IEEE Std C37.114 pdf free download

IEEE Std C37.114 pdf free download.Determining Fault Location on AC Transmission and Distribution Lines.
Another method of determining the line impedance parameters involves the direct measurement of the open circuit, and short-circuit voltages and currents. The accuracy is about the same as calculations based on Carson’s equations. This method requires special equipment and network conditions (i.e., the line must be taken out of service) to set up the tests.
A third method involves the estimation of the line parameters through the solution of two-port equations based on synchronized phasor measurement obtained from direct measurements from a digital relay or a fault recorder. The use of controlled tests to obtain the data and using the higher sampling rate of a digital recorder can result in impedance parameters with a high accuracy. It should be noted that all three techniques rely on an accurate value for the length of the line.
It is suggested that the calculations for most lines can still be made using (‘arson’s equations. These parameters can then be verified using synchronized phasors of method three or by experience from the calculation of the locations from faults with verifiable locations. In spite of the accuracy of the line impedance parameters, the accuracy of fault location will be dependent upon the location technique employed, the sampling rate of the data collected, and the presence of unknown variables, most notably the amount of fault resistance.
Line parameter errors introduced on lines without transpositions arc described in 5.12.
1.4.2 Parameters required for traveling-wave fault locating
When a current-based traveling-wave fault locator is commissioned, the remote units arc programmed with the substation and line name, sensitivity, and default sampling settings. No specific line parameters (impedances, etc.) are required for the remote units. The host personal computer (PC). on command, can receive the data from each of the remote units. Once the PC has the data files, the information is analyzed and the line length can be determined. The only inputs required to analyze fault data with the traveling- wave fault locator are line length and wave velocity. The individual line length can be determined by energizing the line. The procedure is to energize the line in a radial fashion and then measure the time the reflected wave takes to return to the source. The known line length is compared with the length determined by the timing of the reflected wave. This method may not always give accurate results due to the effects of pre-insertion resistors and the closing point on the voltage sine wave. It is not always necessary to rely solely on this method because the line length calibration can also be determined from evaluation of any faults occurring on adjacent line sections.
For single- ended algorithms, both methods could be used. However, for double-ended methods, it could be confusing to use the traditional method, as the fault location could be calculated from both ends of the line, so the true value needs a common reference to be compared with. Furthermore, as for a particular power network, the combination of system source impedance ratios and location of the fault have a major effect on accuracy of single-ended algorithms. When evaluating and comparing errors of various algorithms, it is very important to take this into account. It may be easier to compare various algorithms having a common reference (such as the line length). Staging faults at the end of the line with favorable source impedance ratios could result in a misleading high accuracy.IEEE Std C37.114 pdf download.