6F2S1915 (0.46)
GRZ200 (Soft 031 & 032)
- 50 -
2.1.4
Common application for ZS and ZG
Applications in ZS and ZG are divided into common features and special features. Each feature
secures this distance protection function.
(i)
Power swing block
Operation of power swing block (PSB)
Power swings occur when the output voltages of generators located at different points in the
power system slip relative to one another because of system instabilities. This may be caused
by sudden changes in load magnitude or direction, or by power system faults and their
subsequent clearance. During the course of such a power swing, the impedance locus seen by
the distance protection relay may move (relatively slowly) from the load area into the operating
region of the distance protection. Actually, the relay may see this phenomenon as a three-phase
fault condition and may issue a trip signal if no countermeasure is applied. The majority of
power swings are transient and the power system recovers after a short period. Since a trip
signal from the relay is undesirable in such cases, the function of power swing blocking (PSB)
is provided enabling the operation of the distance protection to be blocked during the power
swing. Figure 2.1-24 illustrates a typical impedance locus as seen by the relay during the
transient power swing.
Figure 2.1-24 Impedance locus during transient power swing
As shown in Figure 2.1-25 (a), for ZS, power swing blocking elements (PSBSOUT and
PSBSIN) are formed as shown in the shaded area. As shown in Figure 2.1-25 (b), for ZG, the
PSBGOUT and PSBGIN elements are provided with the similar characteristic and feature.
Both PSB (PSBS and PSBG) functions do not operate when an earth fault overcurrent (EFL)
element or a negative-sequence phase overcurrent (OCN-PS) element is operating. Note that
the EFL and OCN-PS thresholds are defined with VCT rated value multiplied by 0.2 (i.e.,
secondary rated 1A×0.2 or 5A×0.2).
X
R
Load Area
Distance protection zone (Mho char.)
Impedance locus
during transient
power swing
Summary of Contents for GR 200 Series
Page 1047: ...6F2S1915 0 46 GRZ200 Soft 031 032 1026 Figure 8 3 4 Screen shot from GR TIEMS ...
Page 1354: ...6F2S1915 0 46 GRZ200 Soft 031 032 1333 Appendix 1 Signal list for common function ...
Page 1410: ...6F2S1915 0 46 GRZ200 Soft 031 032 1389 This page is intentionally blank ...
Page 1480: ...6F2S1915 0 46 GRZ200 Soft 031 032 1459 Appendix 6 Ordering ...
Page 1497: ...6F2S1915 0 46 GRZ200 Soft 031 032 1476 Appendix 7 Technical data ...
Page 1518: ...6F2S1915 0 46 GRZ200 Soft 031 032 1497 Appendix 8 Manufacture setting ...
Page 1523: ...6F2S1915 0 46 GRZ200 Soft 031 032 1502 Appendix 10 CT requirement ...
Page 1531: ...6F2S1915 0 46 GRZ200 Soft 031 032 1510 Appendix 12 Engineering exercise ...
Page 1563: ......