Mahmoud Gilany

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

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

A wavelet-based fault location technique for aged power cables

A novel wavelet-based travelling wave cable fault locator scheme is presented in this paper. Using the theory of wavelet singularity detection as a powerful signal processing tool, the initial arrival of the voltage travelling waves at both sides of the power cable and the second arrival of the travelling waves at the first side can be identified reliably without the need for detection the sign of these waves. The developed wavelet processing is applied on the modal coordinated instead of the phase coordinates. The proposed scheme has the ability to eliminate the effect of the change in the propagation velocity of the travelling waves. This will help solving the problem of cable changing parameters especially the changing of the relative permittivity of the cable over its age. Cable changing parameters causes a large error in all fault location techniques, which use the value of velocity of propagation in calculations. Characteristics of the proposed protection algorithm are analyzed by extensive simulation studies using ATP/EMTP. The obtained results indicate an accepted degree of accuracy for the suggested fault locator. In addition, the results prove that the proposed wavelet-based scheme solves the problem of aging cables with changing parameters over the age of the power cable.

An accurate scheme for fault location in combined overhead line with underground power cable

This paper presents an accurate fault location scheme for transmission systems consisting of an overhead line in combination with an underground power cable. The algorithm requires phasor measurements data from one end of the transmission line and the synchronized measurements at the most far end of the power cable. Fault location is derived using distributed line model, modal transformation theory and discrete Fourier transform. The technique can be used on-line or off-line using the data stored in the digital transient recording apparatus. The proposed scheme has the ability to locate the fault whether it is in the overhead line or in the underground power cable. Extensive simulation studies carried out using MATLAB show that the proposed scheme provides a high accuracy in fault location under various system and fault conditions.

A laboratory investigation of a digital protection technique for parallel transmission lines

A digital algorithm for the protection of parallel power transmission lines has been implemented on a 16-bit single board computer. It has been tested on a physical model consisting of two synchronous machines connected through a double circuit line. The algorithm is based on comparing magnitudes of currents of two parallel lines. Details of the experimental set-up and the results of online tests for various operating conditions are presented. A procedure to adjust the relay settings adaptively is also incorporated. The results illustrate the successful operation of the algorithm in detecting faults on parallel lines. >

An PMU double ended fault location scheme for aged power cables

This paper presents an adaptive fault location scheme for aged power cable using synchronized phasor measurements from both end of the cable line. The proposed fault location scheme is derived using the two-terminal synchronized measurements incorporated with distributed line model, modal transformation theory and discrete Fourier transform. The proposed scheme has the ability to solve the problem of cable changing parameters especially the change of the relative permittivity over its age and thus for the operating positive, negative, and zero-sequence capacitance changes. Extensive simulation studies are carried out using alternative transients program ATP/EMTP. The simulation studies show that the proposed scheme provides a high accuracy in fault location calculations under various system and fault conditions. The results show that the proposed method responds very well insensitive to fault type, fault resistance, fault inception angle and system configuration. The proposed scheme solves the problem of aged cables with change of its electric parameters. In addition to, it gives an accurate estimation of the fault resistance.

Generator stator winding protection with 100% enhanced sensitivity

Protection of 100% of a generator stator winding against earth faults is presented in this paper. An adaptive method is proposed to improve the sensitivity of third harmonic ground fault relays against the wide change in the operating conditions.

The Egyptian Electricity Authority strategy for distance relay setting: problems and solutions

Abstract This paper presents a study of the problems associated with improper zone settings of a distance relay. These problems include the difficulties of adjusting the setting when a short line follows a long line or visa versa. It deals also with setting problems like high fault impedance, in-feed current and load encroachment. A proposed setting algorithm suitable for digital relays is presented. It helps in improving the dependence and the selectivity of distance relays.

A New Strategy for Determining Fault Zones in Distance Relays

A new strategy (denoted P-SS) for estimating the correct fault zone in distance relays is introduced. The main difference between the P-SS and conventional setting strategies is that the P-SS does not depend on fixed boundaries for backup zones. It depends on exchanging information between local relays in the same station in addition to a command from the remote end relay. With the proposed strategy, zone-1 covers the entire length of the protected line, zone-2 covers the entire length of any next line irrespective of its length, and zone-3 covers the entire length of any line next to zone-2. The governing rules for the proposed strategy are presented. The strategy is examined against a wide range of setting problems of a real part of a high-voltage network with real relay settings. The results confirm that the P-SS achieves the required accurate, sensitive, and selective relay operation.

A Phasor-Based Double Ended Fault Location Scheme for Aged Power Cables

This paper presents a fault location scheme for aged power cables using phasor measurements from both ends of the cable line. The proposed fault location scheme is derived using two-terminal measurements incorporated with a distributed line model, modal transformation theory, and discrete Fourier transforms. The proposed scheme can solve the problem of cable changing parameters, especially the change of the relative permittivity and thus for the operating positive, negative, and zero sequence capacitance changes. Extensive simulation studies are carried out using the alternative transients program ATP/EMTP. The simulation studies show that the proposed scheme provides a high accuracy in fault location calculations under various system and fault conditions. The results show that the proposed method responds very well, being insensitive to fault type, fault distance, fault resistance, and fault inception angle. The proposed scheme solves the problem of aged cables with change of electric parameters. In addition, it gives an accurate estimation of the fault resistance in all fault types.

Travelling Wave-Based Fault Location Scheme for Aged Underground Cable Combined with Overhead Line

This paper presents a novel wavelet-based travelling wave fault location algorithm for aged underground cables in transmission systems. Such transmission systems consist of overhead lines combined with underground power cables. Applying the singularity detection feature of wavelets as a powerful signal processing tool, the first and second initial arrival of the voltage travelling waves at the first end of the overhead as well as at the terminal end of the aged cable line can be identified reliably without the need for detection the sign of these waves. In this paper modal signals, rather than the phase signals, are the inputs to the relay.The proposed algorithm is capable of eliminating the effect of the change in the propagation velocity of the travelling waves over the age of the cable. It can be used on-line following the operation of digital relays or off-line using the data stored in the digital transient recording apparatus. Extensive simulation studies carried out using ATP/EMTP show that the proposed algorithm provides an accepted degree of accuracy in fault location under different fault conditions.