Alstom MiCOM P846, Technical Manual

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P846/EN OP/D Operation
(OP) 5-4
MiCOM P846
OP
with its capacitive
and CT3 for shunt
reactor) that are connected to the DLO analog inputs (the shunt reactor current is needed to
ctor is open while the line breakers are closed
a:
mpensation with shunt reactors
suring line voltage and shunt reactor
current
Security:
False detections must be avoided in the following categories of phenomena:
−
Low or very low power transfer on the monitored line
−
Distortion on line voltages and currents during faults
−
Fast variations in the line power flow
−
Reversal of power flow direction
−
Power oscillations
−
Sub-synchronous resonances
−
Presence of harmonics
Speed:
−
The DLO must detect any change in the line status in 35 ms or less. This response time
includes the effects of the CTs magnetizing discharge currents, the DLO internal filters
and the delay of its output contacts.
Figure 1 shows the typical configuration of a line in a HV/EHV substation
voltage transformer CVT and current transformers (CT1, CT2 for breakers
avoid a false detection when the line disconne
in order to feed the shunt reactor. The line could then erroneously be considered as closed).
Performance requirements for the DLO in terms of reliability, security and speed are listed
below:
Reliability:
The DLO must detect the open-close status of a line at both ends for the
following categories of phenomen
−
Line closing or opening at local end (with or without a shunt reactor connected)
−
Line opening at remote end (with or without a shunt reactor connected) with line
charging current measured by the DLO
−
Line closing at local end when already open at remote end. MW surge and line charging
measured by the DLO
−
Line opening at both ends with 100% co
−
Line opening with residual CT current measured by the DLO
−
Closing of a line at remote end with DLO mea