Overview
High speed “Line differential protection” for 4 CT sets, 2-3 line ends (L4CPDIF) is a unit type protection system with typical operate time less than one cycle. These types of systems are suitable for the protection of complex transmission network configurations because they exhibit good performance during evolving, inter-circuit, and cross-country faults.
For more detailed information on “Line differential protection”, refer to ABB, Relion 670 Series manuals.
To see other supported functions, click here.
Function Identification
| Function description | IEC 61850 identification |
IEC 60617 identification |
ANSI/IEEE C37.2 device number |
| High speed line differential protection for 4 CT sets, 2-3 line ends | L4CPDIF | 3Id/I > | 87L |
Signals & Setting Parameters
L4CPDIF function block
L4CPDIF Input signals
| L4CPDIF Input signals | |||
| Name | Type | Default | Description |
| I3P1 | GROUP SIGNAL | – | Three phase current samples, group 1 |
| I3P2 | GROUP SIGNAL | – | Three phase current samples, group 2 |
| I3P3 | GROUP SIGNAL | – | Three phase current samples, group 3 |
| I3P4 | GROUP SIGNAL | – | Three phase current samples, group 4 |
| U3P1 | GROUP SIGNAL | – | Three phase voltage samples, group 1 |
| U3P2 | GROUP SIGNAL | – | Three phase voltage samples, group 2 |
| U3P3 | GROUP SIGNAL | – | Three phase voltage samples, group 3 |
| U3P4 | GROUP SIGNAL | – | Three phase voltage samples, group 4 |
| BLOCK | BOOLEAN | 0 | Block of function |
| LOWSENEN | BOOLEAN | 0 | Input for forcing the function enable low sensitivity |
| CCBLK | BOOLEAN | 0 | Block CCC (local) |
L4CPDIF Output signals
| L4CPDIF Output signals | |||
| Name | Type | Description | |
| TRIP | BOOLEAN | Common, main, trip output signal | |
| TRL1 | BOOLEAN | Trip signal from phase L1 | |
| TRL2 | BOOLEAN | Trip signal from phase L2 | |
| TRL3 | BOOLEAN | Trip signal from phase L3 | |
| START | BOOLEAN | Common, main, start output signal | |
| STL1 | BOOLEAN | Start signal from phase L1 | |
| STL2 | BOOLEAN | Start signal from phase L2 | |
| STL3 | BOOLEAN | Start signal from phase L3 | |
| STUNR | BOOLEAN | Start of unrestrained differential protection | |
| COMFBLKD | BOOLEAN | Block due to communication failed | |
| BLKHL1 | BOOLEAN | Block signal due to 2nd or 5th harmonic, phase L1 | |
| BLKHL2 | BOOLEAN | Block signal due to 2nd or 5th harmonic, phase L2 | |
| BLKHL3 | BOOLEAN | Block signal due to 2nd or 5th harmonic, phase L3 | |
| OPENCT | BOOLEAN | An open CT was detected | |
| DIFLBLKD | BOOLEAN | Local line differential function blocked | |
| TRLOCAL | BOOLEAN | Trip from local differential function | |
| TRREMOTE | BOOLEAN | Trip from remote differential function | |
| ALARM | BOOLEAN | Alarm for sustained differential current | |
| INTFLTL1 | BOOLEAN | Internal fault has been detected in phase L1 | |
| INTFLTL2 | BOOLEAN | Internal fault has been detected in phase L2 | |
| INTFLTL3 | BOOLEAN | Internal fault has been detected in phase L3 | |
| SYNLOSS | BOOLEAN | Loss of data synchronism was detected | |
| CHARGEN | BOOLEAN | Charging current compensation is enabled | |
| IDL1 | REAL | Instantaneous differential current, phase L1 | |
| IDL2 | REAL | Instantaneous differential current, phase L2 | |
| IDL3 | REAL | Instantaneous differential current, phase L3 | |
| IDL1MAG | REAL | Magnitude of fund. freq. differential current, phase L1 | |
| IDL2MAG | REAL | Magnitude of fund. freq. differential current, phase L2 | |
| IDL3MAG | REAL | Magnitude of fund. freq. differential current, phase L3 | |
| IBIASL1 | REAL | Magnitude of the bias current, L1 | |
| IBIASL2 | REAL | Magnitude of the bias current, L2 | |
| IBIASL3 | REAL | Magnitude of the bias current, L3 | |
| IREQSTL1 | REAL | Required current level to start, phase L1 | |
| IREQSTL2 | REAL | Required current level to start, phase L2 | |
| IREQSTL3 | REAL | Required current level to start, phase L3 | |
L4CPDIF Non group settings (basic)
| L4CPDIF Non group settings (basic) | |||||
| Name | Values (Range) | Unit | Step | Default | Description |
| GlobalBaseSel | 1 – 12 | – | 1 | 1 | Selection of one of the Global Base Value groups |
| NoOfUsedCTs | 2 – 4 | – | 1 | 2 | Total number of 3-Ph CT sets connected to diff protection |
| TapTransformer | Off On |
– | – | Off | Small tap transformer included in the protected zone |
| DiffMode | Master Slave |
– | – | Master | Differential function mode Master/ Slave |
| ReleaseLocal | Block all Release local |
– | – | Block all | Release of local terminal for trip under test mode |
| TestModeSet | Off On |
– | – | Off | Test Mode Off/On |
L4CPDIF Group settings (basic)
| L4CPDIF Group settings (basic) | |||||
| Name | Values (Range) | Unit | Step | Default | Description |
| Operation | Off On |
– | – | Off | Operation Mode Off / On |
| IdMin | 0.20 – 2.00 | IB | 0.01 | 0.30 | Oper – restr charact., section 1 sensitivity, multiple of IBase |
| IdMinHigh | 0.20 – 10.00 | IB | 0.01 | 0.80 | Initial lower sensitivity, as multiple of IBase |
| tIdMinHigh | 0.000 – 60.000 | s | 0.001 | 1.000 | Time interval of initial lower sensitivity, in s |
| IdUnre | 1.00 – 100.00 | IB | 0.01 | 10.00 | Unrestrained differential current limit, multiple of IBase |
| OpenCTEnable | Off On |
– | – | On | Open CTEnable Off/On |
| tOCTResetDelay | 0.100 – 10.000 | s | 0.001 | 0.250 | Reset delay in s. After delay, diff. function is activated |
| OCTBlockEn | Off On |
– | – | On | Enable Open CT blocking function trip Off/On |
| IdiffAlarm | 0.05 – 1.00 | IB | 0.01 | 0.15 | Sustained differential current alarm, multiple of IBase |
| tAlarmDelay | 0.000 – 60.000 | s | 0.001 | 10.000 | Delay for alarm due to sustained differential current, in s |
| LossSynEn | Off On |
– | – | Off | Loss of data synchronism detection Off/On |
| tLossSynReset | 0.100 – 60.000 | s | 0.001 | 1.000 | Loss of data synchronism detection reset delay in s. After delay, diff. function is activated |
| CCCOpMode | Off U based IDiff reduction |
– | – | Off | Operation mode of charging current compensation |
| VTOnLineGrp1 | No Yes |
– | – | No | Voltage transformer installed on the line at the end, the currents of which are connected to group 1 |
| VTOnLineGrp2 | No Yes |
– | – | No | Voltage transformer installed on the line at the end, the currents of which are connected to group 2 |
| VTOnLineGrp3 | No Yes |
– | – | No | Voltage transformer installed on the line at the end, the currents of which are connected to group 3 |
| VTOnLineGrp4 | No Yes |
– | – | No | Voltage transformer installed on the line at the end, the currents of which are connected to group 4 |
| C0 | 0.001 – 1000.000 | uF | 0.001 | 0.001 | Total zero sequence capacitance of the protected line, in microfarad |
| C1 | 0.001 – 1000.000 | uF | 0.001 | 0.001 | Total positive sequence capacitance of the protected line, in microfarad |
| NoOfLineEnds | 2 – 3 | – | 1 | 2 | Number of physical line ends of the protected line circuit, 2 ends or 3 ends |
| NoOfCTSetsGrp1 | 1 – 2 | – | 1 | 1 | Number of 3-ph CTs at line end, the currents of which are connected to group 1 (1 or 2) |
| NoOfCTSetsGrp2 | 1 – 2 | – | 1 | 1 | Number of 3-ph CTs at line end, the currents of which are connected to group 2 (1 or 2) |
| NoOfCTSetsGrp3 | 1 – 2 | – | 1 | 1 | Number of 3-ph CTs at line end, the currents of which are connected to group 3 (1 or 2) |
| NoOfCTSetsGrp4 | 1 – 2 | – | 1 | 1 | Number of 3-ph CTs at line end, the currents of which are connected to group 4 (1or 2) |
| tChargCurrDelay | 0.010 – 60.000 | s | 0.001 | 0.100 | Delay for compensation of charging current due to initial voltage oscillation, in s |
L4CPDIF Group settings (advanced)
| L4CPDIF Group settings (advanced) | |||||
| Name | Values (Range) | Unit | Step | Default | Description |
| EndSection1 | 0.20 – 2.00 | IB | 0.01 | 1.00 | End of section 1, as multiple of reference current IBase |
| EndSection2 | 1.00 – 10.00 | IB | 0.01 | 3.00 | End of section 2, as multiple of reference current IBase |
| SlopeSection2 | 10.0 – 100.0 | % | 0.1 | 50.0 | Slope in section 2 of operate-restrain characteristic, in % |
| SlopeSection3 | 30.0 – 100.0 | % | 0.1 | 100.0 | Slope in section 3 of operate-restrain characteristic, in % |
| I2/I1Ratio | 5.0 – 100.0 | % | 1.0 | 10.0 | Max. ratio of 2nd harm. to fundamental harm dif. curr. in % |
| I5/I1Ratio | 5.0 – 100.0 | % | 1.0 | 10.0 | Max. ratio of 5th harm. to fundamental harm dif. curr. in % |
| SendInterTrip | No Yes |
– | – | Yes | Send inter-trip to remote ends |
L4CPDIF Monitored data
| L4CPDIF Monitored data | ||||
| Name | Type | Values (Range) | Unit | Description |
| IDL1MAG | REAL | – | A | Magnitude of fund. freq. differential current, phase L1 |
| IDL2MAG | REAL | – | A | Magnitude of fund. freq. differential current, phase L2 |
| IDL3MAG | REAL | – | A | Magnitude of fund. freq. differential current, phase L3 |
| IBIASL1 | REAL | – | A | Magnitude of the bias current, L1 |
| IBIASL2 | REAL | – | A | Magnitude of the bias current, L2 |
| IBIASL3 | REAL | – | A | Magnitude of the bias current, L3 |
| ICL1 | REAL | – | A | Amount of compensated charging current, phase L1 |
| ICL2 | REAL | – | A | Amount of compensated charging current, phase L2 |
| ICL3 | REAL | – | A | Amount of compensated charging current, phase L3 |
Logics & highlights
Two-end power line with one CB and one CT group at each end
Two-end power line with two CB and CT groups at one end
Two-end power line with two CB and CT groups at each end
Three-end power line with two CB and CT groups at one end
Simplified logic diagram for the internal fault detector shown for a two-end power line (one detector for each phase)
Incremental currents flowing towards the internal fault point with a default orientation of CTs
Description of the restrained and unrestrained operate characteristics
Characteristic sections
Charging currents fed from all voltage sources
Capacitances for phaseL1 of a transmission line
Currents calculation (1/3)
Currents calculation (2/3)
Currents calculation (3/3)
Charging current compensation using the exact method (CCCOpMode = U based)
Charging current compensation using the approximate method (CCCOpMode = Idiff reduction)
Simplified logic for open CT detection
Operate region for loss of data synchronism detection
Simplified logic for loss of synchronism detection
Block signal logic for line differential coordination logic
Trip signal logic for line differential coordination logic
Simplified logic for L4CPDIF
Simplified logic for the internal fault detector shown for a two-end power line (one detector for each phase)
