Hybrid Fuzzy Neural Network based Contingency Ranking for Voltage Collapse

M. Pandit, L. Srivastava, and J. Sharma

Keywords

Hybrid fuzzy neural network, feature selection, filter module, imbalanced training set, membership values, contingency ranking

Abstract

This article proposes a method based on hybrid fuzzy neural network (HFNN) comprised of a filter module and ranking module for online voltage contingency screening and ranking, incorporating load uncertainty and flexibility in ranking. A four-stage multi-output Parallel Self-organizing Hierarchical Neural Network (PSHNN) is developed to serve as the ranking module; it is found to be superior to conventional back-propagation (BP) neural network. The filter module reduces the burden on the ranking module by filtering out the noncritical contingencies. Compared to the deterministic crisp ranking, this method offers a more practical and flexible ranking, and is capable of handling contingencies lying on the boundary between two severity classes. Angular-distance-based clustering is used to reduce the dimension of the HFNN. It is difficult and time consuming to deduce the membership rules from complex input- output data. Therefore, in this work a trained artificial neural network is used as a fuzzy inference engine for if-then mapping. The proposed method is tested on IEEE 30-bus test system and a practical 75-bus Indian system and is found to produce accurate results for previously unseen load patterns almost instantaneously.

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