User Guide Transformer Differential 87t

Diffrentielle transformateur

Transformer Differential

ANSI 87T

Parameter Setting Guide

S

Sepam Series 80 Protection Relays

Author: Laurent Pouyadou

Document version: V1.0Date: 29/06/2006

Contents

31.Differential function and matching:

1.1Principle and operation:31.2Need for matching:51.3Use of matched currents:72.Setting of the Idsthreshold:92.1Principle:92.2Setting of the threshold:93.Percentage-based differential:113.1Principle:113.2Setting of the percentage-based curve:124.Restraint principles:124.1Problems relating to harmonics:124.2Choice of self-adaptive or conventional restraint:135.Principle and setting of high set point:155.1Principle:155.2Setting:156.Setting of the conventional restraint:166.1Second-harmonic:166.2Fifth-harmonic:166.3Global restraint (cross-blocking):167.Restraint on closing:168.Restraint on CT loss:179.Additional explanations of self-adaptive restraint:1710.Dimensioning phase-current sensors:1810.1Exceptional operation and on-load tap changer:1810.2Dimensioning:19

Annexes:

Rated power 20

Vector shift 21

Insensitivity to external earth faults 24

Note on the max. function 25

Calculation of low set point and Id/It slope uncertainty 26

Low set point calculation tool for 32

Id/It slope calculation tool 33

Dry-type cast resin transformers 34

Oil-immersed transformers 35

Artificial Neural Network 36

Transformer Differential

ANSI Code 87T

Parameter Setting Guide

1. Differential function and matching:

1.1 Principle and operation:

The differential protection function protects the zone between the main and additional current sensors. It is used here to protect transformers from a few MVA to several tens of MVA from internal faults (inside the protected zone between the two sets of CTs).

The principle of differential protection consists of comparing two currents of the same phase, which are normally equal. If the current entering the protected zone is not equal to the current leaving the zone, the difference in the currents at the extremities of the protected zone give the measurement of the fault current. For transformer protection, things are slightly different though since the primary and secondary currents are necessarily different in terms of amplitude, because of the transformation ratio, and phase, according to the transformer coupling mode.The primary and secondary currents of each phase therefore need to be processed in order to make them equal in normal operation. The current amplitude and phase need to be matched.

The transformer differential function protects the zone between the main current sensors I1, I2, I3 and the additional current sensors I1, I2, I3

According to the current measurement convention, shown in the diagram above, and in compliance with the recommended wiring system, the differential currents Id and through currents It of each phase are calculated using the currents and .

(This block diagram is valid for all three phases)

The differential function picks up if the differential current of at least one phase is greater than the adjustable operating threshold defined by:

a high differential current set point threshold with no tripping restraint (Idmax)

a percentage-based characteristic with two slopes (Id/It and Id/It2) and a low current set point (Ids)

Stability is ensured by the following tripping restraints:

harmonic restraint (for closing and overexcitation phenomena)

transformer energization restraint

CT-loss restraint

Please note: the block diagram for the phase 1 function (outlined by the dotted line) is the same for each of the three phases.

1.2 Need for matching:

The primary and secondary currents have amplitude differences because of the transformation ratio and phase differences because of the transformer coupling.

The currents therefore need to be processed in order for the signals to be compared. Based on the rated power and rated voltages, Sepam calculates the transformation ratio and adjusts the amplitude. The transformer vector shift is used for to match the phase currents.

Transformer secondary (winding 2) current matching:

The matching of winding 2 affects the amplitude and phase and takes into account the transformer vector shift. The IEC 60076-1 standard presumes that the vector shift is given for a transformer connected to a power source, with a phase-rotation sequence of 123. Sepam uses this vector shift value for both 123 and 132 type networks. It is therefore not necessary to complement this value by 12 for a 132 type network.

The table below contains vectorial diagrams and matching formulae based on the vector shift of the transformer for networks with 123 type phase-rotation sequences.

Transformer primary (winding 1) current matching:

Winding 1 is always matched in the same way, whatever the vector shift of the transformer.

Please note: Matching is done by clearing the zero-sequence current in order to make the protection function immune to external earth faults outside the protected zone.

1.3 Use of matched currents:

For each phase, Sepam calculates the differential current and through current using the matched currents.

The differential and through currents per phase are defined by the following formulae:

Differential current: for phase i

Through current: for phase i (see note on the max. function)

The matching equations may be illustrated by applying them to a Dyn11 transformer. Let's take a transformer connected to a load that requires a secondary current with vector magnitude I. To simplify, it is presumed that the transformation ratio is equal to one (i.e. Un=Un).

Please note: the diagram above shows the vectors in bold print (I1,I1,X1.)

Secondary currents:

Matching of secondary currents:

(Vector shift=11) (

and hence

Primary currents:

i.e.

Matching of primary currents:

i.e.

The differential current is calculated by:

Phase 1: and Hence Id1=0



( Id1=Id2=Id3=0, the differential current is therefore zero for each phase.

The protection does not pick up in normal operation.

2. Setting of the Idsthreshold:

2.1 Principle:

The low set point is defined as the maximum differential current that exists in normal transformer operation. The causes of differential current are:

Current transformer measurement errors

Current variants due to the use of an on-load tap changer

Presence of auxiliary windings (e.g. for substation supply)

2.2 Setting of the threshold:

The low set point must reflect the errors induced by the different transformer components: CTs and on-load tap changers: , this is the maximum differential current created by CT measurement errors and the presence of on-load tap changers.

with (: transformer primary current measurement error. (: transformer secondary phase current measurement error. b: range of transformer on-load tap changer taps.

Type of CT5P10P

(,(5%10%

N.B.: The details of the calculations used to obtain this formula are available in the document: Ids low set point and Id/It slope calculation uncertainty

Auxiliary winding: Idaux, differential current induced by the use of an auxiliary winding on the transformer.

where y is the percentage of secondary winding represented by the auxiliary winding

Differential current induced by the relay, Idrelay:

, typically

Magnetizing current of the transformer core which creates a differential current, Idm.

, typically

A safety margin is also taken: typically, 5%.

The Ids threshold is expressed as a percentage of In1 and is obtained by the following formula:

Numerical application:

Case of transformer equipped with 5P20 type CTs on the primary and secondary windings, an on-load tap-changer with a tap range of 10% and an auxiliary winding representing 10% of the secondary winding.

5P type CTs on the transformer primary and secondary windings, therefore (=(=5%.

i.e. Ids=38%

Please note: see the Excel tool for the calculation of Ids, OutilCalcul_Ids.xls

3. Percentage-based differential:

3.1 Principle:

The percentage-based curve comprises several segments defined are follows:

a low set point (Ids), defined previously

2 straight lines with adjustable slopes that cross zero (Id/It and Id/It2)

an adjustable slope change point (slope ch pt) a high set point (Idmax)

To prevent tripping due to high fault currents of external origin, Sepam uses a percentage-based curve. When a high external fault occurs, a high through current circulates. The differential current due to the transformer and its accessories (measurement CT, on-load tap changer and auxiliary winding) is also higher than in normal operation, so the Ids set point is exceeded. However the protection should not trip, since the fault is external. With the Id/It slope, the higher the through current, the higher the differential current tripping threshold will be, thereby ensuring that the function will not trip in the event of external faults.

The second segment, Id/It2, ensures that the function will not trip when an external fault causes at least one CT to saturate. If only the primary CTs saturate, not the secondary CTs, a very high differential current is created. To prevent unwanted tripping in these conditions, the percentage-based curve includes the Id/It2 slope.

The Id/It2 curve ensures that the protection function will not trip in the event of external faults with high through current which saturates at least one of the CTs.

The setting of the slope change point depends on the CTs' capacity to give a correct image of the primary currents during external faults. This zone corresponds to the CT saturation limit.

3.2 Setting of the percentage-based curve:

Id/It1 percentage:

The setting should be sufficient to compensate for measurement errors caused by current with low but significant amplitude.

The Id/It slope value to be set in Sepam is the maximum Id/It value, i.e. maximum Id and minimum It. In the previous paragraph, we established the following:

Ids = + Idaux + Idrelay + Idm + safety margin, which corresponds to the maximum differential current measured in normal operation.

A series of calculations, available in the document Ids low set point and Id/It slope calculation uncertainty,

shows that the minimum through current value is .This results in the following maximum slope value:


Case of a transformer equipped with 5P20 type CTs on the primary and secondary windings, an on-load tap changer with a tap range of 10% and an auxiliary winding representing 10% of the secondary winding.

therefore i.e. a slope of approximately 44%.

Please note: See the Excel tool for the calcuation of the Id/It slope: Id/It_CalculTool.xls Id/It2 percentage:

The curve should be set sufficiently high to compensate for the worst case in which only the CTs at one end saturate and not the others. Typically, the slope is set between 60 and 70%.

Slope change point:

This value is conventionally set at around 6 In. 4. Restraint principles:Now we will look at the restraint part of the block diagram.

4.1 Problems relating to harmonics:

Second-harmonic set point restraint:

Transformer closing causes a very high transient current (8 to 15 In), which only goes through the primary winding and only lasts for a few tenths of a second. It is detected by the protection relay as differential current with a duration that is clearly longer than the protection operating time. With detection based solely on the difference between the matched transformer primary and secondary currents, it would trip the protection. It is therefore necessary for the protection to be capable of distinguishing between differential current due to an internal fault and differential current due to transformer closing.

Experience has shown that the closing current wave contains at least 20% second-harmonic (100 Hz frequency current), whereas the percentage is never greater than 5% for overcurrent due to an internal transformer fault.

To block tripping, the function may simply be locked out when the second-harmonic with respect to the fundamental (50 Hz current) is greater than 15%.

N.B.: Transformer energization or external faults may cause CT saturation. In both cases, saturation increases the second harmonic in the differential current.

The values given previously for a 50Hz network are valid as well for a 60Hz network.

Fifth-harmonic set point restraint:

Magnetizing current Im(1) is a difference between the transformer primary and secondary currents.

(1): with I and I transformer primary and secondary currents, respectively

N: the transformation ratio

The Im current is therefore detected as being fault current by the differential protection even though it is not due to a fault. In normal operation, magnetizing current is very low and does not reach the protection tripping threshold.

However, when the V/Hz ratio increases due to a cause outside the transformer, i.e. overvoltage or a drop in frequency, the magnetic material of the transformer saturates (transformers are generally sized to operate at the saturation limit for the rated supply voltage) and the magnetizing current value increases significantly. The protection operating threshold may be reached.

Experience has shown that magnetizing current due to magnetic saturation contains a high percentage of fifth harmonic (250 Hz frequency) current, at least 30%.

To prevent unwanted tripping due to overvoltage of external origin, saturation may be detected by the presence of fifth harmonic current and the function disabled if the fifth-harmonic set point is exceeded.

To prevent unwanted tripping due to overvoltage (or overfluxing) or external origin, the protection may simply be disabled for more than 30% fifth harmonic current.

Please note: Overexcitation resulting from an increase in the V/Hz ratio causes overfluxing in the power transformer core. The danger incurred results from a thermal process in the core. This process is slow and the transformer can withstand overfluxing for a certain length of time. Instantaneous tripping with this type of operation is unwanted, but detection of the phenomenon and indication or tripping may be useful.

In such cases the Sepam ANSI 24 overfluxing (V/Hz) function should be used.4.2 Choice of self-adaptive or conventional restraint:

There are two types of harmonic restraint functions: self-adaptive and conventional. The choice depends on the transformer's peak closing current. The self-adaptive restraint is very interesting in that it adapts the parameters that define the tripping zone. However, it only operates for transformer energization currents less than eight times the transformer rated current.The self-adaptive restraint is based on a neural network algorithm which ensures external fault stability by analyzing the second and fifth harmonics, diffential currents and through currents.

It guarantees stability in the following cases:

transformer closing

asymmetrical fault outside the zone which saturates the current sensors

transformer operated on a voltage supply that is too high (overfluxing)According to the closing current value, the following may be chosen:

Peak closing current:

Chosen type of restraintSelf-adaptive

or ConventionalConventional

With, rated peak currentIn rated transformer currentPlease note: Qualitatively speaking, the closing current of dry-type transformers is higher than that of oil-immersed transformers, and the lower the transformer power, the higher the closing current. (see e/n = f(P) graph).

For distribution transformers, France Transfo publishes the following values in its data sheets:

For TRIHAL dry-type cast resin transformers from 1000 to 2500kVA (inr peak closing current, peak primary rated current)

For oil-immersed transformers from 1000 to 2500kVA (inr peak closing current, peak primary rated current)

The conventional restraint comprises a second-harmonic set point for each phase and fifth-harmonic set point for each phase. The second-harmonic set point ensures that the function will not pick up in the event of transformer closing or current sensor saturation. The fifth-harmonic set point ensures that the protection function will not pick up in the event of the transformer being connected to a voltage supply that is too high (overfluxing).

5. Principle and setting of high set point:

5.1 Principle:

The high set point allows faults inside the protected zone to be detected by the rise in differential current (an example of this type of fault is a fault across the transformer primary terminals). If the differential current exceeds a predetermined set point (Idmax), the protection function trips faster than an overcurrent protection relay would. In addition, there is no restraint on the high threshold, meaning that once it is activated, it is not affected by any restraint.

5.2 Setting:

A fault inside the zone produces high differential and through currents, situated in the upper right-hand part of the percentage-based curve.

With a conventional restraint, we always opt for activation of the high set point since it ensures tripping for the high through and differential curents created by internal faults.

With the self-adaptive restraint, activation of the high set point may depend on whether or not the CT-loss restraint is implemented. (see paragraph 9.Additional explanations of self-adaptive restraint)

When it is active, the high set point is set above the closing current, typically with a margin of 40% so that the protection function will not be tripped by transformer energizing.

i.e.

6. Setting of the conventional restraint:

6.1 Second-harmonic:

The second-harmonic set point is typically between 15 and 25%. A common value is 15%.

Two points are to be noted:

If the CTs are saturated by energizing, the second-harmonic measured in the differential current increases.

If the cable to the secondary circuit is long, this can reduce the second-harmonic below 15%. In such cases, the second-harmonic set point should be lowered.

6.2 Fifth-harmonic:

The fifth-harmonic set point is typically between 25 and 35%. A typical value is 30%.6.3 Global restraint (cross-blocking):

For each of the second and fifth-harmonics, the restraint may or may not be global.

When the restraint is global (cross-blocking), all three phases are restrained as soon as the harmonic in one phase reaches or exceeds the set point.

When the restraint is not global (no cross-blocking), only the phase with a harmonic greater to or equal to the set point is restrained.

Global restraint operates in the same way for both second and fifth-harmonic restraint.

It is advisable to apply the following settings:

Cross-blocking enabled for second-harmonic restraint.

Cross-blocking disabled for fifth-harmonic restraint.

7. Restraint on closing:

With certain modern transformer technologies, the closing current has very little second harmonic current (less than 15%) and cannot be detected by Sepam.

Furthermore, if there are several transformers in parallel, the energizing of a transformer in the vicinity of another one that is already operating causes demagnetization of the one already in service. There will be closing current in the demagnetized transformer again but, this time, with practically no second harmonic, meaning that it will not be detected by the harmonic restraints. Both cases can therefore cause unwanted tripping.

To compensate for such special cases, the restraint on closing may be used to disable the protection relay for a time delay equivalent to the duration of magnetization.

The current set point condition is: Current set point < No-load current

The no-load current generally represents a few percent of In.

The time delay is typically between 200 ms and 300 ms, representing the average energizing time: 200ms In2 x 1.1510.2 Dimensioning:

The current transformer depends next on the transformer's peak closing current in relation to the rms rated current.

The dimensioning differs according to the closing current:

Peak closing current:

Type of dimensioningCase 1Case 2

With, peak rated current transformer rms rated current

Case 1:

To guarantee standard CT dimensioning and minimum current measurement error with high currents, it is necessary to choose CTs of the 5P 20 type with a rated burden of VACT:

with in the CT secondary current and Rt the sum of the wiring resistance, , and the internal CT resistance, , (VACT corresponds to the apparent power supplied to the secondary circuit for the secondary rated current, the standardized values being 1-2.5- 5-10-15-30 VA)

Please note:

If only the Sepam is connected to the CT secondary circuts, the Sepam's internal resistance is negligible with respect to the wiring resistance. ( Im, It=Im

If Im > Im, It= Im

Ids low set point and Id/It slope calculation uncertainty:

Three examples are presented below, for three different types of coupling transformers.

1. Yyo transformer:

, : transformer primary and secondary rated currents, respectively.

(Generally speaking, the primed symbol characterizes an additional value)

Transformation ratio:

(i: measurement error on transformer primary phase i.(i: measurement error on transformer secondary phase i.b: transformer on-load tap changer tap range (+ or 0.1)

Secondary currents:


With

Primary currents:


With

Differential currents:

Differential current is calculated by:

A simulation has been done with Matlab to establish a combination of [(1,(2,(3] signs and [(1,(2,(3] signs to maximize differential current. The simulation results are as follows:

Ai= [(1,(2,(3]Bi= [(1,(2,(3]

Idi[-( -( -(][( ( (]

This corresponds to the case in which all the primary sensors have an ( at the minimum (negative) and all the secondary sensors an error ( at the maximum (positive).

Differential current may therefore be expressed as:

Through currents and Id/It slope:

Through current is calculated by:

For the same Id maximizing conditions (Id is maximized and It is minimized), through current may be expressed as:

Hence the maximum slope


For b=0.1 which corresponds to an on-load tap changer tap range of + or - 10%

and (=(=0.1, which corresponds to a CT accuracy error of 10%

the false differential current is equal to 28.18%

the minimum slope is equal to 34.44%

2. Dy11 transformer:




(i: measurement error on transformer primary phase i .(i: measurement error on transformer secondary phase i.b: transformer on-load tap changer tap range (+ or 0.1)

Secondary currents:


and hence

Primary currents:


With



The results of the Matlab simulation used to find the maximum differential current are as follows:Ai= [(1,(2,(3]Bi= [(1,(2,(3]

Id1[-( -( -(][( -( (]

Id2[-( -( -(][( ( -(]

Id3[-( -( -(][-( ( (]

This corresponds to the case in which all the primary sensors are at the maximum and one of the three secondary sensors is at the minimum, the other two being at the maximum.Differential current, whatever the phase, may be expressed as


Through current is calculated by:

For the same Id maximizing conditions (Id is maximized and It is minimized), the through current can be expressed as

Hence the maximum slope


For b=0.1 and (=(=0.1,


the minimum slope is equal to 34.44%3. Yd5 transformer:




(i: measurement error on transformer primary phase i .(i: measurement error on transformer secondary phase i.b: transformer on-load tap changer tap range (+ or 0.1)

Secondary currents:


and

Primary currents:


With



The results of the Matlab simulation used to find the maximum differential current are as follows:Ai= [(1,(2,(3]Bi= [(1,(2,(3]

Id1[-( -( -(][( -( (]

Id2[-( -( -(][( ( -(]

Id3[-( -( -(][-( ( (]

This corresponds to the case in which all the primary sensors are at the maximum and one of the three secondary sensors is at the minimum, the other two being at the maximum.Differential current, whatever the phase, may be expressed as:


Through current is calcualted by:

For the same Id maximizing conditions (Id is maximized and It is minimized), the through current may be expressed as

Hence the maximum slope Numerical application:

For b=0.1 and (=(=0.1,


the minimum slope is equal to 34.44%Ids low set point calculation tool:

Id/It slope calculation tool:

TRIHAL dry-type cast resin transformers:

Data sheet extract

Oil-immersed transformers

Data sheet extract

Artificial Neural Networks:

Artificial neural networks are a set of calculation tools and methods used to teach an artificial system different types of behaviors according to input parameter values. During the development of transformer differential protection, the function was "taught" to react in a particular way to four input parameters which are:

Differential and through current fundamental, and

Second-harmonic, , the same for each phase

Differential current fifth-harmonic,

Representation of an artificial neuron:

with the following notations:The neuron input values are xi The output value is Oj

The internal parameters are the weights wij and the threshold (j

Representation of the Artifical Neural Network of the Sepam algorithm:

The input parameter values corresponding to the 5 following types of situation were entered in the neural network learning database:

Normal operation, no faults, with and without connected loads

Transformer closing

Fault outside the protected zone

Internal two-phase fault

Internal phase-to-earth fault

An output value corresponding to protection tripping or no tripping was then given.

The neural network managed all of these cases by setting the internal parameters of each neuron (weight and threshold) to define a behavior that complied with the input and output conditions entered in the learning database. The algorithm obtained was then implemented in Sepam. This type of restraint increases the tripping threshold according to the harmonic current measured. Tests were then performed to determine the profile of the tripping curve that uses this self-adaptive restraint according to harmonic current. The test protocols which produced these curves are those detailed in the paragraph on protection testing.

If the second-harmonic increases, the low set point increases as well. The protection will therefore be more stable with respect to closing or CT saturation.

In normal operation, during which the second-harmonic is low (cf H2=0%), the function is more effective than the conventional restraint since the global tripping threshold is lower.

The same comments as above apply for fifth harmonic and transformer overfluxing.

EMBED Equation.3

EMBED Equation.3

EMBED Equation.3

EMBED Excel.Sheet.8

Amplitude and phase matching

Calculation of differential and through current

Internal fault

valuess

Winding 1 = HV

I1, I2, I3

Dy11

6.6kV / 34kV

I1, I2, I3

VS =11

Sepam

Differential protection

Winding 2 = LV

Winding 1 =HV

Id1

It1

EMBED Equation.3

EMBED Equation.3


Calculation of differential and through current for phase 1

I1, I2, I3

Dy11

34kV/6.6kV

I1, I2, I3

inr/n

= 0

Max

EMBED Word.Picture.8

Vectormagnitudee

Vectormagnitudee

+

Id1

It1

Winding 2 = LV

Sepam

VS =11

I1, I2, I3

6.6kV/34kV

Dy11

I1, I2, I3

Winding 1 =LV

Winding 2 =HV

Sepam

VS =1

I1

I2

I3

I1

I2

I3

EMBED Equation.3

I1

I2

I3

I1

I2

I3

X1

X2

X3

I1

I2

I3

I1

I2

I3

X1

X2

X3

Protection tripping or no tripping

EMBED Equation.3

EMBED Equation.3

EMBED Equation.3

EMBED Equation.3

EMBED Equation.3

EMBED Equation.3

threshold

combination function

weighted sum

activation function

weights

Restraint of percentage-based characteristic

Figure 16.11. Relatve value of closing current according to transformer rated power for oriented-crystal sheets

17-1-

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_1222348469.xlsFeuil1

Rated power in kVA10001250160020002500

inr/n (peak values)1010109.59.5

_1222180884.xlsFeuil1

Rated power in kVA10001250160020002500

inr/n (peak values)109988

_1222178403.unknown

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0.650.91.631.85

0.650.9851.791.95

0.651.222.012.12

0.651.612.312.35

0.652.122.662.64

0.652.673.052.99

0.653.23.453.36

0.653.73.863.75

0.684.174.264.14

0.7654.614.664.54

0.8755.045.064.94

1.025.445.455.34

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2.366.936.966.89

2.737.287.327.27

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9.0410.9211.111.25

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H2 = 0%

H2 = 15%

H2 = 20%

H2 = 25%

It/In

Id/In

Tripping zone with ANN restraint according to second-harmonic

Feuil1

Itrav injectIdiff declIdiff H2 injectIdiff declIdiff H2 injectIdiff declIdiff H2 injectIdiff declIdiff H2 inject

50 ou 60Hz50 ou 60HzH2 = 0%50 ou 60HzH2 = 15%50 ou 60HzH2 = 20%50 ou 60HzH2 = 25%

It/InId/InIdh2/InId/InIdh2/InId/InIdh2/InId/InIdh2/In

00.6500.840.1041.530.3061.790.448

0.50.6500.90.121.630.3261.850.463

10.6500.9850.1461.790.3581.950.488

1.50.6501.220.1832.010.4022.120.53

20.6501.610.2422.310.4622.350.588

2.50.6502.120.3182.660.5322.640.66

30.6502.670.4013.050.612.990.748

3.50.6503.20.483.450.693.360.84

40.6503.70.5553.860.7723.750.938

4.50.6804.170.6264.260.8524.141.035

50.76504.610.6924.660.9324.541.135

5.50.87505.040.7565.061.0124.941.235

61.0205.440.8165.451.095.341.335

6.51.3205.830.8755.841.1685.731.433

71.6506.210.9326.221.2446.121.53

7.5206.580.9876.591.3186.511.628

82.3606.931.046.961.3926.891.723

8.52.7307.281.0927.321.4647.271.818

93.1307.621.1437.671.5347.641.91

9.53.5507.941.1918.011.60282

103.9908.261.2398.351.678.362.09

10.54.4708.581.2878.671.7348.712.178

114.9808.881.33291.89.052.263

11.55.5309.191.3799.311.8629.382.345

126.109.481.4229.621.9249.712.428

12.56.709.781.4679.921.98410.032.508

137.31010.071.51110.222.04410.342.585

13.57.91010.351.55310.522.10410.652.663

148.49010.641.59610.812.16210.952.738

14.59.04010.921.63811.12.2211.252.813

159.56011.21.6811.382.27611.542.885

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H2 = 0%

H2 = 15%

H2 = 20%

H2 = 25%

It/In

Id/In

Zone de dclenchement avec retennue RNA en fonction du taux de H2

Feuil2

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0.650.6750.795

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0.650.8551.28

0.650.951.57

0.651.121.87

0.651.362.17

0.651.622.47

0.651.872.77

0.682.133.06

0.7652.393.35

0.8752.643.64

1.022.883.93

1.323.124.21

1.653.364.49

23.594.78

2.363.825.06

2.734.065.35

3.134.315.64

3.554.585.94

3.994.866.25

4.475.176.57

4.985.56.9

5.535.867.25

6.16.267.63

6.76.688.04

7.317.158.49

7.917.659

8.498.189.56

9.048.7210.2

9.569.2710.88

0%

20%

30%

It/In

Id/In

Tripping zone with ANN restraint according to fifth harmonic

Feuil1

Itrav injectIdiff declIdiff H5 injectIdiff declIdiff H5 injectIdiff declIdiff H5 inject

50 ou 60Hz50 ou 60Hz0%50 ou 60Hz20%50 ou 60Hz30%

It/InId/InIdh5/InId/InIdh5/InId/InIdh5/In

00.6500.6750.070.7950.1770de 0,3 10de 0,35 10.07de 0,59 10.177

0.50.6500.720.0880.890.2340.5de 0,3 10de 0,44 10.088de 0,78 10.234

10.6500.780.1121.020.3061de 0,3 10de 0,56 10.1121.020.306

1.50.6500.8550.1421.280.3841.5de 0,3 10de 0,71 10.1421.280.384

20.6500.950.181.570.4712de 0,3 10de 0,9 10.181.570.471

2.50.6501.120.2241.870.5612.5de 0,3 101.120.2241.870.561

30.6501.360.2722.170.6513de 0,3 101.360.2722.170.651

3.50.6501.620.3242.470.7413.5de 0,3 101.620.3242.470.741

40.6501.870.3742.770.8314de 0,3 101.870.3742.770.831

4.50.6802.130.4263.060.9184.5de 0,36 102.130.4263.060.918

50.76502.390.4783.351.0055de 0,53 102.390.4783.351.005

5.50.87502.640.5283.641.0925.5de 0,75 102.640.5283.641.092

61.0202.880.5763.931.179

6.51.3203.120.6244.211.263

71.6503.360.6724.491.347

7.5203.590.7184.781.434

82.3603.820.7645.061.518

8.52.7304.060.8125.351.605

93.1304.310.8625.641.692

9.53.5504.580.9165.941.782

103.9904.860.9726.251.875

10.54.4705.171.0346.571.971

114.9805.51.16.92.07

11.55.5305.861.1727.252.175

126.106.261.2527.632.289

12.56.706.681.3368.042.412

137.3107.151.438.492.547

13.57.9107.651.5392.7

148.4908.181.6369.562.868

14.59.0408.721.74410.23.06

159.5609.271.85410.883.264

Feuil1

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

0%

20%

30%

It/In

Id/In

Zone de dclenchement avec retenue RNA en fonction du taux de H5

Feuil2

Feuil3

_1222178381.unknown

_1222178307.unknown

_1222178330.unknown

_1222178275.unknown

_1222178118.unknown

_1222178191.unknown

_1222178212.unknown

_1222178137.unknown

_1222177921.unknown

_1222177960.unknown

_1222177914.unknown

_1222176285.unknown

_1222177719.unknown

_1222177867.unknown

_1222177653.unknown

_1222176476.doc

INCORPORER Equation.3

8

INCORPORER Equation.3 INCORPORER Equation.3

Case 1 CT

Case 2 CT

Self-adaptive or conventional restraint

Conventional restraint

_1204960234.unknown

_1213008631.unknown

_1222088295.unknown

_1222176439.unknown

_1204960308.unknown

_1204960138.unknown

_1222176243.unknown

_1222176258.unknown

_1222176187.unknown

_1222170770.unknown

_1222170824.unknown

_1222175693.unknown

_1222175748.unknown

_1222170831.unknown

_1222170808.unknown

_1222170816.unknown

_1222170781.unknown

_1222170610.unknown

_1222170701.unknown

_1222170758.unknown

_1222170673.unknown

_1222169336.ppt

Calculation of phase 1differential and through current


Id1

It1

tx_h2_ph 1tx_h5_ph 1

Harmonic measurements using Id1,Id2 and Id3

Percentage differential

Harmonic restraint

High set point phase 1Id1>Idmax

Restraint on closing

I1I2I3

I1I2I3

Detectionof CT loss

I1I2I3

I1I2I3

Phase 1

Control variable

Control variable

The different control variables are processed by a logic diagram to enable or disable the protection.

Control variable

Control variable

1

_1222170575.unknown

_1222170597.unknown

_1222170501.unknown

_1222170569.unknown

_1222170494.unknown

_1222165932.unknown

_1222165942.unknown

_1222165924.unknown

_1222088083.unknown

_1222088277.unknown

_1222154269.unknown

_1222161523.unknown

_1222161524.unknown

_1222155137.xlsFeuil1

Calculation tool for 87T Id/It slope setting:

Type of CT5P

On-load tap changer10%Parameters to be set5Pliste de choix

Auxliary winding10%10P

Relay error1%

Magnetizing current3%Conventional values10P10%

Safety margin5%5P5%

5%

19%ids due aux TC et au rgleur

Id/It slope to be set44%19%ids Aux, Relais, Magn, Marge

38%somme

N.B.: Set the value to zero if there is no tap changer or auxiliary winding0.8636363636It mini

0.4357894737id/It max

Feuil2

Feuil3

_1222155154.xlsFeuil1

Calculation tool for 87T Ids low threshold setting

Type of CT5P

On-load tap changer10%Parameters to be set5Pliste de choix

Auxliary winding10%10P

Relay error1%

Magnetizing current3%Conventional values10P10%

Safety margin5%5P5%

5%

19%ids due aux TC et au rgleur

Id/It slope to be set38%19%ids Aux, Relais, Magn, Marge

N.B.: Set the value to zero if there is no tap changer or auxiliary winding

Feuil2

Feuil3

_1222154389.unknown

_1222153108.xlsGraph1

0.30.31.754.29

0.31.754.299

Ids

Id/It

Id/It2

Idmax

slope ch pt

Seuil bas

Id/It

Break point

Id/It2

Retenue auto-adaptative

It/In

Id/In

Feuil1

1.Caractristiques du transformateur de puissance:

couplageDyn11

S4MVA

Up20KV

Us1KV

Ibp115.4700538379A

Ibs2309.4010767585A

2.Paramtres des TC:

TCCourant Prim.TCCourant Sec.TC

prim. du TP6001A

sec. du TP30001A

3.Paramtres de la courbe pourcentage:

Ids30en %[30;100]

Id/It25en %[15;50]

Slope change point7[1;18]*In

Id/It260en %[50;100]

seuil haut9In

4.Calcul des segments de la courbe % :

Segment 1Segment 2Segment 3Segment 4

ItIdItIdItIdItIdItId

From00.31.20.371.7574.2159

To1.20.371.7574.2159209

5.Test de points particuliers: (sans retenue auto-adaptative)6.Courants primaires et secondaire du TP pour une inj. donne:

On testera chaque segment en un point (x=sur le segment; y=sur le segment+ 0,5)

InjectionIinj 10.22744A

Segment 1:avec Inj 2>Iinj 1Iinj 21.94369A

Seuil baspoint tester:It0.6milieu du segment

Id0.8abscisse+0,5Mesures du Sepam

I11029.75I'15831.07A

valeurs relles pour le TP:It69.2820323028I21029.75I'25831.07A

Id92.3760430703I30I'30A

Id1136.464It15831.07A

courants injecter:Iinj10.0307920144(Iinj1=Id*(in/In) cf doc word)Id2136.464It25831.07A

Iinj20.1154700538(Iinj2=It*(in/I'n) cf doc word)Id30It30A

Segment 2:

Id/Itpoint tester:It2.9

Id1.225

valeurs relles pour le TP:It334.86315613

Id141.4508159515

courants injecter:Iinj10.047150272

Iinj20.5581052602

Segment 4:

Id/It2point tester:It4

Id2.9


Id334.86315613


Iinj20.7698003589

Feuil1

00000

00000

Seuil bas

Id/It

Break point

Id/It2


It/In

Id/In

Courbe pourcentage

Feuil2

Feuil3

_1222153665.unknown

_1222152475.unknown

_1222088170.unknown

_1222088208.unknown

_1222088263.unknown

_1222088192.unknown

_1222088115.unknown

_1222088138.unknown

_1222088102.unknown

_1222087981.unknown

_1222088030.unknown

_1222088057.unknown

_1222088014.unknown

_1222087998.unknown

_1222087899.unknown

_1222087970.unknown

_1222087884.unknown

_1211722134.unknown

_1213085856.unknown

_1222087565.unknown

_1222087670.unknown

_1222087746.unknown

_1222087587.unknown

_1221990186.doc


I1

I2

I3

I'1

I'2

I3

Load

I

I'

I

X3

X2

X1

_989479328.unknown

_989479537.unknown

_989479242.unknown

_1222068226.xlsGraph1

0.30.31.754.29

0.31.754.299

Ids

Id/It

Id/It2

Idmax

slope ch pt

Seuil bas

Id/It

Break point

Id/It2


It/In

Id/In

Conventional restraint, percentage-based curve

Feuil1


couplageDyn11

S4MVA

Up20KV

Us1KV

Ibp115.4700538379A

Ibs2309.4010767585A

2.Paramtres des TC:


prim. du TP6001A

sec. du TP30001A


Ids30en %[30;100]

Id/It25en %[15;50]


Id/It260en %[50;100]

seuil haut9In




From00.31.20.371.7574.2159

To1.20.371.7574.2159209







I11029.75I'15831.07A


Id92.3760430703I30I'30A

Id1136.464It15831.07A



Segment 2:


Id1.225


Id141.4508159515


Iinj20.5581052602

Segment 4:


Id2.9


Id334.86315613


Iinj20.7698003589

Feuil1

00000

00000

Seuil bas

Id/It

Break point

Id/It2


It/In

Id/In

Courbe pourcentage

Feuil2

Feuil3

_1222087482.unknown

_1221998594.xlsGraph1

0.30.31.754.29

0.31.754.299

Ids

Id/It

Id/It2

Idmax

slope ch pt

Seuil bas

Id/It

Break point

Id/It2


It/In

Id/In

Percentage-based characteristic

Feuil1


couplageDyn11

S4MVA

Up20KV

Us1KV

Ibp115.4700538379A

Ibs2309.4010767585A

2.Paramtres des TC:


prim. du TP6001A

sec. du TP30001A


Ids30en %[30;100]

Id/It25en %[15;50]


Id/It260en %[50;100]

seuil haut9In




From00.31.20.371.7574.2159

To1.20.371.7574.2159209







I11029.75I'15831.07A


Id92.3760430703I30I'30A

Id1136.464It15831.07A



Segment 2:


Id1.225


Id141.4508159515


Iinj20.5581052602

Segment 4:


Id2.9


Id334.86315613


Iinj20.7698003589

Feuil1

00000

00000

Seuil bas

Id/It

Break point

Id/It2


It/In

Id/In

Courbe pourcentage

Feuil2

Feuil3

_1213085931.unknown

_1213086478.unknown

_1213085914.unknown

_1213004383.unknown

_1213008534.unknown

_1213085743.unknown

_1213085815.unknown

_1213084936.unknown

_1213085653.unknown

_1213083651.unknown

_1213084935.unknown

_1213083632.unknown

_1213005367.unknown

_1213008479.unknown

_1213005294.unknown

_1212400814.unknown

_1213003087.unknown

_1213004318.unknown

_1212400955.unknown

_1212401030.unknown

_1212400947.unknown

_1211722705.unknown

_1211781540.unknown

_1212229458.unknown

_1211722277.unknown

_1210400937.unknown

_1210401603.unknown

_1211199787.unknown

_1211720840.unknown

_1211722131.unknown

_1211720838.unknown

_1211697309.unknown

_1210761185.unknown

_1211199775.unknown

_1211027071.unknown

_1210761151.unknown

_1210424454.unknown

_1210401337.unknown

_1210401472.unknown

_1210401507.unknown

_1210401602.unknown

_1210401511.unknown

_1210401490.unknown

_1210401440.unknown

_1210401450.unknown

_1210401411.unknown

_1210401027.unknown

_1210401314.unknown

_1210401016.unknown

_1210400983.unknown

_1209814711.unknown

_1209985240.unknown

_1209990416.unknown

_1209990439.unknown

_1209990467.unknown

_1209985747.unknown

_1209987698.unknown

_1209895921.unknown

_1208088383.unknown

_1209382701.unknown

_1209382702.unknown

_1209385452.doc





_1209385336.unknown

_1209385351.unknown

_1209385401.unknown

_1209385319.unknown

_1209382644.unknown

_1208088356.unknown

_1208088371.unknown

_1205153154.doc


I1

I2

I3

I'1

I'2

I3

If

_989479328.unknown

_989479537.unknown

_989479242.unknown

_1203318302.unknown

User Guide Transformer Differential 87t

Documents

Transcript of User Guide Transformer Differential 87t