new approach of designing and exploatation of electrical traction substations

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Page 1: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS
Page 2: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

1. Connection of electric traction substations on the principle of input-output

2. Electric traction substation connected to the nearby electric power plant

Page 3: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

Connection of electric traction on the principle of input-output with twotransmission feeders equipped with three-poles switches, three-phasebusbar disconnectors and a three-pole disconnectors with earthingblades

Page 4: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

Electric traction substation connected to the nearby electric power plant

Page 5: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

There are two transformers, two transmission feeders, the two bus feeders(high voltage and low voltage), two transformer feeders.Each transformer has its own voltage regulator. Each feeder is fitted in same way.

The number of redundant paths, redundant equipment and devices is a basicfeature of this concept and schemes shown at figures 1 and 2. A variety of sparedelivery paths (which would be used in the case of virtually unimaginablecoincidences failures of the left feeder, right switch and transformer left) andlots of devices make electric traction substations very complicated.

Page 6: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

The solution of this problem is illustrated by applying auxiliary bus

Page 7: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

Saving three measuring transformers of 110 kV (decrease the total cost,including installation, footages and required space).The result: more reliable and simpler substation

Page 8: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

Based on long time researching and studies, as well as broad international survey conducted by the Committee A 50 Office for Research and testing (Office de Recherrches et d'Essais), International Union of Railways, in singlephasesubstations, surge arresters are not applied anymore.

This method of protection when the electric traction substation was built near already protected buses of a power plant is assessed as dangerous for operational reliability and plant staff and removed from the substations in developed countries

Page 9: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

The result: transfersally feeders are not necessary on the 110 kV side .

Scheme of electric traction substations connected via a three-phase transmission line

Transformers that are shown in the picture are without voltage regulators, which are weak spots subjected to failures.Result: increased plant reliability.

Page 10: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

The next step of substation simplification is transformer feeder 110 kV and 25kV feeder lacks and giving to circuit breaker in 110 kV feeder functions ofprotection of transformer , as it shown in the previous figure.

In this case energy measurement is in 25 kV because there are required currentand voltage transformers for the protection.So it is necessary to add kWh meters for measuring losses.

Page 11: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

-using drawable circuit breakers in 25 kV feeders instead circuit breakers and disconnectors which are elements of wrong manipulations;- the application of switch-disconnectors instead circuit breakers in 25 kV transformer feeders;-aplication of combined instrument transformers (CT and VT in one element) in all feeders;

Page 12: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

Bypassing neutral section in separating substations with neutral section and designing electeric traction substations with single transformer - parallel connection of electric traction substations

Page 13: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

Thyristor voltage adjustor is required to make identical voltages in catenary in this case.

Page 14: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

Distance between electric traction substations increase from40 - 50 km to 80 - 90 km.

Peak power reduction wherein speed of trains do not decrease.

Page 15: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

There are necessity for selectivity and accuracy of catenary distant relays withpower direction relay in separating substations, because two substations deliverpower to electric vehicle and ground fault.

Page 16: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

Selectivity of catenary distant relays is acquired with time grading inthree zone toward sources.

Page 17: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

Equivalent circuit of electric traction system 25 kV; 50 Hz for parallelconnected electric traction substations

Short circuit current:

๐‘ฐ๐‘ฒ๐‘บ = ๐‘ผ

๐Ÿ โˆ™ ๐’๐‘ด + ๐’๐‘ป + ๐’๐’†๐’Œ๐’—โ€ฒ โˆ™ ๐’

๐‘จ

๐’๐‘ด - impedance of electric network operator for two pole short circuit on ๐Ÿ๐Ÿ๐ŸŽ ๐’Œ๐‘ฝ busbars in electric traction substation reduced on catenary voltage,

๐’๐‘ป - impedance of single phase transformer of electric traction substations,

๐’๐’†๐’Œ๐’—โ€ฒ - equivalent impedance per unit of length of catenary

Page 18: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

๐’๐‘ด = ๐’‹ โˆ™๐Ÿ,๐ŸŽ๐Ÿ“โˆ™๐‘ผ ๐Ÿ

๐‘บ๐’Œ๐œด

Uโ€“voltage of catenary ๐‘ฝ ,

๐‘บ๐’Œ โ€“ two phase fault power on electric traction substation busbar ๐‘ฝ๐‘จ

๐’๐‘ป = ๐’‹ โˆ™๐’–๐’Œ(%)

๐Ÿ๐ŸŽ๐ŸŽ

๐‘ผ๐Ÿ

๐‘บ๐‘ป๐œด ,

where: ๐’–๐’Œ(%) โ€“ relative short circuit voltage % ,

๐‘บ๐‘ป โ€“ nominal power of transformer ๐‘ฝ๐‘จ

๐’๐’†๐’Œ๐’—โ€ฒ = ๐’๐’—

โ€ฒ โˆ’ ๐œบ๐’๐’Žโ€ฒ +

๐Ÿโˆ’๐’†โˆ’๐’Œโˆ™๐’

๐’Œโˆ™๐’๐Ÿ โˆ’ ๐œบ ๐Ÿ๐’ล ๐‘ฐ

โ€ฒ ๐œด

๐’Œ๐’Ž

Page 19: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

Carson-Pollaczek formulaes:

๐’๐’†๐’Œ๐’—โ€ฒ = ๐’๐’—

โ€ฒ โˆ’ ๐œบ๐’๐’Žโ€ฒ +

๐Ÿ โˆ’ ๐’†โˆ’๐’Œโˆ™๐’

๐’Œ โˆ™ ๐’๐Ÿ โˆ’ ๐œบ ๐Ÿ๐’ล ๐‘ฐ

โ€ฒ ๐œด

๐’Œ๐’Ž

๐’๐‘ฝโ€ฒ โ€“ impedance per unit of length of catenary

๐œด

๐’Œ๐’Ž,

๐’ล ๐‘ฐโ€ฒ โ€“impedance per unit of length of returning current circuit

๐œด

๐’Œ๐’Ž,

๐’ โ€“ distance to electrica traction substation ๐’Œ๐’Ž ,

๐’๐’Žโ€ฒ โ€“ mutual impedance per unit of length catenary- returning current circuit

๐œด

๐’Œ๐’Ž,

๐œบ =๐’๐’Žโ€ฒ

๐’ล ๐‘ฐโ€ฒ ,

where: ๐’Œ = ๐’ล ๐‘ฐโ€ฒ โˆ™ ๐’ˆ ๐’Œ๐’Žโˆ’๐Ÿ - propagation coefficient of gauge

๐’ˆ- admittance per unit of length of gauge๐‘บ

๐’Œ๐’Ž

Page 20: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

Impedance per unit of length of returning current circuit with two rails: ๐’ล ๐‘ฐโ€ฒ =

๐ŸŽ, ๐Ÿ“ ๐’“ล ๐’‚ + ๐’‹ ๐’™โ€ฒ + ๐’™โ€ฒโ€ฒ +๐Ž๐‘ด๐Ÿ,๐Ÿโ€ฒ ๐œด

๐’Œ๐’Ž,

where: ๐’“ล ๐’‚ โ€“resistance of rails๐œด

๐’Œ๐’Ž,

๐’™โ€ฒ- interior reactance per unit of length of rail otpor ๐œด

๐’Œ๐’Ž,

๐’™โ€ฒโ€ฒ- external rail reactance per unit of length ๐œด

๐’Œ๐’Ž,

๐Ž = ๐Ÿ๐…๐’‡ ๐’”โˆ’๐Ÿ - circle frequency Internal reactance pwr unit of length of S-49 rail: ๐’™โ€ฒ = ๐ŸŽ, ๐Ÿ•๐Ÿ“ โˆ™ ๐’“ล ๐’‚External rail reactance per unit of length:

๐’‹๐’™โ€ฒโ€ฒ = ๐ŸŽ, ๐ŸŽ๐Ÿ’๐Ÿ—๐Ÿ‘ โˆ’ ๐’‹๐ŸŽ, ๐Ÿ๐Ÿ’๐Ÿ’๐Ÿ” ๐Ÿ, ๐Ÿ“๐Ÿ‘ + ๐’๐’๐’ˆ ๐‘นล ๐Ÿ โˆ™ ๐œธ

๐œด

๐’Œ๐’Ž

๐‘นล  - radius of equivalent conductor: ๐‘นล  =๐‘ท

๐Ÿ๐…๐’„๐’Ž ,

where P is rail perimeter ๐’„๐’Ž .

Mutual rails impedance per unit of length: ๐’‹๐Ž๐‘ด๐Ÿ,๐Ÿโ€ฒ = ๐ŸŽ, ๐ŸŽ๐Ÿ’๐Ÿ—๐Ÿ‘ โˆ’ ๐’‹๐ŸŽ, ๐Ÿ๐Ÿ’๐Ÿ’๐Ÿ” ๐Ÿ, ๐Ÿ“๐Ÿ‘ +

Page 21: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

Dependance of catenary impedance

per unit of length on distance

for S-49 and UIC 60 rails

Page 22: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

Dependance of catenary impedance arguments on distance for S-49 and UIC 60 rails

Page 23: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

Short circuit current of a single truck

Overall short circuit current on place of fault is addition of currents from two electrical traction substations.

Page 24: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

Dependance of impedance on distance measured by distant relay

Page 25: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

Short circuit impedance measured by impedance relays in separating substations (R-X diagram)

Page 26: NEW APPROACH OF DESIGNING AND EXPLOATATION OF ELECTRICAL TRACTION SUBSTATIONS

CONCLUSION

The existing designs of electric traction substations in exploitation proved to beexpensive, overcomplicated and unnecessary. Consequences are too large costs ofconstruction and maintenance, overcomplicated facilities, lack of diagramsclearness and problems during maintenance.In this paper, we proposed new ways of substations designing and changes indesigns of exploited substations when the reconstruction is needed. It reducescosts, economizes controlling, makes maintenance simplified and improvesclearness of electrical traction substations. Availability and safety of substationsremains high. Parallel connected traction substations could reduce peak powercosts and measurements of energy consumption are simpler. This paper provideselectrical calculations for protective relay adjustments in traction systems.Calculations of impedances and short circuit currents are performed using theWolfram Mathematica program.