CN201077368Y - Electrified railroad homophase traction power supply system - Google Patents

Abstract

The utility model relates to an electrical railway cophase traction power supply system, wherein the traction transformer is an YNd11-connected three-phase transformer (T1). The YN-connected three primary sides, namely A, B and C phases of the transformer (T1) are connected with the common grid system. Three power flow controllers (IC) are arranged between the three d-connected terminals (a, b, c) at low-pressure side of the transformer, and terminal a and terminal b are connected with the electrified railway contacting network (TR). The invention has the advantages that: cophase power supply for the complete railway tracks without split phase can be realized; the voltage of the power supply is stable which ensures that locomotives run with high speed and heavy load; meanwhile, the negative sequence influence, no idle work influence and harmonic wave influence of railway traction load on the common grid system can be eliminated; the invention also has the advantages of low cost and convenient implementation.

Description

A co-phase traction power supply system for electrified railway

technical field

The utility model relates to an electrified railway traction in-phase power supply system.

Background technique

The single-phase system has the advantages of simple structure, low construction cost, convenient operation and maintenance, etc., which determines that single-phase power frequency AC power is generally used to power railway locomotives in electrified railways. The power system hopes that all loads will use the three-phase symmetrical fundamental current from the power grid to make full use of the capacity of equipment and lines and reduce the harm of reactive current and harmonic current to the system. In order to meet this requirement, the electrified railway adopts the scheme of phase sequence rotation and phase-by-phase power supply. Every 20-25km along the railway line is used as a power supply section, and each section is powered by different phases in the power grid in turn. A phase separation section of about 30m is set, and phase separation is carried out by a phase separation device. When the loads of locomotives running on the sections powered by each phase are the same, the power system can be balanced in a large range with three-phase loads.

However, since the traction load of each section cannot be the same at any time, the phase-splitting and segmenting scheme only alleviates the impact of three-phase imbalance to a certain extent, and does not fundamentally solve the impact of single-phase power consumption of railway loads on the entire public grid. Influence. Due to problems affecting power quality, electrified railways are forced to modify design schemes and increase investment, and sometimes they are passive.

At the same time, due to the existence of the electric phase separation device, when the locomotive runs to the end of a power supply section, it must go through a series of complex operations such as degrading and power off, and then slide to the next section and then resume normal operation one by one. Increased the complexity of locomotive operation, and seriously restricted the improvement of locomotive running speed and the play of traction force simultaneously.

For the current state of our country, there is an urgent need to develop high-speed and heavy-haul railways. The existing segmented and phase-separated locomotive traction power supply system is even more unsuitable for high-speed, heavy-duty locomotive traction, mainly manifested in:

High-speed and heavy-duty transportation requires the pantograph of the locomotive to receive current smoothly and continuously, but the existence of the phase separation link makes the current on the pantograph intermittent, which greatly affects the running speed of the locomotive. At the same time, the phase separation link is also one of the weakest links in the whole system. Although there is an automatic over-phase separation device, there are serious problems in its accuracy and reliability due to its high voltage and frequent switching operations, and it cannot completely solve the adverse effects of electric separation on locomotive operation.

High-speed and heavy-duty transportation all require large-capacity power supply. In order to meet the national standard power system restrictions on the power quality of electrified railways, with negative sequence as the most prominent, the reactive power compensation technology used in the original phase-separated power supply method has been unable to adapt. If the adjustable symmetrical compensation technology is adopted in the traction substation, even if the AC-DC-AC power supply (regardless of its reactive power and harmonics) is used on the locomotive, the negative sequence is more prominent because of the larger capacity, technically and economically. It is difficult to achieve the ideal state.

The high-speed railway to be built in my country may be a mixed operation mode of high and medium speeds. If AC-DC-AC power supply locomotives and AC-DC power supply locomotives are mixed, except for negative sequence, reactive power and harmonics still exist, and electric energy The quality cannot be improved, restricting the development of both railways and electric power.

Utility model content

The purpose of this utility model is to provide a power supply system for electrified railway in-phase traction, the system can realize the same-phase power supply for the whole railway line without phase separation, and the power supply voltage is stable, ensuring the high-speed and stable operation of locomotives, especially suitable for high-speed and heavy-duty railways Use; the system can eliminate the negative sequence, reactive power and harmonic effects of the railway traction load on the electric energy of the public grid at the same time, with low cost and convenient implementation.

The utility model solves its technical problems, and the adopted technical scheme is:

A same-phase traction power supply system for electrified railways. Its structural features are: the traction transformer is a three-phase transformer with YNd11 connection, the three primary sides of the transformer with YN connection are connected to the high-voltage public power grid, and the low-voltage of the transformer is d-connected. The three terminals on the side are connected to the three current output terminals of the power flow controller, and two of the terminals are connected to the catenary of the electrified railway at the same time.

和铁道接触网上流过的电流

进行检测、运算，确定潮流控制器的三个电流输出端的输出电流

大小，从而在保证铁道接触网单向供电的同时，也保证牵引变压器次边三相电流

对称且没有谐波。The working principle of the utility model is: after the three-phase high-voltage power on the public high-voltage power grid is transformed by the traction transformer connected by YNd11, the two terminals on the low-voltage side are connected to the railway catenary to supply power to the electric locomotive, realizing Single phase power supply. At the same time, since the three terminals on the low-voltage side of the traction transformer are connected to the current output terminal of the power flow controller, the three-phase current output by the secondary side of the traction transformer is controlled by the current detection of the power flow controller and the pulse width modulation controller.

and the current flowing on the railway catenary

Perform detection and calculation to determine the output current of the three current output terminals of the power flow controller

size, so as to ensure the one-way power supply of the railway catenary, and at the same time ensure the three-phase current of the secondary side of the traction transformer

Symmetrical and without harmonics.

Compared with the prior art, the beneficial effects of the utility model are:

1. All the substations using the utility model on the railway line output the same single-phase voltage to supply power to the railway locomotives, so that the entire railway line does not need to use phase sequence rotation, phase-separated and segmented power supply, and fundamentally avoids power division. Phase link; not only makes the locomotive run reliably, but also enables the locomotive to run at high speed and stably, especially suitable for heavy-duty and high-speed trains.

对称且没有谐波，从而实现铁路牵引负荷从公用电网上三相对称取电，避免了原分相取电产生负序电流，严重影响电网电能质量的问题；消除铁路牵引负荷的大量无功成分与谐波对公用电网电能质量的影响，使铁路和电力系统的经济与安全可靠运行得到保证。2. The current of the secondary side of the traction transformer is compensated by the power flow controller to ensure the three-phase current of the secondary side of the index transformer

Symmetrical and without harmonics, so that the railway traction load can obtain power from the public power grid in three phases, avoiding the negative sequence current generated by the original phase-separated power supply, which seriously affects the power quality of the power grid; eliminating a large number of reactive components of the railway traction load The influence of harmonics and harmonics on the power quality of public grids ensures the economical, safe and reliable operation of railways and power systems.

3. The traction substations of the existing railway lines in my country adopt a large number of YNd11 star-delta connection transformers, which can be transformed to form the same-phase power supply system of the utility model YNd11 star-delta connection transformers. Therefore, the system of the utility model has the widest adaptability to my country's railway power system, is convenient to implement, and has low cost for the transformation of existing railways.

The composition of the above power flow controller is as follows: the primary side of the three-phase step-down transformer with YY connection is connected to the low-voltage side terminal of the three-phase transformer d-connection, two of the three phases on the secondary side of the step-down transformer are connected to the corresponding power electronic switch connected to the current output. The power electronic switch includes four high-power transistors, and the control pole of each high-power transistor is connected with the current detection and pulse width modulation controller; four high-power transistors are connected in series through the emitter and the collector to form two groups of high-power Transistor group, the collectors of two high-power transistor groups are connected in parallel, and the emitters are also connected in parallel; DC energy storage capacitors are connected in parallel between the collectors and emitters of the two high-power transistor groups; the emitters in the two high-power transistor groups The series connection point with the collector constitutes the current output terminal of the power electronic switch.

使牵引变压器的三个次边输出端的电流

对称且没有谐波，满足公用电网的对负序、无功和谐波的要求。这种结构的潮流控制器，控制有效，结构简单，成本低。In this way, under the control of the current detection and pulse width modulation controller, the switching states of the three power electronic switches are controlled in turn, and after being transformed by the step-down transformer, the compensation current is provided to the three-phase secondary side of the traction transformer

so that the currents at the output terminals of the three secondary sides of the traction transformer

Symmetrical and without harmonics, it meets the requirements of public power grids for negative sequence, reactive power and harmonics. The power flow controller with this structure has effective control, simple structure and low cost.

A DC energy storage capacitor is connected in parallel between the non-series collectors and the non-series emitters of the above two high-power transistor groups. The parallel energy storage capacitor can not only effectively compensate the inductive reactive power at the secondary port of the traction transformer, improve the power factor, stabilize the voltage of the primary side of the traction transformer, and filter out high-order harmonics in the load current.

The above-mentioned high-power transistors are integrated gate-commutated thyristors or insulated gate bipolar transistors. These two tubes are mature and reliable high-power power electronic switching tubes.

Below in conjunction with accompanying drawing and specific embodiment, the utility model is further described.

Description of drawings

Fig. 1 is a schematic diagram of the circuit principle of the embodiment of the utility model.

Fig. 2 is a schematic diagram of the circuit principle of a power electronic switch D1 in the power flow controller of the embodiment of the present utility model.

Detailed ways

Example

Figure 1 shows that a specific embodiment of the present invention is: in a same-phase traction power supply system for electrified railways, the traction transformer is a three-phase transformer T1 with YNd11 connection, and the three primary sides of the YN connection of the transformer T1 The three phases A, B, and C are connected to the high-voltage public power grid. The three terminals a, b, and c on the low-voltage side of the transformer d connection are connected to the three current output terminals of the power flow controller IC, and two of the terminals a, b At the same time connect the railway catenary TR. Obviously, the output terminals a, b and c of the three low-voltage sides of the utility model are completely the same, as shown in Figure 1, two terminals a and b can be selected to connect with the railway catenary TR, or b and c Or the two terminals a and c are connected to the electrified railway catenary TR.

The composition of the power flow controller IC in this example is: the primary side of the three-phase step-down transformer T2 with YY connection is connected to the low-voltage side terminals a, b, and c of the three-phase transformer d-connection, and the three-phase terminals on the secondary side of the step-down transformer T2 The two phases a', b' or b', c' or c', a' are connected to the current output terminals x, y or y, z or z, x of the corresponding power electronic switches D1, D2, D3.

Figure 2 shows that the power electronic switch D1 includes four high-power transistors BG, and the control pole of each high-power transistor BG is connected to the pulse width modulation controller CP; the four high-power transistors BG pass through the emitter and the collector Two sets of high-power transistor groups are formed in series, the non-series collectors of the two high-power transistor groups are connected in parallel, and the non-series emitters are also connected in parallel; the series points of the emitter and the collector in the two high-power transistor groups constitute power electronics Switch D1 current output terminals x, y. The composition of the power electronic switches D2 and D3 is exactly the same as that of D1, except that the current output terminals of the power electronic switches D2 and D3 are respectively marked as y, z and z, x in Fig. 1 .

A direct current energy storage capacitor C is connected in parallel between the non-series collectors and the non-series emitters of the two high-power transistor groups.

Figure 2 shows that the high-power transistor BG used in this example is an integrated gate commutated thyristor (IGCT); in actual implementation, an insulated gate bipolar transistor (IGBT) can also be used.

Claims (4)

1. A same-phase traction power supply system for electrified railway, characterized in that: The traction transformer is a three-phase transformer (T1) with YNd11 connection. The three primary sides (A, B, C) of the YN connection of the transformer (T1) are three-phase connected to the high-voltage public grid, and the low-voltage side of the transformer is d-connected. The three terminals (a, b, c) are connected to the three current output terminals of the power flow controller (IC), and two of the terminals (a, b) are simultaneously connected to the electrified railway catenary (TR). 2. A kind of electrified railway co-phase traction power supply system as claimed in claim 1, is characterized in that: the composition of described power flow controller (IC) is: The primary side of the YY-connected three-phase step-down transformer (T2) is connected to the low-voltage side terminals (a, b, c) of the three-phase transformer d-connection, and two phases (a′) of the three-phase secondary side of the step-down transformer (T2) , b' or b', c' or c', a') are connected to the current output terminals (x, y or y, z or z, x) of the corresponding power electronic switches (D1, D2, D3); The power electronic switch (D1, D2, D3) includes four high-power transistors (BG), and the control pole of each high-power transistor (BG) is connected with the current detection and pulse width modulation controller (CP); the four high-power Two transistors (BG) are connected in series through the emitter and collector to form two sets of high-power transistor groups. The unseries collectors of the two high-power transistor groups are connected in parallel, and the unseries emitters are also connected in parallel; the two sets of high-power transistor groups The series connection point of the emitter and the collector constitutes the current output terminal (x, y or y, z or z, x) of the power electronic switch (D1, D2, D3). 3. A kind of electrified railway same-phase traction power supply system as claimed in claim 2, is characterized in that: parallel DC energy storage capacitor ( C). 4. A co-phase traction power supply system for electrified railways according to claim 2, characterized in that: said high-power transistor (BG) is an integrated gate commutated thyristor or an insulated gate bipolar transistor.

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