such as differential, earth-fault current and negative-
sequence current functions.
Current circuit supervision (CCSSPVC) compares the
residual current from a three phase set of current
transformer cores with the neutral point current on a
separate input taken from another set of cores on the
current transformer.
A detection of a difference indicates a fault in the circuit
and is used as alarm or to block protection functions
expected to give inadvertent tripping.
Fuse failure supervision FUFSPVC
SEMOD113820-4 v13
The aim of the fuse failure supervision function
(FUFSPVC) is to block voltage measuring functions at
failures in the secondary circuits between the voltage
transformer and the IED in order to avoid inadvertent
operations that otherwise might occur.
The fuse failure supervision function basically has three
different detection methods, negative sequence and
zero sequence based detection and an additional delta
voltage and delta current detection.
The negative sequence detection algorithm is
recommended for IEDs used in isolated or high-
impedance earthed networks. It is based on the
negative-sequence quantities.
The zero sequence detection is recommended for IEDs
used in directly or low impedance earthed networks. It is
based on the zero sequence measuring quantities.
The selection of different operation modes is possible
by a setting parameter in order to take into account the
particular earthing of the network.
A criterion based on delta current and delta voltage
measurements can be added to the fuse failure
supervision function in order to detect a three phase
fuse failure, which in practice is more associated with
voltage transformer switching during station
operations.
Fuse failure supervision VDSPVC
GUID-6AF2219A-264F-4971-8D03-3B8A9D0CB284 v5
Different protection functions within the protection IED
operates on the basis of measured voltage at the relay
point. Some example of protection functions are:
• Distance protection function.
• Undervoltage function.
• Energisation function and voltage check for the weak
infeed logic.
These functions can operate unintentionally, if a fault
occurs in the secondary circuits between voltage
instrument transformers and the IED. These
unintentional operations can be prevented by fuse
failure supervision (VDSPVC).
VDSPVC is designed to detect fuse failures or faults in
voltage measurement circuit, based on phase wise
comparison of voltages of main and pilot fused circuits.
VDSPVC blocking output can be configured to block
functions that need to be blocked in case of faults in the
voltage circuit.
Voltage based delta supervision DELVSPVC
GUID-6188C4C1-E1D5-421A-B496-96676287EBB2 v2
Delta supervision function is used to quickly detect
(sudden) changes in the network. This can, for example,
be used to detect faults in the power system networks
and islanding in grid networks. Voltage based delta
supervision (DELVSPVC) is needed at the grid
interconnection point.
Current based delta supervision DELISPVC
GUID-30A00AE0-8D3A-4CE8-9379-8D1A0A6078E3 v2
Delta supervision function is used to quickly detect
(sudden) changes in the network. This can, for example,
be used to detect disturbances in the power system
network. Current based delta supervision (DELISPVC)
provides selectivity between load change and the fault.
Present power system has many power electronic
devices or FACTS devices, which injects a large number
of harmonics into the system. The function has
additional features of 2
nd
harmonic blocking and 3
rd
harmonic start level adaption. The 2
nd
harmonic blocking
secures the operation during the transformer charging,
when high inrush currents are supplied into the system.
Delta supervision of real input DELSPVC
GUID-8FAD2CCF-091F-4CDB-8ABF-1BDC874A8403 v2
Delta supervision functions are used to quickly detect
(sudden) changes in the power system. Real input delta
supervision (DELSPVC) function is a general delta
function. It is used to detect the change measured
qualities over a settable time period, such as:
• Power
• Reactive power
• Temperature
• Frequency
• Power factor
13. Control
Synchrocheck, energizing check, and synchronizing
SESRSYN
M12480-3 v16
The Synchronizing function allows closing of
asynchronous networks at the correct moment including
the breaker closing time, which improves the network
stability.
Synchrocheck, energizing check, and synchronizing
(SESRSYN) function checks that the voltages on both
sides of the circuit breaker are in synchronism, or with
Generator protection REG670
1MRK 502 074-BEN M
36 Hitachi Power Grids
© Copyright 2017 Hitachi Power Grids. All rights reserved
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