Hitachi Relion 670 Series Applications Manual page 101

1MRK511407-UUS Rev. N
• If correct fault loop identification is not achieved
• If symmetrical faults are not detected during power swing
• During deadtime of a single pole autoreclosing cycle,
•
•
Instead of the above, a method based on the change of currents (or delta current) supplemented with
the change in ucosφ method is implemented. The phase selection (or correct faulty loop identification) is
accomplished for all types of faults that occur during the power swing even during the deadtime of a
single pole autoreclosing cycle.
It is suggested to perform transient stability studies and hardware-in-loop tests to determine the
placement of power swing unblocking feature in the power network depending upon the power system
operating scenarios.
Blocking all distance protection zones during power swing
This application refers to the blocking of all distance protection zones that may operate for any power
swing and prevent the distance protection zone from issuing a trip signal. Figure
configure ZMBURPSB and ZMFPDIS in ACT tool of PCM600 to achieve blocking of all distance
protection zones during power swing.
Based on system studies, one can set the operation of power swing detection to either one-out-of-three
or two-out-of-three phase mode. In this example,
• For one-out-of-three phase mode, REL1PH is set by configuring ON from FXDSIGN function block
• connect the ZMBURPSB output, PSB_START to input BLKZx (where x = 1,...5, RV and BU) of
ZMFPDIS function block
• adapt PSB and PDIS settings based on the power network and its operating conditions and set
Operation to On in both the function blocks
• set OpModePSU to Off in ZMBURPSB function block, that is, power swing unblocking feature is
disabled.
Phasor measurement unit RES670
Application manual
this unbalance (caused because of two healthy phases carrying power flow) can inhibit PSB
detection and cause maloperation of distance protection zones during power swing or
misoperation of distance protection zones because of the blocking of the supervision elements
by taking single pole tripping output. Consequently, system continuity will be affected during
damped power system oscillations (or slow power swings)
It is recommended for a very weak source behind the relay location that power swing
unblocking feature must be disabled (that is, OpModePSU is set to Off) for secure operation.
Also, output signal START of ZMBURPSB function must be connected to BLKZx of ZMFPDIS
function to achieve blocking of distance measuring zone(s) during power swing.
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Section 7
Impedance protection
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