Doaa Khalil Ibrahim

Adaptive SPAR offers many advantages over conventional techniques. In the case of transient faults, the arcing extinction time can be accurately determined and in the case of a permanent fault, breaker reclosure can be avoided. This paper describes, in some detail, the design of a new Adaptive SPAR technique that extracts high frequencies transients, from the CVT. The main case of study in this paper is the High Dam / Nagh Hamady, Nagh Hamady /Assuit 500 kV double circuit transmission system in the Egyptian network. Fault scenario cases representing different fault locations, inception angles, actual representation to secondary arc characteristics, and with/without shunt reactor existence were extracted from simulation work, and then verified through real field records in that system. The outcome of this study indicates that the proposed technique can be used as an effective means of achieving an adaptive single pole auto reclosure scheme.

High impedance faults (HIFs) are difficult to be detected or classified by overcurrent or distance relays. This paper presents a scheme for high impedance fault detection and classification in extra high voltage transmission line. The scheme recognizes the distortion of the current waveforms caused by the arcs usually associated with HIF using a discrete wavelet transform (DWT) based pattern recognition. The scheme uses a recursive method to sum the absolute values of the high frequency signal generated of line current signals measured at one substation end over one cycle. Proposed detector and classifier are tested under a variety of fault conditions on Egyptian 500 kV transmission line system by extensive simulation studies using HIF model of distribution system that modified to transmission lines. In addition, a real time HIF data recorded is used to validate the performance of the proposed scheme. All achieved results clearly reveal that the proposed scheme can accurately detect and classify HIFs in the transmission lines unaffected by fault type, fault inception angle, fault resistance, and fault location.

It is possible to capture the required travelling wave information contained in fault transients using wavelet transform. This paper presents practical real time testing for the high impedance fault (HIF) detection algorithm based on real time accidents data. The proposed scheme is implemented for HIF detection in extra high voltage transmission lines. The classifier is based on an algorithm that uses recursive method to sum the absolute values of the high frequency signal generated over one cycle and shifting one sample. Characteristics of this scheme are analyzed by extensive real time studies that clearly reveal that this technique can accurately detect HIFs in the EHV transmission lines within only half a cycle from the instant of fault occurrence. The reliability of this scheme is not affected by different fault conditions such as fault distance and fault inception angle.

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Coupling capacitive voltage transformers behave as low pass filters which reject the high frequencies associated with voltage signals, so the effect of HIF on voltage signals is neglected. In addition, using series capacitors (SCs) equipped with metal oxide varistors (MOVs) increases the protection relaying problems and complicates the trip decision. This paper presents a high impedance fault detection algorithm for maximum trip time required of 3/4 cycle. The proposed scheme implemented on two different models of HIF in extra high voltage double-ended transmission lines with series capacitors at the middle of the line. The scheme recognizes the distortion of the voltage waveforms caused by the arcs usually associated with HIFs. The discrete wavelet transform (DWT) based analysis, yields three phase voltages in high frequency range which are fed to Clarke’s transformation to produce ground and aerial modes
voltage components for pattern recognition. The classifier is based on an algorithm that uses recursive method to sum the absolute values of high frequency signals generated over one cycle and shifts one sample. Characteristics of the proposed scheme are fully analyzed by extensive ATP/EMTP simulation studies that clearly reveal that the proposed method can accurately detect HIFs in EHV transmission lines and does not affected by different fault conditions such as fault distance and fault inception angle.

The coupling capacitor voltage transformers transient response during faults can cause protective relay mal-operation or even prevent tripping. This paper presents the CCVT transient response errors and the use of artificial neural network (ANN) to correct the CCVT secondary waveform distortion. In this paper, an ANN program is developed to recover the primary voltage from the distorted secondary voltage. The ANN is trained to achieve the inverse transfer function of the coupling capacitor voltage transformer (CCVT), which provides a good estimate of the true primary voltage from the distorted secondary voltage. The neural network is developed and trained using MATLAB simulations. The accuracy of the simulation program is
confirmed by comparison of its response with that of the target value from the simulation data.

Coupling Capacitor Voltage Transformer (CCVT) secondary voltages, normally applied to conventional schemes, do not comprise appropriate information for schemes that operate on high frequency fault generated transients. However it is possible to capture the required travelling wave information contained in fault transients using a high frequency tap from a CCVT. This paper presents an ATP/EMTP fault simulations studies based algorithm for half cycle high impedance fault detection. The proposed scheme implemented on two different models of HIF in extra high voltage mutually coupled double-ended transmission lines. The scheme recognizes the distortion of the voltage waveforms caused by the arcs usually associated with HIFs. The high pass filter tap yields three phase voltage in the high frequency range which are fed to Clarke’s transformation to decouple the traveling waves of the mutually coupled lines and produces ground mode and aerial modes voltage components to
the classifier for pattern recognition. The classifier is based on an algorithm that uses recursive method to sum the absolute values of the high frequency signal generated over one cycle and shifting one sample. Characteristics of the proposed fault detection scheme are analyzed by extensive simulation studies that clearly reveal that the proposed method can accurately detect HIFs in the EHV transmission lines within only half a cycle from the instant of fault occurrence. The reliability of the proposed scheme does not affected by different fault conditions such as fault distance and fault inception angle.

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This paper proposes a differential protection scheme for transmission lines using the energy conservation law. The real power signals at both ends (sending and receiving) of the line are compared with a prespecified value, if the resultant is more than this value, an internal fault is indicated in the transmission line zone. The proposed technique is evaluated using PSCAD/EMTDC program configurated to model the effect of faults on typical 500 kV transmission line. Extensive simulation studies show that this protection scheme has the ability to discriminate internal faults fast and accurately, and is more reliable than conventional biased differential protection scheme, and suitable for all types of lines. Details of the proposed relay design are given in the paper; also results of some performance studies are given.

Abstract—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.

High impedance faults (HIFs) are difficult to be detected by overcurrent protection relays. This paper presents an ATP/EMTP fault simulations studies based algorithm for high impedance fault detection in extra high voltage transmission line. The scheme recognizes the distortion of the voltage waveforms caused by the arcs usually associated with HIF. The discrete wavelet transform (DWT) based analysis, yields three phase voltage in the high frequency range which are fed to a classifier for pattern recognition. The classifier is based on an algorithm that uses recursive method to sum the absolute values of the high frequency signal generated over one cycle and shifting one sample. A HIF model of distribution is modified for EHV transmission lines. Characteristics of the proposed fault detection scheme are analyzed by extensive simulation studies that clearly reveal that the proposed method can accurately detect HIFs in
the EHV transmission lines.

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.

This paper presents an adaptive fault location scheme for aged power cables using synchronized phasor measurements from both ends of the cable. 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 scheme responds very well to any fault insensitive to fault type, fault resistance, fault inception angle and system configuration. The proposed scheme solves the problem of aged cables with the change of the electric parameters. In addition to, it gives an accurate estimation of the fault resistance.

This paper presents a fault location scheme for transmission systems consisting of an overhead line combined 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 fault recording apparatuses. The proposed scheme has the ability to locate the fault whether it is in the overhead line or in the underground power cable. In addition to, the proposed scheme gives an accurate estimation of the fault resistance at fault location. Extensive simulation studies carried out using MATLAB show that the proposed scheme provides a high accuracy in fault location under various fault conditions.

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.

This paper proposes a particle swarm optimization (PSO) method for solving the economic dispatch (ED) problem in power systems. Many nonlinear characteristics of the generator are considered for practical generator operation, such as ramp rates, prohibited operating zones, and non smooth cost functions. The feasibility of the proposed .method is demonstrated for two different systems, and is compared with both Genetic Algorithm (GA) method and another PSO method in terms of the cost optimization and computation time where an improvement in both terms is achieved.

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.

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.

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.

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.