolar Grounding Fault Location Method of DC Distribution Network Based on Improved ReliefF and Weighted Random Forest

Compared with the pole-to-pole short circuit, the fault characteristics are not obvious when a monopolar grounding fault occurs in a DC distribution network, and it is difficult to locate the fault accurately. To solve this problem, this paper proposes a fault location method based on improved ReliefF and Weighted random forest (WRF). The 24 time and frequency-domain fault features of the postfault aerial mode current are calculated, and the most useful features are selected to form the optimal feature subset for input to the fault location estimator. In this paper, the ReliefF algorithm is utilized for automatic feature selection and obtaining the weights of features. In addition, the WRF algorithm is used to build the fault location estimator. Considering the fault location, fault resistance, noise and time window length, the Matlab/Simulink simulation platform is used to simulate the fault situation and compare it with other algorithms. The simulation results show that the average positioning error of the fault location method is less than 0.1%, which is not affected by the fault resistance and has strong robustness.

Grounding fault location of large turbo generator based on stator winding distribution

Stator grounding is the most common fault of a large generator. If the accurate coil of the fault can be located quickly and effectively, the maintenance progress of the generator can be greatly sped up, and the fault generator can be put back into use as soon as possible. For this purpose, a stator grounding fault location method for a large steam generator is proposed, which takes the distribution of winding potential into account. Firstly, the fault characteristics and the influence of winding potential distribution are analyzed when a single-phase ground fault occurs in a large generator, and the amplitude equation and phase equation of zero sequence voltage are constructed. On this basis, the potential distribution of stator winding can be analytically expressed, so the fault location can be directly calculated by the numerical solution method. Simulation analysis verifies the effectiveness of the proposed method.