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DETECTION OF HIGH IMPEDANCE FAULTS USING ARTIFICIAL NEURAL NETWORKS. By Ibrahim El-Amin Mohammad H. Al-Mubarak. May 2003. Problem Definition. High Impedance Fault (HIF) is a fault on primary distribution (PD) system that cannot be detected by conventional O/C protection
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DETECTION OF HIGH IMPEDANCE FAULTS USING ARTIFICIAL NEURAL NETWORKS By Ibrahim El-Amin Mohammad H. Al-Mubarak May 2003
Problem Definition • High Impedance Fault (HIF) is a fault on primary distribution (PD) system that cannot be detected by conventional O/C protection • 95% of faults on PD feeders occur on O/H lines • Undetected HIFs may result in public hazard and property damage • Primary motivator to design HIF detectors is public safety
Problem Statement and Paper Objective • O/C relays are set to operate for currents between 125-200% of the normal load current • HIFs draw currents in the range of 0-100 A • Objective of paper is to develop an ANN based HIF detector that can also: • Locate the HIF • Distinguish HIFs from normal switching events • Identify the faulty phase
Feeder Simulation with EMTP Fault Diagnosis Data Scaling and Preprocessing ANN Trainging and Testing Solution Approach
Feeder Simulation • EMTP is used because • It can handle switch closing and opening (ideal for transient analysis or fault simulation) • It can simulate unbalanced systems (e.g. single line to ground faults) • Simulation is for 5 cycles (83.33 ms) at a sampling rate of 0.2778 ms • 300 samples/phase for each case, i.e. 1800 samples to represent the 3 phases of the current and voltage waveforms
Feeder Simulation (Cont’d) Phase-C Current Waveform for Load-4 and C1 Switching
Designing and Testing the ANN ANN Targets
Test Results of the ANN Designs w.r.t. Targets 1 3 2 1 3 4 2
Conclusions • Out of the eight design versions, four are promising for HIF diagnosis applications. These are D1F, D2B, D3R & D3B • Design D3R is the best because • 100% accuracy for all test cases and all targets • 100% accuracy for mid-span HIF cases, for extended feeder cases, for varying fault impedance cases and for varying transmission line impedance cases • All errors are for lightly loaded feeder cases, but none of them is in detecting the HIF occurrence • The design fails to distinguish between two fault events but succeeds in not false-indicating a HIF for normal system operation or vice versa