P.3.124
SEL-411L Relay Protection Manual Date Code 20151029
Protection Functions
Fault Location
The FLM field in the summary report shows the method by which the device
calculated fault location. The device uses the method it considers the best
available option (from among TW, ME or SE) at the time. For example, if TW
data are available, then the best method is the TW method, and the FLM field
displays TW as the method used to calculate the fault location. If TW data are
not available but multi-ended data are available, then the FLM field displays
ME, and the TW Location field displays $$$$.
The priority for selecting the best available fault location method is (in
decreasing order) as follows:
➤ TW—Traveling wave method
➤ ME—Impedance-based method using total current
➤ SE—Impedance-based method using single-ended (local)
current
The best available fault location result is available as Analog value
CONFLOC (consolidated fault location). The following analog quantities are
also available:
➤ TWFLOC—Traveling wave-based fault location
➤ 87LOC—Impedance-based using total current
➤ FLOC—Impedance-based using local current
Traveling Wave
The relay supports the traveling wave fault location method for two-terminal
lines. The relay uses the type D (double ended) traveling wave (TW)
algorithm to compute fault locations. A separate, dedicated analog-to-digital
converter samples two three-phase sets of currents (IAW, IBW, and ICW and
IAX, IBX, and ICX) at 1.5625 MHz. If TWCOMI is set to N and TWALTI is
set to NA or 0, the TW fault location algorithm uses the IW currents. If
TWALTI is set and evaluates to logical 1, the TW fault location algorithm uses
the IX currents. If TWCOMI is set to Y, the algorithm uses the combined
currents (IAW+IAX, IBW+IBX, and ICW+ICX).
Setting TWFLIF enables the fault location calculations. Following a
disturbance, the relay estimates the traveling wave arrival information only if
TWFLIF is asserted. If the differential channel is configured (E87CH = 2E2SS
or 2SD in Port 87 settings), then the relay sends the traveling wave arrival
information to the remote terminal. When the relay receives the remote
traveling wave information (via a configured differential communications
channel), the algorithm calculates the fault location. For best performance,
program TWFLIF such that it asserts for internal fault conditions only.
NOTE: If you change the TWFLIF
default settings, be sure to make the
same changes to the ER settings.
The event summary includes the calculated traveling wave fault location
information and makes it available as an analog quantity, TWFLOC. The
traveling wave COMTRADE (.HDR file) also provides traveling wave arrival
information at each terminal. Furthermore, the traveling wave arrival time
(nanoseconds) is also available as DNP analog inputs (see Analog Inputs on
page C.4.30).
Figure 3.74 shows the traveling waves captured at either terminal. Table 3.59
describes the TW fault location settings.
To Next Page
Loading...
