Hitachi Relion 670 Series Applications Manual page 182

Section 8
Current protection
8.9.2 Identification
Function description
Voltage-restrained time overcurrent
protection
8.9.3 Application
The voltage-restrained time overcurrent protection can be used as a backup protection for railway
networks. Especially railway networks with limited short circuit current capacity, such for example,
are Static Frequency Converter fed (or even only partly SFC fed) railway networks can benefit from
such backup functionality. If the fault happens in these networks, the fault current amplitude depends
upon the converter control characteristics, which define the behavior between voltage and current.
However, voltage magnitude will typically be quite low during fault conditions in such networks. A
voltage-restrained or voltage-controlled overcurrent relay can then be set in order to remain in the
picked-up state despite of the low fault current contribution from the converter. As well this will ensure
that the fault will be cleared by a backup trip in case of failure of the main protection.
8.9.3.1 Measured quantities for different railway applications
The voltage-restrained time overcurrent protection function VRPVOC can be applied to the following
railway supply systems:
• Traditional single-phase railway supply systems where catenary to rail voltage and magnitude of
the current flowing through the catenary feeder, will be measured by the function.
• Auto transformer fed railway supply systems, which are used to serve high speed rail and freight
corridors. In these systems, typically the catenary to rail voltage, and the maximum magnitude of
the two currents flowing through the catenary feeder and a negative feeder will be measured by
the function. Alternatively, it is also possible to configure the function to measure the catenary to
feeder voltage instead of the catenary to rail voltage.
• Two-phase, high-voltage railway transmission systems where phase-to-phase voltage and the
maximum magnitude of the two individual phase currents will be measured by the function.
8.9.3.2 Base quantities
GlobalBaseSel defines the particular Global Base Values Group where the base quantities of the
function are set. In that Global Base Values Group, these quantities shall be set as given in the
following table:
176
IEC 61850
identification
VRPVOC
Appropriate ACT configuration is required for any of the above given solutions. For
relevant CT and VT connections and configuration, see
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GUID-7835D582-3FF4-4587-81CE-3B40D543E287 v5
IEC 60617 ANSI/IEEE C37.2
identification device number
2(I>/U<) 51V
GUID-3C6CDA50-285D-4886-B55A-E61923501A71 v1
GUID-1E62D174-FC51-4F16-A7AD-CF9D762E59AD v1
Section 4.2.5.
GUID-2CD5EEEC-27AF-4B76-942D-C0CFD38D41EC v1
Railway application RER670
1MRK506375-UEN Rev. N
Application manual