Overview
The “Self adaptive differential protection for two-winding power transformers” function can be used as a differential protection for any two-winding three-phase power transformers. It is especially suitable for the differential protection of phase-shifting transformers (PST), which is also called phase-angle regulating transformers (PAR). This function is similar to the standard transformer differential protection function T2WPDIF (or 87T), but it can be applied to any type and construction of PST.
For more detailed information on “Self adaptive differential protection for two-winding power transformers” function, 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 |
| Self-adaptive differential protection for two-winding power transformers | PSTPDIF | 3Id/I | 87T |
Signals & Setting Parameters
PSTPDIF function block
PSTPDIF Input signals
| PSTPDIF Input signals | |||
| Name | Type | Default | Description |
| I3PW1 | GROUP SIGNAL | – | Group signal for primary current input, three phase |
| I3PW2 | GROUP SIGNAL | – | Group signal for secondary current input, three phase |
| U3PW1 | GROUP SIGNAL | – | Group signal for primary voltage input |
| U3PW2 | GROUP SIGNAL | – | Group signal for secondary voltage input |
| BLOCK | BOOLEAN | 0 | Block of function and enabling of fast synch of the phase angle shift and ratio |
| BLKRES | BOOLEAN | 0 | Block of trip for restrained differential feature |
| BLKUNRES | BOOLEAN | 0 | Block of trip for unrestrained differential feature |
| BLKNSUNR | BOOLEAN | 0 | Block of trip for unrestr. neg. seq. differential feature |
| BLKNSSEN | BOOLEAN | 0 | Block of trip for sensitive neg. seq. differential feature |
| USEDFLT | BOOLEAN | 0 | Forces the calculation of ratio and phase angle to use default values |
| STOPCOMP | BOOLEAN | 0 | Stops ratio and phase angle compensation and freezes their values |
PSTPDIF Output signals
| PSTPDIF Output signals | |||
| Name | Type | Description | |
| TRIP | BOOLEAN | General trip signal | |
| TRIPRES | BOOLEAN | Trip signal from restrained differential protection | |
| TRIPUNRE | BOOLEAN | Trip signal from unrestrained differential protection | |
| TRNSUNR | BOOLEAN | Trip signal from unrestrained negative sequence differential protection | |
| TRNSSENS | BOOLEAN | Trip signal from sensitive negative sequence differential protection | |
| START | BOOLEAN | General start signal from any phase | |
| STL1 | BOOLEAN | Start signal from phase L1 | |
| STL2 | BOOLEAN | Start signal from phase L2 | |
| STL3 | BOOLEAN | Start signal from phase L3 | |
| INTFAULT | BOOLEAN | Indication that internal fault has been detected | |
| EXTFAULT | BOOLEAN | Indication that external fault/disturbance has been detected | |
| BLK2H | BOOLEAN | General second harmonic block signal from any phase | |
| BLK2HL1 | BOOLEAN | Second harmonic block signal, phase L1 | |
| BLK2HL2 | BOOLEAN | Second harmonic block signal, phase L2 | |
| BLK2HL3 | BOOLEAN | Second harmonic block signal, phase L3 | |
| BLK5H | BOOLEAN | General fifth harmonic block signal from any phase | |
| BLK5HL1 | BOOLEAN | Fifth harmonic block signal, phase L1 | |
| BLK5HL2 | BOOLEAN | Fifth harmonic block signal, phase L2 | |
| BLK5HL3 | BOOLEAN | Fifth harmonic block signal, phase L3 | |
| BLKWAV | BOOLEAN | General block signal, waveform criterion, from any phase | |
| BLKWAVL1 | BOOLEAN | Block signal, waveform criterion, phase L1 | |
| BLKWAVL2 | BOOLEAN | Block signal, waveform criterion, phase L2 | |
| BLKWAVL3 | BOOLEAN | Block signal, waveform criterion, phase L3 | |
| IDALARM | BOOLEAN | Alarm for sustained diff currents in all three phases | |
| IDL1 | REAL | Value of the instantaneous differential current, phase L1 | |
| IDL2 | REAL | Value of the instantaneous differential current, phase L2 | |
| IDL3 | REAL | Value of the instantaneous differential current, phase L3 | |
| IDL1MAG | REAL | Magnitude of fundamental frequency differential current, phase L1 | |
| IDL2MAG | REAL | Magnitude of fundamental frequency differential current, phase L2 | |
| IDL3MAG | REAL | Magnitude of fundamental frequency differential current, phase L3 | |
| IBIAS | REAL | Magnitude of the bias current, which is common to all phases | |
| IDNSMAG | REAL | Magnitude of the negative sequence differential current | |
| IRATIO | REAL | Ratio between W1 and W2 positive sequence current magnitudes | |
| IANGLE | REAL | Angle difference between W1 and W2 positive sequence current phasors | |
| URATIO | REAL | Ratio between W2 and W1 selected voltage magnitudes | |
| UANGLE | REAL | Angle difference between W1 and W2 selected voltage phasors | |
| SELMEAS | INTEGER | Presently used source of measurement for ratio and phase shift calculation (1=default settings, 2=voltage, 4=current, 8=frozen, 16=external freeze) | |
| DIFRATIO | REAL | Ratio between W1 and W2 magnitudes | |
| DIFANGLE | REAL | Angle difference between W1 and W2 phasors | |
PSTPDIF Non group settings (basic)
| PSTPDIF Non group settings (basic) | |||||
| Name | Values (Range) | Unit | Step | Default | Description |
| GlobalBaseSelW1 | 1 – 12 | – | 1 | 1 | Global base selector for winding 1 |
| GlobalBaseSelW2 | 1 – 12 | – | 1 | 1 | Global base selector for winding 2 |
| SelPhaseVoltW1 | Phase L1 Phase L2 Phase L3 Phase L1L2 Phase L2L3 Phase L3L1 Positive sequence |
– | – | Phase L1 | Group signal for primary voltage input |
| SelPhaseVoltW2 | Phase L1 Phase L2 Phase L3 Phase L1L2 Phase L2L3 Phase L3L1 Positive sequence |
– | – | Phase L1 | Group signal for secondary voltage input |
| ZSCurrSubtrW1 | Off On |
– | – | On | Enable zero sequence current subtraction for W1 side, On / Off |
| ZSCurrSubtrW2 | Off On |
– | – | On | Enable zero sequence current subtraction for W2 side, On / Off |
| DefaultPhShift | -180 – 180 | Deg | 1 | 0 | Default phase angle shift between two sides, used when U and I are not available. This angle shall be positive when W2 is leading the W1. This angle shall be negative when W2 is lagging W1. |
| ReverseAngle | Off On |
– | – | Off | When enabled it will force the sign change of the measured phase angle shift across transformer |
| DiffRatioMax | 1.002 – 1.500 | – | 0.001 | 1.050 | Maximum allowed ratio between W1 and W2 magnitudes |
| DiffRatioMin | 0.500 – 0.998 | – | 0.001 | 0.950 | Minimum allowed ratio between W1 and W2 magnitudes |
| DiffAngleMax | 0.1 – 90.0 | Deg | 0.1 | 90.0 | Maximum allowed phase angle between W1 and W2 |
| DiffAngleMin | -90.0 – -0.1 | Deg | 0.1 | -90.0 | Minimum allowed phase angle between W1 and W2 |
PSTPDIF Group settings (basic)
| PSTPDIF Group settings (basic) | |||||
| Name | Values (Range) | Unit | Step | Default | Description |
| Operation | Off On |
– | – | Off | Operation Off / On |
| IDiffAlarm | 0.02 – 0.50 | IB | 0.01 | 0.05 | Differential current alarm, multiple of IBase in GlobalBaseSelW1 |
| tAlarmDelay | 0.000 – 60.000 | s | 0.001 | 10.000 | Time delay for differential currents alarm level |
| IdMin | 0.10 – 0.60 | IB | 0.01 | 0.20 | Section 1 sensitivity, multiple of IBase in GlobalBaseSelW1 |
| IdUnre | 4.00 – 60.00 | IB | 0.01 | 10.00 | Unrestrained protection limit, multiple of IBase in GlobalBaseSelW1 |
| CrossBlockEn | Off On |
– | – | On | Operation Off/On for cross-block logic between phases |
| NegSeqDiffEn | Off On |
– | – | On | Operation Off/On for negative sequence differential protections |
| IMinNegSeq | 0.04 – 0.80 | IB | 0.01 | 0.08 | Negative sequence current limit, multiple of IBase in GlobalBaseSelW1 |
| NegSeqROA | 30.0 – 120.0 | Deg | 0.1 | 60.0 | Operate angle for internal / external negative sequence fault discriminator |
| tTripNSSens | 0.040 – 60.000 | s | 0.001 | 0.100 | Time delay for negative sequence sensitive trip |
PSTPDIF Group settings (advanced)
| PSTPDIF Group settings (advanced) | |||||
| Name | Values (Range) | Unit | Step | Default | Description |
| EndSection1 | 0.65 – 1.50 | IB | 0.01 | 1.25 | End of section 1, multiple of IBase in GlobalBaseSelW1 |
| EndSection2 | 1.55 – 5.00 | IB | 0.01 | 3.00 | End of section 2, multiple of IBase in GlobalBaseSelW1 |
| SlopeSection2 | 10.0 – 50.0 | % | 0.1 | 40.0 | Slope in section 2 of operate-restrain characteristic, in % |
| SlopeSection3 | 30.0 – 100.0 | % | 0.1 | 80.0 | Slope in section 3 of operate-restrain characteristic, in % |
| I2/I1Ratio | 5.0 – 60.0 | % | 0.1 | 15.0 | Max. ratio of 2nd harmonic to fundamental harmonic differential current in % |
| I5/I1Ratio | 5.0 – 60.0 | % | 0.1 | 25.0 | Max. ratio of 5th harmonic to fundamental harmonic differential current in % |
PSTPDIF Monitored data
| PSTPDIF Monitored data | ||||
| Name | Type | Values (Range) | Unit | Description |
| IDL1MAG | REAL | – | % | Magnitude of fundamental frequency differential current, phase L1 |
| IDL2MAG | REAL | – | % | Magnitude of fundamental frequency differential current, phase L2 |
| IDL3MAG | REAL | – | % | Magnitude of fundamental frequency differential current, phase L3 |
| IBIAS | REAL | – | % | Magnitude of the bias current, which is common to all phases |
| IDNSMAG | REAL | – | % | Magnitude of the negative sequence differential current |
| IRATIO | REAL | – | – | Ratio between W1 and W2 positive sequence current magnitudes |
| IANGLE | REAL | – | deg | Angle difference between W1 and W2 positive sequence current phasors |
| URATIO | REAL | – | – | Ratio between W2 and W1 selected voltage magnitudes |
| UANGLE | REAL | – | deg | Angle difference between W1 and W2 selected voltage phasors |
| SELMEAS | INTEGER | 1=Default used 2=Voltage used 4=Current used 8=Meas frozen 16=External freeze |
– | Presently used source of measurement for ratio and phase shift calculation (1=default settings, 2=voltage, 4=current, 8=frozen, 16=external freeze) |
| DIFRATIO | REAL | – | – | Ratio between W1 and W2 magnitudes |
| DIFANGLE | REAL | – | deg | Angle difference between W1 and W2 phasors |
Logics & highlights
Possible arrangements for phase-shifting transformer differential protection
Typical CT location and definition of positive current direction
Simplified logic to determine the actual transformation ratio and phase-angle shift
Description of the restrained and the unrestrained operate characteristics
Negative-sequence based differential current calculation
Operating characteristic of the internal/external fault discriminator
Treatment of measured currents within IED for PSTPDIF function
PSTPDIF function simplified logic diagram for Phase L1
PSTPDIF function simplified logic diagram for internal/external fault discriminator
PSTPDIF function internal grouping of tripping signals
PSTPDIF function internal grouping of logical signals
Differential current alarm logic
