Power Systems Lab · 18 modules · all computed in your browser
Travelling-wave fault location
Bewley lattice, double- and single-ended TW location, reflection coefficients, time-sync error.
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Power Systems Lab · 18 modules · all computed in your browser
Bewley lattice, double- and single-ended TW location, reflection coefficients, time-sync error.
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Line and fault
Γ bus A / B
-0.33 / 0.00
Γ / τ at fault
-0.97 / 0.03
Double-ended
59.90 km (err -103 m)
Single-ended
60.08 km or 139.92 km
Bewley lattice diagram
Current travelling waves at the terminals
Arrivals at A
| t (µs) | wave amplitude | path |
|---|---|---|
| 204.22 | -0.968 | F→A |
| 612.67 | -0.312 | F→A→A↺F |
| 1021.11 | -0.101 | F→A→A↺F→A↺F |
| 1429.56 | -0.032 | F→A→A↺F→A↺F→A↺F |
| 1838.01 | -0.010 | F→A→A↺F→A↺F→A↺F→A↺F |
Single-ended methods take the time between the first arrival and the reflection from the fault. A wave reflected from the remote bus arrives at 1157.3 µs and gives the mirror answer L − d, so relays check polarity, use the other end, or use the impedance-based estimate to pick the right one.
Learn it
A fault launches voltage and current steps that travel along the line at close to the speed of light, roughly 0.3 km per microsecond. Timing their arrival at the line terminals locates the fault far more precisely than impedance methods, which suffer from fault resistance, infeed and mutual coupling. With synchronized clocks at both ends, the difference in arrival times gives the location directly. With one end, the relay times the echo from the fault itself, which needs the fault to reflect and suffers from ambiguity with reflections from the remote bus.
Quiz · 0/3
1. Why is double-ended TW location insensitive to fault resistance?
2. How far does a 1 µs sync error move a double-ended estimate?
3. A fault at a voltage zero crossing…