Direct-current ice melting system and direct-current ice melting method for subway overhead line system

Abstract

The invention discloses a direct-current ice melting system of a subway overhead line system, which comprises an overhead line system and a running rail, and further comprises a subway rectification module and a direct-current ice melting module, the subway rectification module and the direct current ice melting module are connected with the contact network. The invention further discloses a direct-current ice melting method of the subway overhead line system. The direct-current ice melting device can stably output direct-current ice melting current in a large range to meet the ice melting requirements under different scenes, meanwhile, different wiring modes are adopted according to the ice melting requirements to melt ice on a plurality of contact nets or walking rails at the same time, and the operation time is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of transportation, and in particular to a direct current ice melting system and a direct current ice melting method for a subway overhead contact network. Background Art

[0002] In recent years, with the rapid urbanization of my country and the continuous increase in urban population, urban traffic has become increasingly congested. As a daily means of transportation for citizens, subways offer many advantages and have therefore experienced rapid development. However, this rapid development also presents some challenges. When subway vehicles are powered by overhead catenary systems, rain, snow, and freezing weather particularly impact the catenary. The catenary is a crucial power supply for subway traction. When ice forms on the catenary surface, it severely impacts the normal current flow of the pantograph, reducing the reliability of the subway power supply and threatening driving safety. Small areas of line ice can be removed using manual or mechanical methods (such as hammering with tools) or high-pressure steam. However, for large, long-distance lines, these methods are inefficient and ineffective. Therefore, installing advanced and reliable ice-melting equipment in traction substations to safely and quickly remove ice from large areas of the catenary is of great economic and social significance. Based on current domestic and international technological advances, DC ice-melting technology is the most mature and feasible ice-melting method. Its basic principle is to melt ice using the heat energy generated by the DC current flowing through the conductors.

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

[0004] Existing DC de-icing systems often utilize a rectifier. AC power is supplied by the system, which then rectifies it into DC power. This power is then used to de-ice iced lines. However, the DC power supply has a narrow current (and voltage) range, making it difficult to meet the melting current requirements in diverse scenarios (e.g., varying line lengths or environments). Furthermore, existing DC de-icing systems for subways utilize power switching between two energy-feeding devices to generate DC current to achieve DC de-icing of the overhead contact network. However, this requires two energy-feeding devices and a large number of switching devices. Summary of the Invention

[0005] The purpose of the present invention is to provide a DC ice-melting system for subway contact networks. The device can stably output a wide range of DC ice-melting currents to meet the ice-melting needs in different scenarios. At the same time, different wiring methods are used according to the ice-melting needs to simultaneously melt ice on multiple contact networks or running rails, saving operation time.

[0006] A DC ice melting system for a subway catenary includes a catenary and running rails, and further includes: The subway rectifier module steps down the voltage of the incoming AC power from the city grid and then outputs stable DC power through high-efficiency rectification and voltage regulation technology; The DC ice melting module converts the AC power from the city power grid into controllable DC power through rectification and can also step up the input DC power to form a closed loop with the contact network, generating Joule heat until the ice covering the contact network is melted. The subway rectifier module and the DC ice melting module are both connected to the contact network.

[0007] Furthermore, the contact network and running rails include left and right contact networks and left and right running rails respectively.

[0008] Furthermore, 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 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.

[0009] Furthermore, the DC ice melting module is composed of a rectifier circuit and a Boost circuit; The rectifier circuit adopts a three-phase bridge fully controlled rectifier circuit, which is composed of six thyristors and an RC network connected in parallel with them; the boost circuit adopts a symmetrical three-level boost circuit, which is composed of two inductors, two capacitors and four anti-parallel diode switching tubes.

[0010] Furthermore, one end of the converter cabinet is connected to the left-line contact network and the left-line running rail respectively; a ground switch connection is set at the far end between the left-line contact network and the left-line running rail.

[0011] Furthermore, one end of the converter cabinet is connected to the left and right contact networks respectively; a ground switch is provided at the far end between the left and right contact networks.

[0012] Furthermore, the subway rectifier module includes a step-down transformer, a rectifier unit, a positive bus, a negative bus 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 busbar is connected to the left and right line contact networks respectively, and the negative busbar is connected to the left and right line running rails respectively.

[0013] A DC de-icing method for a subway overhead contact network comprises the following steps: connecting an input end of a rectifier cabinet to a low-voltage side of a step-down transformer of a 380V step-down substation, wherein the step-down transformer of the 380V step-down substation steps down 35kV AC power to 380V AC power; The 380V AC power is rectified by the rectifier cabinet to output a DC voltage lower than 500V, and then converted by the voltage of the boost circuit of the converter cabinet to output a DC voltage higher than 500V. The contact network and the far end of the running rail on the same line are short-circuited through the grounding knife. The positive and negative output terminals of the converter cabinet are connected to the contact network and running rail on the same line respectively, thus forming a closed loop. The converter cabinet outputs DC current to the contact network and running rail on the same line. The DC current flows through the contact network and running rail, generating Joule heat. When the current reaches the minimum ice-melting current, the ice on the contact network and running rail on the same line begins to melt. Alternatively, two ground switches are used to short-circuit the far ends of the left and right contact lines. The positive and negative output terminals of the converter cabinet are connected to the left and right contact lines, respectively, forming a closed loop. The converter cabinet outputs a DC current to the left and right contact lines. The DC current flows through the left and right contact lines, generating Joule heating. When the current reaches the minimum ice-melting current, the ice on the left and right contact lines begins to melt. The DC ice-melting module of the present invention comprises a rectifier cabinet, a converter cabinet, and a switch cabinet. The rectifier cabinet's three-phase bridge-type fully-controlled rectifier circuit and the boost circuit within the converter cabinet achieve continuous DC voltage regulation over a wide range, thereby controlling the ice-melting current. This allows for effective ice melting in different scenarios (different lengths and environments). The symmetrical three-level boost circuit used within the rectifier cabinet effectively reduces voltage stress on the switching transistors by increasing the number of levels compared to conventional two-level boost circuits, lowering switching losses and improving system efficiency and stability.

[0014] In the DC de-icing mode, the present invention utilizes two different connection methods at the far end of the catenary or running rails, enabling simultaneous de-icing of two catenary lines, or of the catenary and running rails on the same line, to meet diverse de-icing requirements on subway lines. Using a ground switch instead of a switch for remote connection between the catenary and running rails offers cost savings and convenient connection.

[0015] The power input of the present invention is drawn from the 380V AC power in the 380V step-down substation, which saves the manufacturing cost of the switch cabinet compared to the introduction from the positive and negative busbars 1500V. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The system topology of the present invention Figure 1 ; Figure 2 The system topology of the present invention Figure 2 ; Figure 3 This is the electrical topology diagram of the DC ice melting module of the present invention. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the existing known technologies. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Example 1

[0018] like Figure 1 A DC ice melting system for a subway catenary is shown, comprising a catenary and running rails, and further comprising: The subway rectifier module steps down the voltage of the incoming AC power from the city grid, and then outputs stable DC power through high-efficiency rectification and voltage regulation technology to meet the power supply needs of high-power, long-distance subway lines. The DC de-icing module outputs controllable DC power through rectification after the AC power is stepped down from the city grid, and can also step up the input DC power to form a closed loop with the contact network, generating Joule heat until the ice covering the contact network is melted. The subway rectifier module and the DC de-icing module are both connected to the contact network.

[0019] The contact network and running rails of the present invention respectively include left and right contact networks and left and right running rails.

[0020] The DC ice melting 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 a contact network; the step-down transformer is connected to a medium voltage ring network.

[0021] like Figure 3 As shown, the DC ice-melting module of the present invention consists of a rectifier circuit and a boost circuit. The rectifier circuit uses a three-phase bridge-type fully controlled rectifier circuit, consisting of six thyristors (VT1, VT2, VT3, VT4, VT5, and VT6) and an RC network connected in parallel with them. The boost circuit uses a symmetrical three-level boost circuit, consisting of two inductors (L1 and L2), two capacitors (C1 and C2), and four anti-parallel diodes (D1, D2, D3, and D4).

[0022] 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 provided with a DC output side.

[0023] 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 busbar is connected to the left and right line contact networks respectively, and the negative busbar is connected to the left and right line running rails respectively. Example 2

[0024] 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 networks respectively; a grounding switch is arranged at the far end between the left and right contact networks.

[0025] The subway system draws medium-voltage 35kV AC power from the city grid. After being stepped down by a step-down transformer in the traction substation, it is fed into a rectifier unit, which, through efficient rectification and voltage regulation, outputs stable 1500V DC power, meeting 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, with the line switched on and off by switches K2 and K3. The negative output power of the rectifier unit is connected to the negative busbar, which has a voltage level of 1500V DC. The positive busbar is connected to and disconnected from the subway overhead line by switches K4, K5, K6, K7, K8, and K9, while the negative busbar is connected to the running rails. The DC de-icing system consists of a rectifier cabinet, a converter cabinet, and a 380V switchgear. It is installed in a 380V step-down substation. The DC de-icing system's rectifier cabinet input is connected to the low-voltage side of the step-down transformer in the 380V step-down substation, with the 380V switchgear controlling the line switching. The step-down transformer of the 380V step-down substation steps down the 35kV AC to 380V AC. The 380V AC is rectified by the rectifier cabinet to output controllable DC power. The converter cabinet can step up the input DC power, and the output end of the converter cabinet is connected to the contact network.

[0026] When the subway catenary is covered with ice and DC de-icing is required, the device closes the 380V switch cabinet K10 and the circuit breaker K1, and the DC de-icing mode is turned on. When the de-icing mode is turned on, there are two ways to connect the catenary and the far end of the running rail. The first way is the same as in Example 1, which is to connect the running rail and the end of the catenary on the same line through the ground switch, such as Figure 1 As shown; the second method is as in Example 2, which is to connect the ends of the left-line contact network and the right-line contact network by two ground cutters, such as Figure 2 If you press Figure 1 As shown in the wiring diagram, the contact network and the far end of the running rail of the same line are short-circuited through the grounding knife. The positive and negative output terminals of the converter cabinet are connected to the contact network and running rail of the same line respectively, thus forming a closed loop. The converter cabinet outputs DC current to the contact network and running rail of the same line. The DC current flows through the contact network and running rail to generate Joule heat. When the current reaches the minimum ice melting current, the ice on the contact network and running rail of the same line begins to melt. Figure 2 As shown in the wiring diagram, the far ends of the left and right contact networks are short-circuited through two ground switches. The positive and negative output terminals of the converter cabinet are connected to the left and right contact networks respectively, thus forming a closed loop. The converter cabinet outputs DC current to the left and right contact networks. The DC current flowing through the left and right contact networks generates Joule heat. When the current reaches the minimum ice-melting current, the ice on the left and right contact networks begins to melt.

[0027] like Figure 3 The DC ice-melting module of the present invention consists of a rectifier cabinet, a converter cabinet, a switch cabinet, etc., and is installed in a 380V step-down substation. The rectifier cabinet input end of the DC ice-melting 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 35kV AC power to 380V AC power. The 380V AC power is rectified by the rectifier cabinet and can output a DC voltage below 500V. If it undergoes voltage conversion through the converter cabinet boost circuit, it can output a DC voltage above 500V. Through these two-stage conversion, a wide range of controllable DC ice-melting current can be output to achieve effective ice melting in different scenarios (different lengths and different environments).

[0028] When the DC de-icing mode is activated, two different connection methods are used at the far end of the catenary and the running rails to meet the diverse de-icing needs of subway lines. For example, de-icing can be achieved on the catenary of two lines, or on the catenary and running rails on the same line. The far end of the catenary can be short-circuited using a ground cutter.

[0029] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A DC ice melting system for a subway contact network, comprising a contact network and running rails, characterized in that: Also includes: The subway rectifier module steps down the voltage of the incoming AC power from the city grid, and then outputs stable DC power to the overhead line through efficient rectification and voltage regulation technology. The DC ice melting module converts the AC power from the city power grid into controllable DC power through rectification and can also step up the input DC power to form a closed loop with the contact network, generating Joule heat until the ice covering the contact network is melted. The subway rectifier module and the DC ice melting module are both connected to the contact network.

2. The DC ice melting system for subway overhead wire according to claim 1, characterized in that: The contact network and running rails respectively include left and right contact networks and left and right running rails.

3. The DC ice melting system for subway overhead wire according to claim 2, characterized in that: 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 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.

4. The DC ice melting system for subway overhead wire according to claim 2, characterized in that: The DC ice melting module is composed of a rectifier circuit and a Boost circuit; The rectifier circuit adopts a three-phase bridge fully controlled rectifier circuit, which is composed of six thyristors and an RC network connected in parallel with them; the boost circuit adopts a symmetrical three-level boost circuit, which is composed of two inductors, two capacitors and four anti-parallel diode switching tubes.

5. The DC ice melting system for subway overhead wire according to claim 3, characterized in that: One end of the converter cabinet is connected to the left-line contact network and the left-line running rail respectively; a ground switch connection is arranged between the left-line contact network and the left-line running rail at the far end.

6. The DC ice melting system for subway overhead wire according to claim 3, characterized in that: One end of the converter cabinet is connected to the left and right contact networks respectively; a ground switch is provided at the far end between the left and right contact networks.

7. The DC ice melting system for subway overhead wire according to claim 1, characterized in that: The subway rectifier module includes a step-down transformer, a rectifier unit, a positive bus, a negative bus 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 busbar is connected to the left and right line contact networks respectively, and the negative busbar is connected to the left and right line running rails respectively.

8. A DC de-icing method for subway contact network, characterized in that: The method comprises the following steps: the input end 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 power to 380V AC power; The 380V AC power is rectified by the rectifier cabinet to output a DC voltage lower than 500V, and then converted by the voltage of the boost circuit of the converter cabinet to output a DC voltage higher than 500V. The contact network and the far end of the running rail on the same line are short-circuited through the grounding knife. The positive and negative output terminals of the converter cabinet are connected to the contact network and running rail on the same line respectively, thus forming a closed loop. The converter cabinet outputs DC current to the contact network and running rail on the same line. The DC current flows through the contact network and running rail, generating Joule heat. When the current reaches the minimum ice-melting current, the ice on the contact network and running rail on the same line begins to melt. Or the far ends of the left-line contact network and the right-line contact network are short-circuited through two ground switches, and the positive and negative output terminals of the converter cabinet are connected to the left-line contact network and the right-line contact network respectively, thus forming a closed loop. The converter cabinet outputs DC current to the left-line contact network and the right-line contact network. The DC current flows through the left-line contact network and the right-line contact network to generate Joule heat. When the current reaches the minimum ice-melting current, the ice on the left-line contact network and the right-line contact network begins to melt.

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