ABB Relion 670 Series Applications Manual page 210

Section 13
Secondary system supervision
13.3 Voltage based delta supervision DELVSPVC(78V)
13.3.1 Function revision history
13.3.2 Identification
Function description
Voltage based delta supervision
13.3.3 Application
In a weak grid networks, fault detection and operation of other protection functions is reliably
done by delta supervision functionality. In this type of network, a delta based release criteria is
used to release the trip signal. The measurement of delta differs from country to country between
magnitude, vector or sample based detection.
In this function, a voltage based delta supervision is implemented in a phase segregated design.
The delta function has the following features:
• Instantaneous sample based delta detection
• True RMS value based delta detection
• DFT magnitude based delta detection
• Vector shift protection
The Delta detection mode is selected on the basis of application requirements. For example,
Instantaneous sample based delta supervision is very fast; the delta is detected in less than a cycle
typically. Hence, instantaneous sample based delta supervision can be used for functions that are
used as protection enablers or fault detectors
All the other supervision modes like RMS/DFT Mag or Angle requires minimum one cycle for delta
detection and can be used for time delay functions.
Angle shift mode
Use of distributed generation (DG) units is increasing due to liberalized markets (deregulation)
and the global trend to use more renewable sources of energy. They generate power in the range
of 10 kW to 10 MW and most of them are interconnected to the distribution network. They can
supply power into the network as well as to the local loads. It is not common to connect
generators directly to the distribution networks and thus the distributed generation can cause
some challenges for the protection of distribution networks. From the protection point of view,
one of the most challenging issue is islanding.
Islanding is defined as a condition in which a distributed generation unit continues to supply
power to a certain part of the distribution network when power from the larger utility main grid is
no longer available after opening of a circuit-breaker.
Islanding is also referred as Loss of Mains (LOM) or Loss of Grid (LOG). When LOM occurs, neither
the voltage nor the frequency is controlled by the utility supply. Also, these distributed generators
are not equipped with voltage and frequency control; therefore, the voltage magnitude of an
islanded network may not be kept within the desired limits resulting into undefined voltage
204
IEC 61850
identification
DELVSPVC
© Copyright 2017 Hitachi Power Grids. All rights reserved
IEC 60617 ANSI/IEEE C37.2
identification device number
– 7V_78V
Phasor measurement unit RES670
1MRK 511 407-UUS Rev. J
GUID-579ED249-B8C9-4755-9E80-28E2BA8E5377 v2
GUID-383C6822-E9FC-475E-82B3-0D4E247AEF72 v1
GUID-C7108931-DECA-4397-BCAF-8BFF3B57B4EF v2
GUID-D179DBA4-B068-4A1E-A53E-477BD3B6ACFC v2
Application manual