Table 6 The numerical values of the current imbalance coefficients based on the correlation factors for the protection scheme.
Experiment number | Fault position | The current imbalance coefficients based on the Pearson similarity function for the protection scheme Imbalance coefficients during the fault period UFi2 = The maximum value of (UFiab2, UFibc2, or UFica2) | |||||||
|---|---|---|---|---|---|---|---|---|---|
Unbalance/balance | riab | ribc | rica | UFiab2 (%) | UFibc2 (%) | UFica2 (%) | UFi2 (%) | ||
Experiment 1 | Winding-to-neutral fault (C1-N) | Unacceptable imbalanced current (Tripping action) | − 1.0 | − 1.0 |  + 0.8 | 50 | 50 | 130 | 130 |
Experiment 2 | Winding-to-neutral fault (C2-N) | − 1.0 | − 1.0 |  + 1.0 | 50 | 50 | 150 | 150 | |
Experiment 3 | Winding-to-neutral fault (C3-N)) | − 1.0 | − 0.90 |  + 1.0 | 50 | 40 | 150 | 150 | |
Experiment 4 | Winding-to-neutral fault (B1-N) |  + 0.80 | − 1.0 | − 0.95 | 130 | 50 | 45 | 130 | |
Experiment 5 | Winding-to-neutral fault (B2-N) |  + 0.95 | − 1.0 | − 0.90 | 145 | 50 | 40 | 145 | |
Experiment 6 | Turn-to-turn fault (A1-A2) | − 1.0 |  + 0.95 | − 1.0 | 50 | 145 | 50 | 145 | |
Experiment 7 | Turn-to-turn fault (A2-A3) | − 0.52 | − 0.25 | − 0.80 | 2 | 25 | 30 | 30 | |
Experiment 8 | Winding-to-winding fault (B1-C1) | − 0.80 | − 1.0 |  + 0.75 | 30 | 50 | 125 | 125 | |
Experiment 9 | Winding-to-winding fault (B2-C2) | − 0.90 | − 1.0 |  + 0.95 | 40 | 50 | 145 | 145 | |
Experiment 10 | Winding-to-winding fault (B3-C3) | − 0.85 | − 1.0 |  + 0.80 | 35 | 50 | 130 | 130 | |
Experiment 11 | Phase A loss |  + 0.41 | − 0.44 | − 0.37 | 91 | 6 | 13 | 91 | |
Experiment 12 | Power transformer shutdown |  + 0.30 | − 1.0 | − 0.10 | 80 | 50 | 40 | 80 (Actually, the tripping has been accomplished) | |
