CHAPTER 4: SETPOINTS PROTECTION
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL 4–197
Figure 4-80: System behavior from Case 3
Application Settings
Application Example for Voltage Ride Through
In some regions, generators/energy resources may be required to remain
interconnected (i.e. ride- through) during system disturbances for a specified time
duration. This requirement is referred to as dynamic network support or Low Voltage
Ride Through (LVRT). Electricity regulatory bodies may have standards for LVRT and give
operating characteristics – examples of this are shown in the following figure, see (A)
German BDEW and (B) North American NERC.
Figure 4-81: Examples of operating characteristics for LVRT
In such low voltage conditions, the protection devices are required to not trip, and the
energy resource can continue to support the grid under transient low voltages. To meet
these requirements, the configurable curve points can be used to create the
PICKUP
DROPOUT
t
xVT
Vnom
Operating
Characteristic
PKP
dropout delay
Ph UV
Counter
1
2 = threshold
counter reset to 0
TRIP
Time
slot for
voltage
drops
timer expired
and reset
t
t
t
t
1. 00
0. 95
0. 90
timer expired
and reset
counter reset to 0
timer started
timer started
NO TRIP by curve or counter
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