Series-coded centralized track circuit system

Abstract

The present disclosure provides a series-coded centralized track circuit system, belonging to the technical field of rail transit. In this series-coded centralized track circuit system, the primary side of the first choke unit is used to connect to the rail, the secondary side of the first choke unit is connected to the outdoor power supply end of the indoor sending unit, the first end of the indoor sending unit is used to connect to the output end of the coding transmitter, the second end of the indoor sending unit is used to connect to the track circuit power supply, the primary side of the second choke unit is used to connect to the rail, the secondary side of the second choke unit is connected to the outdoor power receiving end of the indoor receiving unit, the first end of the indoor receiving unit is used to connect to the output end of the coding transmitter, and the second end of the indoor receiving unit is used to drive the track relay. The present disclosure can achieve the simplification, centralization, and high reliability of the track circuit system, and reduce the maintenance cost.

Description

Technical Field

[0001] The present disclosure relates to the technical field of rail transit, and particularly to a series-coded centralized track circuit system. Background Art

[0002] The railway track circuit system is a general term for commanding and controlling train operation, providing train position information, transmitting command information to trains, and integrating various control devices. The 25Hz AC phase-sensitive track circuit (hereinafter referred to as: 25Hz track circuit) is a kind of in-station track circuit technology used for electrified railways. The steel rail in the 25Hz track circuit is both the return path of the 50Hz traction current of electric locomotives and the path of the 25Hz track circuit. To ensure that the track circuit is not interfered by the traction current, a choke transformer is used to achieve double-loop electrical isolation, and the frequency difference between the 25Hz track circuit and the 50Hz electrified traction current is utilized to distinguish the nature of the electrical signals transmitted in the steel rail, so as to realize the sharing of the steel rail channel by the traction current and the track circuit current. With the continuous increase of train speed, in order to control train operation more safely, a function of sending frequency-shift coded information for controlling train operation speed to the locomotive is added to the 25Hz track circuit.

[0003] Due to the continuous expansion of the functions of the 25Hz track circuit, combined with high-speed and heavy-haul trains, the actual traction (return) current exceeds 1000A, which continuously reduces the electrical isolation effect of the choke transformer and reduces the anti-interference ability of the track circuit; secondly, various electrical equipment and devices added to expand the functions not only reduce the reliability of the track circuit system, but also increase the workload of on-site maintenance personnel. Summary of the Invention

[0004] Embodiments of the present disclosure provide a series-coded centralized track circuit system to achieve the simplification, centralization, and high reliability of the track circuit system, and reduce the maintenance cost.

[0005] Embodiments of the present disclosure provide a series-coded centralized track circuit system, including a first choke unit, a second choke unit, an indoor sending unit, and an indoor receiving unit.

[0006] The primary side of the first choke unit is used to connect to the steel rail, the secondary side of the first choke unit is connected to the outdoor power supply end of the indoor sending unit, the first end of the indoor sending unit is used to connect to the output end of the coded transmitter, and the second end of the indoor sending unit is used to connect to the track circuit power supply.

[0007] The primary side of the second choke unit is used to connect to the rail, the secondary side of the second choke unit is connected to the outdoor power receiving end of the indoor receiving unit, the first end of the indoor receiving unit is used to connect to the output end of the coding transmitter, and the second end of the indoor receiving unit is used to drive the track relay;

[0008] Both the first choke unit and the second choke unit are choke transformer signal coils.

[0009] In an exemplary embodiment of the present disclosure, a traction interference absorption protection box is provided on the secondary side of the first choke unit, and the access point of the traction interference absorption protection box is connected in parallel with the track power supply circuit.

[0010] In an exemplary embodiment of the present disclosure, the indoor sending unit includes a sending track voltage regulating transformer, capacitor C11, a first coding sending transformer, and capacitor C12.

[0011] The primary side of the first coding sending transformer is used to connect to the output end of the coding transmitter, the secondary side of the first coding sending transformer is connected in series to the track circuit power supply circuit, and the signal output from the secondary side of the first coding sending transformer is output to the outdoor power supply end through capacitor C11 and capacitor C12.

[0012] The primary side of the sending track voltage regulating transformer is used to connect to the track circuit power supply, and the signal on the secondary side of the sending track voltage regulating transformer is output to the outdoor power supply end through capacitor C11, capacitor C12, and the secondary side coil of the first coding sending transformer.

[0013] In an exemplary embodiment of the present disclosure, capacitor C13 is connected in series on the primary side of the first coding sending transformer.

[0014] In an exemplary embodiment of the present disclosure, the indoor receiving unit includes capacitor C21, a second coding sending transformer, capacitor C23, and a cable simulation resistor RX.

[0015] The primary side of the second coding sending transformer is used to connect to the output end of the coding transmitter, the secondary side of the second coding sending transformer is connected in series to the track circuit power receiving circuit, and the signal output from the secondary side of the second coding sending transformer is output to the outdoor power receiving end through capacitor C21.

[0016] The track voltage received by the outdoor power receiving end drives the track relay through the secondary side coil of the second coding sending transformer, capacitor C23, and the cable simulation resistor RX.

[0017] In an exemplary embodiment of the present disclosure, the series coding centralized track circuit system further includes a candidate compensation capacitor and a switching switch.

[0018] The switching switch is used to switch the secondary side coil of the second coded transmission transformer to be connected to the capacitor C23 or the candidate compensation capacitor.

[0019] In an exemplary embodiment of the present disclosure, a capacitor C24 is connected in series to the primary side of the second coded transmission transformer.

[0020] In an exemplary embodiment of the present disclosure, the turns ratio of the signal coil of the choke transformer is 1:40.

[0021] The beneficial effects of the series-coded centralized track circuit system provided by the embodiments of the present disclosure are as follows:

[0022] In the embodiments of the present disclosure, the primary sides of the first choke unit and the second choke unit are connected to the rail, and can obtain the signals and currents on the rail. The secondary sides are respectively connected to the outdoor power supply end of the indoor sending unit and the outdoor power receiving end of the indoor receiving unit, so as to realize the sharing of the traction current, the track circuit current and the coded information through the rail channel.

[0023] Among them, in this embodiment, the track transformer is cancelled. At the same time, because the attenuation of the 2000Hz coded frequency shift caused by the track transformer is eliminated, the coding is completely merged with the track circuit loop. Not only the taps of the signal coil of the choke transformer are reduced, but also the coded isolation inductor and the 25Hz isolation capacitor are cancelled. The choke unit circuit is simpler and has fewer components, thus realizing the simplification, centralization and high reliability of the track circuit system, and reducing the maintenance cost. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings.

[0025] Figure 1 is the traction return current path diagram in the traditional track circuit system;

[0026] Figure 2 is the track circuit loop current path diagram in the traditional track circuit system;

[0027] Figure 3 is the parallel transmission and isolation schematic diagram of the indoor sending unit in the traditional track circuit system;

[0028] Figure 4 is the parallel transmission and isolation schematic diagram of the indoor receiving unit in the traditional track circuit system;

[0029] Figure 5 It is a schematic diagram of a series-coded centralized track circuit system provided by an embodiment of the present disclosure;

[0030] Figure 6 is Figure 5 the series-coded current path diagram of the indoor sending unit in

[0031] Figure 7 is Figure 5 the series-coded current path diagram of the indoor receiving unit in

[0032] In the figure:

[0033] 1 - rail, 2 - outdoor power supply end, 3 - outdoor power receiving end, 4 - track relay, 5 - first choke unit, 6 - second choke unit, 7 - indoor sending unit, 8 - indoor receiving unit, 9 - first codeless sending transformer, 10 - second codeless sending transformer, 11 - sending track voltage regulating transformer. Specific embodiments

[0034] In order to enable those skilled in the art to better understand this solution, the technical solutions in the embodiments of this solution will be clearly described below in conjunction with the accompanying drawings in the embodiments of this solution. Obviously, the described embodiments are part of the embodiments of this solution, rather than all of the embodiments. Based on the embodiments in this solution, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this solution.

[0035] The term "including" in the specification, claims, and above-mentioned accompanying drawings of this solution, as well as any other variations, means "including but not limited to", and is intended to cover non-exclusive inclusion, and is not limited to the examples listed in the text. In addition, terms such as "second" and "second" are used to distinguish different objects, rather than to describe a specific order.

[0036] In the traditional track circuit system, each 25Hz track circuit section is respectively composed of an indoor isolation box at the power supply end, an outdoor trackside XB box and the track transformer inside the box, an outdoor isolation box, a current-limiting resistor, a choke transformer and a rail lead wire, a rail lead wire at the power receiving end, a choke transformer, a trackside XB box and the current-limiting resistor inside the box, a track transformer, an outdoor isolation box, an indoor isolation box at the power receiving end, a protective box, a binary two-position relay, etc.

[0037] There are three current loops in the 25Hz track circuit: the traction current loop, the track circuit loop, and the codeless loop. The working principles of each loop are introduced below:

[0038] (1) Traction current loop

[0039] Such as Figure 1As shown in the figure, the current output by the traction substation of the electric locomotive is connected to the locomotive through the overhead catenary. After passing through the locomotive traction motor, it returns to the traction substation through two rails 1. The current returning to the substation through the rails 1 is called the traction return current. When the two rails 1 are normal, the return current directions of the two rails 1 are the same and the magnitudes are equal; when the currents of the two rails 1 flow into the 1 and 2 terminals of the choke transformer respectively and flow out from the center tap 3, since the current directions of the choke transformer 1-3 and 2-3 are opposite, a directional variable magnetic field cannot be generated. Therefore, no 50Hz traction current is induced and output on the secondary side of the choke transformer, thus realizing the 50Hz traction current loop and the 25Hz track circuit loop.

[0040] (2)Track circuit loop

[0041] The 25Hz track circuit power supply, after being output by the track transformer at the sending end, enters the secondary side of the sending-end choke transformer, and induces and outputs the rail surface voltage between the 1-2 terminals of the primary side of the choke transformer, and is sent to the two rails 1 through the lead wires respectively; at the receiving end of the track circuit, the rail surface voltages of the two rails 1 respectively enter the 1-2 terminals of the primary side of the receiving-end choke transformer. Since the current directions of the 1-3 and 3-2 coils are the same, the track voltage is induced and output on the secondary side of the receiving-end choke transformer. After passing through the receiving-end track transformer, it drives the track relay 4 to pick up, proving that there is no train occupying this track section; when a train occupies, the train wheels short-circuit the rail surface voltages of the two rails 1, and the receiving end cannot receive the rail surface voltage, and the track relay 4 drops, indicating that there is a train occupying this track section.

[0042] (3)Coded track circuit loop

[0043] Track circuit coding means that, indoors, through the track transformers and choke transformers at the sending end and receiving end, a frequency-shift electrical signal with a center frequency of 1700Hz - 2600Hz containing train operation speed control information is sent to the two rails 1. Its frequency-shift signal is superimposed on the 25Hz track circuit loop in a parallel manner. To avoid the mutual interference and absorption of electrical signals in two different loops, indoor and outdoor isolation devices are respectively set in the 25Hz track circuit loop. Such as Figure 3 L + C1 in is the crosstalk blocking element for coded track circuit, and C3 blocks the 25Hz track circuit signal from entering the coded track circuit element: Figure 4 L2 in is the crosstalk blocking element for coded track circuit, and C4 blocks the 25Hz track circuit signal from entering the coded track circuit element to ensure the normal transmission of signals in the corresponding loop.

[0044] The implementation of the present disclosure will be described in detail below with reference to specific drawings:

[0045] According to the actual existing operation requirements of the 25Hz track circuit, this embodiment comprehensively considers factors such as anti-interference problems under the state of large traction return current, effective superposition of coding, reduction of phase shift, and reduction of outdoor trackside equipment, breaks through the original technical structure of the 25Hz track circuit system, simplifies and reconstructs the 25Hz track circuit system, so that the track circuit system achieves the goals of simplicity, centralization, high reliability, and low maintenance.

[0046] Specifically, as Figure 5 shown, the series-coding centralized track circuit system of this embodiment includes a first choke unit 5, a second choke unit 6, an indoor sending unit 7, and an indoor receiving unit 8.

[0047] The primary side of the first choke unit 5 is used to connect to the rail 1, the secondary side of the first choke unit 5 is connected to the outdoor power supply end 2 of the indoor sending unit 7, the first end of the indoor sending unit 7 is used to connect to the output end of the coding transmitter, and the second end of the indoor sending unit 7 is used to connect to the track circuit power supply.

[0048] The primary side of the second choke unit 6 is used to connect to the rail 1, the secondary side of the second choke unit 6 is connected to the outdoor power receiving end 3 of the indoor receiving unit 8, the first end of the indoor receiving unit 8 is used to connect to the output end of the coding transmitter, and the second end of the indoor receiving unit 8 is used to drive the track relay 4.

[0049] Both the first choke unit 5 and the second choke unit 6 are choke transformer signal coils.

[0050] In this embodiment, the primary sides of the first choke unit 5 and the second choke unit 6 are connected to the rail 1, which can obtain the signals and currents on the rail 1, and the secondary sides are respectively connected to the outdoor power supply end 2 of the indoor receiving unit 8 and the outdoor power receiving end 3 of the indoor sending unit 7, realizing the sharing of the rail 1 channel for traction current, track circuit current, and coding information.

[0051] Among them, the first end of the indoor sending unit 7 is connected to the output end of the coding transmitter, receives and processes the coding information, and outputs it to the outdoor power supply end 2; the second end of the indoor sending unit 7 is connected to the track circuit power supply and outputs the track circuit power supply to the outdoor power supply end 2.

[0052] The first end of the indoor receiving unit 8 is connected to the output end of the coding transmitter, receives and processes the coding information, and outputs it to the outdoor power receiving end 3; the track voltage received by the power receiving end rail surface is output through the second end of the indoor sending unit 7 to drive the track relay 4, realizing the mutual compatibility between the power receiving end coding and the track circuit loop.

[0053] In this embodiment, the track transformer is cancelled. At the same time, since the attenuation of the 2000Hz codeless frequency shift caused by the track transformer is eliminated, the codeless and the track circuit loop are completely merged. This not only reduces the tapping of the signal coil of the choke transformer, but also cancels the codeless isolation inductor and the 25Hz isolation capacitor. The choke unit circuit is simpler and has fewer components, thus realizing the simplification, centralization and high reliability of the track circuit system and reducing the maintenance cost.

[0054] In an embodiment of the present disclosure, a traction interference absorption protection box is provided on the secondary side of the first choke unit 5, and the access point of the traction interference absorption protection box is connected in parallel with the track power supply loop.

[0055] In this embodiment, considering that in the railway track circuit system, when the traction current passes through the rail 1, if the traction current is unbalanced, it will interfere with the 25Hz track circuit loop and the codeless loop.

[0056] To solve the above problems, 50Hz traction interference absorption protection boxes (i.e., outdoor adjustment protection boxes) are provided on the secondary sides of both the first choke unit 5 and the second choke unit 6 to absorb and suppress interference signals.

[0057] Furthermore, the access points of the 50Hz traction interference absorption protection boxes are merged with the access points of the track circuit loop, further reducing the reflection impedance of the 50Hz absorption loop to the rail 1 side and improving the ability to resist unbalanced current.

[0058] Similarly, a traction interference absorption protection box is also provided on the secondary side of the second choke unit 6, and the access point of the traction interference absorption protection box is connected in parallel with the track power receiving loop.

[0059] In an embodiment of the present disclosure, the indoor sending unit 7 includes a sending track voltage adjustment transformer 11, a capacitor C11, a first codeless sending transformer 9 and a capacitor C12.

[0060] The primary side of the first codeless sending transformer 9 is used to connect to the output end of the codeless transmitter. The secondary side of the first codeless sending transformer 9 is connected in series to the track circuit power supply loop, and the signal output from the secondary side of the first codeless sending transformer 9 is output to the outdoor power supply end 2 through the capacitor C11 and the capacitor C12.

[0061] The primary side of the sending track voltage adjustment transformer 11 is used to connect to the track circuit power supply. The signal on the secondary side of the sending track voltage adjustment transformer 11 is output to the outdoor power supply end 2 through the capacitor C11, the capacitor C12 and the secondary side coil of the first codeless sending transformer 9.

[0062] In this embodiment, in the traditional track circuit system, a parallel coding method is usually adopted, that is, the coding circuit is in parallel with the track circuit loop. To avoid the mutual interference and influence between the coding circuit and the track circuit loop, various isolation inductors, capacitors and other devices need to be set, and the circuit structure is complex.

[0063] In this embodiment, the coding transmitter adopts a series coding method, which can cancel various isolation inductors, capacitors and other devices, simplify the circuit structure and the number of components of the 25Hz track circuit system, reduce the failure rate of the track circuit system, and improve the system reliability.

[0064] Among them, at the first end of the indoor sending unit 7, the capacitor C11 is an absorption capacitor, which can absorb the interference signal on the secondary side of the first coding sending transformer 9. At the same time, considering that the coding frequency shift is only about 2000Hz, which is relatively close to the 25Hz power supply frequency of the track circuit, the inductance of the first coding sending transformer 9 is also relatively high, and its 25Hz impedance is also relatively high. If it is directly connected in series to the track circuit power supply loop, the loss of the track circuit loop is too large to ensure the normal operation of the track circuit.

[0065] To reduce the loss of the 25Hz track circuit, in this embodiment, the secondary side coil of the first coding sending transformer 9 and the capacitor C12 form a 25Hz series resonance circuit, which can reduce the loss of the first coding sending transformer 9 to the track circuit loop, so as to ensure the normal operation of the track circuit.

[0066] At the second end of the indoor sending unit 7, the 25Hz track circuit signal output by the sending track voltage adjustment transformer 11 uses the low impedance characteristic of the 25Hz series resonance circuit formed by the secondary side coil of the first coding sending transformer 9 and the capacitor C12 to output the track power supply to the outside, realizing the mutual compatibility between the coder at the power supply end and the track circuit loop.

[0067] In an embodiment of the present disclosure, a capacitor C13 is connected in series to the primary side of the first coding sending transformer 9.

[0068] In this embodiment, the capacitor C13 is a frequency shift isolation capacitor, which allows the coding frequency shift signal to pass through smoothly, and at the same time prevents other unnecessary frequency components from entering the subsequent circuit links.

[0069] In an embodiment of the present disclosure, the indoor receiving unit 8 includes a capacitor C21, a second coding sending transformer 10, a capacitor C23 and a cable simulation resistor RX.

[0070] The primary side of the second coded transmission transformer 10 is used to connect to the output end of the coded transmitter. The secondary side of the second coded transmission transformer 10 is connected in series to the power receiving circuit of the track circuit. The signal output from the secondary side of the second coded transmission transformer 10 is output to the outdoor power receiving end 3 through the capacitor C21.

[0071] The track voltage received by the outdoor power receiving end 3 drives the track relay 4 through the secondary side coil of the second coded transmission transformer 10 and the capacitor C23.

[0072] In this embodiment, at the first end of the indoor receiving unit 8, the secondary side of the second coded transmission transformer 10 is connected in series to the power receiving circuit of the 25Hz track circuit. The signal output from the secondary side of the second coded transmission transformer 10 is output to the outdoor power receiving end 3 through the interference absorption capacitor C21.

[0073] At the second end of the indoor receiving unit 8, the track voltage received from the rail surface of the power receiving end drives the track relay 4 through the 25Hz series resonance circuit formed by the secondary side coil of the second coded transmission transformer 10 and the capacitor C23, realizing the mutual compatibility between the power receiving end coding and the track circuit loop.

[0074] In an embodiment of the present disclosure, the series-coded centralized track circuit system further includes a candidate compensation capacitor and a switching switch.

[0075] The switching switch is used to switch the connection between the secondary side coil of the second coded transmission transformer 10 and the capacitor C23 or the candidate compensation capacitor.

[0076] In this embodiment, there may be multiple candidate compensation capacitors, such as Figure 5 the capacitors C24, C25, C26, and C27. The multiple candidate compensation capacitors have different capacitance values. The position of the switching switch can be adjusted according to actual needs to connect the capacitor C23 or the candidate compensation capacitor to the secondary side coil of the second coded transmission transformer 10 to form a resonance circuit with a specified resonance frequency and adjust the phase of the track circuit.

[0077] In this embodiment, considering that the rail 1 in the track circuit presents an inductive characteristic to the 25Hz transmission loop, which will affect the phase of the track circuit signal at the receiving end. To solve the above problem, this embodiment sets the capacitor C23 and multiple candidate compensation capacitors. The secondary side of the second coded transmission transformer 10 and the capacitor C23 or the candidate compensation capacitor form a series resonance circuit. When the resonance point is at 25Hz, it does not affect the phase of the track circuit. When the resonance point is lower than 25Hz, the resonance circuit presents an inductive characteristic; when the resonance point is higher than 25Hz, it presents a capacitive characteristic. By adjusting the capacitance of the resonance capacitor, while changing the resonance point of the resonance circuit, the impedance property of the resonance circuit is also changed, thereby compensating the phase of the track circuit received signal.

[0078] In one embodiment of the present disclosure, a capacitor C24 is connected in series to the primary side of the second electrically coded transmission transformer 10.

[0079] In this embodiment, the capacitor C24 is a frequency-shift isolation capacitor, which allows the electrically coded frequency-shift signal to pass through smoothly, while preventing other unwanted frequency components from entering the subsequent circuit section.

[0080] In one embodiment of the present disclosure, the turns ratio of the signal coil of the choke transformer in the first choke unit 5 and the second choke unit 6 is 1:40.

[0081] In this embodiment, a large number of experimental studies by the inventors have shown that setting the turns ratio of the signal coil of the choke transformer to 1:40 can enable the transmission efficiency of the signal in the track circuit to reach the optimal state.

[0082] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present disclosure.

Claims

1. A series code-generating centralized track circuit system, characterized in that: It includes a first choke unit, a second choke unit, an indoor transmitting unit and an indoor receiving unit, The primary side of the first choke unit is used to connect to the rail, the secondary side of the first choke unit is connected to the outdoor power supply end of the indoor sending unit, the first end of the indoor sending unit is used to connect to the output end of the electric coding transmitter, and the second end of the indoor sending unit is used to connect to the track circuit power supply. The primary side of the second choke unit is used to connect to the rail, the secondary side of the second choke unit is connected to the outdoor power receiving end of the indoor receiving unit, the first end of the indoor receiving unit is used to connect to the output end of the electric coding transmitter, and the second end of the indoor receiving unit is used to drive the track relay; The indoor transmission unit includes a transmission track voltage adjustment transformer, a capacitor C11, a first coded transmission transformer and a capacitor C12. The primary side of the first electro-encoded transmission transformer is used to connect to the output end of the electro-encoded transmitter, the secondary side of the first electro-encoded transmission transformer is connected in series to the track circuit power transmission loop, and the signal output by the secondary side of the first electro-encoded transmission transformer is output to the outdoor power transmission end through capacitors C11 and C12; The primary side of the transmitting track voltage regulating transformer is used to connect to the track circuit power supply, and the secondary side signal of the transmitting track voltage regulating transformer is output to the outdoor power transmission end through capacitor C11, capacitor C12 and the secondary side coil of the first coded transmitting transformer.

2. The tandem code-generating centralized track circuit system according to claim 1, characterized in that: A traction interference absorption protection box is provided on the secondary side of the first choke unit, and an access point of the traction interference absorption protection box is connected in parallel with the track power transmission circuit.

3. The tandem code-generating centralized track circuit system according to claim 1, characterized in that: A capacitor C13 is connected in series to the primary side of the first coding transmission transformer.

4. The tandem code-generating centralized track circuit system according to claim 1, characterized in that: The indoor receiving unit includes a capacitor C21, a second electronically coded transmitting transformer, a capacitor C23 and a cable simulation resistor RX. The primary side of the second electric code transmission transformer is used to connect to the output end of the electric code transmitter, and the secondary side of the second electric code transmission transformer is connected in series to the track circuit receiving circuit. The signal output by the secondary side of the second electric code transmission transformer is output to the outdoor receiving end through the capacitor C21; The track voltage received by the outdoor power receiving end drives the track relay through the secondary side coil of the second coded transmitting transformer, the capacitor C23 and the cable simulation resistor RX.

5. The tandem code-generating centralized track circuit system according to claim 4, characterized in that: Also included are candidate compensation capacitors and switching switches, The switching switch is used to switch the secondary side coil of the second coded transmitting transformer to be connected with the capacitor C23 or the candidate compensation capacitor.

6. The tandem code-generating centralized track circuit system according to claim 4, characterized in that: A capacitor C24 is connected in series to the primary side of the second coding transmission transformer.

7. The tandem code-generating centralized track circuit system according to claim 1, characterized in that: The transformation ratio of the signal coils of the choke transformers in the first choke unit and the second choke unit is 1:40.

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