This paper presents a single-ended traveling wave-based fault location method for a hybrid transmission line: an overhead line combined with an underground cable. Discrete wavelet transformation (DWT) is used to extract transient information from the measured voltages. Support vector machine (SVM) classifiers are utilized to identify the faulty-section and faulty-half. Bewley diagrams are observed for the traveling wave patterns and the wavelet coefficients of the aerial mode voltage are used to locate the fault. The transient simulation for different fault types and locations are obtained by ATP using frequency-dependent line and cable models. MATLAB is used to process the simulated transients and apply the proposed method. The performance of the method is tested for different fault inception angles (FIA), different fault resistances, non-linear high impedance faults (NLHIF), and non-ideal faults with satisfactory results. The impact of cable aging on the proposed method accuracy is also investigated.

A Machine Learning and Wavelet-Based Fault Location Method for Hybrid Transmission Lines

Partial discharges (PDs) generate wideband radio-frequency interference which can be used for noninvasive monitoring of discharges. This paper presents a novel method based on this principle for PD monitoring of substations. The significant advantage of this method lies in the ability to detect PD sources in energized equipment anywhere within a substation compound during normal operating conditions. The results obtained from the prototypes installed in the U.K. and U.S. substations are reported. Results include correlation with apparent charge and daily recordings obtained before, during, and after the failure of a 132-kV current transformer and 69-kV voltage transformer.

RF-Based Partial Discharge Early Warning System for Air-Insulated Substations

This paper presents a novel wavelet-based fault-location scheme for aged cable systems when synchronized digital fault recorded data are available at the two terminals of each cable. The proposed scheme estimates the fault location in multiend-aged cable systems using the theory of wavelet singularity detection as a powerful signal processing tool. The arrival of the first and second voltage traveling waves at both ends of the power cables can be identified reliably. The developed wavelet processing scheme is applied on the modal coordinates instead of the phase coordinates. The proposed scheme has the ability to eliminate the impact of the change in the propagation velocity of the traveling waves on the fault-location calculations. This will help solve the problem of cable changing parameters, especially the change of the relative permittivity of the cable with age. The method is valid even with faults that are very close to busbars. Characteristics of the proposed fault-location scheme are analyzed by extensive simulation studies using Alternative Transients Program/Electromagnetic Transients Program. The results indicate an accepted degree of accuracy for the suggested fault locator

Traveling-Wave-Based Fault-Location Scheme for Multiend-Aged Underground Cable System

Electromagnetic interference levels on sensitive electronic equipment are quantified experimentally and theoretically in air and gas insulated substations of different voltages. Measurement techniques for recording interference voltages and currents and electric and magnetic fields are reviewed and actual interference data are summarized. Conducted and radiated interference coupling mechanisms and levels in substation control wiring are described using both measurement results and electromagnetic models validated against measurements. The nominal maximum field and control wire interference levels expected in the switchyard and inside the control house from switching operations, faults, and an average lightning strike are estimated using high frequency transient coupling models. Comparisons with standards are made and recommendations given concerning equipment shielding and surge protection. >

Transient electromagnetic interference in substations

This paper proposes an extensive fault location model for underground power cable in distribution system using voltage and current measurements at the sending-end. First, an equivalent circuit that models a faulted underground cable system is analyzed using distributed parameter approach. Then, the analysis of sequence networks in three-phase network is obtained by applying the boundary conditions. This analysis is used to calculate a fault distance in single section using voltage and current equations. The extension to multi-section is further analyzed based on Korean distribution systems. This method is an iterative process to determine a faulted section from the network. Finally, the case studies are evaluated with variations of fault distance and resistance, which also includes the evaluation of its robustness to load uncertainty.

Fault Location for Underground Power Cable Using Distributed Parameter Approach

A time-domain model is described for predicting transient bus currents, electromagnetic fields, and cable-coupling effects caused by switching actions in high-voltage substations. Having been validated against measured transient data, the model provides a basis for predicting EMI effects resulting from abnormal switching actions, such as phase-to-ground faults, which are difficult to stage for measurement. From such worst-case estimates, the adequacy of the latest standards for microprocessor-controlled substation protection can be assessed. >

Prediction of electromagnetic field and current transients in power transmission and distribution systems

A new concept for fault location has been developed which uses fault-generated waves to perform both real-time and after-the-fact fault location on single-phase underground residential distribution cable systems that are up to a mile in length. In either mode, faults are located with an accuracy of less than 2 percent of the length of the cable circuit. Thus, a fault can easily be located as being between two adjacent transformers. A device based on the concept would be installed at the normally open point of a radial URD tap, and would monitor the circuit for fault-created transients. When triggered by either a real-time fault transient or an after-the-fact thumper impulse, the conceptual device would provide a digital readout of the distance to the fault, allowing for rapid isolation of the faulted section of cable. >

A novel concept for URD cable fault location

Bus current transients, electric and magnetic field transients, and current transients coupled onto control and CT cables produced by switching operations in a 115 kV ring bus have been measured and characterized. The similarities and differences among transients observed when energizing and deenergizing relatively short sections of bus during disconnect switch and circuit breaker opening and closing operations are summarized and discussed. The results are used to further the understanding of switching transient characteristics and to validate a model that predicts the detailed nature of the transients reported, for use in ongoing investigations to assure continued satisfactory performance in substation protection equipment. >

Measurement of switching transients in 115 kV substation

High frequency transient electromagnetic interference (EMI) caused by faults, lightning, and switching on high voltage circuits in substations is characterized and quantified using a mobile four-channel transient EMI measurements system and validated traveling wave transient analysis models More than 800 waveforms of high voltage switching transients and staged-faults were measured in air- and gas-insulated substations and used to validate a system of interrelated substation interference coupling models The highest transient EMI levels expected from initial conditions of 2PU (Per Unit) disconnect switching, a 2PU circuit breaker fault, and a 10 kA lightning strike inside substations through 500 kV are calculated using the models These initial conditions, believed to be nominally worst case for these three high voltage EMI sources, are defined as follows For disconnect switching, the 2PU initial condition represents the maximum peak phase-to-ground voltage that can occur across a switch gap restriking at its greatest separation An initial condition of 2PU peak phase-to-ground voltage can occur on an open and adjacent substation bus during switching from a remote location A 10 kA lightning strike represents the maximum current expected to be attached directly to a 500 kV bus as a result of a shielding failure Volume 1 ofmore » this report contains a summary and recommendations; volume 2 covers the computer models; volume 3 provides detailed results of the interference tests; and volumes 4 and 5, available on demand, contain data logs, raw data plots, and digital waveforms« less

C.M. Wiggins

Papers

Transient electromagnetic interference in substations

Prediction of electromagnetic field and current transients in power transmission and distribution systems

A novel concept for URD cable fault location

Measurement of switching transients in 115 kV substation

Electromagnetic transients in substations. Volume 3, Test results: Final report