Setting Guidelines; General; Setting Of Common Parameters; Negative Sequence Based - Hitachi Relion 670 Series Applications Manual

1MRK511407-UUS Rev. N
13.2.3

Setting guidelines

13.2.3.1

General

The negative and zero sequence voltages and currents always exist due to different non-symmetries in
the primary system and differences in the current and voltage instrument transformers. The minimum
value for the operation of the current and voltage measuring elements must always be set with a safety
margin of 10 to 20%, depending on the system operating conditions.
Pay special attention to the dissymmetry of the measuring quantities when the function is used on long
untransposed lines, on multicircuit lines and so on.
The settings of negative sequence, zero sequence and delta algorithm are in percent of the base voltage
and base current for the function. Common base IED values for primary current (IBase), primary voltage
(VBase) and primary power (SBase) are set in Global Base Values GBASVAL. The setting
GlobalBaseSel is used to select a particular GBASVAL and used its base values.
13.2.3.2

Setting of common parameters

Set the operation mode selector Operation to Enabled to release the fuse failure function.
The voltage threshold VPPU is used to identify low voltage condition in the system. Set VPPU below the
minimum operating voltage that might occur during emergency conditions. We propose a setting of
approximately 70% of VBase.
The drop off time of 200 ms for dead phase detection makes it recommended to always set SealIn to
Enabled since this will secure a fuse failure indication at persistent fuse fail when closing the local
breaker when the line is already energized from the other end. When the remote breaker closes the
voltage will return except in the phase that has a persistent fuse fail. Since the local breaker is open there
is no current and the dead phase indication will persist in the phase with the blown fuse. When the local
breaker closes the current will start to flow and the function detects the fuse failure situation. But due to
the 200 ms drop off timer the output BLKZ will not be activated until after 200 ms. This means that
distance functions are not blocked and due to the "no voltage but current" situation might issue a trip.
The operation mode selector OpModeSel has been introduced for better adaptation to system
requirements. The mode selector enables selecting interactions between the negative sequence and
zero sequence algorithm. In normal applications, the OpModeSel is set to either V2I2 for selecting
negative sequence algorithm or V0I0 for zero sequence based algorithm. If system studies or field
experiences shows that there is a risk that the fuse failure function will not be activated due to the system
conditions, the dependability of the fuse failure function can be increased if the OpModeSel is set to V0I0
OR V2I2 or OptimZsNs. In mode V0I0 OR V2I2 both negative and zero sequence based algorithms are
activated and working in an OR-condition. Also in mode OptimZsNs both negative and zero sequence
algorithms are activated and the one that has the highest magnitude of measured negative or zero
sequence current will operate. If there is a requirement to increase the security of the fuse failure function
OpModeSel can be selected to V0I0 AND V2I2 which gives that both negative and zero sequence
algorithms are activated and working in an AND-condition, that is, both algorithms must give condition for
block in order to activate the output signals BLKV or BLKZ.
13.2.3.3

Negative sequence based

The relay setting value 3V2PU is given in percentage of the base voltage VBase and should not be set
lower than the value that is calculated according to equation 99.
Phasor measurement unit RES670
Application manual
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Section 13
Secondary system supervision
IP15000-1 v1
M13683-3 v5
M13683-9 v9
M13683-17 v9
189