CN106877314A - A traction power supply system with multiple power electronic transformers with common DC bus on the low-voltage side - Google Patents

Abstract

The invention discloses a kind of many electric power electric transformer tractive power supply systems of low-pressure side common DC bus, including the multiple electric power electric transformers being connected in parallel on high voltage AC bus, the low-voltage direct side of the multiple electric power electric transformer output is in parallel to form low-voltage direct bus, is connected to the traction invertor of motor on the low-voltage direct bus.Multiple electric power electric transformers are connected in parallel to low-voltage direct bus in the present invention, and when the pantograph of certain electric power electric transformer is offline, other electric power electric transformers still can be motor energy supply.

Description

A traction power supply system with multiple power electronic transformers with common DC bus on the low-voltage side

technical field

The invention relates to the technical field of power supply, in particular to a multi-power electronic transformer traction power supply system with a low-voltage side common DC bus.

Background technique

At present, China is the country with the largest scale and fastest development of high-speed railway in the world. According to the statistics of the International Union of Railways (UIC), as of December 2016, CRRC products have been exported to 102 countries and regions on six continents, covering 83% of the countries and regions with railways in the world. The operating mileage of China's high-speed rail has reached 21,000 km, accounting for more than 60% of the total mileage of high-speed rail in the world. The latest "Medium and Long-Term Railway Network Planning" proposes that by 2020, a number of major landmark projects will be completed and put into operation, and the scale of the railway network will reach 150,000 kilometers, including 30,000 kilometers of high-speed railways, covering more than 80% of large cities. Focusing on the implementation of the national "One Belt, One Road" and "Going Global" strategies, China is increasing its efforts in overseas railway projects and promoting the construction of railway interconnection with neighboring countries, with great potential for development.

As shown in Figure 1, the traction transformer is the power source and an important part of the electric locomotive transmission system. When supplying power, a pantograph 3 and a traction transformer 6 are connected between the AC traction network 1 and the rail 2. The traction transformer 6 passes through the main The converter 4 is connected to the traction motor 5 .

The traction transformer 6 has a large volume and weight, occupies a large passenger space, and consumes a large amount of additional energy. The new generation of power electronic traction transformer PETT, as shown in Figure 2, the high-voltage AC side 7 is connected to the AC traction network, and the output side of the new generation of power electronic traction transformer is the low-voltage DC side 8. Due to the use of medium and high frequency transformers, not only has The electrical isolation, bidirectional power transmission and voltage conversion functions of the traditional industrial frequency traction transformer, and has many advantages such as reducing the weight and volume by more than 50%, high power factor, low harmonic content, low pollution, etc. of great importance.

World-renowned locomotive manufacturers have successively made design plans and test prototypes for PETT, but there are few reports on the research on traction power supply systems with multiple power electronic transformers. The research and development of traction power supply systems with multiple power electronic transformers has become a new generation of international lightweight and high-performance Strategic heights for electric locomotives.

Contents of the invention

In order to solve the deficiencies of the prior art, the present invention provides a traction power supply system with multiple power electronic transformers with a common DC bus on the low-voltage side. In the present invention, multiple power electronic transformers are connected to the low-voltage DC bus in parallel. When a certain power electronic transformer When the pantograph is offline, other power electronic transformers can still supply energy to the motor.

A multi-power electronic transformer traction power supply system with a common DC bus on the low-voltage side, including multiple power electronic transformers connected in parallel to the high-voltage AC bus, and the low-voltage DC sides output by the multiple power electronic transformers are connected in parallel to form a low-voltage DC bus. A traction inverter connected to the low-voltage DC bus to supply power to the electric motor.

Further, the low-voltage DC bus is connected to a hybrid energy storage system, and the low-voltage DC bus is connected to a hybrid energy storage device. On the one hand, it can supply energy in a short time when the pantograph-catenary is offline, and on the other hand, it can absorb the energy generated by regenerative braking. energy, and reduce the harmonics injected by the power electronic transformer into the traction network.

Further, the power electronic transformers are all connected behind the pantograph connected to the high-voltage AC busbar.

Further, there are multiple traction inverters, all of which are connected in parallel to the low-voltage direct current bus, and each traction inverter supplies power to its corresponding motor.

Further, the hybrid energy storage system is composed of batteries and supercapacitors.

Further, a resistor for realizing soft start of the power electronic transformer is connected in parallel to the switch on the pantograph.

Further, a filter is connected in series between the pantograph and the power electronic transformer. When the energy of regenerative braking is large, the power electronic transformer transmits energy to the traction network, and the filter is used to filter the feed current at this time.

Further, the front-stage rectification link of the power electronic transformer adopts a cascaded H-bridge structure, the DC side of each H-bridge is connected to a DC-DC converter, multiple DC-DC converters are connected in parallel, and multiple DC-DC converters are connected in parallel. The positive poles of the converter output are connected respectively, the negative poles of the output are connected respectively, and the low-voltage direct current sides output by multiple power electronic transformers are connected in parallel to form a low-voltage direct current bus.

Further, the rectification link of the power electronic traction transformer adopts SPWM modulation, the DC side of the H-bridge is connected in parallel with a capacitor, and a resonant converter is connected behind it, and the resonant converter consists of two H-bridges, a resonant capacitor, a resonant inductor, and a high-frequency The resonant converter adopts phase-shift control, and the output terminals of the resonant converter are connected in parallel to form the low-voltage DC output terminal of the power electronic transformer.

Further, the filter is an L filter circuit.

Further, the DC-DC converter is a resonant converter.

Compared with prior art, the beneficial effect of the present invention is:

(1) A resistor is connected in parallel to the switch on the pantograph, which can realize the soft start of the power electronic transformer of the locomotive and reduce the impact on the power electronic transformer when starting.

(2) The high-frequency resonant converter is adopted in the DC-DC link of the power electronic transformer in the present invention, which can not only reduce the volume of the transformer, but also reduce the switching loss.

(3) In the present invention, multiple power electronic transformers are connected in parallel to the low-voltage DC bus. When the pantograph of a certain power electronic transformer is offline, other power electronic transformers can still supply energy to the motor.

(4) The hybrid energy storage device is connected to the low-voltage DC bus, which can supply energy in a short time when the pantograph-catenary is offline.

(5) A hybrid energy storage device is connected to the low-voltage DC bus, which can absorb the energy generated by regenerative braking and reduce the harmonics injected by the power electronic transformer into the traction network.

Description of drawings

The accompanying drawings constituting a part of the present application are used to provide further understanding of the present application, and the schematic embodiments and descriptions of the present application are used to explain the present application, and do not constitute improper limitations to the present application.

Figure 1 is a structural diagram of a traditional traction power supply system;

Figure 2 is a structural diagram of a power electronic transformer;

Fig. 3 is a structural diagram of a multi-power electronic transformer traction power supply system;

Among them, 1. AC traction network, 2. Rail, 3. Pantograph, 4. Main converter, 5. Traction motor, 6. Traction transformer, 7. High voltage AC side, 8. Low voltage DC side, 9. Low voltage DC bus.

detailed description

It should be pointed out that the following detailed description is exemplary and intended to provide further explanation to the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terminology used here is only for describing specific implementations, and is not intended to limit the exemplary implementations according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural, and it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, they mean There are features, steps, operations, means, components and/or combinations thereof.

As introduced in the background technology, the prior art has disadvantages such as a large impact of pantograph-catenary off-line on the traction system, and large harmonics injected into the power grid during regenerative braking of the locomotive. In order to solve the above technical problems, this application proposes a low-voltage side Multi-power electronic transformer traction power supply system with common DC bus.

In a typical implementation of the present application, a multi-power electronic transformer traction power supply system with a common DC bus on the low-voltage side is provided, as shown in Figure 3, where the dotted line box represents a row of electric locomotives, and the PETT structure is shown in Figure 2 . In the present invention, a plurality of PETTs are connected behind the pantograph to convert high-voltage AC power into low-voltage DC power, and then the low-voltage DC bus 9 supplies power to each motor, and multiple traction inverters are connected in parallel to the low-voltage DC bus.

In the present invention, a hybrid energy storage system composed of a battery and a supercapacitor is connected to a low-voltage DC bus, and the hybrid energy storage system composed of a battery and a supercapacitor is connected to a low-voltage DC bus. A small amount of energy is fed back into the traction network, and this feedback current contains large harmonic components. The connected hybrid energy storage system can absorb this part of the feedback energy and reduce the harmonic content in the traction network; 2) When the pantograph is caused by When the vibration, excessive and other reasons are offline, the hybrid energy storage device can provide short-term functions for the electric locomotive, and reduce the adverse impact of the pantograph-catenary offline on the power electronic transformer.

In addition, this application connects a resistor in parallel at the switch on the pantograph, which can realize the soft start of the power electronic transformer of the locomotive; a filter is connected in series between the pantograph and the power electronic transformer, and when the energy of regenerative braking is large, the power electronic The transformer transmits energy to the traction network, and the filter is used to filter the feed current at this time. Preferably, the filter is an L filter circuit.

As shown in Figure 2, the front-stage rectification link of the power electronic transformer adopts a cascaded H-bridge structure. The DC side of each H-bridge is connected to a DC-DC converter, and multiple DC-DC converters are connected in parallel. The positive poles of the DC converter output are connected respectively, and the negative poles of the output are connected respectively; the low-voltage DC sides output by multiple power electronic transformers are connected in parallel to form a low-voltage DC bus 9; the traction inverter is connected to the low-voltage DC bus 9 to supply power to the motor; the low-voltage The hybrid energy storage system is connected to the DC bus 9 . The DC-DC converter is a resonant converter.

Working principle: This application connects multiple PETTs behind the pantograph to convert high-voltage AC into low-voltage DC, and then supplies power to each motor from the low-voltage DC bus. Multiple traction inverters are connected in parallel on the low-voltage DC bus. A hybrid energy storage system consisting of a battery and a supercapacitor is connected to it. Among them: the power electronic traction transformer is shown in Figure 2, and its rectification link is composed of cascaded H-bridges, using SPWM modulation; the DC side of the H-bridges is connected in parallel with a capacitor, followed by a resonant converter, and the resonant converter consists of two H Bridge, resonant capacitor, resonant inductor, and a high-frequency transformer. The resonant converter adopts phase-shift control; the output terminals of the resonant converter are connected in parallel to form the low-voltage DC output terminal of the power electronic transformer; the low-voltage DC output terminals of multiple power electronic transformers are all Connect to a bus to form a low-voltage DC bus.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, there may be various modifications and changes in the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

Claims (10)

1. many electric power electric transformer tractive power supply systems of a kind of low-pressure side common DC bus, it is characterized in that, including it is in parallel even It is connected on the multiple electric power electric transformers on high voltage AC bus, the low-voltage direct side of the multiple electric power electric transformer output Parallel connection forms low-voltage direct bus, is connected to the traction invertor of motor on the low-voltage direct bus.

2. many electric power electric transformer tractive power supply systems of a kind of low-pressure side common DC bus as claimed in claim 1, its It is characterized in connect mixed energy storage system on the low-voltage direct bus.

3. many electric power electric transformer tractive power supply systems of a kind of low-pressure side common DC bus as claimed in claim 1, its It is characterized in, after electric power electric transformer is both connected to the pantograph being connected with high voltage AC bus.

4. many electric power electric transformer tractive power supply systems of a kind of low-pressure side common DC bus as claimed in claim 1, its It is characterized in that the quantity of the traction invertor is multiple, and multiple traction invertors are connected in parallel on low-voltage direct bus, and each leads Draw inverter to respective motor.

5. many electric power electric transformer tractive power supply systems of a kind of low-pressure side common DC bus as claimed in claim 2, its It is characterized in that the mixed energy storage system is made up of battery with super capacitor.

6. many electric power electric transformer tractive power supply systems of a kind of low-pressure side common DC bus as claimed in claim 3, its It is characterized in, the one in parallel resistance of the soft start for being used to realize electric power electric transformer at switch in the pantograph.

7. many electric power electric transformer tractive power supply systems of a kind of low-pressure side common DC bus as described in claim 3 or 6, It is characterized in that, series filter between the pantograph and electric power electric transformer, when the energy of regenerative braking is larger, electric power Electronic transformer is used for feeding current filtering now to Traction networks transmission energy, wave filter.

8. many electric power electric transformer tractive power supply systems of a kind of low-pressure side common DC bus as claimed in claim 1, its It is characterized in that the prime rectification link of electric power electric transformer uses the DC side connection DC-DC of Cascade H bridge construction, each H bridge to become Parallel operation, in parallel between multiple DC-DC converters, the positive pole circuit of multiple DC-DC converter outputs is respectively connected with, the negative pole of output Circuit is respectively connected with, and the low-voltage direct side of multiple electric power electric transformer outputs is in parallel to form low-voltage direct bus, the DC-DC Converter is controlled resonant converter.

9. many electric power electric transformer tractive power supply systems of a kind of low-pressure side common DC bus as claimed in claim 1, its It is characterized in that power electronics tractive transformer rectification link is modulated using SPWM, the equal shunt capacitance of DC side of H bridges connects behind Controlled resonant converter, controlled resonant converter is become by two H bridges, resonant capacitance, resonant inductances, and a high frequency transformer composition, resonance Parallel operation uses phase shifting control, the controlled resonant converter output end low-voltage direct output end for forming electric power electric transformer in parallel.

10. many electric power electric transformer tractive power supply systems of a kind of low-pressure side common DC bus as claimed in claim 7, its It is characterized in that the wave filter is L filter circuits.