Hitachi Relion 670 Series Applications Manual page 183

1MRK506375-UEN Rev. N
Application
Single-phase railway
supply system
Auto transformer fed
railway supply system
Two-phase, high-
voltage railway
transmission system
8.9.4 Features of VRPVOC function
The VRPVOC function module has two independent protections, each consisting of:
• One overcurrent step with the following built-in features:
•
•
• One undervoltage step with the following built-in feature:
•
In the case of a fault in the railway grid, the converters feeding the railway network will see an
undervoltage condition and limit the fault current. In such cases, to ensure tripping under such
conditions, voltage restrained/controlled protection can be used. Due to the slow recovery of the
voltage after the fault, the voltage-controlled type of protection might be more suited for such SFC
fed systems.
Sometimes, in order to obtain the desired application functionality, it is necessary to provide
interaction between the two protection elements within the VRPVOC function by appropriate IED
configuration (for example, overcurrent protection with under-voltage seal-in).
8.9.4.1 Undervoltage seal-in
To apply the VRPVOC function, the configuration is done according to
figure, the pickup of the overcurrent stage will enable the undervoltage stage. Once enabled, the
undervoltage stage will start a timer, which causes function tripping, if the voltage does not recover
above the set value. To ensure a proper reset, the function is blocked two seconds after the trip
signal is issued.
Railway application RER670
Application manual
IBase Value
Set as rated CT primary current in case of
line/feeder protection.
Set as rated primary current of the protected
object in case of transformer, convertor, or
generator protection.
Set as rated CT primary current in case of
line/feeder protection.
Set as rated primary current of the protected
object in case of transformer, convertor, or
generator protection.
Set as rated CT primary current in case of line
protection.
Set as rated primary current of the protected
object in case of transformer or generator
protection.
Selectable definite time delay or Inverse Time IDMT characteristic
Voltage restrained/controlled feature is available in order to modify the start level of the
overcurrent stage in proportion to the magnitude of the measured voltage
Definite time delay
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UBase Value
Set UBase as rated catenary to rail voltage
RMS value. For example: 25 kV.
Set UBase as rated catenary to rail voltage if
only one VT is available. For example: 25kV.
Set UBase as rated catenary to negative
feeder voltage if two VTs are available. For
example: 50 kV.
Set UBase as rated phase-to-phase voltage
RMS value. For example: 132 kV.
GUID-7C9071BF-8062-48E9-9D3D-E75DED073540 v1
GUID-13BE02D3-1322-4075-859B-617CFF608657 v8
Figure 69. As seen in the
Section 8
Current protection
177