Performance of conventional nonpilot distance relay is affected by ground fault resistance, prefault system conditions, mutual effects of parallel lines and shunt capacitance influences The work presented in this paper addresses the problems encountered by conventional non pilot distance relay when protecting two terminal parallel transmission lines One of the key points of this paper is the detailed analysis of the apparent impedance as seen from the relaying point taking into account the effects of transmission line parameter uncertainties, mutual effects of parallel lines for simple and more complex configuration, shunt capacitance influences and variations in the system external to the protected line Based on extensive computer simulations of the infeed/outfeed, fault resistance, mutual coupling and shunt capacitance effects on the relay characteristics, an adaptive digital distance relaying scheme is proposed using radial basis function neural network which provides more efficient approach for training, computation, adaptation and tripping than the conventional feed forward network using back propagation algorithm In addition, the proposed adaptive scheme improves the performance of distance relay for double-circuit lines using modified compensation factor Moreover, the scheme does not require separate communication channel for data transmission The results of computer simulation show the improvement of sensitivity and selectivity of the relay

High-Resistance Faults on Two Terminal Parallel Transmission Line: Analysis, Simulation Studies, and an Adaptive Distance Relaying Scheme

The presence of various types of intercircuit faults on a series-compensated parallel transmission line combined with the effect of mutual coupling and fault resistance makes the protection system quite complicated. In this paper, the authors have proposed a new adaptive digital distance relaying scheme which takes care of all such abnormalities of the conventional ground distance relays and measures the correct value of impedance during phase-to-phase and phase-to-phase-to-ground intercircuit faults. The proposed adaptive scheme is based on the derivation of the compensated value of impedance using symmetrical component theory. Furthermore, it does not require remote-end data. To validate the proposed scheme, numerous computer simulations have been carried out on an existing part of the Indian 400-kV, 300-km-long series-compensated parallel transmission line using MATLAB/SIMULINK software. Simulation results demonstrate the effectiveness of the proposed scheme since the maximum percentage error is within ±5%.

A New Adaptive Distance Relaying Scheme for Mutually Coupled Series-Compensated Parallel Transmission Lines During Intercircuit Faults

Accurate fault location algorithm for double-circuit series compensated lines using a limited number of two-end synchronized measurements

This paper presents a new digital distance relaying scheme which takes care of a simultaneous open conductor and ground fault occurring coincidently on the same phase at the same point on a series-compensated double-circuit line. The effect of series compensation, mutual zero-sequence coupling, remote infeed/outfeed, and fault resistance on the relay reach has been considered by the proposed scheme. The conventional digital distance relay having facility of series compensation fails to provide adequate protection in the presence of such conditions. The proposed scheme is based on the derivation of the compensated values of impedance using symmetrical component theory. To validate the proposed scheme, numerous computer simulations have been carried out using MATLAB/SIMULINK software on an existing 400-kV, 300-km-long series-compensated double-circuit transmission line. At the end, a comparative evaluation between the proposed scheme and the conventional scheme having a facility of series compensation is carried out. Simulation results demonstrate the effectiveness of the proposed scheme since the percentage error is within ±4.19%.

A New Digital Distance Relaying Scheme for Series-Compensated Double-Circuit Line During Open Conductor and Ground Fault

A technique using wavelet packets is presented for accurate fault location on power lines with branches. It relies on detecting fault-generated transient traveling waves and identifies some waves reflected back from discontinuities and the fault point. Wavelet packets analysis is used to decompose and reconstruct high-frequency fault signals. An eigenvector matrix consists of local energies of high-frequency content of the fault signal; the faulty section is determined by comparing local energies in the eigenvector matrix with a given threshold. With the faulty section determined, the time ranges of two reflected waves related with fault point would be found out, then the fault point is located. The paper shows the theoretical development of the algorithm, and together with the results obtained using EMTP simulation software modeling, a simple 10 kV overhead line circuit.

http://ieeexplore.ieee.org/iel5/8110/22441/01047251.pdf

Fault location using wavelet packets

A methodology for evaluating and visualising the response of power system distance protection units most commonly used is presented A general case, with different topologies, of a double-circuit transmission line is considered and different types of inter-circuit faults are treated Single line and simple faults are simplified cases of the general one Faults are treated by means of the adequate connection between the sequence networks, where different types of faults are represented by a resistance star associated to both lines and ground Different combinations of these resistances result in different types of faults Fault conditions are introduced to sequence networks of the rest of the system through phase current controlled current sources, and the resulting sequence voltages at the fault point are applied to fault resistances through sequence voltage controlled voltage sources To calculate faults the mesh analysis method has been modified to take into account the dependencies fixed by the controlled sources Real previous state of the power system (load flow, sequence source impedances at both ends and sequence impedance between ends) is taken into account A useful and reliable way of representation is presented to obtain the expected response of different types of distance units in multi-circuit lines in presence of inter-circuit simultaneous faults

A useful methodology for analyzing distance relays performance during simple and inter-circuit faults in multi-circuit lines

Uncertainty sources, when relaying double lines with distance relays, during simple or intercircuit faults, are evaluated. Tendencies on errors and their magnitude are easily viewed in a forward reach settings vs. real fault distance covered plane. Contributions of different factors are separated and relations among them are established using the mentioned plane. Desired situations to be evaluated include any type of fault, for any previous state and any fault resistance, as well as any type of distance unit. The intent of the analysis presented is not only to evaluate known tendencies of distance relay responses, in double or single lines, but also to identify the causes and to show the usefulness of the employed methodology for any other type of study to be performed when calculating settings, analysing or designing the best protection philosophy in double or single lines.

Evaluation of uncertainties in double line distance relaying. A global sight

With the appearance on the market of electronic test equipment that is controlled by software from personal computers, automation of classical test methods has been achieved and new methods have been developed. For engineers and technicians in charge of performing integrity and application tests, steady-state and dynamic tests can provide helpful information used in design, commissioning and preventive and corrective maintenance. These test methods result in savings of time and the cost involved in these tasks. Since 1990, the Spanish electric utility, Iberdrola, and the Electrical Department of the University of the Basque Country have been developing tools to: automate protective relay testing; analyze the location and characteristics of faults in the power network on the basis of oscillographic records; and simulate real or hypothetical fault conditions on a protective relay in order to monitor its behavior. Two automatic relay testing systems and experience of their use are introduced in this article. Particular testing protocols of different relays are incorporated and all useful features available to increase the automation grade are considered. Both systems minimize power system protection relay maintenance times and costs and improve the quality and reliability of relay management.

Optimized relay testing systems

ISSN 0895-0156/02/$17.00©2002 IEEE To what extent is the use of transient tests prevalent in the policy of utilities: Acceptance tests Incidence analysis New modular relay definitions Optimal settings Corrective maintenance Relay selection? The main incentive of our research was to tackle the development of diverse tools that, in conjunction, made it possible to establish conclusions to answer this question.

M. Agrasar

Papers

A useful methodology for analyzing distance relays performance during simple and inter-circuit faults in multi-circuit lines

Evaluation of uncertainties in double line distance relaying. A global sight

Optimized relay testing systems

Simulation and transient testing of numerical relays