Rockwell Automation Publication 750-AT006D-EN-P - January 2022 93
Chapter 6 Active Front End Tuning
13:192[BasicPLL Err Limit] can be adjusted to allow more tolerance with respect to various line conditions. However, because the Loss of
Synchronization is a very critical condition, the maximum allowed error limit that can be entered is 20%.
Loss of Synchronization detection can be delayed if needed by setting 13:193 [BasicPLL Err Dly]. This parameter prevents raising a Loss of
Synchronization exception unless the PLL Error Limit exceeds the threshold condition for a certain period. Because Loss of Synchronization
is a very critical condition, the maximum time delay allowed is 5 ms, which is approximately equivalent to ¼ cycle.
Power Disturbance Module
The Power Disturbance Module is an algorithm that detects abnormal grid conditions. It can detect the following abnormal conditions.
• loss of synchronization
•voltage sag
• high frequency variation
• phase loss
•power loss
You can determine the action taken when the Power Disturbance Module detects one of these conditions. You can choose the following
actions.
•Ignore
•Alarm
•Ride Through
•Fault
You cannot choose Ignore for Loss of Synchronization. The Power Disturbance Module can be also be used as a diagnostics tool for
evaluating and recording the abnormal conditions.
Loss of Synchronization
As mentioned Phase Locked Loop on page 90, the operation of the AFE relies on accurate detection of the line voltage’s angle. The Power
Disturbance Module continuously monitors detection error. It detects the condition if the error exceeds a certain threshold. Wrong
connections and transient conditions on the grid cause loss of synchronization. Transient conditions include the following.
• power interruption
•voltage sag
• sudden frequency disturbance
• angle jump
Loss of Synchronization is a critical condition. You can choose Ride Through or Fault by configuring 13:181 [PLL LOS Det Actn]. When Ride
Through is selected, the drive activates the ride through function when it detects a Loss of Synchronization condition for a period of time
that is configured using 13:172 [RideThrough Time]; see Ride Through Mode
on page 94. If the Loss of Synchronization condition is cleared
before this time expires, the converter resumes normal operation. If the Loss of Synchronization condition is still active even after the Ride
Through time expires, the drive initiates a major fault.
Voltage Sag
Voltage sag is the loss or reduction of grid voltage for a short period of time. This can range from a few milliseconds to a few seconds. The
Power Disturbance Module monitors the input voltage in real time. It detects a voltage sag condition when one or more of the line voltages
phase drop by more than 50% of its nominal value. You can choose the actions Ignore, Alarm, Ride Through, or Fault by configuring
13:173 [VltgSag Det Actn]. When Ride Through is selected, the drive activates the Ride Through function when it detects a voltage sag
condition for a period of time that is configured using 13:172 [RideThrough Time]; see Ride Through Mode
on page 94. If a voltage sag
condition is cleared before this time expires, the converter resumes normal operation. If the voltage sag condition is still active after the
Ride Through time expires, the converter performs as configured in 13:174 [VltgSagRTExpActn].
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