davidbeach
Electrical
- Mar 13, 2003
- 9,509
I am trying to refine our line constants calculations to account for differences between the calculations and actual faults. Our Z1 values seem pretty close, but it is quite clear that our Z0 values could be improved. Historically the line constants have been calculated considering only the three conductors of the transmission line (and mutual impedance with other adjacent transmission lines). As a first step I have added the under built distribution neutral into the calculations where present, and that makes a significant difference. There are a few other things that I'd like to be able to look at, but need a bit more information. Documented references would be great.
1. Does the presence of 750 VDC lines (light rail traction power) parallel to our AC lines need to be accounted for? If so, how?
2. Are there any good references for calculation of the affect of rails as ground conductors, such as electrical properties of the rail and how the grounding of the rail (typically impedance grounded) should be accounted for?
3. In the development of the calculations in Anderson (Analysis of Faulted Power Systems) he makes the assumption that any ground conductors are grounded at both ends; does the presence of multiple grounds alter the results?
4. The calculations for the transformation from phase impedances to sequence impedances (Anderson) makes the assumption that there are three phases. What affect on the results would there be if instead of two circuits in phase with each other the lines in question have a mutual 30 degree phase shift?
Thanks.
1. Does the presence of 750 VDC lines (light rail traction power) parallel to our AC lines need to be accounted for? If so, how?
2. Are there any good references for calculation of the affect of rails as ground conductors, such as electrical properties of the rail and how the grounding of the rail (typically impedance grounded) should be accounted for?
3. In the development of the calculations in Anderson (Analysis of Faulted Power Systems) he makes the assumption that any ground conductors are grounded at both ends; does the presence of multiple grounds alter the results?
4. The calculations for the transformation from phase impedances to sequence impedances (Anderson) makes the assumption that there are three phases. What affect on the results would there be if instead of two circuits in phase with each other the lines in question have a mutual 30 degree phase shift?
Thanks.