This paper presents new techniques for locating and diagnosing faults on electric power distribution feeders. The proposed fault location and diagnosis scheme is capable of accurately identifying the location of a fault upon its occurrence, based on the integration of information available from disturbance recording devices with knowledge contained in a distribution feeder database. The developed fault location and diagnosis system can also be applied to the investigation of temporary faults that may not result in a blown fuse. The proposed fault location algorithm is based on the steady-state analysis of the faulted distribution network. To deal with the uncertainties inherent in the system modeling and the phasor estimation, the fault location algorithm has been adapted to estimate fault regions based on probabilistic modeling and analysis. Since the distribution feeder is a radial network, multiple possibilities of fault locations could be computed with measurements available only at the substation. To identify the actual fault location, a fault diagnosis algorithm has been developed to prune down and rank the possible fault locations by integrating the available pieces of evidence. Testing of the developed fault location and diagnosis system using field data has demonstrated its potential for practical use.

Automated fault location and diagnosis on electric power distribution feeders

A fault location algorithm for distribution feeders based on matching during-fault voltage sags is presented. The basic principle of the algorithm is based on the fact that when a fault occurs on the feeder, voltage sags propagate presenting different characteristics for each feeder node. Knowing the voltage sag characteristics, it is possible to locate the faulty node or the faulty area of the feeder. This voltage-based approach ensures the efficiency and robustness of the algorithm, which provides suitable and accurate results. An overhead, three-phase, three-wire, 13.8 kV, 134-node, real-life feeder model is used to evaluate the algorithm. Test results show that the algorithm is quite suitable due to not only the faulted point being located, but also a faulted area being identified providing important information to direct the maintenance crew seeking to repair any fault inflicted damage.

Improved Fault Location on Distribution Feeders Based on Matching During-Fault Voltage Sags

This paper proposes a new algorithm for localizing phase to ground faults in an electric power distribution system. Fault-originated traveling waves propagate along the distribution paths in both directions away from the fault point and are reflected at line terminations, junctions between feeders, laterals, and the fault location. Depending on the paths which traveling waves reciprocate through, the transient signal at each node contains certain path characteristic frequencies (PCFs). Energy spectrum of the transient signal has high density around the path characteristic frequencies. On this basis, the transient voltage is decomposed by a wavelet filter and its energy spectrum is decomposed into different levels. Depending on the bandwidth of the wavelet filter and the path characteristic frequencies, the decomposed signal in each level contains a certain percentage of energy. Then, a neural network-based methodology is proposed as a power distribution line fault locator. Energy percentage in each level is the candidate feature for training the artificial neural network. Simulations and the training process for the neural network are performed respectively using ATP/EMTP and MATLAB. It is shown that the results of the proposed algorithm are quite satisfactory.

Path Characteristic Frequency-Based Fault Locating in Radial Distribution Systems Using Wavelets and Neural Networks

A system is proposed to locate faults on transmission lines using the traveling wave phenomenon. Prony method is used to analyze the voltage or current signal at the local bus and extract its modal information. This information represents the traveling wave generated by the fault and can be used to estimate its location. Artificial neural networks (ANNs) are used to estimate the fault location based on the modal information. Two schemes are presented: the first with a voltage input signal; and the second with a current input signal. Training and testing data are obtained by ATP-EMTP simulations. Tests were done to study the effect of fault resistance variation and fault incidence angle on both schemes. The system has the advantages of utilizing single-end measurements, using either a voltage or current signal; no pre-fault data is required.

ANN-based techniques for estimating fault location on transmission lines using Prony method

This paper presents a novel method for locating short-circuit faults in electric power systems. The origins of the method are in the concept of vulnerability contours, which is used in assessing the likelihood of voltage sags effecting a given network area. The method is applied in an off-line step and an on-line step. The on-line step consists of measuring voltage sags at selected system buses. The off-line step consists of estimating the most likely fault location by matching measured voltage sags with the ones calculated through the fault simulations. In the process, the fault resistance is estimated as well. To cope with the inherent uncertainty in the problem, fuzzy logic reasoning is applied. The performance of the method is demonstrated using some typical examples. Since the actual measurements of voltage sags were unavailable, fault simulations were conducted to emulate a real measuring process.

Fault Location Using Voltage Measurements

The authors present digital fault location techniques for transmission systems when digital fault recorded data are available at one terminal or two terminals. The systems under consideration are a 115 kV loop transmission system with data available at two terminals and a 69 kV radial transmission system with data available at one terminal. The data under consideration were recorded using digital fault recorders. The conversion of the data to workable data files and the techniques developed to achieve the highest accuracy in determining the fault location are discussed. Intermediate load buses and loads are considered in determining the fault location. An example of the effect of neglecting the presence of these loads is discussed. The fault location techniques are based on both the apparent impedance concept and the use of the three-phase voltage and current phasors. A test case with the exact fault location is presented. The techniques were developed on an IBM PC. >

C.M. Fallon

Papers

Fault location techniques for radial and loop transmission systems using digital fault recorded data