logic for weak-end infeed and current reversal, included
in Current reversal and weak-end infeed logic for
residual overcurrent protection (ECRWPSCH) function.
Current reversal and weak-end infeed logic for
residual overcurrent protection ECRWPSCH
M13928-3 v8
The Current reversal and weak-end infeed logic for
residual overcurrent protection (ECRWPSCH) is a
supplement to Scheme communication logic for residual
overcurrent protection ECPSCH.
To achieve fast fault clearing for all earth faults on the
line, the directional earth fault protection function can
be supported with logic that uses tele-protection
channels.
This is why the IEDs have available additions to the
scheme communication logic.
M13928-6 v2
If parallel lines are connected to common busbars at
both terminals, overreaching permissive communication
schemes can trip unselectively due to fault current
reversal. This unwanted tripping affects the healthy line
when a fault is cleared on the other line. This lack of
security can result in a total loss of interconnection
between the two buses. To avoid this type of
disturbance, a fault current reversal logic (transient
blocking logic) can be used.
M13928-8 v5
Permissive communication schemes for residual
overcurrent protection can basically operate only when
the protection in the remote IED can detect the fault.
The detection requires a sufficient minimum residual
fault current, out from this IED. The fault current can be
too low due to an opened breaker or high-positive
and/or zero-sequence source impedance behind this
IED. To overcome these conditions, weak-end infeed
(WEI) echo logic is used. The weak-end infeed echo is
limited to 200 ms to avoid channel lockup.
Direct transfer trip DTT
Low active power and power factor protection LAPPGAPC
GUID-25A2A94F-09FE-4552-89F8-CF22632A7A0D v2
Low active power and power factor protection
(LAPPGAPC) function measures power flow. It can be
used for protection and monitoring of:
• phase wise low active power
• phase wise low power factor
• phase wise reactive power and apparent power as
service values
Following features are available:
• Definite time stage for low active power protection
• Definite time stage for low power factor protection
• Individual enabling of Low active power and Low
power factor functions
• Low active power trip with 2 selection modes '1 out of
3' and '2 out of 3'
• Phase wise calculated values of apparent power,
reactive power, active power and power factor are
available as service values
• Insensitive to small variations in voltage and current
Compensated over and undervoltage protection
COUVGAPC
GUID-229EB419-0903-46FA-9192-BBB35725C841 v2
Compensated over and undervoltage protection
(COUVGAPC) function calculates the remote end voltage
of the transmission line utilizing local measured voltage,
current and with the help of transmission line
parameters, that is, line resistance, reactance,
capacitance and local shunt reactor. For protection of
long transmission line for in zone faults, COUVGAPC can
be incorporated with local criteria within direct transfer
trip logic to ensure tripping of the line only under
abnormal conditions.
Sudden change in current variation SCCVPTOC
GUID-413851A9-5EB7-4C48-8F5D-E30E470EFFAF v2
Sudden change in current variation (SCCVPTOC)
function is a fast way of finding any abnormality in line
currents. When there is a fault in the system, the current
changes faster than the voltage. SCCVPTOC finds
abnormal condition based on phase-to-phase current
variation. The main application is as a local criterion to
increase security when transfer trips are used.
Carrier receive logic LCCRPTRC
GUID-79AB9B9E-9200-44D7-B4EE-57C9E7BB74A9 v2
In Direct transfer trip (DTT) scheme, the received CR
signal gives the trip to the circuit breaker after checking
certain local criteria functions in order to increase the
security of the overall tripping functionality. Carrier
receive logic (LCCRPTRC) function gives final trip output
of the DTT scheme.
Features:
• Carrier redundancy to ensure security in DTT scheme
• Blocking function output on CR Channel Error
• Phase wise trip outputs
Negative sequence overvoltage protection LCNSPTOV
GUID-C5CBB6A2-780D-4008-98E3-455A404D32CB v2
Negative sequence components are present in all types
of fault condition. Negative sequence voltage and
current get high values during unsymmetrical faults.
Zero sequence overvoltage protection LCZSPTOV
GUID-4CF3EC6A-D286-4808-929B-C9302418E4ED v2
Zero sequence components are present in all abnormal
conditions involving earth. They can reach considerably
high values during earth faults.
Negative sequence overcurrent protection LCNSPTOC
GUID-C4F99554-88BC-4F11-9EFE-91BCA6ED1261 v2
Negative sequence components are present in all types
of fault condition. They can reach considerably high
values during abnormal operation.
Line differential protection RED670
1MRK 505 379-BEN N
Hitachi Power Grids 47
© Copyright 2017 Hitachi Power Grids. All rights reserved
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