Fault Feeder Research Articles

Fault Line Selection Method for Distribution Network Based on Angle Similarity

Aiming at the problem that the current distribution network protection technology has a low accuracy of line selection, the method of fault line selection based on angle similarity is proposed. A plurality of fault feature quantities of each feeder in different operating states are collected to form a historical database. The clustering centers of fault classes and non-fault classes are obtained by fuzzy clustering analysis. Similarly, the real-time data of each feeder is collected to form a sample of the feature to be tested. The degree of similarity between the feature samples to be tested and the historical feature samples is analyzed by angle similarity. The sample to be tested is classified into a fault class or a non-fault class, and finally the fault feeder is accurately selected.

Centralized radial feeder protection in electric power distribution using artificial neural networks

Abstract The paper deals with a new way of determining a fault location in an electric power distribution radial feeder using an artificial neural network (ANN) and presents a new centralized protection method based on ANN. The aim of the devised algorithm is to detect the presence of a fault in a radial feeder and to disconnect faulted laterals from the distribution network. The protection schemes that are currently in use cannot leave the whole feeder energized by disconnecting faulted laterals only without even short de-energization of the healthy part of the feeder. A simulation model is also made for training the ANN and for testing the results. Current values for faulty and healthy states are generated by the simulation model and are used as training and testing data for the algorithm. The purpose of the algorithm is to make a decision which feeder circuit breakers should trip. The simulation model and the ANN are modeled by using MATLAB tools. The results show that the tripping of circuit breakers initiated by the algorithm is correct for all states.

Research on Fast Determination of Feeder Fault Based on Intelligent Alarm

According to the present situation that it is difficult for power dispatcher to identify and handle different types of feeder faults in time. This paper analyses the relationship between different types of feeder faults and 10kV bus grounding signal, 10kV bus voltage changes, bus grounding signal frequency, feeder switch trip signal, load change of fault feeder. On this basis, the mathematical calculation model based on the calculation of alarm signal and Telemetry data calculation is established. Then sends out intelligent alarm based on calculation results. It can quickly distinguish all kinds of faults, the accuracy of judgment is over 98%. It greatly improves the accuracy and efficiency of fault judgment and handling, also reduces user outage and risk of personal electric shock.

Faulty Feeder Identification and Fault Area Localization in Resonant Grounding System Based on Wavelet Packet and Bayesian Classifier

Accurate fault area localization is a challenging problem in resonant grounding systems (RGSs). Accordingly, this paper proposes a novel two-stage localization method for single-phase earth faults in RGSs. Firstly, a faulty feeder identification algorithm based on a Bayesian classifier is proposed. Three characteristic parameters of the RGS (the energy ratio, impedance factor, and energy spectrum entropy) are calculated based on the zero-sequence current (ZSC) of each feeder using wavelet packet transformations. Then, the values of three parameters are sent to a pre-trained Bayesian classifier to recognize the exact fault mode. With this result, the faulty feeder can be finally identified. To find the exact fault area on the faulty feeder, a localization method based on the similarity comparison of dominant frequency-band waveforms is proposed in an RGS equipped with feeder terminal units (FTUs). The FTUs can provide the information on the ZSC at their locations. Through wavelet-packet transformation, ZSC dominant frequency-band waveforms can be obtained at all FTU points. Similarities of the waveforms of characteristics at all FTU points are calculated and compared. The neighboring FTU points with the maximum diversity are the faulty sections finally determined. The proposed method exhibits higher accuracy in both faulty feeder identification and fault area localization compared to the previous methods. Finally, the effectiveness of the proposed method is validated by comparing simulation and experimental results.

Protection Coordination for Reliable Marine DC Power Distribution Networks

This paper presents demonstration of a protection scheme integrated into marine DC power distribution networks to investigate the coordination between each protection action. The integrated protection scheme is based on three different time-frame protection actions: fast action - bus separation by a solid-state bus-tie switch, medium action - feeder protection by high-speed fuses, and slow action - power supply protection by generator deexcitation. As the backup protection of the power supply protection, AC fuses are installed between generators and rectifiers. To coordinate each protection action, the influences of the inductance in the bus-tie switch and the DC-link capacitance are investigated by DC short-circuit tests with the different inductance and capacitance values. The protection scheme, coordinated by the above investigation, is verified by system-level short-circuit tests for bus and feeder faults. To validate the protection scheme for various fault conditions, low- and high-impedance fault currents are analytically calculated for the bus faults and simulated for the feeder faults. Time-current curve analyses show that the coordinated protection scheme can effectively protect marine two-bus DC power distribution networks with correct operations of the protection measures and enough time margins between the different actions.

Voltage and Current Measuring Technologies for High Voltage Direct Current Supergrids: A Technology Review Identifying the Options for Protection, Fault Location and Automation Applications

After the occurrence of a DC-side feeder faults on HVDC transmission systems, protection and fault detection systems are anticipated to minimize their onerous effects, by initiating fault-clearing actions such as selective tripping of circuit breakers. Following the successful fault clearance, a subsequent action of significant importance, is the meticulous estimation of its location as a means to accelerate the line restoration, reduce down-time, limit recovery and repair costs, and hence elevate the overall availability and reliability of the transmission system. In order to capture DC-side fault transients for protection and fault location applications, measuring equipment is required to be placed on HVDC installations. This paper focuses primarily on reviewing the available technologies from the perspective of enabling protection, fault location and automation applications in HVDC systems. The review constitutes a mapping of protection and fault location functions, against the available voltage and current measuring technologies, ultimately unlocking insights for selecting measuring equipment based on the desirable characteristics of protection and fault location systems. The review also revealed that the frequency characteristics of each sensing scheme, primarily refers to the bandwidth of the primary sensor, whereas the overall bandwidth of the complete measuring scheme may be further restricted by the secondary converter and corresponding data acquisition system and signal processing electronics. It was also identified that the use of RC voltage dividers has prevailed for voltage measurements for HVDC applications, due to their superior advantages. The choice of a suitable device for current measurement, depends mainly on the fault detection method used and the frequency range it operates. In particular, the review revealed that fault detection and protection methods are mainly concentrated in a frequency spectrum ranging from a few kHz to 100 kHz, while fault location methods require measurements with a frequency range from 100 kHz up to 2 MHz.

Enhancement on the Fault Ride through Capability of Power Distribution Systems Linked by Distributed Generation due to the Impedance of Superconducting Fault Current Limiters

Recently, studies on connecting distributed generation (DG) to power distribution systems through DC links have been actively conducted. When a fault in feeder of this power distribution system occurs, a voltage dip can happen in the grid. In order to prevent voltage dips, there are several solutions such as the application of a superconducting fault current limiter (SFCL). If a SFCL with a larger impedance is applied, the voltage dip of the grid is effectively prevented. However, this action can bring about the malfunction or the delayed operation of the over-current relay (OCR) due to the decreased fault current, which causes another problem of protection coordination between the protective relays. On the other hand, if the impedance of the SFCL is too low, excessive reactive power is supplied by the fault ride-through (FRT) regulation and the active power is reduced. This causes an active power imbalance on the DC link and increases the DC link’s voltage. As previous solutions to prevent the rise of DC links’ voltage, the deloading method and the application of a chopper resistor have been suggested. In this paper, a technique called active power tracking control (APTC), was proposed to suppress the rise of DC links’ voltage. Case studies considering the impedance of SFCL in the constructed power distribution system were carried out, and the rise of DC links’ voltage could be effectively suppressed without any significant delay in the operation of the OCR. This study is expected to solve both the voltage dip of the grid and the rise of DC links’ voltage when distributed generation is connected to a grid.

Adaptive Frequency Estimation Method for ROCOF Islanding Detection Relay

Rate-of-change-of-frequency (ROCOF) is one of the most popular local islanding detection methods due to its simplicity and low cost. However, the method suffers from significant non-detection zone (NDZ) and experiences security issues due to non-islanding events. In this article, an enhancement of the ROCOF relay, improving frequency estimation is proposed and compared to standard methods. Results are obtained through real-time hardware-in-the-loop (RT-HIL) simulations using an IEC61850 compliant STM32F746NG microprocessor acting as a ROCOF relay. Feasibility of the method has been proven experimentally. As demonstrated, it has an ability to significantly mitigate a number of nuisance trippings for non-islanding events. For the CIGRE medium voltage benchmark distribution network, the proposed method provided full security at the setting of 0.5 Hz/s for adjacent feeder faults, whereas the standard methods happened to fail even at the setting of 1 Hz/s. Additionally, as shown, an improvement of the relay security can lead to reduction of NDZ.

Maximal overlap discrete wavelet transform and deep learning for robust denoising and detection of power quality disturbance

This study presents a new technique for power quality (PQ) disturbance detection. The technique focuses on voltage sags and interruptions that are related to various faults, i.e. transmission line, feeder, and transformer faults. A maximal overlap discrete wavelet transform-based PQ detection algorithm is proposed to provide accurate points of disturbance initiation and recovery. The proposed PQ detection algorithm is robust even without a detection threshold and independent of the sampling frequency of PQ recording. In consideration of the presence of noise conditions, the preprocessed PQ waveforms are converted into 2D binary vectors using space vector transformation. Then, an improved stacked sparse denoising autoencoder combined with supervised backpropagation training is proposed as a robust classifier. Results show that the proposed method is suitable for detecting various types of PQ disturbances and possesses high recognition accuracy despite insufficient training samples.

Variable impedance fault current bypass circuit for fault arc suppression in distribution network

The existing fault current bypass circuit to extinguish fault arc does not take into account the influence of the load connected to the fault feeder, which may cause the arc suppression failure because the fault current cannot be reduced. This study proposes a variable impedance fault current bypass circuit for fault arc suppression, which is composed of a checking branch and an adjusting branch. The checking branch is utilised to identify the correctness of fault phase detection needed in establishing the bypass. The adjusting branch can change the impedance of the bypass based on the load connected to the fault feeder to reduce the fault current, and this branch can maintain the recovery voltage of fault location close to zero after the arc was extinguished. The performance of the proposed method, the arc suppression coil, the active method and the traditional bypass method was compared by simulation experiments. The results demonstrate that the performance of the proposed method is not influenced by the load. The proposed method can restrain the fault current and recovery voltage close to zero without being affected by the harmonic components, thus, which is beneficial to extinguish the fault arc without reignition.

Research on fault feeder detection with adaptive notch filter in non-effective neutral point to ground system’ single phase to ground fault

It is difficult to detect single-phase grounding fault in non-effective neutral point to ground system because of its weak current and unstable arc. In this paper, a kind of self-adaptive notch filter is used to extract the fundamental wave of current signals. This method is verified by Matlab/Simulink simulation. The result confirms that the method can realize fault line detection timely and accurately.

Fault feeder detection method utilized steady state and transient components based on FFT backstepping in distribution networks

A novel cut-in point for fault detection issue is introduced by dividing the transient zero sequence current (TZSC) into the steady-state components (SSCs) and transient components (TCs), a comprehensive detection method based on the coordinated SSCs and TCs is presented. For the SSCs criterion, the TZSCs within the second power cycle are used as the research objects, the local SSCs are obtained based on Fast Fourier transformation (FFT), if there is unique phase difference of the local SSCs is larger than Π/4, the correlation coefficients of SSCs are used to detect the fault feeder; Otherwise goes into the TCs criterion stage, the global SSCs based on the backstepping method is calculated, accordingly, the TCs can be obtained by subtracting SSCs, the difference between fault feeder and healthy feeders are enhanced by using the extremum of TCs and bubble sort method, lastly, the cross-correlation distance (CCD) is introduced to detect the fault feeder. The proposed method not only has high detection accuracy but also needs least time length, the correctness and extensive applicability have been verified by the results from the radial distribution network simulation model, arc fault model, improved IEEE-13 node system and field test.

Single-phase-to-ground fault detection with distributed parameters analysis in non-direct grounded systems

The fast and accurate detection of the single-phase-to-ground fault is of great significance for the reliability and safety of the power supply. In this paper, novel algorithms for distribution network protection were proposed with distributed parameters analysis in non-direct grounded systems. At first, novel generating mechanisms of zero-sequence voltage and residual current were proposed. Then the compositions of residue parameters, including residual current and residual admittances, were decomposed in detail. After that, an improved algorithm for a fault resistance calculation of a single phase-to-earth fault was also proposed, and the algorithm is much more convenient as it only needs to measure the variation of the zero-sequence voltage and does not need the prerequisites of the faulty feeder selection. Furthermore, the fault feeder can also be selected by an improved calculation algorithm of zero-sequence admittance of the faulty feeder, which cannot be affected by the asymmetry of the network. Theoretical analysis and the MATLAB/Simulink simulation results demonstrate the effectiveness of the proposed algorithms.

Modeling and Application of Hybrid Power Flow Controller in Distribution Systems

The smartening of distribution systems with distributed generation, storage devices, and intelligent loads have created challenges for the operation of distribution feeders, which can be addressed with power-electronics based controllers. However, the capital-intensive nature of these controllers is an obstacle for their wide use. The Hybrid Power Flow Controller (HPFC) is shown here to provide an adequate solution to the application of flexible ac transmission systems controllers to distribution systems, and hence the merits and the added value of this controller are discussed here through detailed modeling and simulations, examining its impact on a distribution system under different conditions. Thus, in this paper, a detailed dynamic model of the HPFC is developed and implemented in PSCAD, describing and proposing control strategies to properly operate this controller in distribution-system applications, such as an effective and simple procedure for starting up the device. The developed model is used to demonstrate the effectiveness of the controller for solving problems in distribution systems, such as voltage sags associated with feeder faults and power flow fluctuations due to intermittent renewable generation using a benchmark network as an illustrative example.

Detecting Single-Phase-to-Ground Fault Event and Identifying Faulty Feeder in Neutral Ineffectively Grounded Distribution System

In neutral ineffectively grounded distribution systems, a conventional zero-sequence voltage criterion to detect a single-phase-to-ground (SPG) fault event suffers from some drawbacks, and existing fault feeder selection techniques demonstrate low reliability in the field. For improvement, a new protection scheme is proposed in this paper. It is composed of a fault event detection unit and a fault feeder identification unit. Based on data distribution kurtosis of transient zero-sequence current, the former unit is employed to detect whether a SPG fault event has occurred and capture a fault starting moment. According to the behavior of average data distribution skewness, the latter unit is employed to identify which feeder is faulty. Superior to the zero-sequence voltage criterion, the proposed scheme can reliably detect the SPG fault event under a three-phase voltage imbalance condition and intermittent arc grounding fault. Besides, it is also found that the proposed scheme can validly identify a faulty feeder even under high background noises. Case test results indicate that the proposed scheme is able to work well with not only simulation data but also recorded field data, which demonstrates the high value in engineering practice.

Lyapunov-Based Large Signal Stability Assessment for VSG Controlled Inverter-Interfaced Distributed Generators

Inverter-interfaced distributed generators (IIDGs) have been widely applied due to their control flexibility. The stability problems of IIDGs under large signal disturbances, such as large load variations and feeder faults, will cause serious impacts on the system. The virtual synchronous generator (VSG) control is an effective scheme for IIDGs to increase transient stability. However, the existing linearized stability models of IIDGs are limited to small disturbances. Hence, this paper proposes a Lyapunov approach based on non-linearized models to assess the large signal stability of VSG-IIDG. The electrostatic machine model is introduced to establish the equivalent nonlinear model. On the basis of Popov’s theory, a Lyapunov function is derived to calculate the transient stability domain. The stability mechanism is revealed by depicting the stability domain using the locus of the angle and the angular frequency. Large signal stability of the VSG-IIDG is quantified according to the boundary of the stability domain. Effects and sensitivity analysis of the key parameters including the cable impedance, the load power, and the virtual inertia on the stability of the VSG-IIDG are also presented. The simulations are performed in PSCAD/EMTDC and the results demonstrate the proposed large signal stability assessment method.

Mathematical morphology‐based single phase‐to‐ground fault feeder selector for a resonant grounded distribution system

In this letter, we present a new single phase‐to‐ground fault feeder selector for a resonant grounded distribution system based on mathematical morphology. A combined morphological filter, which is the average of open–closing and close–opening, is employed to extract the transient component and decaying DC component from the zero‐sequence current signal of each feeder. Afterward, two indices are introduced to measure these components and to distinguish the fault feeder from healthy feeders. Simulation studies are conducted using PSCAD/EMTDC, and the results verify the effectiveness of the proposed method. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Multi-agent based coordinated protection systems for distribution feeder fault diagnosis and reconfiguration

This paper presents an innovative peer-to-peer agent-based protection system for fault diagnosis and automatic power restoration in power distribution networks. In practice, modern digital relays play a vital role for handling faults by allowing different switching configurations of opening and closing the circuit breakers in power networks. An effective fault detection and diagnosis along with backup protection is essential in order to save the systems from collapse and reconfigure them properly after an outage. In the proposed agent-based protection scheme, a hierarchy of two categories of agents- (i) Relay agent and (ii) Configuration agent is designed where the agent communication plays an important role to effectively diagnose the fault conditions and thereby, restore the system through proper relay coordination. An open ring feeder distribution system is considered to evaluate the performance of the proposed protection scheme. Furthermore, the impacts of both communication failure and physical protection misoperation are also addressed in this paper through effective backup protection provided by the coordination of agents.

An Iterative Method for Detecting and Localizing Islands Within Sparse Matrixes Using DSSim-RT

Nowadays, the simulation tools used to perform power system analysis are evolving into the many-core computation era; some of these techniques propose to tear the power system network into several subnetworks (islands) for its parallel processing. The island's detection is an issue considered by the power flow analysis due to management activities such as feeder reconfiguration, fault detection, and isolation, among others, that generate topological changes. These methods include graph theory, checking the circuit breaker status and on-site measurements, decision trees, frequency deviation, and pattern recognition, among other techniques, which are focused to detect topology changes that may generate islands and affect the state estimation of the system. In contrast, other techniques such as the approximate minimum degree perform a reorganization of the $Y_{{\text{BUS}}}$ matrix that describes the network components and their connectivity, looking to factorizing the $Y_{{\text{Bus}}}$ matrix to solve the power flow problem. These techniques are very functional and efficient; however, some of them require detailed information of the network, and are addressed to cover meshed and radial network configurations separately. This paper presents an iterative algorithm that uses the compressed coordinate branch-to-node matrix for detecting, classifying, and grouping islands within sparse matrixes, describing mesh or radial networks. This algorithm is a valuable tool to simplify islands location and can be implemented using any programing language due to its simplicity. This method is used in Distribution System Simulator - Real Time Version (DSSim-RT), which is a simulator based in OpenDSS, for tearing the power system network to allow the multithread power flow analysis of distribution systems in real time.

High‐impedance fault detection in electrical power distribution systems using moving sum approach

High-impedance faults (HIFs) in electrical power distribution systems produce a very random, non-linear and low-magnitude fault current. The conventional overcurrent (OC) relaying-based distribution system protection schemes find difficulty in detecting such low-current HIFs. In this study, a simple two criteria-based protection scheme is proposed for detection and isolation of HIFs in multi-feeder radial distribution systems. It utilises one-cycle sum of superimposed components of residual voltage for HIF detection and the maximum value of one-cycle sum of superimposed components of negative-sequence current for faulted feeder identification. The performance of the proposed scheme is evaluated for a wide variety of possible test cases by generating data through power systems computer-aided design/electro-magnetic transient design and control software. Results clearly show that the proposed scheme can assist conventional OC relay for detection and isolation of HIFs in distribution systems with any grounding connections in a more reliable and faster way.