1. High impedance faults detection in electrical power systems Dr. Khaled M. EL-Naggar College of Technological Studies, Kuwait

2. High impedance faults Definition Why it is a problem Different techniques for detection Comparison & Evaluation ANN-GA Technique Conclusions

5. Hi-Z faults produce primary current levels of 0 to 100 Amps

10. Causes The main causes of HIFs are tree branches touching a phase conductor, Broken line on ground (Downed Conductor)Almost all HIFs involve the ground directly orindirectly.

11. Fault currents on various surfaces Surface Fault current (A)Dry Asphalt 0Dry Sand 0Wet Asphalt 1Wet Sand 5 Dry grass 25Concrete(non-reinforced) 10 Wet grass 50Concrete (reinforced) 70

13. Detect partially failing insulation before complete failure which can lead to power outages and loss of production

15. Small fault current (10 – 100 Amps)

16. Current values will continue to fluctuate

17. Significant harmonic currents

18. Random arcing

20. Electrical Detection Methods Open Conductor Detection This electrical HIF detection method detects loss of voltage to determine a broken conductor. The system measures the phase voltage at each end of a single phase lateral. When the voltage of any phase drops below the specified threshold, a signal is sent to upstream device. The upstream device opens if voltage is present at the upstream device.

21. Ratio RelaysThe ratio of the negative sequence or zero sequence to positive sequence current is calculated and when this ratio exceeds a predetermined value, a trip signal is produced

22. Phase current rate of change The phase current rate of change is high (quick ) at the moment of fault, while the current changes progressively with load variation. This algorithm monitors the sample difference at the corresponding sampling point of two subsequent cycles

25. 3rd ,5th and 7th harmonic detection The variations in amplitudes and phase angles of the third, fifth and seventh order harmonic currents are monitored

28. Wavelet analysis

31. Particle SwarmIi(actual) − Ii(calculated ) = errori Fitness Function to be minimized based on the error (absolute or square)

32. High Impedance Fault Detection and Relaying Scheme Data Collection, CT& PT Sampling Waveforms Genetic Algorithm Signal Analysis (GA) ANN Based Detection

33. Input Data Fundamental Component Lower Harmonics Higher Harmonics GR Current before the highest transient value Current after the highest transient value Current Rate of change cycle to cycle

34. Study Cases Normal Load switching Capacitor switching Load switching + Capacitor switching HIF HIF + Capacitor switching HIF + Capacitor switching + Load switching

35. Study System 11 KV Radial system 19 11 KV feeders 11/0.4 KV Transformers Loads Capacitors

37. Different phases

38. Different inception angle

39. Different loading conditions

40. Different capacitor switching conditions

42. Personnel hazard

43. Property damage

44. Poor customer service

45. HIFs Detection techniques classified as

46. Mechanical

48. Regardless the method used, not all HIFs are detectable. For example, the case where a conductor near the end of a feeder breaks and falls to the ground.