A direct current deicing system and method for a metro catenary

Abstract

This invention discloses a DC de-icing system for subway overhead contact lines, comprising an overhead contact line and running rails, and further including a subway rectifier module and a DC de-icing module; both the subway rectifier module and the DC de-icing module are connected to the overhead contact line. This invention also discloses a DC de-icing method for subway overhead contact lines. This invention can stably output a wide range of DC de-icing currents to meet de-icing needs under different scenarios, and can simultaneously melt ice on multiple overhead contact lines or running rails using different wiring methods according to de-icing requirements, saving operation time.

Description

Technical Field

[0001] This invention relates to the field of transportation technology, specifically to a DC de-icing system and method for subway overhead contact lines. Background Technology

[0002] In recent years, with the rapid urbanization in my country and the continuous rise in urban population, urban traffic has become increasingly congested. Subways, as a common mode of daily travel for citizens, offer many advantages and have therefore experienced rapid development. However, this rapid development has also brought some challenges. When subway vehicles use overhead contact lines for power supply, the impact of rain, snow, and ice on these lines is particularly pronounced. The contact line is a crucial power supply facility providing electricity for subway traction. When ice accumulates on the contact line surface, it severely affects the normal current collection of the pantograph, reduces the reliability of subway power supply, and thus threatens train safety. While small-scale line icing can be removed manually or mechanically (e.g., by striking with a mallet) or using high-pressure steam de-icing, these methods are inefficient and ineffective for large-scale, long-distance lines. Therefore, installing advanced and reliable de-icing devices in traction substations to safely and quickly remove ice from large areas of the contact line is of significant economic and social importance. From the current technological level both domestically and internationally, DC de-icing technology is the most mature and feasible de-icing method. Its basic principle is to use the heat energy generated by the direct current flowing through the conductor to melt the ice layer.

[0003] DC de-icing technology has been successfully applied in power transmission lines, and corresponding research has been conducted on DC de-icing of electrified railway contact networks. Manufacturers such as Zhuzhou Electric Locomotive Works and Xuji Group have also conducted research on DC de-icing of contact networks. However, there are currently no examples of DC de-icing technology being used in urban rail transit lines across the country.

[0004] Existing DC de-icing devices typically employ a single rectifier unit. The system provides AC power, which is then rectified into DC power for de-icing the iced lines. However, the DC power output has a limited current (voltage) range, making it difficult to meet the varying current requirements of different line lengths or environments. Furthermore, existing research on DC de-icing devices for subways utilizes power feedback between two sets of power feeders to generate DC current for contact network de-icing. This approach requires two power feeders and a large number of switching devices. Summary of the Invention

[0005] The purpose of this invention is to provide a DC de-icing system for subway contact networks. This device can stably output a wide range of DC de-icing current to meet the de-icing needs under different scenarios. At the same time, it can use different wiring methods to melt the ice on multiple contact networks or running rails simultaneously, saving operation time.

[0006] A DC de-icing system for subway overhead contact lines includes an overhead contact line and running rails, and further includes:

[0007] The subway rectifier module steps down the AC power from the urban power grid and then outputs stable DC power through efficient rectification and voltage regulation technology.

[0008] The DC de-icing module rectifies the AC power after it is stepped down from the city power grid and outputs controllable DC power. It can also step up the input DC power to form a closed loop with the contact network, generating Joule heat until the ice on the contact network is melted.

[0009] The aforementioned subway rectifier module and DC de-icing module are both connected to the overhead contact line.

[0010] Furthermore, the overhead contact line and the running rails respectively include left and right overhead contact lines and left and right running rails.

[0011] Furthermore, the DC ice-melting module includes a 380V switch cabinet, a rectifier cabinet, and a converter cabinet, which are connected in sequence;

[0012] One end of the 380V switchgear is connected to a step-down transformer, and the other end of the converter cabinet is connected to the overhead contact line; the step-down transformer is connected to the medium-voltage ring network.

[0013] Furthermore, the DC ice-melting module consists of a rectifier circuit and a boost circuit;

[0014] The rectifier circuit is a three-phase bridge fully controlled rectifier circuit, consisting of six thyristors and their parallel RC network; the Boost circuit is a symmetrical three-level Boost circuit, consisting of two inductors, two capacitors and four anti-parallel diodes.

[0015] Furthermore, one end of the converter cabinet is connected to the left-line contact wire and the left-line running rail respectively; a grounding switch is installed at the far end between the left-line contact wire and the left-line running rail.

[0016] Furthermore, one end of the converter cabinet is connected to the left and right contact wires respectively; a grounding switch is installed at the far end between the left and right contact wires.

[0017] Furthermore, the metro rectifier module includes a step-down transformer, a rectifier unit, a positive busbar, a negative busbar, and several switches;

[0018] One end of the step-down transformer is connected to the medium-voltage ring network, and the other end is connected to one end of the rectifier unit; the other end of the rectifier unit is connected to the positive and negative busbars respectively; the positive busbars are connected to the left and right contact networks respectively, and the negative busbars are connected to the left and right running rails respectively.

[0019] A DC de-icing method for subway overhead contact lines includes the following steps: the input terminal of the rectifier cabinet is connected to the low-voltage side of the step-down transformer of a 380V step-down substation, and the step-down transformer of the 380V step-down substation steps down the 35kV AC power to 380V AC power.

[0020] The 380V AC power is rectified by the rectifier cabinet to output a DC voltage lower than 500V, and then the voltage is transformed by the Boost circuit of the converter cabinet to output a DC voltage higher than 500V.

[0021] By short-circuiting the far end of the contact wire and the running rail of the same line through the grounding switch, the positive and negative output terminals of the converter cabinet are connected to the contact wire and the running rail of the same line respectively, thus forming a closed loop. The converter cabinet outputs DC current to the contact wire and the running rail of the same line. The DC current flowing through the contact wire and the running rail generates Joule heat. When the current reaches the minimum de-icing current, the ice on the contact wire and the running rail of the same line begins to melt.

[0022] Alternatively, the far ends of the left and right contact wires can be short-circuited using two grounding switches. The positive and negative output terminals of the converter cabinet are connected to the left and right contact wires respectively, forming a closed loop. The converter cabinet outputs DC current to the left and right contact wires. The DC current flowing through the left and right contact wires generates Joule heat. When the current reaches the minimum de-icing current, the ice on the left and right contact wires begins to melt. In this invention, the DC de-icing module consists of a rectifier cabinet, a converter cabinet, and a switch cabinet. It utilizes the three-phase bridge fully controlled rectifier circuit in the rectifier cabinet and the Boost circuit in the converter cabinet to achieve continuous DC voltage regulation over a wide range, thereby controlling the magnitude of the de-icing current. This allows for effective de-icing under different scenarios (different lengths and different environments). Compared to the ordinary two-level Boost circuit, the symmetrical three-level Boost circuit used in the rectifier cabinet effectively reduces the voltage stress on the switching transistors, lowers switching losses, and improves system efficiency and stability by increasing the number of levels.

[0023] In the DC de-icing mode of this invention, two different wiring methods are used at the far end of the contact wire or running rail. This allows for the simultaneous melting of ice on two contact wires or on the same contact wire and running rail, thus meeting the diverse de-icing needs of subway lines. Using a grounding switch instead of a grounding switch for the far-end connection between the contact wire and the running rail offers advantages such as cost savings and convenient and quick connection.

[0024] The power input of this invention is drawn from the 380V AC power in the 380V step-down substation, which saves the manufacturing cost of the switchgear compared to drawing power from the 1500V positive and negative busbars. Attached Figure Description

[0025] Figure 1 The system topology of this invention Figure 1 ;

[0026] Figure 2 This is the system topology of the present invention. Figure 2 ;

[0027] Figure 3 This is the electrical topology diagram of the DC ice-melting module of the present invention. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Example 1

[0029] like Figure 1 The above describes a DC de-icing system for a subway overhead contact line, comprising an overhead contact line and running rails, and further including:

[0030] The subway rectifier module steps down the AC power from the urban power grid and then outputs stable DC power through efficient rectification and voltage regulation technology to meet the power supply needs of high-power, long-distance subway lines. The DC de-icing module rectifies the AC power from the urban power grid to output controllable DC power and can also step up the input DC power to form a closed loop with the contact network, generating Joule heat until the ice on the contact network melts. Both the subway rectifier module and the DC de-icing module are connected to the contact network.

[0031] The overhead contact system and running rail of the present invention include left and right overhead contact systems and left and right running rails, respectively.

[0032] The DC de-icing module of the present invention includes a 380V switch cabinet, a rectifier cabinet, and a converter cabinet, which are connected in sequence; one end of the 380V switch cabinet is connected to a step-down transformer, and one end of the converter cabinet is connected to the contact network; the step-down transformer is connected to the medium-voltage ring network.

[0033] like Figure 3 As shown, the DC ice-melting module of this invention consists of a rectifier circuit and a boost circuit. The rectifier circuit is a three-phase bridge fully controlled rectifier circuit, which consists of six thyristors VT1, VT2, VT3, VT4, VT5, and VT6 and their parallel RC network; the boost circuit is a symmetrical three-level boost circuit, which consists of two inductors L1 and L2, two capacitors C1 and C2, and four anti-parallel diodes D1, D2, D3, and D4.

[0034] The Ua, Ub, and Uc terminals on the AC input side are connected to the rectifier circuit, which is also connected to the Boost circuit. The Boost circuit is set up on the DC output side.

[0035] The subway rectifier module includes a step-down transformer, a rectifier unit, a positive busbar, a negative busbar, and several switches; one end of the step-down transformer is connected to the medium-voltage ring network, and the other end is connected to one end of the rectifier unit; the other end of the rectifier unit is connected to the positive and negative busbars respectively; the positive busbars are connected to the left and right contact networks respectively, and the negative busbars are connected to the left and right running rails respectively. Example 2

[0036] The difference between Example 2 and Example 1 lies in the arrangement of the converter cabinet and the grounding switch. In Example 2, one end of the converter cabinet is connected to the left and right contact wires respectively; a grounding switch is installed at the far end between the left and right contact wires.

[0037] The subway system draws medium-voltage 35kV AC power from the city power grid. After being stepped down by the traction substation's step-down transformer, the voltage is fed into the rectifier unit. Through efficient rectification and voltage regulation technology, a stable 1500V DC power is output to meet the power supply requirements of high-power, long-distance subway lines. The positive output power of the rectifier unit is connected to the positive busbar, and the circuit is controlled by switches K2 and K3. The negative output power of the rectifier unit is connected to the negative busbar. The voltage level of the positive busbar is 1500V DC. The positive busbar is controlled by switches K4, K5, K6, K7, K8, and K9 to connect to the subway contact network, while the negative busbar is connected to the running rail. The DC de-icing device consists of a rectifier cabinet, a converter cabinet, and a 380V switch cabinet, and is installed in the 380V step-down substation. The input terminal of the rectifier cabinet of the DC de-icing device is connected to the low-voltage side of the step-down transformer in the 380V step-down substation, and the circuit is controlled by the 380V switch cabinet. The step-down transformer in the 380V step-down substation steps down the 35kV AC power to 380V AC power. The 380V AC power is rectified by the rectifier cabinet to output controllable DC power. The converter cabinet can step up the input DC power and the output terminal of the converter cabinet is connected to the contact network.

[0038] When the subway contact network becomes icy and DC de-icing is required, the device closes the 380V switch cabinet K10 and circuit breaker K1, thus activating the DC de-icing mode. When activating the de-icing mode, there are two connection methods for the distal ends of the contact network and the running rail. Method one, as in Example 1, connects the ends of the running rail and the contact network on the same line via a grounding switch, such as... Figure 1 As shown; Method 2, as in Example 2, connects the ends of the left and right contact wires using two grounding switches, as shown. Figure 2 As shown. If according to Figure 1 The wiring diagram shows that the far end of the contact wire and the running rail on the same line is short-circuited via a grounding switch. The positive and negative output terminals of the converter cabinet are connected to the contact wire and the running rail on the same line, respectively, thus forming a closed loop. The converter cabinet outputs DC current to the contact wire and the running rail on the same line. The DC current flowing through the contact wire and the running rail generates Joule heat. When the current reaches the minimum de-icing current, the ice on the contact wire and the running rail on the same line begins to melt. If... Figure 2As shown in the wiring diagram, the far ends of the left and right contact wires are short-circuited by two grounding switches. The positive and negative output terminals of the converter cabinet are connected to the left and right contact wires respectively, thus forming a closed loop. The converter cabinet outputs DC current to the left and right contact wires. The DC current flowing through the left and right contact wires generates Joule heat. When the current reaches the minimum de-icing current, the ice on the left and right contact wires begins to melt.

[0039] like Figure 3 The DC de-icing module of this invention consists of a rectifier cabinet, a converter cabinet, and a switch cabinet, and is installed in a 380V step-down substation. The input terminal of the rectifier cabinet of the DC de-icing device is connected to the low-voltage side of the step-down transformer of the 380V step-down substation. The step-down transformer of the 380V step-down substation steps down the 35kV AC to 380V AC. The 380V AC can be rectified by the rectifier cabinet to output a DC voltage lower than 500V. If the voltage is further transformed by the voltage transformation of the Boost circuit of the converter cabinet, a DC voltage higher than 500V can be output. Through the above two-stage transformation, a controllable DC de-icing current with a large range can be output to achieve effective de-icing under different scenarios (different lengths and different environments).

[0040] When the DC de-icing mode is activated, the diverse de-icing needs of subway lines can be met through two different connection methods at the far ends of the contact wire and the running rail. For example, it can melt the ice on the contact wires of two lines or melt the ice on the contact wire and the running rail of the same line; and it can achieve short-circuiting of the far end of the contact wire through the grounding scissors.

[0041] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A DC de-icing system for a subway overhead contact line, comprising an overhead contact line and running rails, characterized in that, Also includes: The subway rectifier module steps down the AC power from the urban power grid and then outputs stable DC power through efficient rectification and voltage regulation technology to the overhead contact line. The DC de-icing module rectifies the AC power after it is stepped down from the city power grid and outputs controllable DC power. It can also step up the input DC power to form a closed loop with the contact network, generating Joule heat until the ice on the contact network is melted. The aforementioned subway rectifier module and DC de-icing module are both connected to the overhead contact line; The aforementioned overhead contact system and running rails respectively include left and right overhead contact systems and left and right running rails; The DC ice-melting module includes a 380V switch cabinet, a rectifier cabinet, and a converter cabinet, which are connected in sequence. One end of the 380V switchgear is connected to a step-down transformer; the step-down transformer is connected to a medium-voltage ring network. The DC ice-melting module consists of a rectifier circuit and a boost circuit; The rectifier circuit is a three-phase bridge fully controlled rectifier circuit, consisting of six thyristors and an RC network connected in parallel with them; the Boost circuit is a symmetrical three-level Boost circuit, consisting of two inductors, two capacitors and four anti-parallel diodes. One end of the converter cabinet is connected to the left contact wire and the left running rail respectively, and a grounding switch is installed at the far end between the left contact wire and the left running rail; or, one end of the converter cabinet is connected to the left and right contact wires respectively, and a grounding switch is installed at the far end between the left and right contact wires.

2. The DC de-icing system for a subway overhead contact line according to claim 1, characterized in that, The subway rectifier module includes a step-down transformer, a rectifier unit, a positive busbar, a negative busbar, and several switches; One end of the step-down transformer is connected to the medium-voltage ring network, and the other end is connected to one end of the rectifier unit; the other end of the rectifier unit is connected to the positive and negative busbars respectively; the positive busbars are connected to the left and right contact networks respectively, and the negative busbars are connected to the left and right running rails respectively.

3. A DC de-icing method for subway overhead contact lines, applied to the DC de-icing system for subway overhead contact lines as described in claim 1, characterized in that, The steps include: the input terminal of the rectifier cabinet is connected to the low-voltage side of the step-down transformer of the 380V step-down substation, and the step-down transformer of the 380V step-down substation steps down the 35kV AC to 380V AC. The 380V AC power is rectified by the rectifier cabinet to output a DC voltage lower than 500V, and then the voltage is transformed by the Boost circuit of the converter cabinet to output a DC voltage higher than 500V. By short-circuiting the far end of the contact wire and the running rail of the same line through the grounding switch, the positive and negative output terminals of the converter cabinet are connected to the contact wire and the running rail of the same line respectively, thus forming a closed loop. The converter cabinet outputs DC current to the contact wire and the running rail of the same line. The DC current flowing through the contact wire and the running rail generates Joule heat. When the current reaches the minimum de-icing current, the ice on the contact wire and the running rail of the same line begins to melt. Alternatively, the far ends of the left and right contact wires can be short-circuited using two grounding switches. The positive and negative output terminals of the converter cabinet are connected to the left and right contact wires respectively, thus forming a closed loop. The converter cabinet outputs DC current to the left and right contact wires. The DC current flowing through the left and right contact wires generates Joule heat. When the current reaches the minimum de-icing current, the ice on the left and right contact wires begins to melt.

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