Accuracy And Twfl With Cvts; Underground And Overhead Cables; Automatic Fault Location; How To Test The Tw Fault Location In Lab - GE RPV311 Technical Manual

RPV311
2.2

Accuracy and TWFL with CVTs

2.3

Underground and Overhead Cables

3

Automatic Fault Location

4

How to Test the TW Fault Location in Lab

RPV311-TM-EN-7
The accuracy of the TWFL lies mostly in the proper identification of the traveling
wave in both ends of the line and the accuracy of the GPS clock. The theoretical best
possible accuracy is ± 60 meters using a GPS clock with 100ns accuracy, as the GPS
accuracy enhances the fault location becomes more accurate. The average error is ±
150 meters.
CVTs and bus composition would not influence on the correct time location of the
traveling wave and that is the most important factor in the fault location using TW,
as shown in the equation presented below. The CVT and bus composition could
affect the quality of the TW registered and it could make it difficult for the automatic
locator algorithm to locate the fault, but the traveling wave will be registered in the
COMTRADE file, it will be just a matter of correctly pointing it out. Reason features an
option for locating the fault in those cases, explained in Chapter 12: Software – RPV
Tools - TW Fault Locator, where the user tells the software where the wavefront is
and then the software calculates the fault location based on that point.
There are no restraints regarding the fact that the cable is underground. In the
calculation of the fault location, there is a parameter k (as presented in the fault
location formula aforementioned) that depends on the physical characteristics of the
wire. When the TW fault locator method is used on combination of cable the k
parameter becomes the mean value of the k of each separate wire, it will not
represent the actual k of the line at the faults location, it is an approximation. The
method will work but with less accuracy.
Note:
The maximum number of RA333 that can be connected to the RPV311 is 4.
The RA333 module has to be connected to the RPV311 processing module before
its initialization. Otherwise a log message will tell the user to reboot the device.
The RPV Manager software is a tool design for management of COMTRADE files,
configuration and fault location. One of its features is the automatic TW fault
location.
The RPV Manager download the COMTRADE files from both terminals of the line,
performs the fault location calculations, displays the fault location results in its
interface and sends the location via MODBUS to the supervisory system.
Details on the configuration procedure, please refer to Chapter Software – RPV
Manager.
Chapter 9 – TW Fault Locator
145