A Survey of Fault Prediction and Location Methods in Electrical Energy Distribution Networks

Nowadays, smart monitoring devices such as digital fault indicator (DFI) have been installed in distribution systems to provide sufficient information for fault location. However, it is still a challenge to extract effective features from massive data for single-line-to-ground (SLG) fault-section location. This work proposes a novel method of fault-section location using a 1-D convolutional neural network (1-D CNN) and waveform concatenation. After SLG fault occurs, DFI measures the transient zero-sequence currents at double-ends of the line section, which could be concatenated to construct characteristic waveform. The features of characteristic waveforms would be extracted adaptively by 1-D CNN to locate the fault section. Furthermore, the problem where the on-site recorded data are hard to collect would be solved because 1-D CNN only needs a small number of samples for training in practical applications. The experimental results verified that the proposed method could work effectively under various fault conditions, even if a few DFIs are out of order.

Location of Single-Line-to-Ground Fault Using 1-D Convolutional Neural Network and Waveform Concatenation in Resonant Grounding Distribution Systems

A new method is proposed to identify the location of transient events, including incipient faults, in power distribution systems, by using synchronized measurements from an emerging class of sensors, called waveform measurement units (WMUs). WMUs capture the voltage and current waveforms in time domain. The proposed method consists of three steps. The first step is to characterize the oscillatory modes of the transient components of all the captured synchronized voltage and current waveforms from all WMUs, by conducting a multi-signal modal analysis. The second step is to construct a circuit model for the underlying distribution feeder at the identified dominant mode(s) of the transient event. The final step is to identify the location of the transient event with the means of a method that involves certain forward and backward analyses of the constructed circuit model. The proposed method requires installing as few as only two WMUs. It can also utilize several synchronized waveform measurements when several WMUs are available. The performance of the proposed method is assessed on the IEEE 33-bus test system; for different cases of transient events, such as sub-cycle incipient faults, multi-cycle incipient faults, permanent faults, as well as benign yet informative events such as capacitor bank switching. Both the accuracy and the robustness of the proposed method are verified. The analysis and results in this paper provide new insights on possible applications of synchronized WMU measurements; while they also address a highly challenging problem in power distribution networks.

Synchronous Waveform Measurements to Locate Transient Events and Incipient Faults in Power Distribution Networks

When a single-phase-to-ground (SPG) fault occurs in a distribution network, the current is weak, and the fault conditions are complex; the existing fault detection technologies do not show reliable performance. Unlike the existing detection methods, we introduced a fundamental component shift and multiple-transient-feature fusion method in this article. To remove the fundamental component (FC) that contained in the transient zero-sequence current (TZSC), Hilbert transform was used to calculate the analytic signal of TZSC. Then, the shift factor was introduced to remove the FC such that all the transient features can be kept. Second, three typical transient features indexes were calculated. Then, the multiple evidence estimation method was used to fuse the transient features indexes. Finally, selected the feeder with the maximum fault degree as the faulty feeder. To verify the accuracy and extensive applicability of the proposed method, developed the sample radial distribution network model with different fault conditions, arc fault model, and the modified IEEE-34-node test system with power electronics generator and wind energy conversion systems, the proposed method shows good performance.

Faulty Feeder Detection Based on Fundamental Component Shift and Multiple-Transient-Feature Fusion in Distribution Networks

Single-phase-to-ground fault section location in flexible resonant grounding distribution networks using soft open points

As a result of small fault current, high level of noise and a large penetration of distributed generators (DG), in the neutral non-effectively grounded medium-voltage (MV) distribution networks, it is quite difficult to locate the faulted line section for single phase to ground faults. In this paper, using a technique based on synchronized measurements in distribution networks, a fault location method based on the analysis of the energy of the transient zero-sequence current in the selected frequency band (SFB) is proposed. The equivalent impedance of the distribution network with lateral branches is studied with an equivalent network, and the phase-frequency characteristics of the equivalent impedance are analyzed. The SFB, within which the transient energy of the faulty line section is larger than that of the healthy line sections is determined. A combined fault-section location criterion is proposed and the implementation scheme is illustrated with the distribution level phasor measurement units. Numerical simulations of the IEEE 34 node system and the field experiments of a 10kV distribution network validate the feasibility and effectiveness of the proposed method.

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Location of Single Phase to Ground Faults in Distribution Networks Based on Synchronous Transients Energy Analysis

High fault transition resistance and the integration of distributed generations (DGs) make it difficult for single phase-to-earth fault location in distribution systems. This paper presents a method for single phase-to-earth fault section location in low resistance grounding system based on the measured synchronized zero sequence admittance. The measured zero sequence admittance is calculated by local PMU and then be sent to the operation center. The upstream or downstream of the fault point is judged based on the measured admittance angle. This fault section method is not affected by fault transition resistance, and can be suitable for different grid connected transform grounding modes of DG. The feasibility and accuracy of this proposed method is proved by the PSCAD simulation results.

Zero Sequence Admittance based Fault Location in Low Resistance Grounding Distribution System

The application of μMPMU in the fault diagnosis of distribution network is increasingly widespread. In addition to the waveform data of the μMPMUs near the fault point, some existing fault diagnosis algorithms require the waveform of μMPMU at other locations. However, the μMPMU measurement signal far from the fault location may not reach the trigger recording condition. Aiming at the difficulty of cooperative fault recording of μMPMU, this paper proposes a new collaborative trigger recording scheme based on blockchain. In this scheme, every μMPMU acts as a node and a blockchain network is constructed. The smart contract is used to stipulate the rule of coordinated trigger recording. The μMPMUs that spontaneously start the recording inform others to perform coordinated fault recording, and the waveform data are stored in a blockchain structure for the master station summoning. In this paper, the pros and cons of the blockchain-based scheme and the existing master station based coordinated fault recording scheme are analyzed, which provides a new research approach for the coordinated start-up of μMPMU fault recording in the distribution network.

Coordinated Fault Recording Scheme of μMPMU in Distribution Network Based on Blockchain

Distribution networks in China and several other countries are predominantly neutral inefficiently grounding systems (NIGSs), and more than 80% of the faults in distribution networks are single-phase-to-ground (SPG) faults. Because of the weak fault current and imperfect monitoring equipment configurations, methods used to determine the faulty line sections with SPG faults in NIGSs are ineffective. The development and application of distribution-level phasor measurement units (PMUs) provide further comprehensive fault information for fault diagnosis in a distribution network. When an SPG fault occurs, the transient energy of the faulted line section tends to be higher than the sum of the transient energies of other line sections. In this regard, transient energy-based fault location algorithms appear to be a promising resolution. In this study, a field test plan was designed and implemented for a 10 kV distribution network. The test results demonstrate the effectiveness of the transient energy-based SPG location method in practical distribution networks.

Chen Fang

Papers

Location of Single Phase to Ground Faults in Distribution Networks Based on Synchronous Transients Energy Analysis

Zero Sequence Admittance based Fault Location in Low Resistance Grounding Distribution System

Coordinated Fault Recording Scheme of μMPMU in Distribution Network Based on Blockchain

Field experiment using transient energy method to locate a single-phase to ground fault

An online self-correction method to improve accuracy of split-core current transformer in low-voltage distribution networks