IL304136A

IL304136A - Protective device for protecting an electrical track-field infrastructure, track-field power supply apparatus and method for limiting potential shifts in an electrical track-field infrastructure

Info

Publication number: IL304136A
Application number: IL304136A
Authority: IL
Original assignee: Gts Deutschland Gmbh
Priority date: 2022-06-30
Filing date: 2023-06-29
Publication date: 2024-01-01
Also published as: EP4307508A1; CA3205062A1; DE102022206731A1

Description

PROTECTIVE DEVICE FOR PROTECTING AN ELECTRICAL TRACK FIELD INFRASTRUCTURE, TRACK-FIELD POWER SUPPLY APPARATUS AND METHOD FOR LIMITING POTENTIAL SHIFTS IN AN ELECTRICAL TRACK-FIELD INFRASTRUCTURE BACKGROUND OF THE INVENTION id="p-1" id="p-1" id="p-1"

[0001] The invention relates to a protective device for protecting an electrical track-field infrastructure from AC interference voltages, a track-field power supply apparatus and method for limiting potential shifts in an electrical track field infrastructure comprising a feed, at least one DC supply line and at least one protective device and a method for limiting potential shifts in an electrical track-field infrastructure. id="p-2" id="p-2" id="p-2"

[0002] Track-field power supply apparatus for supplying field elements (loads in the track-field) is known from EP 3 247 015 A1 [1]. id="p-3" id="p-3" id="p-3"

[0003] For driving operation by means of electrical traction, a contact wire system consisting of a substation feed, switching points, masts and a contact wire (overhead line) is set up along the path. This means that a galvanically connected, low-impedance line is present along the route. In the case of electric traction operation, in many European countries the overhead line for the driving current is supplied with a single-phase AC voltage from a substation with 15 kV 16.7 Hz. In practice, the return current is approximately 1/3 via the rail, 1/3 via a return conductor (ground cable) and to 1/3 via the ground. id="p-4" id="p-4" id="p-4"

[0004] The feed sections for the contact wire can be 10 to 20 km long, depending on the design. The interference is therefore carried over long distances (feed sections). The linear current-bearing elements (contact wire, rail and ground cable) form a single-wind transformer with respect to the cables of the rail safety technology, which are located in the cable channels (cable trough) guided in parallel. Magnetic fields which induce voltages and currents in metallic contact parts are formed between the contact wire and the reverse current-carrying conductors. One speaks of interference voltages and currents. Particularly affected are longitudinally guided conductors along the rail section, e.g., cables of the power supply and control for field elements of the conducting and safety technology. id="p-5" id="p-5" id="p-5"

[0005] By means of interference voltages, potential shifts occur, wherein "potential shifts" are understood to include shifts of the absolute voltage relative to ground potential caused by the superposition of induced AC voltage components on a static DC feed. id="p-6" id="p-6" id="p-6"

[0006] A further critical case in which the highest interference voltages arise is the "driving line short circuit. " A driving line short circuit is produced in most cases by a contact wire falling down on the rail, for example by fallen trees, icing and structural damage to the masts. The duration of these short-circuit currents is 1–2 periods of the 16.7 Hz power supply, i.e., 60–120 milliseconds, depending on the switchgear assembly. id="p-7" id="p-7" id="p-7"

[0007] In directive 819.0804 of DB [2], 250 VAC are specified for long-term interference (driving operation) and 1500 VAC for short-term interference (drive line short circuit) as limit values for the system protection. Because the interference voltage is dependent on the interference length, a galvanic separation of the power supply and control lines is provided in known track field installations at certain distances (control distances) in order to ensure that these values are not exceeded. The distances of the galvanic separations (control distances), which are relevant in this context in the case of railway systems, are typically approximately 2.5 km, in the maximum case up to 6.km. This galvanic isolation occurs with AC lines by means of transformers and in DC lines by means of longitudinal voltage decouplers (LSE) [3], [4]. A disadvantage of this is the high technical effort for the potential-free power transmission with the associated monitoring apparatus in a switch cabinet on the route. The additional apparatus further reduces the availability of the overall installation. id="p-8" id="p-8" id="p-8"

[0008] The power supply apparatus known from [1] comprises a 2-pole bus line segmented by load bus coupling elements with a positive and a negative line conductor. The loads are connected to the bus line via the load bus coupling elements. The energy is supplied via at least one feed bus coupling element. The two line conductors have a low impedance to one another (feed) and are operated with DC voltage. The power supply apparatus known from [1] is an Isolée Terre (IT) system. A limitation of the superimposed interference voltage takes place by limiting the galvanically connected cable length (interference length) and/or by using expensive reduction cables, which reduce the inductive coupling by a special cable sheath structure. An interference voltage therefore effects a superimposition of the induced AC contact wire voltage on the DC power supply voltage.

OBJECT OF THE INVENTION id="p-9" id="p-9" id="p-9"

[0009] The object of the invention is to propose a protection device, a track field power supply apparatus and a method which enable a limitation of potential shifts in an electrical track-field infrastructure, in particular also for use in a DC energy bus.

DESCRIPTION OF THE INVENTION id="p-10" id="p-10" id="p-10"

[0010] This object is achieved according to the invention by a protective device according to claim 1, a track-field power supply apparatus according to claim and a method according to claim 16. id="p-11" id="p-11" id="p-11"

[0011] The protective device according to the invention for protecting an electrical track-field infrastructure from AC interference voltages comprises: a line conductor which is at positive potential (positive line conductor), a line conductor which is at negative potential (negative line conductor), a voltagelimiting device comprising a first voltage-direction-dependent electronic switching device and a second voltage-direction-dependent electronic switching device, wherein the voltage-direction-dependent electronic switching devices have a diode function, wherein the first voltage-direction-dependent electronic switching device is connected between the line conductor which is at positive potential and ground, and without electromagnetic interference blocks in the direction from the line conductor at positive potential to ground potential, wherein the second voltage-direction-dependent electronic switching device is connected between the line conductor which is at negative potential and ground and without interference blocks in the direction from ground potential to the line conductor which is at negative potential. id="p-12" id="p-12" id="p-12"

[0012] The protective device according to the invention is installed with a low- impedance connection to the ground potential (ground rail or the like) and has at least one connection to the positive line conductor and at least one connection to the negative line conductor. id="p-13" id="p-13" id="p-13"

[0013] The connection according to the invention of the voltage-direction- dependent switching devices ensures that the potential of the positive wire is never shifted below the ground potential and that the potential of the negative wire is never shifted above the ground potential. As a result, a load connected to the line conductors can be effectively protected against high voltages relative to the ground potential by interference voltages. id="p-14" id="p-14" id="p-14"

[0014] As soon as a line conductor reaches ground potential, the corresponding voltage-direction-dependent switching device becomes conductive and represents a low-impedance connection to ground potential. The protective device according to the invention therefore effects a brief one sided ground fault (ground fault of one of the line conductors) of the IT power supply apparatus. id="p-15" id="p-15" id="p-15"

[0015] The protective device is in particular an input and/or output protection apparatus, i.e., a protective device, which protects the input or the output (depending on the feed direction) of a component of a track-field infrastructure. id="p-16" id="p-16" id="p-16"

[0016] A voltage-direction-dependent electronic switching device with diode function comprises at least one electronic element. which is high-impedance or low-resistance depending on the voltage applied to it. This can be an active or a passive electronic component. Preferably, the voltage-direction- dependent electronic switching devices are diodes or controllable switches, in particular switched transistors. In the case of diodes, the cathode of the first diode is connected to the positive line conductor, while the anode of the first diode is connected to ground potential; the anode of the second diode is connected to the negative line conductor, while the cathode of the second diode is at ground potential. In normal operation (i.e., without interference voltage), the switching devices are therefore connected in blocking direction (i.e., high-impedance). A switching device can also comprise multiple voltagedirection-dependent electronic elements connected in series. id="p-17" id="p-17" id="p-17"

[0017] In an advantageous embodiment of the protective device according to the invention, at least one of the voltage-direction-dependent electronic switching devices is connected in series with a resistor for current limitation. The resistor connected in series prevents the switching device from blowing when, in addition to a ground fault, traction return currents also flow at the same time via ground. Multiple resistors can also be connected in series to the voltage-direction-dependent electronic switching device. id="p-18" id="p-18" id="p-18"

[0018] A particularly preferred embodiment of the protective device according to the invention comprises a first surge protection apparatus, wherein the first surge protection apparatus is electrically connected between the positive line conductor of the supply line and ground potential, and a second surge protection apparatus, wherein the second surge protection apparatus is electrically connected between the negative line conductor of the supply line and ground potential. The first surge protection apparatus with the first switching device and the second surge protection apparatus with the second switching device each form a parallel circuit. In this way, overvoltages caused by lightning events can be reduced. id="p-19" id="p-19" id="p-19"

[0019] The protective device according to the invention can be present as a separate unit or integrated in a sleeve for galvanic connection of pipe sections. id="p-20" id="p-20" id="p-20"

[0020] The invention also relates to a track-field power supply apparatus comprising a feed, at least one DC supply line and at least one previously described protection device, wherein the line conductors are part of a DC supply line, which is electrically connected to the feed and is supplied with energy by the feed. id="p-21" id="p-21" id="p-21"

[0021] The track-field power supply apparatus is an installation with the Isolée Terre (IT) network configuration. By means of the protective device according to the invention, when a superimposed voltage causes a voltage shift beyond the ground potential (in the case of positive line conductor in the negative direction, in the case of negative line conductor in the positive direction), a temporary one-sided voltage limitation is brought about by means of a ground fault on one side, which leads to a temporary loss of the IT properties of the power supply apparatus. id="p-22" id="p-22" id="p-22"

[0022] A particularly preferred embodiment of the track-field power supply apparatus according to the invention provides that a balancing resistor assembly is connected between positive and negative line conductors of the DC supply line in series with the feed, wherein the balancing resistor assembly comprises two identical resistor units connected in series and the center tap of the balancing resistor assembly is at ground potential. This results in the DC voltage, which is "floating" due to the IT property of the power supply apparatus, being distributed uniformly with respect to the ground potential with intact insulation (i.e., without effect of the inductive interference). This means that both the voltage of the positive line conductor relative to ground potential and the voltage of the negative line conductor relative to ground potential is half the DC feed voltage. A resistor unit can comprise multiple resistant components. id="p-23" id="p-23" id="p-23"

[0023] A shift of the voltage ratios provides information on the insulation conditions in the installation. Therefore, measuring units for measuring the voltages dropping across the resistor units are preferably provided. By means of the measuring units, shifts of the potentials of the line conductor relative to the ground potential can be detected. As a result, insulation faults can be detected and their extent can be estimated. In addition, an insulation monitor for IT networks can be used for insulation monitoring. id="p-24" id="p-24" id="p-24"

[0024] In a particularly preferred embodiment, the DC supply line is a bus line. id="p-25" id="p-25" id="p-25"

[0025] In this case, the bus line is divided into bus segments by bus coupling elements, each bus coupling element comprising further switching devices (segmentation switches) for electrical separation of the bus line. id="p-26" id="p-26" id="p-26"

[0026] The bus coupling elements preferably comprise at least one feed bus coupling element for connecting the feed to the bus line and at least one load bus coupling element for connecting a load to the bus line. id="p-27" id="p-27" id="p-27"

[0027] In a specific embodiment, the balancing resistor assembly is part of the feed bus coupling element. As a result, a compact design of the components can be achieved. id="p-28" id="p-28" id="p-28"

[0028] In order to protect the load bus coupling elements even in the case of feeding from both sides, it is preferable for a protective device to be arranged on each side of a load bus coupling element. Between two load bus coupling elements, two protective devices are thus preferably electrically connected to the bus segment delimited by the two load bus coupling elements. id="p-29" id="p-29" id="p-29"

[0029] Furthermore, it is advantageous if a protective device is arranged on the side of the feed bus coupling element facing away from the feed. In this way, the feed can also be protected against interference voltages or interference currents. id="p-30" id="p-30" id="p-30"

[0030] As an alternative to a bus lines divided into bus segments, the bus line can be a galvanically connected bus line. id="p-31" id="p-31" id="p-31"

[0031] Preferably, multiple protective devices are provided also in the case of a galvanically connected bus line. These are preferably spaced apart from one another by a few kilometers. id="p-32" id="p-32" id="p-32"

[0032] The invention also relates to a method for limiting potential shifts, i.e., the voltage relative to the ground potential caused by the superimposition of the interference voltage in an electrical track-field infrastructure caused by an interference voltage by means of an above-described protection device. id="p-33" id="p-33" id="p-33"

[0033] In a particularly preferred method variant, an automatic voltagedependent potential limitation takes place, in particular depending on the signs of the voltages of the line conductors with respect to ground potential. id="p-34" id="p-34" id="p-34"

[0034] It is particularly preferred if the potentials of the line conductors are set symmetrically around the ground potential by means of a balancing resistor assembly. An insulation fault disclosure is preferably carried out by measuring the voltages dropping across the resistor units. id="p-35" id="p-35" id="p-35"

[0035] Further advantages of the invention can be found in the description and the drawings. Likewise, according to the invention, the aforementioned features and those which are to be explained below can each be used individually or together in any desired combinations. The embodiments shown and described are not to be understood as an exhaustive list, but, rather, have an exemplary character for the description of the invention.

Claims

1. A protective device (1, 1’) for protecting an electrical track-fieldinfrastructure from AC interference voltages, the protective device (1, 1’) comprising:a line conductor (2a, 2b) being at a positive potential and a line conductor (2a, 2b) being at a negative potential,a voltage limiting device comprising a first voltage-direction-dependent electronic switching device (4a) and a second voltage-direction-dependent electronic switching device (4b),wherein the voltage-direction-dependent electronic switching devices (4a, 4b) has a diode function,wherein the first voltage-direction-dependent electronic switching device (4a) is connected between the line conductor (2a) which is at a positive potential and ground and without electromagnetic interference blocking in the direction from the line conductor (2a) which is at a positive potential to the ground potential,wherein the second voltage-direction-dependent electronic switching device (4b) is connected between the line conductor (2b) which is at a negative potential and ground and without interference blocking in the direction from ground potential to the line conductor (2b) which is at a negative potential.

2. The protective device (1, 1’) according to claim 1, characterized in thatthe voltage-direction-dependent electronic switching devices (4a, 4b) are diodes or controllable switches, in particular switched transistors.

3. The protective device (1, 1’) according to any of the preceding claims,characterized in that for current limitation at least one of the voltage-direction- dependent electronic switching devices (4a, 4b) is connected in series with a resistor (17).

4. The protective device (1) according to any of the preceding claims,characterized in that it further comprises:a first surge protection apparatus (5a), the first surge protection apparatus (5a) being electrically connected between the positive line conductor (2a) of the supply line (2) and ground potential;a second surge protection apparatus (5b), the second surge protection apparatus (5b) being electrically connected between the negative line conductor (2b) of the supply line (2) and ground potential;wherein the first surge protection apparatus (5a) together with the first switching device (4a) and the second surge protection apparatus (5b) together with the second switching device (4b) respectively form a parallel connection.

5. A sleeve for the galvanic connection of pipe sections comprising at leastone protective device (1) according to any of claims 1 to 4.

6. A track-field power supply apparatus (8, 8′) comprising a DC feed (11),at least one DC supply line (2, 2′) and at least one protective device (1, 1′) according to any of claims 1 to 4, wherein the line conductors (2a, 2b) are part of the DC supply line (2, 2'), which is electrically connected to the feed (11), and are supplied with power by the feed (11).

7. The track-field power supply apparatus (8, 8′) according to claim 6,characterized in that a balancing resistor assembly (14) is connected downstream of the feed (11) between positive and negative line conductors (2a, 2b) of the DC supply line (2), the balancing resistor assembly (14) comprising two identical series-connected resistor units (18) and the center tap (15) of the balancing resistor assembly (14) being at ground potential.

8. The track-field power supply apparatus according to claim 7,characterized in that measuring units are provided (19) for measuring the voltages dropping across the resistor units (18).

9. The track-field power supply apparatus (8, 8’) according to any of claimsto 8, characterized in that the DC supply line (2) is a bus line.

10. The track-field power supply apparatus (8) according to claim 9, characterized in that the bus line (2) is divided into bus segments by bus coupling elements (10, 12), each bus coupling element (10, 12) comprising further switching devices (S1) for electrical separation of the bus line (2).

11. The track-field power supply apparatus (8) according to claim 10, characterized in that the bus coupling elements comprise at least one feed bus coupling element (12) for connecting the feed (11) to the bus line (2) and at least one load bus coupling element (10) for connecting a load (9) to the bus line (2).

12. The track-field power supply apparatus (8) according to claim 11 and any of the claims 6 to 7, characterized in that the balancing resistor assembly (14) is part of the feed bus coupling element (12).

13. The track-field power supply apparatus (8) according to claim 11 or 12, characterized in that a protective device (1) is arranged on each side of a load bus coupling element (10).

14. The track-field power supply apparatus (8) according to any of claims to 13, characterized in that a protective device (1, 1') is arranged on the side of the feed bus coupling element (12) facing away from the feed (11).

15. The track-field power supply apparatus (8′) according to claim 9, characterized in that the bus line (2') is a galvanically connected bus line.

16. The track-field power supply apparatus (8, 8′) according to any of claims to 15, characterized in that multiple protective devices are provided which are preferably spaced apart from one another by a few kilometers.

17. A method for limiting potential shifts in an electrical track-field infrastructure caused by an interference voltage by means of a protective device according to any of claims 1 to 4.

18. The method for operating a track-field power supply apparatus (8, 8') according to any of claims 6 to 16, characterized in that an automatic voltagedependent potential limitation takes place, in particular depending on the signs of the voltages of the line conductors (2a, 2b) relative to ground potential.

19. The method according to claim 18, characterized in that the potentials of the line conductors (2a, 2b) are set symmetrically around the ground potential by means of a balancing resistor assembly (14).