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Table 6 Causes and effects on distance protection due to IBRs

From: Transmission line protection challenges influenced by inverter-based resources: a review

Distance protection (21)
Function References Technology Cause Effect
Zone impedance (zone 1, zone 2) 21 [32] IBR Control system parameters, current limit setting The relay impedance can be far away from the actual fault impedance
[34] IBR Low SC current, reactive current rise time The initial fault impedance by distance relay moves closer to zone 1 setting even for zone 2 faults
[39] WF-III The frequencies of the fault current and voltage can be well apart Oscillating impedance
[33] IBR Phase angles are controlled by inverter control system The impedance has a great amplitude and phase offset
[40] Back-to-back Converter Power electronic converters do not tend to contribute to the fault current The impedance by relay is very high and it can see outside of the protection zones
[44] VSC Design of control system, lower SC-current level The measured impedance locus has transients. The impedance moves in and out from the effective zone during the fault
[36] IBR Low-magnitude currents that may behave incoherently with the voltages Phase distance element zone 1 may overreach; zone 2 may drop out; oscillating apparent impedance
[37] IBR Inverter control system Effect on impedance, zone 1 overreach
[41] VSC-HVDC Reactive power control of VSC-HVDC Relay tends to overestimate the fault distance
[42, 43] WF/VSC-HVDC Different FRT controls, control of current amplitude and phase Malfunction of the distance relay; the higher line distance relay zone 2 is narrowed
[45] IBR Inverter reactive power current Over reach or under reach of impedance measurement
[46,47,48] WF-III Depends on the operating mode Affects the trip boundaries of the distance relay
Overcurrent starting 50 [35] IBR Inverters are nonlinear electronic devices Insufficient SC-current, delay in operation
Directional element 32P [38] WF-III The short-circuit current mainly consists of a transient component and a steady-state component Effect on positive-sequence voltage polarized impedance relay
[36] IBR Current limited by the inverter The phase directional element may misbehave when a three-phase fault disconnects the IBR
32Q [36] IBR Negative-sequence current limited The negative-sequence directional element may misbehave
[49] WF-III Low voltage ride requirements The relationship between the current and voltage phase angle in negative-sequence is not readily known
[50] IBR, WF-III Improper magnitude and phase angle of negative-sequence current The negative-sequence current is not the leading voltage as in a conventional source
[51] WF-III Low-voltage ride through requirements Improper magnitude and phase angle of the negative-sequence current
Fault-type identification and selection FID [52] WF-III Slip and crowbar resistance The approximately unequal positive and negative currents will critically affect the phase selectors according to their variation components