InteliPro, SW version 1.4,
©
ComAp
–
April 2014
InteliPro 1.4 Comprehensive Guide - rev. 1
2-19
Dynamic grid support
Dynamic grid support function is used to support balanced status of the grid by retaining the
connection of the generator to mains even during large voltage drops. The relay will not trip
immediately in case of undervoltage, instead it will compare the measured voltage with the preset red
curve. The shape of the curve is determined by voltage levels in setpoints
If the measured voltage falls below the red curve, a trip is issued. The time delay after which the
protection starts to follow the curve from the beginning can be set in the setpoint
QU (undervoltage dependent directional reactive power) protection
QU, or undervoltage dependent directional reactive power protection is used to disconnect a power
supply from the mains in case that the grid balance is threatened. This is achieved by evaluation of
more variables
–
this function evaluates combination of mains voltage, current and reactive power at
the decoupling point and only if all of the following conditions are fulfilled, the protection will activate:
1. Voltages in all three p
hases drops below the setpoint „
2. Currents in all three phases exceed the set threshold (setpoint "
3. The amount of produced reactive power drops below the threshold (determined by the setpoint
As soon as all the above conditions are met, the protection will activate and issue a trip to open the
GCB ("
"). In case of no response (CB Feedback will not
deactivate), second trip ("
") is issued in order to separate the generator from the network
after time delay 2 ("
") by the MCB.
If the voltage returns back and exceed the set limit ("
"), the protection trip state will be
deactivated and fault can be reset.
The conventional fault reset applies, which determines the time after the function will be reactivated
since the condition of voltage return above 95% Un in all three phases and frequency returns to the
range of 47,50 Hz and 50,05 Hz.
