Claims
- 1. A method for locating a fault in a transmission line, the transmission line comprising a sending end and a receiving end, a plurality of tap loads connected to the transmission line each at a tap node location, a tap load connected to each of the plurality of tap nodes, with an equivalent tap node at an equivalent tap node location, the equivalent tap node dividing the transmission line into a sending side and a receiving side, the sending end comprising a measuring device, the receiving end comprising a measuring device, the method comprising:
obtaining measured circuit parameters including measured pre-fault and faulted current and voltage values at the sending end and at the receiving end of the transmission line; calculating the equivalent tap node location using measured current and voltage values at the sending end and at the receiving end of the transmission line; calculating an equivalent load impedance of the tapped loads at the equivalent tap node; calculating a first fault location assuming that the fault is located on the sending side of the equivalent tap node; calculating a second fault location assuming that the fault is located on the receiving side of the equivalent tap node; and selecting the calculated fault location from one of either the first fault location and the second fault location, by selecting the fault location having a value within a predetermined range.
- 2. The method of claim 1 further comprising calculating a phase angle difference due to unsynchronized measurement using the measured pre-fault current and the measured pre-fault voltage values.
- 3. The method of claim 2 wherein the obtaining measured circuit parameters further comprises obtaining measured circuit parameters from the sending end measuring device and the receiving end measuring device.
- 4. The method of claim 3 wherein the obtaining measured circuit parameters further comprises obtaining the values, Vp1S, Ip1S, T1, Vp1R, Ip1R, T1, V1S, I1S, T1, V1R, and I1R,T1 where:
Vp1S is the positive sequence pre-fault complex voltage from the sending end to ground, Ip1S, T1 is the positive sequence pre-fault complex current from the sending end to the equivalent tap node, Vp1R is the positive sequence pre-fault complex voltage from the receiving end to ground, IP1R, T1 is the positive sequence pre-fault complex current from the receiving end to the equivalent tap node, V1S is the positive sequence faulted complex voltage from the sending end to ground, I1S,T1 is the positive sequence faulted complex current from the sending end to the equivalent tap node, V1R is the positive sequence faulted complex voltage from the receiving end to ground, and I1R,T1 is the positive sequence faulted complex current from the receiving end to the equivalent tap node, and the transmission line is a three phase transmission line.
- 5. The method of claim 4 wherein the calculating an equivalent tap node location comprises calculating the equivalent tap node location mS, T1 from the following quadratic equation:
- 6. The method of claim 5 wherein the calculating a phase angle further comprises calculating the phase angle, δ, according to the following equation:
- 7. The method of claim 5 wherein the measured data is synchronized and the phase angle, δ, is zero.
- 8. The method of claim 6 wherein the calculating an equivalent tap load impedance of the tapped loads comprises calculating the equivalent tap load impedance of the tapped loads according to the following equation:
- 9. The method of claim 8 wherein the calculating a first fault location comprises calculating a first fault location according to the following equation:
- 10. The method of claim 9 wherein the calculating a second fault location comprises calculating a second fault location according to the following equation:
- 11. The method of claim 10 wherein the selecting the calculated fault location comprises selecting the calculated fault location from one of either mS,F and mR,F by selecting the one having a value within a predetermined range representing a full distance between two nodes.
- 12. The method of claim 11 wherein the predetermined range is from zero to one.
- 13. A system for locating a fault in a transmission line having a sending end and a receiving end, and a plurality of tap loads connected to the transmission line each at a tap node location, a tap load connected to each of the plurality of tap nodes, with an equivalent tap node at an equivalent tap node location, the equivalent tap node dividing the transmission line into a sending side and a receiving side, the system comprising:
a processor for calculating a fault location in the transmission line; a sending end measuring device connected to the processor for taking pre-fault and faulted measurements of the sending end of the transmission line; a receiving end measuring device connected to the processor for taking pre-fault and faulted measurements of the receiving end of the transmission line; and wherein the processor is adapted to obtain measured circuit parameters including measured pre-fault and faulted current and voltage values from the sending end measuring device and the receiving end measuring device, calculate the equivalent tap node location using measured pre-fault and faulted current and voltage values at the sending end and at the receiving end of the transmission line, calculate an equivalent load impedance of the tapped loads, calculate a first fault location assuming that the fault is located on the sending side of the equivalent tap node, calculate a second fault location assuming that the fault is located on the receiving side of the equivalent tap node, and select the calculated fault location from one of the first fault location and the second fault location, by selecting the fault location having a value within a predetermined range representing a full distance between two nodes.
- 14. The system of claim 13 wherein the processor is further adapted to calculate a phase angle difference due to unsynchronized measurement using the measured pre-fault current and the measured pre-fault voltage values.
- 15. The system of claim 14 wherein the sending end measuring device comprises a voltage sensor.
- 16. The system of claim 14 wherein the sending end measuring device comprises a current sensor.
- 17. The system of claim 14 wherein the receiving end measuring device comprises a voltage sensor.
- 18. The system of claim 14 wherein the receiving end measuring device comprises a current sensor.
- 19. The system of claim 14 wherein the sending end measuring device is connected to the processor through a data link.
- 20. The system of claim 14 wherein the receiving end measuring device is connected to the processor through a data link.
- 21. The system of claim 14 wherein the sending end measuring device comprises a memory for storing pre-fault measurements.
- 22. The system of claim 14 wherein the receiving end measuring device comprises a memory for storing pre-fault measurements.
- 23. The system of claim 14 wherein the processor is adapted to obtain the values, Vp1S, Ip1S, T1, Vp1R, Ip1R, T1, V1S, I1S,T1,V1R, and I1R, T1 where:
Vp1S is the positive sequence pre-fault complex voltage from the sending end to ground, Ip1S, T1 is the positive sequence pre-fault complex current from the sending end to the equivalent tap node, Vp1R is the positive sequence pre-fault complex voltage from the receiving end to ground, Ip1R, T1 is the positive sequence pre-fault complex current from the receiving end to the equivalent tap node, V1S is the positive sequence faulted complex voltage from the sending end to ground, I1S, T1 is the positive sequence faulted complex current from the sending end to the equivalent tap node, V1R is the positive sequence faulted complex voltage from the receiving end to ground, and IR, T1 is the positive sequence faulted complex current from the receiving end to the equivalent tap node, and the transmission line is a three phase transmission line.
- 24. The system of claim 23 wherein the processor is adapted to calculate the equivalent tap node location MS Tfrom the following quadratic equation:
- 25. The system of claim 24 wherein the processor is adapted to calculate the phase angle, δ, according to the following equation:
- 26. The system of claim 24 wherein the measured data is synchronized and the phase angle, δ, is zero.
- 27. The system of claim 25 wherein the processor is adapted to calculate the equivalent tap load impedance of the tapped loads according to the following equation:
- 28. The system of claim 27 wherein the processor is adapted to calculate a first fault location according to the following equation:
- 29. The system of claim 28 wherein the processor is adapted to calculate a second fault location according to the following equation:
- 30. The system of claim 29 wherein the processor is adapted to select the calculated fault location from one of either mS, F and mR, F by selecting the one having a value within a predetermined range representing a full distance between two nodes.
- 31. The system of claim 30 wherein the predetermined range is from zero to one.
- 32. The system of claim 30 wherein the transmission line is a single phase transmission line.
- 33. A computer-readable medium having instructions stored thereon for locating a fault in a transmission line, the transmission line comprising a sending end and a receiving end, a plurality of tap loads connected to the transmission line each at a tap node location, a tap load connected to each of the plurality of tap nodes, with an equivalent tap node at an equivalent tap node location, the equivalent tap node dividing the transmission line into a sending side and a receiving side, the sending end comprising a measuring device, the receiving end comprising a measuring device, the instructions, when executed on a processor, causing the processor to perform the following:
obtaining measured circuit parameters including measured pre-fault and faulted current and voltage values at the sending end and at the receiving end of the transmission line; calculating the equivalent tap node location using measured current and voltage values at the sending end and at the receiving end of the transmission line; calculating an equivalent load impedance of the tapped loads; calculating a first fault location assuming that the fault is located on the sending side of the equivalent tap node; calculating a second fault location assuming that the fault is located on the receiving side of the equivalent tap node; and selecting the calculated fault location from one of either the first fault location and the second fault location, by selecting the fault location having a value within a predetermined range.
- 34. The computer-readable medium of claim 33 further comprising calculating a phase angle difference due to unsynchronized measurement using the measured pre-fault current and the measured pre-fault voltage values.
- 35. The computer-readable medium of claim 33 wherein the obtaining measured circuit parameters further comprises obtaining measured circuit parameters from the sending end measuring device and the receiving end measuring device.
- 36. The computer-readable medium of claim 35 wherein the obtaining measured circuit parameters further comprises obtaining the values, Vp1S, Ip1S, T1, Vp1R, Ip1R, T1, V1S, I1S,T1, V1R, and I1R, T1 where:
Vp1S is the positive sequence pre-fault complex voltage from the sending end to ground, Ip1S, T1 is the positive sequence pre-fault complex current from the sending end to the equivalent tap node, Vp1R is the positive sequence pre-fault complex voltage from the receiving end to ground, Ip1R, T1 is the positive sequence pre-fault complex current from the receiving end to the equivalent tap node, V1S is the positive sequence faulted complex voltage from the sending end to ground, I1S, T1 is the positive sequence faulted complex current from the sending end to the equivalent tap node, V1R is the positive sequence faulted complex voltage from the receiving end to ground, and I1R, T1 is the positive sequence faulted complex current from the receiving end to the equivalent tap node, and the transmission line is a three phase transmission line.
- 37. The computer-readable medium of claim 36 wherein the calculating an equivalent tap node location comprises calculating the equivalent tap node location mS, T1 from the following quadratic equation:
- 38. The computer-readable medium of claim 37 wherein the calculating a phase angle further comprises calculating the phase angle, δ, according to the following equation:
- 39. The computer-readable medium of claim 37 wherein the measured data is synchronized and the phase angle, δ, is zero.
- 40. The computer-readable medium of claim 38 wherein the calculating an equivalent load impedance of the tapped load comprises calculating the equivalent load impedance of the equivalent tapped load according to the following equation:
- 41. The computer-readable medium of claim 40 wherein the calculating a first fault location comprises calculating a first fault location according to the following equation:
- 42. The computer-readable medium of claim 41 wherein the calculating a second fault location comprises calculating a second fault location according to the following equation:
- 43. The computer-readable medium of claim 42 wherein the selecting the calculated fault location comprises selecting the calculated fault location from one of either mS, F and mR, F by selecting the one having a value within a predetermined range representing a full distance between two nodes.
- 44. The computer-readable medium of claim 43 wherein the predetermined range is from zero to one.
- 45. The computer-readable medium of claim 33 wherein the transmission line is a single phase transmission line.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is related to co-pending and commonly assigned U.S. patent application Ser. No. ______, filed herewith entitled “Systems and Methods for Locating Faults on a Transmission Line with a Single Tapped Load” (Attorney Docket No.: ABTT-0230/B000570).