ABB RELION REF615R, Technical Manual

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10.2.3 Functionality
The fault location function FLO performs the estimation of apparent distance to fault and
fault resistance. The calculation is performed by comparing the pre-fault current and
voltage phasor by fault current and voltage phasor along with line parameters.
The fault loop is determined and the respective voltage and current phasor are selected for
the fault location algorithm. The pre-fault current and voltage phasor are used to calculate
the pre-fault load impedance, and fault current and voltage phasor are used to calculate the
apparent impedance during the fault. The load impedance, apparent impedance and line
parameters are used to estimate the fault resistance and distance to fault.
10.2.4 Operation principle
The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are “Enable” and “Disable”.
The operation of FLO can be described with a module diagram. All the modules in the
diagram are explained in the next sections.
V_A
V_B
I_A
I_B
I_C
FLT_DIST
FLT_ LOOP
FLT_R
XF_ LOOP
Buffering
logic
Fault
loop
determination
Fault
location
V_C
GUID-5DC1EB9F-1A27-4D25-BAC9-612504B55491 V1 EN
Figure 273: Functional module diagram
Buffering logic
The Buffering logic module buffers the three-phase voltage and current phasor input
values (DFT values of V_A, V_B, V_C, I_A, I_B, I_C). Once the phase current magnitude
is more than the
Phase Level setting, the pre-fault buffer freezes and the updating of fault
buffer is started. The fault buffer freezes once the buffer is updated fully. The fault
location algorithm is started only if the Relay Trip signal is detected.
1MRS240050-IB C
Section 10
Recording functions
REF615R 527
Technical Manual