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Section 11
Secondary system supervision
The vector shift detection guarantees fast and reliable detection of mains failure in almost all
operational conditions when a distributed generation unit is running in parallel with the mains
supply, but in certain cases this may fail.
If the active and reactive power generated by the distributed generation units is nearly
balanced (for example, if the power mismatch or unbalance is less than 5...10%) with the active
and reactive power consumed by loads, a large enough voltage phase shift may not occur
which can be detected by the vector shift algorithm. This means that the vector shift
algorithm has a small non-detectionzone (NDZ) which is also dependent on the type of
generators, loads, network and start or operate value of the vector shift algorithm.
Other network events like capacitor switching, switching of very large loads in weak network
or connection of parallel transformer at HV/MV substation, in which the voltage magnitude is
not changed considerably (unlike in faults) can potentially cause maloperation of vector shift
algorithm, if very sensitive settings are used.
The vector shift detection also protects synchronous generators from damaging due to
islanding or loss-of-mains.
11.3.3
Setting guidelines
Operation : This setting is used to enable/disable the delta supervision function.
Umin : The minimum start level setting should be set as % of UBase . This setting enables the
function to start detecting delta. Typical setting is 10% of
phase to ground , this setting is taken as 50% of the set value.
set as
MeasMode : This setting is used to detect the mode of measurement; phase to phase or phase
to ground .
OpMode : This setting is used to select the mode of operation. For protection applications, this
should be set to
mode or DFT mag mode.
DelU> : This setting is used to detect the start value for instantaneous sample, RMS, DFT mag
based delta detection. Set a typical value of 50% of
detection.
DelUang> : This setting is used for angle based delta detection. This setting could be used to
detect islanding condition. A typical setting of 8-10 deg. is good to detect a major islanding
condition.
DeltaT : This setting defines the number of old cycles data to be used for delta calculation in
RMS/DFT Mag and angle mode. Typical value is 2 cycles. This value is not used if
chosen as instantaneous 1 cycle or instantaneous 2 cycle.
tHold : This setting defines the pulse length for supervision start signal. Typical value is 100 ms.
11.4
Current based delta supervision DELISPVC
11.4.1
Identification
Function description
Current based delta supervision
246
Instantaneous 1 cycle old . Load supervision can be done using vector shift
IEC 61850
identification
DELISPVC
GUID-9356F1C8-9EBA-43E3-8445-CB74E12BC57E v2
UBase . If the MeasMode setting is
UBase to use this function as fault
GUID-4F012876-FA0A-4A97-9E23-387974304CED v2
IEC 60617
ANSI/IEEE C37.2
identification
device number
–
7I < >
Busbar protection REB670
1MRK 505 370-UEN D
OpMode is
GUID-0B735A27-6A7D-40E1-B981-91B689608495 v1
Application manual
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