Restrictions on right of way and increasing power demand has boosted development of six phase transmission. It offers a viable alternative for transmitting more power, without major modification in existing structure of three phase double circuit transmission system. Inspite of the advantages, low acceptance of six phase system is attributed to the unavailability of a proper protection scheme. The complexity arising from large number of possible faults in six phase lines makes the protection quite challenging. The proposed work presents a hybrid wavelet transform and modular artificial neural network based fault detector, classifier and locator for six phase lines using single end data only. The standard deviation of the approximate coefficients of voltage and current signals obtained using discrete wavelet transform are applied as input to the modular artificial neural network for fault classification and location. The proposed scheme has been tested for all 120 types of shunt faults with variation in location, fault resistance, fault inception angles. The variation in power system parameters viz. short circuit capacity of the source and its X/R ratio, voltage, frequency and CT saturation has also been investigated. The result confirms the effectiveness and reliability of the proposed protection scheme which makes it ideal for real time implementation.

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An improved fault detection classification and location scheme based on wavelet transform and artificial neural network for six phase transmission line using single end data only

This paper describes the performance of the protection system used for the first commercially operated six-phase transmission line in the world-New York State Electric & Gas's 93 kV (phase to phase and phase to ground) line from Goudey Station to Oakdale substation (USA) during faults in the winter of 1993. The paper briefly describes the basics of the High-Phase Order Transmission Demonstration Project and the integration of available state of the art microprocessor based relays, with a programmable logic relay (designed for the protection of conventional three-phase systems) in a hierarchical six-phase protection system. The operation of the protection system during two faults on the line in January and February 1993 is reported. The modeling of the six-phase line in a conventional three-phase short circuit study program is also considered and a comparison between the measured and calculated fault currents is presented.

Relay protection operation for faults on Nyseg's six-phase transmission line

The demand of electrical energy is continuously increasing. High phase order transmission system is a viable alternative due to increasing costs of right of way. Six phase transmission lines can carry more power for same phase to phase voltage with the same right of way economically. Protection of six phase transmission lines has been a very challenging task. Earlier simulations of six phase transmission line have been done in PSCAD/EMTDC software. In this paper MATLAB® software and its associated Simulink® and Simpowersystem® toolboxes have been used to simulate the six phase transmission line. Application of Artificial Neural Network for protection of six phase transmission line against ground faults is presented, which the authors believe has not been reported earlier. Fundamental components of six phase voltages and currents have been used as inputs for training of the artificial neural network for detection and classification of faulted phase using neural network toolbox of MATLAB®. A sample 765 kV system of 60 km length has been selected for study. The study takes into account the effect of variation in fault inception angle, fault distance location and fault resistance. The results indicate the suitability of proposed technique and its adaptability to changing system conditions.

Detection and classification of faults on six phase transmission line using ANN

This paper introduces a high-speed relaying approach based on the wavelet analysis of the fault generated traveling waves dedicated for high-phase order power transmission lines. In this approach, a suitable wavelet is chosen and tuned at a suitable band of frequencies to capture the fault generated high frequency traveling waves superimposed on the power frequency waves in a modal domain. Then, the energies of the captured signals are used for making a trip decision. The introduced approach is tested and validated by a computer simulation using an ElectroMagnetic Transient Program (EMTDC). The results show that the approach has the ability for high-speed fault detection, classification and faulted phase(s) selection irrespective of the fault inception angle, fault resistance and line terminals.

http://ieeexplore.ieee.org/iel5/9986/32068/01492131.pdf

High-phase order power transmission lines relaying approach based on the wavelet analysis of the fault generated traveling waves

To overcome the constraints on land availability, infrastructure and environmental problems, six-phase transmission lines have been proposed as a potential alternative to increase the power transfer capability of existing transmission lines without major modification in the existing structure of three-phase double-circuit system. The non-availability of a proper protection scheme due to large number of possible faults has been the prime reason behind the low popularity and acceptance of six-phase system. In this regard, the present work proposes a protection scheme for six-phase transmission line based on the hybridization of discrete wavelet transform and modular artificial neural network. The fault information (approximate coefficients) in the voltage and current signals is captured using discrete wavelet transform. The standard deviation of the coefficients of voltage and current signals in each phase is then computed and given as input to modular artificial neural network, which aims at identifying the faulty section/zone and estimate its location. Test results exhibit that the proposed scheme effectively discriminates the faulted section and estimates the fault location with maximum error of 0.675 %. It offers primary protection to the total line length and also provides remote backup protection for the adjacent reverse section of the line using data at relaying point only and thus avoids the need of a communication link.

A modular neuro-wavelet based non-unit protection scheme for zone identification and fault location in six-phase transmission line

The protection and control requirements needed for a 115 kV line after it was reconfigured to operate as a single-circuit six-phase line as part of a high-phase-order demonstration project are discussed. Addressed are the required modification and/or additions needed for the existing protection and control equipment. The criteria selected for the protection of the transmission line are described, including the transformers required for six-phase reconfiguration. The commercially available digital protection systems applicable to the protection of the line and their limitations are reviewed. Requirements for protection and control panels, their location for optimal wiring, and facilities to perform tests and measurements are also covered. >

H.J. Pierce

Papers

Selection and application of relay protection for six phase demonstration project