25 kV Equipment Sizing Calculationv5_ (1).pdf
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. DESIGN OF 25 KV OVERHEAD EQUIPMENT (OHE) SYSTEM FOR ELEVATED LINES AND POWER SUPPLY & SCADA FOR BOTH UNDERGROUND AND ELEVATED LINES INCLUDING CHECKING OF DESIGN OF RECEIVING SUBSTATION AND DESIGN VALIDATION OF DELHI MRTS PHASE III PROJECT – LOT I
25 KV TRACTION EQUIPMENT SIZING CALCULATIONS January, 18th 2013
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CONTENTS
1. INTRODUCTION ..................................................................................................................... 4 1.1. Reference documentation ................................................................................................ 4 1.2. Abbreviations ................................................................................................................... 5 2. TRACTION TRANSFORMERS .............................................................................................. 6 2.1. Power consumption of TSS’s ........................................................................................... 6 2.1.1. Normal operation (5 traction substations working) .................................................... 6 2.1.2. Failure cases .............................................................................................................. 7 2.2. Voltage in pantograph .................................................................................................... 11 2.2.1. Normal operation (5 traction substations working) .................................................. 11 2.2.2. Failure cases ............................................................................................................ 12 2.3. Conclusions .................................................................................................................... 13 3. BOOSTER TRANSFORMERS ............................................................................................. 15 4. 25 KV FEEDERS .................................................................................................................. 19 4.1. Rated current calculation (In) ......................................................................................... 19 4.1.1. Main track ................................................................................................................. 19 4.1.2. Depot Calculation ..................................................................................................... 20 4.2. Calculation with current in case of nominal overload of the transformer (Io) ................. 21 4.3. Voltage drop ................................................................................................................... 23 4.4. Short circuit criteria ........................................................................................................ 23 4.4.1. 4.4.2. 4.4.3. 4.4.4. 4.4.5. 4.4.6.
Simply Single Line Scheme ..................................................................................... 25 Equivalent Single Line Scheme ............................................................................... 25 Impedance Calculations ........................................................................................... 26 Calculation of the continuous current of short circuit (Isc) ....................................... 28 Calculation of the Maximum Current Asymmetric ShortCircuit (Is) ........................ 28 Rupture capacity and connection ............................................................................. 29
4.5. Conductor sizing ............................................................................................................ 29 4.5.1. Type of Conductor .................................................................................................... 29 4.5.2. Size of Conductor ..................................................................................................... 30 5. RETURN CABLES................................................................................................................ 35 5.1. Return cables ................................................................................................................. 35 5.2. Return conductor ............................................................................................................ 35 5.2.1. Rated current calculation (In) ................................................................................... 35 5.2.2. Voltage drop ............................................................................................................. 36 5.2.3. Short circuit criteria .................................................................................................. 36 6. INDUCED VOLTAGE CALCULATION ................................................................................ 36 7. CIRCUIT BREAKERS RATING ............................................................................................ 38
25 KV Traction Equipment Sizing Calculations
. 8. INTERRUPTERS RATING ................................................................................................... 39 9. CURRENT TRANSFORMERS RATING .............................................................................. 40
Annex 1. Technical data of 26/45 kV XLPE insulated copper cable used for calculation. Annex 2. Guide for calculation of cable capacity under short time operation currents. Annex 3. Technical data of aluminium cables used for calculation. Annex 4. Rolling stock data used for calculation
25 KV Traction Equipment Sizing Calculations
1. Introduction The present document aims to determine the rating of the equipment foreseen for the 25 kV traction network in the scope of the design of 25 kV Overhead Equipment (OHE) system for the Mukundpur – Gokulpuri – Shiv Vihar section (Line 7) including Mukundpur and Vinod Nagar Depots. 1.1. Reference documentation Comparative Study of various Schemes of underground ASS & Recommendations for DMRC PhaseIII. DMRD. Edition Nov 2011. ArdanuyBarsyl. Edition of 17/08/2012 DMRC Project Line 7. Detail Design Consultant. CCDD1. Traction simulation sizing study ArdanuyBarsyl. Edition of 17/08/2012
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1.2. Abbreviations DMRC
Delhi Metro Rail Corporation Limited
UG
Underground (Package, Station or Section)
ELV
Elevated (Package, Station or Section)
DPT
Depot
ASS
Auxiliary Substation
RSS
Receiving Substation
TSS
Traction Substation
PD
Propriety Development
TVF
Tunnel Ventilation Fan
TEF
Tunnel Emergency Fan
ECS
Environment Control System
S&T
Signal & Telecommunication
TR
Transformer
DG
Diesel Generator
CCB
Coupling Circuit Breaker
VDE
Association of German Electrical Engineers
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2. Traction Transformers The Traction Simulation Study for the Line 7 extension has been performed by M/s Ardanuy using RailPower software. In this chapter the results and main conclusions obtained from the study are included. 2.1. Power consumption of TSS’s Different alternatives have been simulated to get the power consumptions in transformers of the Tractions Substations. The values have been obtained taking into account these assumptions: Total Trip: Mukundpur – Shiv Vihar, 57.705 km, 37 stations. Rolling Stock with 6 coach compositions (DMTMMTDM) and full loaded (1,800 people). Total weight of Rolling Stock is 371.25 Tons (Tare weight is 252 Tons, 42 Tons/car). It is assumed that up to 75% of the power generated by train braking is able to be regenerated in electrical power by the motors of the train (Regenerative braking performance will be 0.75). Braking force will be supplied by the train motor brakes until the maximum engine brake force for each speed is given. If it is necessary more braking force than the motor is able to generate, it will be provided by pneumatic brake. By default, it is considered a value of train power factor of 1. Auxiliary Power Consumption of trains (according to values provided by DMRC): 33 kVA/car (198 kVA whole train) Headway of 135 seconds between trains in same direction (what means 68 trains at same time in the system) 2.1.1.
Normal operation (5 traction substations working)
Maximum, average and RMS (maximum RMS value for integration period of 1 hour) power values for Traction Substations during the peak hour are shown in the following table.
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SIMULATED VALUES OF POWER CONSUMPTION IN TSS DHKN INA VNNG YMVH MKPR (KVA)
(KVA)
(KVA)
(KVA)
(KVA)
TRF1
TRF1
TRF1
TRF1
TRF1
MAX
19.630
37.103
24.233
32.028
19.422
RMS
12.114
17.219
16.388
17.006
12.625
AVG15 min.
11.146
13.556
15.625
14.875
10.773
AVG5 min.
11.478
14.640
16.072
15.431
11.067
Table 1. Simulated values of power consumption in TSS. Normal operation
According to these values, transformers with nominal power of 40/50 MVA are plenty dimensioned to feed the whole line present. The overload conditions that each transformer should be complied are: Overloads above 150% of nominal power (40 MVA) during less than 15 minutes in a 3 hour cycle. Overloads above 200% of nominal power (40 MVA) during less than 5 minutes in a 3 hour cycle. It can be seen the worst case (transformer more loaded) for this simulation is transformer of Dhaula Kuan TSS. There is not any instant in the simulation when the power is higher than 150% of nominal power (40x1,5 = 60 MVA), therefore both conditions of overloading are complied. 2.1.2.
Failure cases
Feed extensions cases have been simulated, for failures of 1, 2, 3 and 4 TSS. The worst case for each type of operation (N1, N2, N3 and N4) has been simulated. The following list shows the worst case simulated for each operation mode (the worst case for each operation mode is the case where the electrical sector fed by 1 TSS is the longest): N1 Case. Failure of TSS3 (INA): Dhaula Kuan will feed from Neutral Section in K.P 9+200 to Neutral Section in 34+935. N2 Case. Failure of TSS1 (Mukund Pur) and TSS2 (Dhaula Kuan): INA will feed from dead end of the line (Mukund Pur Station) to K.P. 34+845.
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N3 Case. Failure of TSS1 (Mukund Pur), TSS2 (Dhaula Kuan) and TSS3 (INA): Vinod Nagar will feed from dead end of the line (Mukund Pur Station) to K.P. 48,685. N4 Case. Failure of TSS2 (Dhaula Kuan), TSS3 (INA), TSS4 (Vinod Nagar) and TSS5 (Yamuna Vihar): Mukund Pur will feed the whole line Simulations for feed extension cases have been realized taking into account the following headways: Case
Headway.
Case N1
135 seconds
Case N2
240 seconds
Case N3
480 seconds
Case N4
1,200 seconds
Table 2. Headway for failure cases
CASE N1: FAILURE OF TSS3 (INA) In this case, Dhaula Kuan will be feeding from Neutral Section in K.P 9+200 to Neutral Section in 34+935. The rest of the line will be fed as normal operation case. FAILURE OF INA TSS
0+680 MKPR TSS
9+200 SP
34+935 SP
17+045 DHKN TSS
42+140 VNNG TSS
48+775 SP
54+000 YMVH TSS
Figure 1 Case N1. Failure of TSS3 (INA)
SIMULATED VALUES OF POWER CONSUMPTION IN TSS DHKN VNNG YMVH MKPR (KVA) (KVA) (KVA) (KVA) MAX
TRF1 19.630
TRF1 54.085
TRF1 32.028
TRF1 19.422
RMS
12.114
31.826
17.006
12.625
AVG15 min.
11.146
28.252
14.875
10.773
AVG5 min.
11.478
29.627
15.431
11.067
Table 3. Simulated values of power consumption in TSS. Case N1
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The worst case for this simulation is the transformer of Dhaula Kuan TSS. In order to comply with criteria of overload above 150% during less than 15 minutes in a 3 hours cycle, the nominal power of this transformer will be dimensioned for 40 MVA. CASE N2: Failure of TSS1 (Mukund Pur) and TSS2 (Dhaula Kuan) In this case, headway of 4 minutes has been taken into account. INA will be feeding from dead end of the line (Mukund Pur Station) to K.P. 34+845. The rest of the line will be fed as normal operation case. FAILURE OF MUKUND PUR AND DHAULA KUAN TSS
25+400 INA TSS
34+935 SP
42+140 VNNG TSS
48+775 SP
54+000 YMVH TSS
Figure 2. Case N2. Failure of TSS1 (Mukundpur) and TSS2 (Dhaula Kuan)
SIMULATED VALUES OF POWER CONSUMPTION IN TSS INA VNNG YMVH (KVA) (KVA) (KVA) MAX
TRF1 52.217
TRF1 15.360
TRF1 16.613
RMS
26.356
11.453
8.412
AVG15 min.
23.080
9.207
6.581
AVG5 min.
25.082
10.494
7.366
Table 4. Simulated values of power consumption in TSS. Case N2
The worst case for this simulation is the transformer of INA TSS. In order to comply with criteria of overload above 150% during less than 15 minutes in a 3 hours cycle, the nominal power of this transformer will be dimensioned for 40 MVA. CASE N3: Failure of TSS1 (Mukund Pur), TSS2 (Dhaula Kuan) and TSS3 (INA) In this case, headway of 8 minutes has been taken into account. Vinod Nagar will be feeding from dead end of the line (Mukund Pur Station) to K.P. 48,685. The rest of the line will be fed as normal operation case.
25 KV Traction Equipment Sizing Calculations
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FAILURE OF MUKUND PUR AND DHAULA KUAN AND INA TSS
42+140 VNNG TSS
48+775 SP
54+000 YMVH TSS
Figure 3. Case N3. Failure of TSS1 (Mukundpur), TSS2 (Dhaula Kuan) and TSS3 (INA)
SIMULATED VALUES OF POWER CONSUMPTION IN TSS VNNG YMVH (KVA) (KVA) MAX
TRF1 34.550
TRF1 10.473
RMS
19.605
4.864
AVG15 min.
16.523
3.668
AVG5 min.
17.910
4.201
Table 5. Simulated values of power consumption in TSS. Case N3
The worst case for this simulation is the transformer of Vinod Nagar TSS. In order to comply with criteria of overload above 150% during less than 15 minutes in a 3 hours cycle, the nominal power of this transformer will be dimensioned for 40 MVA. CASE N4: Failure of TSS2 (Dhaula Kuan), TSS3 (INA), TSS4 (Vinod Nagar) and TSS5 (Yamuna Vihar) In this case, headway of 20 minutes has been taken into account. Mukund Pur will be feeding the entire line. FAILURE OF DHAULA KUAN, INA, VINOD NAGAR AND YAMUNA VIHAR TSS
0+680 MKPR TSS
Figure 4. Case N4. Feeding from TSS1 (Mukundpur)
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POWER CONSUMPTION IN TSS MKPR (KVA) MAX
TRF1 22.458
RMS
10.910
AVG15 min.
8.854
AVG5 min.
9.768
Table 6. Simulated values of power consumption in TSS. Case N4
In order to comply with criteria of overload above 150% during less than 15 minutes in a 3 hours cycle, the nominal power of the Mukumpur SST transformer will be dimensioned for 40 MVA. 2.2. Voltage in pantograph 2.2.1.
Normal operation (5 traction substations working)
Voltage in the train pantographs have been calculated considering Normal Operation of electrification system (5 Traction Substations working at same time). For this calculation the following has been taken into account: Value of lump impedance of the catenary system 25 kV feeding cable impedance Exit voltage at the electrical traction substations Exit current at the substations Current consumed by each train, which will correspond to the results of the simulations Location of the substations and neutral sections The voltages presented below are the maximum and minimum that can be produced on the pantograph with the foreseeable circulation graph (headway of 135 seconds).
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VOLTAGE IN TRAIN PANTOGRAPH
DIRECTION
MIN
MAX
AVG
(V)
(V)
(V)
MUKUNDPUR – SHIV VIHAR
26,563 27,939 27,332
SHIV VIHAR  MUKUNDPUR
26,517 28,150 27,341
Table 7. Voltage in train pantograph. Normal operation
For normal operation, minimum voltage in the line is 26,517 V, over the threshold established in the normative EN 50163 “Railway applications  Supply voltages of traction systems”, for traction systems of AC 25 kV (Umin1 = 19,000 V). 2.2.2.
Failure cases
Except in the case of N1, the headway between trains should increase as shown below to assure that the voltage drop in the pantograph trains complies with the values established in norm EN 50163 (where Umin1 = 19,000 V): Case
Headway.
Case N2
4 minutes
Case N3
8 minutes
Case N4
20 minutes
Table 8. Headway for N2, N3 and N4 failure cases.
In the following table, values of voltage in the train pantographs are shown for the different cases of feed extensions. VOLTAGE IN TRAIN PANTOGRAPH CASE
DIRECTION MIN (V) MAX (V) AVG (V)
CASE N1: FAILURE TSS3
DW LINE
25,550
27,939
27,138
FEED FROM TSS2
UP LINE
25,681
28,150
27,134
CASE N2: FAILURE TSS1 AND TSS2
DW LINE
19,737
28,054
26,979
FEED FROM TSS3
UP LINE
22,859
28,333
27,084
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VOLTAGE IN TRAIN PANTOGRAPH CASE
DIRECTION MIN (V) MAX (V) AVG (V)
CASE N3: FAILURE TSS1,TSS2 AND TSS3
DW LINE
20,159
28,082
26,691
FEED FROM TSS4
UP LINE
23,337
28,130
26,800
CASEN N4: FAILURE TSS2, TSS3, TSS4 AND
DW LINE
20,478
28,535
26,668
UP LINE
21,027
28,420
26,615
TSS5 FEED FROM TSS1
Table 9. Voltage in train pantograph. Failure cases
In N1 situation, the minimum value of voltage in train pantograph is 25,550 V. This value is over the threshold established in the normative EN 50163 (where Umin1 = 19,000 V) In N2 situation, the minimum value of voltage in train pantograph is 19,737 V. This value is over the threshold established in the normative EN 50163 (where Umin1 = 19,000 V) In N3 situation, the minimum value of voltage in train pantograph is 20,159 V. This value is over the threshold established in the normative EN 50163 (where Umin1 = 19,000 V) In N4 situation, the minimum value of voltage in train pantograph is 20,478 V. This value is over the threshold established in the normative EN 50163 (where Umin1 = 19,000 V) 2.3. Conclusions Main conclusions obtained for the study are summarized below: From electrical simulations, it can be deduced that 40/50 MVA transformers are sufficiently dimensioned to support headway of 135 seconds with the model of train considered and the 5 substations working at normal operation. There are no overloads exceeding 50% in any of the transformers of 40/50 MVA (nominal power value). From the simulations of failure of one of the Traction Substations (feed extensions cases) it can be deduced for the worst case will be failure of INA TSS. In this case the transformers of 40/50 MVA (Dhaula Kuan TSS) comply with the criteria of overload. With respect to drop voltage along the line, for cases simulated the voltages in train pantographs are over the threshold established in the normative EN 50163 “Railway applications  Supply voltages of traction systems” (where Umin1 = 19,000 V)
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From the simulations of failure of more than 1 Traction Substation (feed extension N2, N3 and N4) headway must be increased in order to reduce the number of trains and therefore maximum drop voltage along the OCS will be reduced complying with the values established in norm EN 50163 (where Umin1 = 19,000 V).
With these operation conditions and headways, it can be deduced that for the worst cases that all transformers will be plenty dimensioned for 40/50 MVA.
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3. Booster Transformers Currently, in existing lines of DMRC there are two kinds of Booster Transformers, with the following characteristics: Nominal Rating
Rated
Current
150 kVA
and 366 A at 409 V
280 kVA
500 A at 560 V
voltage
Overload rating (15 ms)
550 A
750 A
Impedance at full load at 0.15 ohm (Max)
0.15 ohm (Max)
75º Centigrade
Guaranteed max no load 225 W
350 W
losses
Guaranteed
max
load 4000 W
6500 W
losses Table 10. Booster transformers used in DMRC
The maximum current calculated for outgoing feeders for the main line in Line 7 is 439.58 A according to the electrical dimensioning of the Line 7 simulated with RailPower. This value of current is the RMS value corresponding to n2 failure situation (Mukundpur TSS and Dhaula Kuan TSS failure) for the feeder cable to Down Line at Mukundpur side. Capacity of booster transformers will be calculated with the expression:
SBT
IRC UBT
Where: SBT = Capacity of the booster transformer (VA). UBT = Voltage in the booster transformer (V). IRC = Return current which cross the booster transformer (A) η = Performance of the Booster transformer
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Figure 5. Scheme of operation with Booster transformers
Considering that the voltage of the return conductor in the connection with rails is zero, the voltage of the booster transformer can be calculated according to the expression:
UBT
IRC (z RC LRC
z BT )
Where: UBT = Voltage in the booster transformer (V). IRC = Return current which cross the booster transformer (A) ZRC = Impedance per km of the return conductor (ohm/km) LRC = Length of return conductor between the adjacent connections of RC with the rail (km). ZBT = Impedance of the booster transformer (ohm) Calculating these parameters: IRC (A) η ZRC (ohm/km) LRC (km) ZBT (ohm/km)
439.58 0.85 0.119+j0.402 2.6
0.016+j0.078
From electrical dimensioning of the Line 7 (Maximum RMS value of case N2) Typical value Calculated from catalogue Maximum distance between two adjacent RC to rail connections According calculated in annex 2 of Traction Simulation Sizing Study
UBT (V)
514.12
Calculated with previous data
Sa (kVA)
265.92
Calculated with previous data Table 11. Sizing of BT
Therefore, the Booster transformer of 280 kVA can be selected for the worst case. Nevertheless, taking into account the location of every BT along the line (distance to TSS) and the distances between adjacent BTs, and considering that every TSS feed the line with
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this value maximum of current, these parameters can be calculated for every booster transformer and therefore, accurate sizing of every booster transformer can be done. In the following table these calculations are shown:
BT
Ch.
imp. Return feeder (ohm/km)
imp. BT (ohm)
RC distance RC Voltage BT BT connection current (V) Power Power railRC (A) (BT (kVA) (kVA) (km) Voltage)
BT701 0+214
0.119+0.402i 0.016+0.078i
0.797
369.55
152.82
66.44
150
BT703 6+855
0.119+0.402i 0.016+0.078i
1.465
74.08
51.36
4.48
150
BT705 8+570
0.119+0.402i 0.016+0.078i
1.428
58.28
39.51
2.71
150
BT707 9+710
0.119+0.402i 0.016+0.078i
1.793
28.58
23.74
0.80
150
BT709 12+155 0.119+0.402i 0.016+0.078i
1.909
165.58
145.66
28.37
150
BT711 16+790 0.119+0.402i 0.016+0.078i
1.835
425.29
360.84
180.55
280
BT713 19+289 0.119+0.402i 0.016+0.078i
1.822
240.18
202.48
57.21
150
BT715 20+433 0.119+0.402i 0.016+0.078i
1.352
138.53
89.49
14.58
150
BT717 34+127 0.119+0.402i 0.016+0.078i
1.425
38.01
25.72
1.15
150
BT719 36+700 0.119+0.402i 0.016+0.078i
2.287
107.68
111.77
14.16
150
BT721 38+700 0.119+0.402i 0.016+0.078i
2.270
229.70
236.83
64.00
150
BT723 41+240 0.119+0.402i 0.016+0.078i
2.475
384.67
429.67
194.45
280
BT725 43+650 0.119+0.402i 0.016+0.078i
2.158
339.54
334.06
133.45
150
BT727 45+555 0.119+0.402i 0.016+0.078i
2.084
213.33
203.32
51.03
150
BT729 47+818 0.119+0.402i 0.016+0.078i
2.273
63.40
65.44
4.88
150
BT731 50+100 0.119+0.402i 0.016+0.078i
2.066
111.47
105.40
13.82
150
BT733 51+950 0.119+0.402i 0.016+0.078i
2.103
267.11
256.65
80.65
150
BT735 54+305 0.119+0.402i 0.016+0.078i
2.453
403.94
447.38
212.61
280
BT737 56+855 0.119+0.402i 0.016+0.078i
1.729
105.98
85.21
10.62
150
Table 12. Detailed calculation of Line 7 BTs (Up line)
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According to these calculations it can be sized the booster transformers: Up line Booster Transformer
Dn line
Capacity (kVA)
Booster Transformer
Capacity (kVA)
BT701
150
BT702
150
BT703
150
BT704
150
BT705
150
BT706
150
BT707
150
BT708
150
BT709
150
BT710
150
BT711
280
BT712
280
BT713
150
BT714
150
BT715
150
BT716
150
BT717
150
BT718
150
BT719
150
BT720
150
BT721
150
BT722
150
BT723
280
BT724
280
BT725
150
BT726
150
BT727
150
BT728
150
BT729
150
BT730
150
BT731
150
BT732
150
BT733
150
BT734
150
BT735
280
BT736
280
BT737
150
BT738
150
Table 13. Line 7 BTs (Up and down lines)
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4. 25 kV Feeders Dimensioning of 25 kV feeders has been developed according to the worst criterion of following ones: Maximum admissible current for conductors will be taken into account in order to select the cable according to the maximum calculated current in normal conditions. Voltage drop will be calculated in order to maintain minimum voltage above the minimum voltage required for operation, which is 19 kV, according to EN. Conductors must withstand mechanical and thermal loads during a short circuit. Firstly, the value of currents foreseen in all of these cases is calculated. With all of these values of currents, the size of the conductors which compose the feeders are checked. 4.1. Rated current calculation (In) 4.1.1.
Main track
The maximum current calculated for feeding of the main line in Line 7 can be obtained from “Power Consumption Assessment” for the electrical dimensioning of the Line 7: Mukundpur – Shiv Vihar. According to results given by the software, the worst case regarding currents is when Mukundpur TSS and Dhaula Kuan TSS fail. In such case, INA TSS must feed the section fed by these two substations in normal operation. FAILURE OF MUKUND PUR AND DHAULA KUAN TSS
25+400 INA TSS
34+935 SP
42+140 VNNG TSS
48+775 SP
54+000 YMVH TSS
Figure 6. Worst case from the current values point of view. Case N2.
In this case, according to the results given by the software, the currents in each outgoing feeder from Mukundpur substation are:
Case AVG RMS MAX
F1 DOWN LINE
F1 UP LINE
F2 DOWN LINE
F2 UP LINE
353.69 439.58 1152.14
339.30 384.58 774.55
162.07 192.75 364.55
86.84 160.73 349.99
Table 14. Current in feeder cables obtained in Traction Simulation Study in case N2
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Where F1 are the feeders which feed the Mukundpur side and F2 are the feeders which feed the Shiv Vihar side of OHE. Therefore, the feeders must be sized for an In of 439.58 A. In the chapter 4.5 the conductors of feeders are sized according to this value of current. 4.1.2.
Depot Calculation
For Depot, the following cases have been considered: Starting up of one train. Several trains in stabling tracks consuming auxiliary power (33% of trains stabled in depot). The maximum current obtained between these two situations will be considered for sizing the feeder cables from TSS to Depot. Current in the starting up For the starting up of the trains, the maximum current consumed by one train is 240 A according to rolling stock data received (annex 4). It is considered that only one train is starting up at depot at the same time. Current because of auxiliary power consumption The power required by auxiliaries of the rolling stock (6 cars) is 198 kVA. In Mukundpur Depot there are 18 stabling track with capacity for 36 trains formed by 6 cars. Considering that 33 % of the trains will be consuming maximum power at the same time, the current through the feeder will be:
In
n Sa U n min
Where: n = number of trains consuming auxiliary power at the same time Sa = apparent power of auxiliaries of the rolling stock (6 cars) in kVA. Unmin = minimum admissible voltage in kV.
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Unmin (kV)
19
Minimum admissible voltage
n
12
33% of total capacity of stabling tracks
Sa (kVA)
198
According to Rolling Stock data
In (A)
125.05
Calculated with previous data
Table 15. Current in feeder cable in Mukundpur Depot. Case of 12 trains with auxiliary power consumption
In Vinod Nagar Depot there are 45 stabling track with capacity for 45 trains formed by 6 cars. Considering that 33 % of the trains will be consuming maximum power at the same time, the current through the feeder will be:
In
n Sa U n min
Where: n = number of trains consuming auxiliary power at the same time Sa = apparent power of auxiliaries of the rolling stock (6 cars) in kVA. Unmin = minimum admissible voltage in kV. Unmin (kV)
19
Minimum admissible voltage
n
15
33% of total capacity of stabling tracks
Sa (kVA)
198
According to Rolling Stock data
In (A)
156.31
Calculated with previous data
Table 16. Current in feeder cable in Vinod Nagar Depot. Case of 15 trains with auxiliary power consumption
Therefore the maximum current considered to size the feeder cable to Mukundpur and to Vinod Nagar Depot will be given by the starting up of train case. In the chapter 4.5 the conductors of feeders are sized according to these values of current. 4.2. Calculation with current in case of nominal overload of the transformer (Io) In the previous chapter, the nominal current in the worst case of overload has been determined according to results given by “Power Consumption Assessment”. However, traction transformers must have an overloading capacity of traction transformer of 50%loading for 15 minutes and 100% overloading for 5 minutes, after the transformer has attained steady temperature on continuous operation at full load, with interval between two successive overloading of 3 hours. 25 KV Traction Equipment Sizing Calculations
21
Therefore, in case of the maximum overload of the transformer, the current will be bigger than obtained by calculations, because the transformer capacity has been selected in order to fulfill this overloading requirement. Taking this into account, the capacity of the transformer considered for calculations must be of 40 MVA. The maximum current given by the transformer in overload situation can be obtained by:
So Un
Io With:
So = apparent power in kVA in 50% and 100% overload. Un = nominal voltage in kV. Therefore, the currents will be: Un (kV)
25
25
Sn (kVA)
60000
80000
In (A)
2400
3200
Table 17. Currents given by traction transformer in overload cases
These currents will pass through 4 feeders existing in the substation (up and down, Mukundpur and Shiv Vihar sides). The quantity of the total current which goes for every feeder will not be the same. To make the calculation, the same percentages which have been obtained in the Power Consumption Assessment calculation have been considered. In the case of failure n2, these percentages are: RMS
%
F1 DN
439.58
37%
F1 UP
384.58
33%
F2 DN
192.75
16%
F2 UP
160.73
14%
Table 18. RMS values of current in every feeder cable of INA TSS. N2 case
Taking these percentages into account, the most loaded feeder in the overload situation will take the 37% of the total current. Therefore, the feeder must be dimensioned for withstand 888 A during 15 minutes and 1184 A for 5 minutes.
25 KV Traction Equipment Sizing Calculations
22
In the chapter 4.5 the conductors of feeders are sized according to these values of current. 4.3. Voltage drop Voltage drop calculated in Traction Simulation Study for Line 7 has already into account the length of the feeders which feed main tracks from TSS’s. Therefore, they are suitable according to this criterion. Regarding feeder to Depots, voltage drop must be calculated according to expression:
U
L I
R
j X
Where: L = Length of the conductor (km) I = Current of the conductor (A) R = conductor resistance ( /km) X = conductor reactance ( /km) The voltage drop will be: Feeder
Mukundpur Depot
Vinod Nagar Depot
L (km)
1.2
1.7
Distance from drawings
I (A)
240
240
From chapter 4.2
R (Ω/km)
0.0754
0.0754
Calculated from catalogue
X (Ω/km)
0.115
0.115
Calculated from catalogue
ΔU (V)
39.60
56.10
Calculated with previous data
Table 19. Voltage drop calculation for feeder cables in depots
4.4. Short circuit criteria When sizing and selecting equipment, and electrical components must be taken into account in accordance with VDE (Association of German Electrical Engineers) determinations, not only due to permanent loads the current and voltage, but surges caused by short circuits. Shortcircuit currents are usually several times higher than nominal therefore cause high dynamic and thermal overloads. The short circuit currents traversing land can also be the cause of contact stresses and unacceptable interference. Short circuits can cause the destruction of equipment and components or cause damage to people if the design does not take into account the maximum shortcircuit currents.
25 KV Traction Equipment Sizing Calculations
23
For calculation of short circuit currents will follow the guidelines VDE 0102, and 2/11.75 1/11.71 parts. Two methods exist to perform the calculation, one, the absolute impedance calculation, and the other, the dimensionless impedance calculation or per unit. It has been selected the calculation per unit method for this design. The “per unit method” simplifies the calculation when there are two or more levels of voltage and interest the effective value. It also presents other advantages: Manufacturers specify the impedances in percent of the nominal values given in the plates. The impedances per unit of the same type of apparatus are very close values, although their ohmic values are very different. If you do not know the impedance of a device, you can select from tabulated data that provide reasonably accurate values. The impedance of a transformer unit is equal in the primary than in the secondary and is not dependent on the type of connection of the windings. To follow the method per unit must establish two arbitrary values, such condition all others. Normally the base values chosen are: A [MVA] power for the entire circuit B [kV] to a voltage level For a different voltage level, the voltage value of the base has to be multiplied by the transformation ratio of the transformer which separates the two levels. In calculating circuit currents requires knowledge of the temporal variations since the short circuit occurs until it reaches the permanent shortcircuit current. As in practice as quickly as possible short circuit current by circuit breakers or other devices, knowledge of temporal variations of the shortcircuit current is only necessary to select and size the equipment and components in some cases. The parameters involved in the calculation of the short circuit currents are: I"k: is the rms value of the symmetrical shortcircuits current, is the moment when the short circuit occurs. From this value the following currents are determined. Is: Maximum current asymmetric short, is the maximum instantaneous value of the current, which occurs after the short circuit occurs. Also known as peak value or impulse current. This value may know electrodynamics forces.
25 KV Traction Equipment Sizing Calculations
24
Isc: Permanent Short Circuit Current, is the rms value of the symmetrical shortcircuit current, which endures after completion of all transients. Used to determine the thermal stress on machinery. Ia: balanced current court, is the rms symmetrical shortcircuit current flowing through a switch on the instant you start separating contacts. Used to determine the performance characteristics of the switch off apparatus. This design will be carried out calculations phase short circuits, and these, short circuit away from the generator. Thus one must take into account that VDE 0102 values permanent short circuit current (Icc) and cutting the symmetrical current (Ia) coincide with the current value of the symmetric initial short circuit current (I"k). 4.4.1.
Simply Single Line Scheme
The following diagram shows only those different voltage levels, and the status of power transformers and substation different outputs, in order to perform the calculation of short circuit currents: TT 220 kV/25 kV 40 MVA Ucc=13.8%
CIT
TSS OHE FEEDER TO UP LINE
FEEDER TO DN LINE
FEEDER TO FEEDER TO UP LINE DN LINE
Figure 7. Simply Single Line Scheme.
4.4.2.
Equivalent Single Line Scheme
To obtain the equivalent circuit simply replace the transformer by its respective impedance. The short circuit in the feeder cables will have its maximum value just outside of the substation, as the absence lead length the short circuit effect is not reduced by the line
25 KV Traction Equipment Sizing Calculations
25
impedance. The impedances for conductors and switchgear are negligible and will not be included in the schemes or calculations. The equivalent circuit is reflected in the figure below. The figure also marked the possible points where it can happens different electrical short circuits.
Figure 8. Equivalent circuit.
4.4.3.
Impedance Calculations
To perform the calculation method impedances adapted per unit it has to be fixed, first, arbitrary baseline values. These values determined for each element in intensity per unit. Values are taken as basis: SB = 20 MVA UB = 220 kV The table shows the values per unit based on an equal basis for all power system substations. UB (kV)
220
25
SB (MVA)
20
20
90,9
800
IB (A)
Table 20. Short circuit current per unit based calculation
Observations of the table: SB = Apparent power kVA basis for the entire system, arbitrary value.
25 KV Traction Equipment Sizing Calculations
26
UB = Voltage basis for each kV voltage level is obtained by multiplying the transformation ratio between two voltage levels. IB = current per unit A for each voltage level is obtained from the equation:
I
1000 S U
Values in percent transformers having its reference voltage circuit (Ucc). The shortcircuit impedance (ZCC) approximately matches the value shorted reagent (Xcc), so the error made by omitting the resistance is minimal and does not affect the final results ZCC ≈ Xcc With the results of the baseline values for each voltage level it is possible to calculate the impedance by referring to the power unit base. The generic equation for this calculation is:
Z ( pu)
Z cc S B 100 S N
where: Zcc impedance circuit is in percent. SB is the power base. Sn is the rated power of the electrical machine. The equivalent impedance of the network is obtained as follows: Z net
SB S cc
where: SB is the power base. SCC is the shortcircuit power of the network (given by electrical company). The results are shown in the following table: Component Characteristics NET RT
Scc = 8800 MVA Sn = 40 MVA Zcc = 13.8%
Impedance per unit referred to SB = 20 MVA ZN = 0,0023 pu ZRT = 0,069 pu
Table 21. Impedance per unit calculation
25 KV Traction Equipment Sizing Calculations
27
4.4.4.
Calculation of the continuous current of short circuit (Isc)
As mentioned above permanent short circuit current (Icc) is equal to the symmetrical initial
I k"
current (I"k) and cutting the symmetrical current (Ia). I cc
Ia
The calculation uses the equation of the Law’s Ohm using values per unit: icc
u z eq
Where u = 1 when calculating per unit, and zeq the calculated value in the table above for each point. Then the resulting values are multiplied by the base value of current, as the voltage level, obtaining the absolute value of the constant intensity at each point shorting: I cc
icc I B
Short
Equivalent
circuit
Impedance
Point
[pu]
A
ZeqA = 0,0023
iccA = 434,78
IB = 90,9
IccA = 39521,74
B
ZeqB = 0,069
iccB = 14,49
IB = 800
IccB = 11592
Shortcircuit current [pu]
Permanent Base current [A]
shortcircuit current [A]
Table 22. Short circuit continuous current calculation
4.4.5.
Calculation of the Maximum Current Asymmetric ShortCircuit (Is)
Also called surge current is the maximum value and its value is given by the equation:
IS
x
2 I cc
Where “x” is a factor which depends on the relationship between the effective resistance and the reactance of the circuit impedance. As the resistive value is unknown, take x = 1.8 which is an accepted value for these cases. Thus, following the above equation using a value x = 1.8, the impulse current in each shortcircuit point will be the value shown in the following table:
25 KV Traction Equipment Sizing Calculations
28
Maximum Current
Shortcircuit
Permanent SC
point
current (kA)
A
IscA = 39.52
IsA = 100.60
B
IscB = 11.59
IsB = 29.50
Asymmetric SC (kA)
Table 23. Maximum ShortCircuit Asymmetric Current calculation
4.4.6.
Rupture capacity and connection
For the election of the switches are fundamental two variables: Breaking capacity (or power off). Is defined by cutting symmetrical current (Ia). It is expressed in MVA
Sr
Un Ia
Connection capacity (or power connection). Is defined by the maximum asymmetric short circuit current (IS). It is expressed in MVA
Sc
Electric Point
Cutting Symmetrical Current (kA)
Un Is
Breaking Capacity
Surge Current
(MVA)
(kA)
Connection Capacity (MVA)
A
IaA = 39.52
SrA = 8694.4
IsA = 100.60
ScA = 22132
B
IaB = 11.59
SrB = 289.75
IsB = 29.5
ScB = 737.5
Table 24. Breaking and connection capacity calculation
4.5. Conductor sizing 4.5.1.
Type of Conductor
Medium Voltage Cables are manufactured with XLPE insulation. It is very remarkable features cables, both losses in the dielectric, thermal and electrical resistivity and dielectric strength.
25 KV Traction Equipment Sizing Calculations
29
Being able to work at a service temperature of 90°C, these cables have the possibility of transmitting more power than any current wire section. In addition, its smaller size makes it more manageable cable, easier to install, lighter and easier to transport. Type
Single pole
Simple Nominal Voltage
26 kV
Nominal voltage between phases
45 kV
Maximum voltage between phases
52 kV
Voltage pulses
250 kV
Maximum permanent temperature allowable in the conductor Screen
90ºC
Copper
Isolation
Polyethylene (XLPE)
Envelope
Polyvinil Chloride (PVC) Table 25. Conductor characteristics
4.5.2.
Size of Conductor
The feeders will be installed into canalization from the TSS to the viaduct. On the viaduct they will be installed on the parapet, supported by brackets. In case of the feeders of Depots, they will be into canalization from the TSS to the depot FP and from the FP to OHE. Therefore, the lower admissible current will occur when the cables are laid down buried into canalization. According to supplier’s information, the admissible nominal current for an underground copper cable 1x240 mm2 is 501 A (see annex 1), when it is buried at 1.2 m depth, with ground temperature of 25ºC and a ground thermal resistivity of 1 K·m/W. Considering that in the worst case, the groud temperature will reach the 40ºC it will be needed to consider a deration factor of 0.88. Therefore, the maximum nominal current of 1x240 mm2 copper cable will be 440 A. 4.5.2.1. Permanent current In case of main tracks, maximum average current will be 439.58 A per feeder, so 219.79 A per each 240 mm2 cable in permanent operation. Therefore this 240 mm2 cable is valid with a safety factor of 2. 25 KV Traction Equipment Sizing Calculations
30
In case of Depots, maximum nominal current will be 240 A, so one copper cable of 240 mm2 can withstand this current with a safety factor of 1.8. 4.5.2.2. Short time operation current Regarding short time operation currents caused by overloading of the transformer, the capacity of one conductor is given by expression:
IKB
I Z fkB (annex 2, chapter 18.6.5, expression 18.122)
Where: 
IKB is the admissible current for short time operation

Iz is the admissible current for permanent operation

fkB is overloading factor, given by 2
In IZ
1 fKB
tb
e (annex 2, chapter 18.6.5, expression 18.126)
tb
1 e Where: 
In is the initial current before the overload (nominal current)

tb is the duration of the overload

τ is time constant of the cable (1/5 of the time taken from the curve to almost reach the permissible final temperature). It is given by the expression:
q IZ
B
2
(annex 2, chapter 18.6.2, expression 18.117)
Where: 
q is the cross section of the conductor

B is a constant related with the conductor properties, environment temperature and the maximum temperature admissible for the cable permanent operation. It is given by the expression:
B
c
1
0 20
c (annex 2, chapter 18.6.2, expression 18.118) 20
20 c
25 KV Traction Equipment Sizing Calculations
31
Where: 
Θc is the final temperature in the cable by overload current

Θ0 is the initial temperature in the cable before the overload

χ20 is the conductivity of the conductor. For copper 56·106 1/Ω·m

c is the specific heat of the material. For copper 3.45·106 J/K·m3

α20 is the heat transferring factor. For copper 0.00393 K1
Therefore, the admissible currents for100% and for 50% of overload in the cable will be: 100% overload
50% overload
Source of data
θc (ºC)
90
90
θ0 (ºC)
50
50
5,60E+07 0,00393 3,45E+06 240 440
5,60E+07 0,00393 3,45E+06 240 440
In (A)
219.8
219.8
tb (s)
300
900
6,06E+15 1803,18 2.268 998.12
6,06E+15 1803,18 1.469 646.58
Admissible temperature for un XLPE cable Initial temperature in the cable before the overload From Annex2 table 18.37 From Annex2 table 18.37 From Annex2 table 18.37 Cross section of the cable Chapter 4.5.2 of this document Nominal current in each cable of feeder (Half of RMS value 439.58A, obtained from Traction simulation study) Duration of overload: 5 minutes (300s) and 15 min (900s) for 100% and 50% of overload. Calculated with previous data Calculated with previous data Calculated with previous data Calculated with previous data
χ20 (1/Ωm) α20 (1/K) c (J/Km3) q (mm2) Iz (A)
B (A2s/m4) τ fkB IkB (A)
Table 26. Short time operation capacity calculation for 240 sqmm copper cable
Therefore, one 240 mm2 cable is able to withstand 998.12 A for 5 minutes and 646.58 during 15 minutes. According to calculated in chapter 4.2 of this document, the feeder cable (2 cables of 240 mm2) must be dimensioned for withstand 888 A during 15 minutes and 1184 A for 5 minutes, so each cable of 240 mm2 should be able of withstand 444 A during 15 minutes and 592 A for 5 minutes. Therefore, 240 mm2 cables are able to withstand the overload currents with safety factors of 1.45 and 1.68.
25 KV Traction Equipment Sizing Calculations
32
4.5.2.3. Short circuit current Regarding of the maximum short circuit current supported by the cable, it can be obtained as it is shown in the following figure. As it can be seen in this figure, short circuit current considering duration of fault of 3 s is 19 kA, higher to short circuit current calculated in chapter 4.4.4. Therefore, copper conductor of 240 mm2 selected is valid for this application.
25 KV Traction Equipment Sizing Calculations
33
2
Current (kA)
Section of conductor (mm ) Duration (s) Figure 9. Short circuit capacity of 240 sqmm copper cable
25 KV Traction Equipment Sizing Calculations
34
5. Return Cables 5.1. Return cables In front of substations, rails will be connected to substation by means of 3.3 kV cables. Their aim is to carry the return traction current from rails to substation, so they must withstand the same current than 25 kV feeders. Therefore they will be made up of the same number of cables and cross section, as the 25 KV feeders. 5.2. Return conductor One all aluminium conductor with a nominal cross section of 233 sq.mm and a copper equivalent of 140 sq.mm will be used as Return Conductor. Dimensioning of this return conductor has been developed according to the worst criterion of following ones: Maximum admissible current for conductors will be taken into account in order to select the cable according to the maximum calculated current in normal conditions. Voltage drop will be calculated in order to maintain minimum voltage above the minimum voltage required for operation, which is 19 kV, according to EN. Conductors must withstand mechanical and thermal loads during a short circuit. 5.2.1.
Rated current calculation (In)
In the Return current system foreseen, the return conductor must carry the same current as catenary. Therefore it must be dimensioned for carrying the same current calculated in the chapter 4.1.1., (439.58 A). The maximum admissible current for one all aluminium conductor (AAC) with a nominal cross section of 233 sq.mm is 584 A in the following conditions (annex 3): Environmental temperature: 40ºC Solar radiation 900 W/m2. Wind: 0.6 m/s Maximum conductor temperature: 80ºC Frequency: 50Hz Applying a deration factor of 0.9 to take into account the solar radiation and other deration factor of 0.89 to take into account that the worst environmental temperature will be 50ºC, the maximum admissible current will be 467.78 A, so the conductor selected is valid for the nominal current.
25 KV Traction Equipment Sizing Calculations
35
In stations, return conductor will be made by means a 233 sq.mm stranded aluminium conductor, with insulated sleeve. It will be laid under platforms. 5.2.2.
Voltage drop
Voltage drop calculated in Traction Simulation Study for Line 7 has already into account the characteristics of return conductors, so it is not needed any additional calculation. 5.2.3.
Short circuit criteria
Regarding of the maximum short circuit current supported by the Return conductor, it can be obtained by means of following expression:
Where: I: Short circuit current (A) t: Short circuit duration (s) K: parameter which depends of kind of conductor (Cu or Al) and of its isolation. In present case with aluminium conductors, K = 94 will be assumed (jump of temperature from steady temperature to short circuit temperature minimum), so worst scenario has been assumed. S: cross section of the conductor (mm2) Therefore, the minimum section required to withstand the short circuit current calculated in chapter 4.4.4 will be: I (A)
11600 0.25
t (s)
Calculated in chapter 4.4.4 of this document Short circuit duration (estimated as conservative value)
K 2
S (mm )
94
Value for aluminium conductor
61.7
Calculated with previous data
Table 27. Return conductor sizing under short circuit current criteria
Therefore, aluminium conductor of 233 mm2 selected is valid as return conductor. 6. Induced Voltage Calculation According to IEC 6028713:2002, induced voltage per unit length in a conductor can be determined by the following expression:
25 KV Traction Equipment Sizing Calculations
36
E
2
f M I 10
3
V km
Where: f: is the frequency of the nominal voltage waveform I: is the maximum permanent current main conductor M: is the mutual inductance between two conductors arranged in parallel given by the expression:
M
0,46 log
2 Dm Dp
mH km
where: Dm: is the distance between the two conductors Dm Dp: is the equivalent diameter of conductor induced D p
D d' 2 4 S
For cable 26/45kV XLPE, Cu 240 Sqmm the characteristics are: d = 18.3 mm d' = 20.1 mm D = 38.5 mm Screen = 16 mm2
Figure 10. Cross section of XLPE insulated cable
The maximum drop voltage in case of the end of the cable being earthed is given by the expression:
25 KV Traction Equipment Sizing Calculations
37
V
E L
where: E: induced voltage per unit length in a conductor L: Length of conductor According to this length in each case, the drop of voltage will be obtained per each feeder: Dhaula
Mukundpur
Kuan
INA
Vinod Nagar
Maujpur
Rajouri
Kashemere
Garden
Gate
f (Hz)
50
50
50
50
50
50
50
I (A)
219.79
219.79
219.79
219.79
219.79
219.79
219.79
Dm (mm)
8
8
8
8
8
8
8
Dp (mm)
4.514
4.514
4.514
4.514
4.514
4.514
4.514
M (mH/km)
0.252
0.252
0.252
0.252
0.252
0.252
0.252
E(V/km)
17.46
17.46
17.46
17.46
17.46
17.46
17.46
L (km)
1.5
1.5*
1.2
0.7
2.1
1.1*
2.75*
∆V (V)
26.19
26.19
20.94
12.22
36.65
45.41
48.01
(*) Length obtained earthing the sheath cable in it center point Table 28. Induced Voltage Calculation
Therefore, in all cases the voltage in the sheath can be lower than touch voltage by earthing the cables in one end or in their center point and no sheath voltage limiters will be required. 7. Circuit Breakers rating Circuit breakers are foreseen in the outgoing feeders in traction substations (TSSs), and in depot’s Feeding posts, installed in the incoming feeder from TSS and in the incoming feeder from main tracks. In any case, circuit breakers must be able to actuate in short circuit conditions. Therefore, for the election of the circuit breakers are fundamental two variables: Breaking capacity (or power off). Is defined by cutting symmetrical current (Ia). It is expressed in MVA Connection capacity (or power connection). Is defined by the maximum asymmetric short circuit current (IS). It is expressed in MVA
25 KV Traction Equipment Sizing Calculations
38
These variables have been calculated in the chapter 4.4.6 of these documents, and, regarding 25 kV circuit breakers they are: Cutting Symmetrical Current: Ia = 11.59 kA Breaking Capacity: Sr = 289.75 MVA Surge Current: Is = 29.5 kA Connection Capacity: Sc = 737.5 MVA Regarding voltage, they must able to withstand nominal values foreseen in the traction system: Rated voltage: 25 kV Maximum service voltage (permanent): 27.5 kV Therefore, the characteristics required for the circuit breakers foreseen in Mukundpur and Vinod Nagar Depot Feeding posts, as well in feeders of Rajouri Garden FP, Dhaula Kuan FP and Welcome FP will be: Rated voltage
kV
25
Maximum service voltage (permanent)
kV
27.5
Service frequency
Hz
50
Number of phases
1
Erection
Outdoor
Rated current
A
2000
3 sec. Short time current
kA
25
Symmetrical breaking capacity
kA
25
Rated peak withstand current
kA
40
Table 29. Circuit Breakers characteristics
8. Interrupters rating Interrupters foreseen in the OHE have to be able to operate under load conditions. According to calculations shown in the chapter 4.1 the maximum nominal current through each feeder is 439.58 A.
25 KV Traction Equipment Sizing Calculations
39
Catenaries for up and down tracks are paralleled in SSP’s along the track. Therefore, the interrupters will be dimensioned for the total current of the two tracks: In= 439.58 + 384.58 = 824.16 A. Regarding voltage, they must able to withstand nominal values foreseen in the traction system: Rated voltage: 25 kV Maximum service voltage (permanent): 27.5 kV Therefore, the characteristics required for the interrupters foreseen in the switching posts of Line 7 will be: Rated voltage
kV
25
Maximum service voltage (permanent)
kV
27.5
Service frequency
Hz
50
Number of phases
1
Erection
Outdoor
Rated current
A
2000
Table 30. Interrupters characteristics
9. Current Transformers rating Current transformers will be used in depot’s Feeding post for current measuring and protection. Therefore, they must be rated for the nominal current foreseen in depots which is 240 A according to calculations included in chapter 4.1.2. In addition, current transformers will be used in feeders in: Rajouri Garden FP Dhaula Kuan FP Welcome FP Regarding voltage, they must able to withstand nominal values foreseen in the traction system: Rated voltage: 25 kV Maximum service voltage (permanent): 27.5 kV 25 KV Traction Equipment Sizing Calculations
40
Therefore, the characteristics required for the current transformers in OHE part will be: Voltage / earth insulation
kV
27.5
Frequency
Hz
50
Erection
Outdoor
Insulation withstand voltage (permanent)
kV
36
Core 1
600/1, 5P10, 20VA Protection class
Core 2
600/1, 5P10, 15VA Protection class
kA
20 / 40
Secondary Core
Withstand Overcurrent (1s /peaks)
Table 31. Current transformers characteristics
25 KV Traction Equipment Sizing Calculations
41
ANNEX 1. TECHNICAL DATA OF 26/45 KV XLPE INSULATED COPPER CABLE USED FOR CALCULATION.
25 KV Traction Equipment Sizing Calculations
media tensión
anexo b
DATOS TÉCNICOS DEL CABLE VOLTALENE H 26/45 kV (conductor de cobre) RHZ1
CARACTERÍSTICAS DIMENSIONALES (Valores aproximados) 1 x sección conductor (Cu)/sección pantalla (Cu) (mm2)
26/45 kV 1x35/16 1x50/16 1x70/16 1x95/16 1x120/16 1x150/16 1x185/16 1x240/16 1x300/16 1x400/16 1x500/16 1x630/16 1x800/16 1x1000/16
Código
20117861 20117862 20117863 37011335 20052424 20992340 20013787 20084553 20001742 20117864 37011342 20106569 20117865 20117866
∅ conductor (mm)
7 8 9,7 11,4 12,6 14,1 15,9 18,3 20,5 23,1 26,3 29,6 34,1 38,7
∅ aislamiento (mm)
∅ pantalla (mm)
∅ cable (mm)
Peso (kg/km)
Radio de curvatura estático (posición final) (mm)
24,9 25,8 27,6 29,2 30,5 30,9 32,7 35,1 37,8 38,9 42 45,4 49,9 53,5
26,9 29,2 31 32,6 33,9 34,3 36,1 38,5 41,2 42,3 45,4 48,8 53,3 56,9
34,4 35,4 37,2 38,7 40 40,4 42,2 44,6 47,3 48,4 51,5 54,9 60 63,6
1320 1460 1720 2010 2290 2520 2910 3500 4180 4910 6020 7410 9490 11550
550 566 595 619 640 646 675 714 757 774 824 878 960 1018
Radio de curvatura dinámico (durante tendido) (mm)
688 708 744 774 800 808 844 892 946 968 1030 1098 1200 1272
CARACTERÍSTICAS ELÉCTRICAS 26/45 kV Tensión nominal simple, Uo (kV) Tensión nominal entre fases, U (kV) Tensión máxima entre fases, Um (kV) Tensión a impulsos, Up (kV) Temperatura máxima admisible en el conductor en servicio permanente (ºC) Temperatura máxima admisible en el conductor en régimen de cortocircuito (ºC)
26 45 52 250 90 250
(Valores aproximados) 1 x sección conductor Intensidad máxima (Cu)/sección pantalla admisible enterrado* (Cu) (mm2) (A) 26/45 kV 1x35/16 1x50/16 1x70/16 1x95/16 1x120/16 1x150/16 1x185/16 1x240/16 1x300/16 1x400/16 1x500/16 1x630/16 1x800/16 1x1000/16
171 202 248 297 338 381 431 501 565 644 731 824 921 1007
Intensidad máxima admisible al aire** (A)
Resistencia del conductor a 20 ºC (Ω/km)
Reactancia inductiva (Ω/km)
Capacidad (µF/km)
174 207 258 314 361 411 472 558 640 743 860 984 1132 1269
0,524 0,387 0,268 0,193 0,153 0,124 0,0991 0,0754 0,0601 0,047 0,0366 0,0283 0,0221 0,0176
0,159 0,152 0,144 0,136 0,132 0,125 0,121 0,115 0,112 0,106 0,102 0,098 0,095 0,090
0,135 0,144 0,161 0,175 0,186 0,209 0,226 0,249 0,275 0,341 0,375 0,411 0,460 0,546
*Condiciones de instalación: una terna de cables directamente enterrada o bajo tubo a 1,2 m de profundidad, temperatura de terreno 25 ºC y resisitividad térmica 1 K·m/W. **Condiciones de instalación: una terna de cables al aire (a la sombra) a 40 ºC. NOTA: valores obtenidos para una terna de cables al tresbolillo y en contacto. Para el cálculo de la reactancia inductiva con los conductores en cualquier disposición aplicar la fórmula (A) de la página 214. IMPORTANTE: Para los valores concretos de intensidades máximas según los conexionados de pantalla se ruega contactar con Prysmian.
201
ANNEX 2. GUIDE FOR CALCULATION OF CABLE CAPACITY UNDER SHORT TIME OPERATION CURRENTS.
25 KV Traction Equipment Sizing Calculations
ANNEX 3. TECHNICAL DATA OF ALUMINIUM CABLES USED FOR CALCULATION.
25 KV Traction Equipment Sizing Calculations
Prysal Aluminio
Características Técnicas Cables según norma IRAM 63003
Sección nominal
Formación
Diámetro
Masa
exterior
aprox.
Carga de rotura calculada
aprox.
Resistencia
Intensidad
eléctrica máxima
de corriente
a 20oC y
admisible (1)
c. c. 2
mm
N° x mm
mm
kg/km
kg
ohm/km
A
10
7 x 1,35
4,1
27
195
2,7842
78
16
7 x 1,70
5,1
43
302
1,7558
104
25
7 x 2,15
6,5
70
457
1,0977
139
35
7 x 2,52
7,6
95
594
0,7990
171
50
7 x 3,02
9,1
135
827
0,5563
215
70
19 x 2,15
10,8
190
1242
0,4025
265
95
19 x 2,52
12,6
260
1611
0,2930
324
120
19 x 2,85
14,3
335
2061
0,2291
380
150
37 x 2,25
15,8
405
2648
0,1877
431
185
37 x 2,52
17,7
510
3137
0,1496
498
240
37 x 2,85
20,0
650
4013
0,1170
584
300
61 x 2,52
22,7
840
5172
0,0907
687
400
61 x 2,85
25,7
1075
6615
0,0709
804
500
61 x 3,23
29,1
1381
8247
0,0552
942
625
91 x 2,96
32,6
1732
10645
0,0439
1087
800
91 x 3,35
36,9
2218
13234
0,0343
1266
1000
91 x 3,74
41,1
2764
15995
0,0275
1445
1265
91 x 4,21
46,3
3503
20268
0,0217
1657
(1) Para conductor expuesto a una radiación solar de 900 W/m², considerando una emisividad de 0,6, al nivel del mar y viento de 0,6 m/seg, temperatura ambiente de 40º C, temperatura máxima admisible de 80°C y una frecuencia de 50 Hz.
Acondicionamientos: Bobinas de madera
31
ANNEX 4. ROLLING STOCK DATA USED FOR CALCULATION
25 KV Traction Equipment Sizing Calculations
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