Two-terminal Fault Location Method Research Articles

A two-terminal fault location method for gas switch prefire in linear transformer driver.

Large-scale linear transformer drivers (LTDs) are composed of numerous high-power gas switches, and switch prefire is a frequent operational fault. To detect and locate the faulty switch accurately and efficiently, a two-terminal location method is proposed. A B-dot sensor is integrated on the gas switch's shell to collect the discharging signal. All the B-dot sensors are connected in parallel through cables of equal length. The fault position can be determined by the time delay of the signals at the two terminals. A diode is inserted between the B-dot sensor's coil and the cable core to ensure low-loss transmission of the signal. Two methods are applied in fault location, including time-of-arrival (TOA) and time reversal (TR). For the TOA method, an energy criterion and a phase criterion are applied and compared. The accuracy of the energy criterion is greatly influenced by the signal-to-noise ratio, while the phase criterion requires a reasonable estimate of the actual delay to account for the impact of phase periodicity. The TR method based on a precise simulation model is established, which demonstrates high precision in location. The TR method has been tested and validated on a single stage LTD module. Moreover, the location method for double switches prefire is discussed theoretically. The method proposed in this paper will be helpful to improve the efficiency of the commissioning, operation, and maintenance of the large-scale LTD devices.

An accurate unsynchronized fault location method on practically transposed transmission lines with closed-form solutions

This paper proposes an unsynchronized two-terminal fault location method on three phase practically transposed transmission lines.Compared to the existing fault location methods, the proposed method considers the asymmetry of the practically transposed transmission lines during the fault in practice. First, the proposed method constructs the practically transposed transmission lines by connecting three untransposed transmission line sections. For each section, the fully distributed parameters line model is adopted to ensure the modeling accuracy. According to the physical laws that the line should obey, the unsynchronized angle is estimated with analytical formulation before the fault. Next, the closed-form solutions of fault location are derived for different fault events, to avoid the risks of unconvergence using the iterative algorithms. In the numerical experiments, the proposed method shows higher accuracy of fault location than the existing fault location methods, regardless of fault types, locations and impedances. The proposed method also demonstrates robustness against various unsynchronized angles, loading conditions, measurement noises and line lengths.

Unsynchronized fault location on untransposed transmission lines with fully distributed parameter model considering line parameter uncertainties

This paper proposes an unsynchronized two-terminal fault location method on three phase untransposed transmission lines considering line parameter uncertainties. The method utilizes three phase voltage and current phasor measurements before and during the fault, without requirement of synchronization between two terminals. The proposed method first formulates the fault location problem considering line parameter uncertainties in a standard syntax, where the distributed parameters as well as the asymmetry of untransposed transmission lines are carefully considered to ensure accurate representation of physical laws before and during the fault. The location of the fault and unknown parameters of the untransposed transmission line are introduced as states of the system. Afterwards, the states of the system, including the location of the fault, are systematically solved using the state estimation algorithm. Extensive numerical experiments validate that the proposed method has higher accuracy compared to the existing fault location methods considering line parameter uncertainties, regardless of fault types, locations and impedances.

Two-Terminal Fault Location Method of Distribution Network Based on Adaptive Convolution Neural Network

When a single-phase ground fault occurs in a distribution network, it is generally allowed to operate with faults for one to two hours, which may lead to further development of the fault and even threaten the safe operation of the power system. Therefore, when a small current system has a ground fault, it must be quickly diagnosed to shorten the time of operation with fault. In this paper, an adaptive convolutional neural network (ACNN)-based fault line selection method is proposed for a distribution network. This method improves the feature extraction ability of the network by improving the pooling model. Compared with deep belief network (DBN), it can improve the accuracy of fault classification by 7.86% and reduce the training time by 42.7%. On this basis, the secondary fault location is identified using the principle of two-terminal fault location. In this research, fault data obtained by Simulink simulation is used as training set, and ACNN model is built based on TensorFlow framework. The analysis of results proves that the model has a high fault recognition rate and fast convergence speed. It can be used as an auxiliary hand for fault diagnosis in distribution networks.

A Fault Location Method for DC Lines Connected With DAB Terminal in Power Electronic Transformer

Power electronic transformer (PET) composed of modular dual active bridge (DAB) blocks has a promising future in ac-dc hybrid distribution network because of its energy routing ability. The key element that restrains the development of PET is the vulnerability of power electronic devices during faults, especially dc faults. DC faults (mostly line faults) have very short transient process and no obvious fundamental frequency, which means fault location is difficult to be realized for dc lines in distribution network. Considering that fault location plays an important role in realizing fast fault clearance and recovery, this paper analyzed fault characteristics of dc line faults with respect to the basic structure of modular DAB block and proposed a two-terminal fault location method based on transient voltages measured in dc line boundaries. To evaluate the validity of proposed method, numerical simulations with different fault conditions were implemented in PSCAD/EMTDC. The simulation results indicate that the proposed fault location method located the faulted point quickly and correctly.

Location of Faulty Section and Faults in Hybrid Multi-Terminal Lines Based on Traveling Wave Methods

Traveling-wave-based fault location methods are widely used for modern power systems owing to their high accuracy on two-terminal lines. However, they perform poorly on hybrid multi-terminal lines. Many traveling-wave-based methods have been developed recently to solve this problem, but they have high computational burdens and complex fault location procedures. To tackle this challenge, a new fault location method is presented in this paper. First, to ensure that the implementation of the proposed method is not affected by different line parameters, a normalization algorithm is used for hybrid multi-terminal lines, which consist of overhead lines and cables. To reduce the complexity, a novel fault section identification method that depends only on the first three arrival times is applied to separate a three-terminal fault section from the multi-terminal lines. Consequently, the fault can be located using a corresponding two-terminal fault location method in this fault section. To verify its effectiveness, fault case studies and performance evaluations are performed in the PSCAD and MATLAB/Simulink environment. The simulation results reveal that the proposed method can correctly identify the fault section and accurately locate the faults, which is simple and suitable for hybrid multi-terminal lines.

A New PMU-Based Fault Location Algorithm for Three-Terminal

Existing two-terminal fault location method can not be directly applied to the three-terminal transmission lines, this paper presents a new PMU-based fault location algorithm for three-terminal transmission lines. The development of the algorithm takes advantage of PMU measurement data synchronization, uses distributed parameter line model, first of all judging the fault zone after a failure, uses Thevenin's Theorem to merge the non-slip fault, so the three-terminal system is simplified the two-terminal system, Then we can use the two-terminal fault location principle of fault location. Through MATLAB simulation shows the correctness of the algorithm.

A Fault Location Technique for Two-Terminal Multisection Compound Transmission Lines Using Synchronized Phasor Measurements

This paper presents a fault location technique for two-terminal multisection compound transmission lines, which combine overhead lines with underground power cables, using synchronized phasor measurements acquired by global positioning system (GPS) based phasor measurement units (PMUs) or digital relays with embedded PMU or by fault-on relay data synchronization algorithms. The technique is extended from a two-terminal fault location method with synchronized phasor measurements as inputs. A novel fault section selector is proposed to select the fault line section in advance. The proposed technique has the ability to locate a fault no matter where the fault is on overhead line or underground power cable. The adopted technique has a solid theoretical foundation and is direct and simple in terms of computational complexity. Both extensive simulation results and field test results are presented to demonstrate the effectiveness of the proposed scheme. The proposed technique has already been implemented in the Taiwan power system since the year 2008. Up to the present, the proposed technique yields excellent performance in practice.