What is it about?

This paper presents an intelligent approach for detecting unstable swings during distance relay operation using the S-transform signal processing technique and artificial neural networks. Test results showed that the proposed approach using S-transform, multi-layer perceptron network and probabilistic neural network can accurately detect and classify fault, stable swing, unstable swing, fault clearance and post fault events for correct distance relay operation.

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Why is it important?

The conventional power swing schemes used in distance relay operation are not fast enough to detect and distinguish a fault, stable swing and unstable swing and this may lead to unintended tripping of protection devices. Therefore, there is a need for fast detection of unstable swings so as to improve the reliability of distance relay operation. To address the need for fast detection of unstable swings so as to improve the reliability of distance relay operation, a new scheme for detecting a fault, stable swing and unstable swing at transmission lines is proposed by using the S-transform and artificial neural networks.

Perspectives

Power oscillation is inherent to power systems which may result from any event such as line switching, short circuit faults, generator tripping or load shedding. During power oscillation, apparent impedance at relay location may decrease and enter the relay tripping zone. The current power system utilises conventional power swing methods, mainly out of step (OOS) detector, to distinguish a fault, stable swing and unstable swing. Though widely used, the method is proven to be slow in the detection process, leading to frequent unintended tripping of operation devices. Thus, there is a need to perform fast detection of power system disturbances to prevent major equipment damages, minimise the spread of power outrages and maintain power system stability.

ahmad farid abidin
Universiti Teknologi MARA

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This page is a summary of: Intelligent detection of unstable power swing for correct distance relay operation using S-transform and neural networks, Expert Systems with Applications, November 2011, Elsevier, DOI: 10.1016/j.eswa.2011.05.050.
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