Rail transit power supply system, control method and related device

Abstract

The embodiment of the invention provides a rail transit power supply system and a control method. The rail transit power supply system comprises a rectifier unit and a bidirectional converter which are connected in parallel between an alternating-current bus and a direct-current contact network; the controller is used for monitoring the direct current output side current of the rectifier unit and monitoring the direct current side current of the bidirectional converter; and controlling and increasing the direct-current side voltage of the bidirectional converter under the condition of determining that a circulating current exists between the rectifier unit and the bidirectional converter according to the direct-current output side current of the rectifier unit and the direct-current side current of the bidirectional converter. According to the rail transit power supply system and the control method, the circulating current can be effectively suppressed, and the problem of electric energy waste caused by the circulating current in the prior art is reduced.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of power electronics technology, and specifically to a rail transit power supply system, a control method, and related devices. Background Art

[0002] The rail transit power supply system is an important system that provides stable power for rail trains. The rail transit power supply system can convert the power of the AC power grid into DC power to supply power to the DC overhead line.

[0003] In the prior art, the rail transit power supply system includes a parallel rectifier unit and a bidirectional converter, which are used to convert AC power into DC power suitable for the DC contact network of rail transit. The rectifier unit can convert AC power into DC power to supply the DC contact network, while the bidirectional converter can realize the bidirectional flow of electric energy. Specifically, the bidirectional converter can feed back excess DC power to the AC grid during the energy feedback process.

[0004] However, in the prior art, due to the parallel structure of the rectifier unit and the bidirectional converter, a circulating current may be generated, which may cause a waste of electric energy. Summary of the invention

[0005] The present application provides a rail transit power supply system and control method, which can improve the utilization rate of electric energy to a certain extent.

[0006] In a first aspect, an embodiment of the present application provides a rail transit power supply system, comprising: a rectifier unit and a bidirectional converter connected in parallel between an AC bus and a DC contact network; a controller for monitoring the DC output side current of the rectifier unit and the DC side current of the bidirectional converter; and controlling the increase of the DC side voltage of the bidirectional converter when it is determined that there is a circulating current between the rectifier unit and the bidirectional converter based on the DC output side current of the rectifier unit and the DC side current of the bidirectional converter.

[0007] Optionally, based on the DC output side current of the rectifier unit and the DC side current of the bidirectional converter, it is determined that there is a circulating current between the rectifier unit and the bidirectional converter, including: the DC side current direction of the bidirectional converter is flowing from the DC contact network into the bidirectional converter, and the DC side current is greater than the specified energy-feed starting current threshold of the bidirectional converter, and the DC output side current of the rectifier unit is greater than the specified output current first threshold.

[0008] Optionally, the controller controls the bidirectional converter to increase the DC side voltage of the bidirectional converter until the controller determines that there is no circulating current between the rectifier unit and the bidirectional converter.

[0009] Optionally, the controller believes that there is no circulating current between the rectifier unit and the bidirectional converter, including: the DC side current direction of the bidirectional converter is from the bidirectional converter to the DC contact network, and the DC side current is not less than 0; or, the DC output side current of the rectifier unit is not greater than a specified output current second threshold; wherein the specified output current second threshold is not greater than the specified output current first threshold.

[0010] Optionally, the controller controls the bidirectional converter to periodically increase the DC side voltage of the bidirectional converter until it is determined that there is no circulating current between the rectifier unit and the bidirectional converter; wherein the controller controls the DC side voltage of the bidirectional converter to increase by a specified amplitude in each cycle.

[0011] Optionally, the controller statistically controls the number of voltage increases of the DC side voltage of the bidirectional converter; when the DC output side current of the rectifier unit is less than the specified output current second threshold, the controller controls the periodic reduction of the DC side voltage of the bidirectional converter, reducing the specified amplitude each time until the number of voltage reductions of the DC side voltage of the bidirectional converter is equal to the number of voltage increases.

[0012] In the second aspect, an embodiment of the present application also provides a control method for a rail transit power supply system, including: monitoring the DC output side current of a rectifier unit in the rail transit power supply system and monitoring the DC side current of a bidirectional converter in the rail transit power supply system; when it is determined that there is a circulating current between the rectifier unit and the bidirectional converter based on the DC output side current of the rectifier unit and the DC side current of the bidirectional converter, controlling the increase of the DC side voltage of the bidirectional converter.

[0013] Optionally, based on the DC output side current of the rectifier unit and the DC side current of the bidirectional converter, it is determined that there is a circulating current between the rectifier unit and the bidirectional converter, including: the DC side current direction of the bidirectional converter is flowing from the DC contact network into the bidirectional converter, and the DC side current is greater than the specified energy-feed starting current threshold of the bidirectional converter, and the DC output side current of the rectifier unit is greater than the specified output current first threshold.

[0014] Optionally, the method also includes: a step of controlling the increase of the DC side voltage of the bidirectional converter, including: controlling the increase of the DC side voltage of the bidirectional converter until the controller determines that there is no circulating current between the rectifier unit and the bidirectional converter.

[0015] Optionally, the controller believes that there is no circulating current between the rectifier unit and the bidirectional converter, including: the DC side current direction of the bidirectional converter is from the bidirectional converter to the DC contact network, and the DC side current is not less than 0; or, the DC output side current of the rectifier unit is not greater than a specified output current second threshold; wherein the specified output current second threshold is not greater than the specified output current first threshold.

[0016] Optionally, the step of controlling the increase of the DC side voltage of the bidirectional converter includes: controlling the bidirectional converter to periodically increase the DC side voltage of the bidirectional converter until it is determined that there is no circulating current between the rectifier unit and the bidirectional converter; wherein, within each cycle, the DC side voltage of the bidirectional converter is controlled to increase by a specified amplitude.

[0017] Optionally, the method also includes: statistically controlling the number of voltage increases of the DC side voltage of the bidirectional converter; and when the DC output side current of the rectifier unit is less than the specified output current second threshold, controlling the periodic reduction of the DC side voltage of the bidirectional converter, reducing the specified amplitude each time, until the number of voltage reductions of the DC side voltage of the bidirectional converter is equal to the number of voltage increases.

[0018] In a third aspect, an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the control method of the rail transit power supply system as described above is implemented.

[0019] In a fourth aspect, an embodiment of the present application provides a computer program product, which, when executed by a processor, implements the control method of the rail transit power supply system as described above.

[0020] In multiple implementations provided in the present application, the controller of the bidirectional converter monitors the DC side current of the bidirectional converter and the DC output side current of the parallel rectifier unit, and when it is considered that there is a circulating current between the two, the bidirectional converter is controlled to increase its DC side voltage, so that the circulating current can be effectively suppressed, thereby reducing the energy waste caused by the circulating current in the related technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0022] Figure 1 A topological diagram of a rail transit power supply system provided for one embodiment of the present application.

[0023] Figure 2 A topological diagram of a rail transit power supply system is provided for one embodiment of the present application, in which the internal topological structure of a substation is detailed.

[0024] Figure 3 A module schematic diagram of a rail transit power supply system provided for one embodiment of the present application.

[0025] Figure 4 A voltage and current relationship diagram of a bidirectional converter provided for one embodiment of the present application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0027] In the description of the embodiments of the present application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0028] In the related art, the substation of the rail transit power supply system includes parallel rectifiers and bidirectional converters. The rectifier can rectify AC power into DC power and supply it to the DC contact network, while the bidirectional converter can realize the bidirectional flow of electric energy and feed back the excess DC power to the AC grid in the energy feedback mode.

[0029] However, there will be voltage fluctuations in the AC power grid, especially when the voltage of the AC power grid increases, the DC output voltage of the rectifier unit will increase accordingly. When the DC output voltage of the rectifier unit is greater than the energy-feed starting voltage of the bidirectional converter, the bidirectional converter will work in the energy feedback mode to generate energy-feed current, while the rectifier unit will work in the rectification mode to output traction current, thereby generating a circulating current between the rectifier unit and the bidirectional converter. The circulating current is specifically manifested as the current circulating between the rectifier unit and the bidirectional converter, rather than being transmitted to the load in the DC contact network. This will not only cause a waste of electric energy, but also lead to reduced efficiency of the rail transit power supply system and additional losses of the components.

[0030] See also Figure 1 and Figure 2. The rail transit power supply system 100 may include an AC power grid 110, a DC overhead line 112, and a plurality of substations 114. The rail transit power supply system 100 utilizes the AC power in the AC power grid 110 to convert into DC power to supply power to the DC overhead line 112. Specifically, the substation 114 includes a transformer 122, a transformer 124, a rectifier unit 118, and a bidirectional converter 120. The rectifier unit 118 may be connected to the AC bus 126 through the transformer 122, and the DC output side of the rectifier unit 118 is connected to the DC overhead line 112. The AC side of the bidirectional converter 120 may be connected to the AC bus 126 through the transformer 124, and the DC side of the bidirectional converter 120 is connected to the DC overhead line 112. The AC bus 126 is connected to the AC power grid 110, or the AC bus 126 may also be a part of the AC power grid 110.

[0031] Please also read Figure 1 , Figure 2 and Figure 3 . An embodiment of the present application provides a rail transit power supply system 100. The rail transit power supply system 100 may include: a rectifier unit 118 and a bidirectional converter 120 connected in parallel between an AC bus 126 and a DC contact network 112; a controller 128 for monitoring the DC output side current of the rectifier unit 118 and the DC side current of the bidirectional converter 120; when it is determined that there is a circulating current between the rectifier unit 118 and the bidirectional converter 120 based on the DC output side current of the rectifier unit 118 and the DC side current of the bidirectional converter 120, the bidirectional converter 120 is controlled to increase the DC side voltage of the bidirectional converter 120.

[0032] In this embodiment, the rail transit power supply system 100 can be used to convert the electric energy of the AC bus 126 into the DC power required by the DC contact network 112, so as to provide the electric energy required for traction of the tram.

[0033] In this embodiment, the rectifier unit 118 can be used to rectify the AC power from the AC power grid 110 into DC power and supply it to the DC contact network. Specifically, the rectifier unit 118 can include a plurality of rectifier elements, such as a diode rectifier bridge or a thyristor rectifier. Optionally, in this embodiment, the rectifier unit 118 can be a diode rectifier unit.

[0034] In this embodiment, the bidirectional converter 120 has the ability of bidirectional electric energy flow. The bidirectional converter 120 can convert the AC power from the AC power grid 110 into DC power and supply it to the DC contact network 112 to meet the traction power demand of the tram. The bidirectional converter 120 can also invert the excess DC power into AC power when the tram brakes, and feed it back to the AC power grid 110. In this way, the energy utilization rate of the rail transit power supply system 100 is improved through the bidirectional energy flow mechanism of the bidirectional converter 120.

[0035] In this embodiment, the controller 128 can monitor the DC output side current of the rectifier unit 118, and monitor the DC side current of the bidirectional converter. In addition, the controller 128 can control the bidirectional converter 120 to suppress the circulating current when it is considered that there is a circulating current based on the monitoring results. In some embodiments, the controller 128 may include: a current detection module and a control module. The current detection module can be used to detect the DC output side current of the rectifier unit 118 and the DC side current of the bidirectional converter 120, and can feed back to the control module an electrical signal representing the DC output side current intensity of the rectifier unit 118 and an electrical signal representing the DC side current intensity of the bidirectional converter. The control module can determine whether the DC output side current of the rectifier unit 118 and the DC side current of the bidirectional converter are abnormal based on the electrical signal provided by the current detection module.

[0036] Circulating current refers to the current that flows ineffectively between the rectifier unit 118 and the bidirectional converter 120. The circulating current will not participate in the power output of the tram, but will cause power waste and additional loss of electronic components. When the control module detects the circulating current, the controller 128 will control the bidirectional converter 120 to increase the DC side voltage to reduce the voltage difference between the DC output side of the rectifier unit 118 and the DC side of the bidirectional converter, thereby suppressing the circulating current.

[0037] Please also read Figure 2 and Figure 4 In some embodiments, based on the DC output side current of the rectifier unit 118 and the DC side current of the bidirectional converter 120, it is determined that there is a circulating current between the rectifier unit 118 and the bidirectional converter 120, including: the DC side current direction of the bidirectional converter 120 flows from the DC contact network 112 to the bidirectional converter 120, the DC side current is greater than the specified energy-feed starting current threshold of the bidirectional converter 120, and the DC output side current of the rectifier unit 118 is greater than the specified output first current threshold.

[0038] In this embodiment, the rectifier unit 118 can be a diode rectifier unit. The DC output side voltage of the diode rectifier unit is closely related to the input voltage of the AC power grid 110. When the voltage of the AC power grid 110 fluctuates greatly, especially when the voltage of the AC power grid 110 increases, the DC output side voltage of the diode rectifier unit will increase as the voltage of the AC power grid 110 increases. Specifically, due to the characteristics of the diode rectifier unit itself, the DC output side voltage is a rectified voltage for the input AC voltage. When the voltage of the AC power grid 110 increases, the DC output side voltage of the diode rectifier unit also increases accordingly. As a result, the DC output side voltage of the diode rectifier unit is higher than the DC side voltage of the bidirectional converter. In this way, a circulating current is formed between the two via the DC contact network 112 and the AC bus 126. In this embodiment, the bidirectional converter 120 can include two modes: a power supply mode for supplying power to the DC contact network 112, and an energy feedback mode for feeding back DC power to the AC power grid 110. After the circulating current is formed, the bidirectional converter 120 is already in the energy feedback mode.

[0039] In this embodiment, the specified energy feedback starting current threshold can be used as a critical value to determine whether the bidirectional converter 120 is in the energy feedback mode. When the current flowing from the DC overhead line 112 into the bidirectional converter 120 is greater than the specified energy feedback starting current threshold, it can be determined that the bidirectional converter 120 is in the energy feedback mode.

[0040] The controller 128 can monitor the DC output side current of the rectifier unit 118 and the DC side current of the bidirectional converter 120, and determine whether there is a circulating current between the rectifier unit 118 and the bidirectional converter 120 based on the monitoring results. Specifically, when the DC side current direction of the bidirectional converter 120 flows from the DC contact network 112 to the bidirectional converter 120, and the DC side current of the bidirectional converter 120 is greater than the specified energy feedback starting current threshold, it indicates that the bidirectional converter 120 is in the energy feedback mode. At the same time, if the DC output side current of the rectifier unit 118 is greater than the specified output current first threshold, this indicates that the rectifier unit 118 is providing a large current to the DC contact network 112. When the above two conditions are met at the same time, that is, the bidirectional converter 120 is in the energy feedback mode, and the rectifier unit 118 is still supplying a large amount of power, it is determined that a circulating current has been formed.

[0041] When the controller 128 determines that there is a circulating current, the controller 128 can control the bidirectional converter 120 to increase the DC side voltage to reduce the voltage difference with the DC output side voltage of the rectifier unit 118, thereby suppressing the generation of the circulating current.

[0042] In some embodiments, the bidirectional converter 120 also corresponds to a specified traction power supply starting current threshold. The specified traction power supply starting current threshold can be used as a critical value to define whether the bidirectional converter 120 is in the traction power supply mode. When the current flowing from the bidirectional converter 120 to the DC contact network 112 is greater than the specified traction power supply starting threshold, it can be determined that the bidirectional converter 120 is in the traction power supply mode, that is, the bidirectional converter 120 converts the electric energy of the AC power grid 110 into DC electric energy, supplies the DC contact network 112, and provides traction power for the tram. Among them, when the current flows from the bidirectional converter 120 to the DC contact network 112 as the positive direction, the specified traction power supply starting current threshold is greater than the specified energy feed starting current threshold, and the specified traction power supply starting current threshold is greater than 0, and the specified energy feed starting current threshold is less than 0. Furthermore, in some embodiments, when the current flows from the bidirectional converter 120 to the DC contact network 112 as the positive direction, the DC side current of the bidirectional converter 120 is greater than the specified energy feed starting current threshold, and the DC side current of the bidirectional converter 120 is less than the specified traction power supply starting current threshold, indicating that the bidirectional converter 120 is in a no-load state.

[0043] In this embodiment, by monitoring the DC side current of the bidirectional converter 120, the controller 128 can accurately determine the current mode of the bidirectional converter 120. When the bidirectional converter 120 is in a no-load state, if the DC output side current of the rectifier unit 118 is large, and the DC side voltage of the bidirectional converter 120 is lower than the DC output side voltage of the rectifier unit 118, the bidirectional converter 120 may enter the energy feedback mode, i.e., cause a circulating current. At this time, the controller 128 can control the bidirectional converter 120 to increase the DC side voltage to reduce the voltage difference between the DC output side of the rectifier unit 118 and suppress the generation of the circulating current.

[0044] In this embodiment, the setting values ​​of the designated traction power supply starting current threshold and the designated energy feed starting current threshold can be configured according to the requirements and operating conditions of the rail transit power supply system 100. Generally, when the current flows from the bidirectional converter 120 to the DC overhead line 112 as the positive direction, the designated traction power supply starting current threshold is greater than the designated energy feed starting current threshold, and the designated traction power supply starting current threshold is greater than 0, and the designated energy feed starting current threshold is less than 0, so as to clearly distinguish different states of the bidirectional converter 120.

[0045] In some embodiments, the controller 128 controls the bidirectional converter 120 to increase the DC side voltage of the bidirectional converter 120 until the controller 128 determines that there is no circulating current between the rectifier unit 118 and the bidirectional converter 120 .

[0046] In this embodiment, when the controller 128 detects that there is a circulating current between the rectifier unit 118 and the bidirectional converter 120, the controller 128 will control the bidirectional converter 120 to gradually increase the DC side voltage. By increasing the DC side voltage of the bidirectional converter 120, the voltage difference between the bidirectional converter 120 and the rectifier unit 118 can be reduced, thereby effectively suppressing the generation of circulating current. The controller 128 continuously detects the DC output side current of the rectifier unit 118 and the DC output side current of the bidirectional converter 120. When the controller 128 determines that there is no circulating current between the rectifier unit 118 and the bidirectional converter 120, that is, the current tends to be stable, the controller 128 stops increasing the DC side voltage of the bidirectional converter 120.

[0047] In this embodiment, the controller 128 suppresses the circulating current by increasing the DC side voltage of the bidirectional converter 120 , thereby ensuring the stability of the rail transit power supply system 100 .

[0048] In some embodiments, the controller 128 believes that there is no circulating current between the rectifier unit 118 and the bidirectional converter 120, including: the DC side current direction of the bidirectional converter 120 flows from the bidirectional converter 120 to the DC contact network 112, and the DC side current is greater than 0; or, the DC output side current of the rectifier unit 118 is not greater than the specified output current second threshold; wherein the specified output current second threshold is not greater than the specified output current first threshold.

[0049] In this embodiment, when the DC side current of the bidirectional converter 120 flows from the bidirectional converter 120 to the DC contact network 112, and the DC side current value is greater than 0, it indicates that the bidirectional converter 120 has exited the energy feedback mode. In this case, the DC side current direction indicates that there is no circulating current between the rectifier unit 118 and the bidirectional converter 120.

[0050] Alternatively, when the DC output side current of the rectifier unit 118 is not greater than the specified output current second threshold, it indicates that the output current of the rectifier unit 118 to the DC contact network 112 has been reduced to a normal range. In this embodiment, the specified output current second threshold may be a specified critical value for determining whether the DC side output current of the rectifier unit 118 has been reduced to a safe range. The specified output current second threshold is set to be less than or equal to the specified output current first threshold. The specified output current first threshold is used to determine whether the DC side output current of the rectifier unit 118 exceeds the normal range and may cause a circulating current; and the specified output current second threshold is used to determine whether the DC side output current has returned to a normal working state and the circulating current has been effectively suppressed.

[0051] Through these two methods, the controller 128 can accurately identify whether the circulating current has been suppressed, thereby ensuring the stable operation of the rail transit power supply system.

[0052] In some embodiments, the controller 128 controls the bidirectional converter 120 to periodically increase the DC side voltage of the bidirectional converter until it is determined that there is no circulating current between the rectifier unit 118 and the bidirectional converter 120; wherein the controller 128 controls the DC side voltage of the bidirectional converter 120 to increase by a specified amplitude in each cycle.

[0053] In this embodiment, when the controller 128 determines that there is a circulating current between the rectifier unit 118 and the bidirectional converter 120, the controller 128 will take measures to suppress the circulating current. Specifically, the controller 128 periodically controls the bidirectional converter 120 to increase the DC side voltage until it is considered that there is no circulating current. In each cycle, the controller 128 controls the DC side voltage of the bidirectional converter 120 to increase by a specified amplitude. The specified amplitude can be a pre-set voltage increment, which is used to gradually adjust the DC side voltage of the bidirectional converter 120. By increasing the specified amplitude in each cycle, the controller 128 can smoothly increase the DC side voltage of the bidirectional converter 120, reduce the voltage difference between the DC output side of the rectifier unit 118, and thus gradually suppress the generation of the circulating current. Specifically, the controller 128 detects the current circulating current state at the beginning of each cycle. If the controller 128 determines that there is still a circulating current, it means that the circulating current has not been effectively suppressed, and the controller 128 increases the DC side voltage of the bidirectional converter 120 by a specified amplitude in this cycle. When the DC side voltage of the bidirectional converter 120 is gradually increased, the circulating current flowing through the bidirectional converter 120 will also gradually decrease. When the circulating current is suppressed below the specified circulating current threshold, the controller 128 determines that there is no circulating current, indicating that the circulating current has been effectively suppressed. At this time, the controller 128 will stop further increasing the DC side voltage of the bidirectional converter 120.

[0054] In this embodiment, periodically increasing the DC side voltage of the bidirectional converter 120 helps to avoid instability of the rail transit power supply system caused by too fast or too large voltage adjustment. Through gradual adjustment, the rail transit power supply system can maintain stable and reliable operation while suppressing circulating current.

[0055] In some embodiments, the controller 128 statistically controls the number of voltage increases of the DC side voltage of the bidirectional converter 120; when the DC output side current of the rectifier unit 118 is less than the specified output current second threshold, the controller 128 controls the periodic reduction of the DC side voltage of the bidirectional converter 120, reducing the specified amplitude each time until the number of voltage reductions of the DC side voltage of the bidirectional converter 120 is equal to the number of voltage increases.

[0056] In this embodiment, when the controller 128 detects that there is a circulating current between the rectifier unit 118 and the bidirectional converter 110, the controller 128 suppresses the circulating current by periodically increasing the DC side voltage of the bidirectional converter 120. Specifically, the controller 128 increases the DC side voltage of the bidirectional converter 120 by a specified amplitude in each cycle, and counts the number of times the voltage is increased. In this process, the controller 128 continuously monitors the operating status of the rectifier unit 118 and the bidirectional converter 120. When the voltage of the AC power grid 110 decreases from a higher level to a normal level, the DC output side voltage of the rectifier unit 118 will decrease accordingly. Since the DC output side voltage of the rectifier unit 118 is related to the input voltage of the AC power grid 110, the reduction in the voltage of the AC power grid 110 causes the DC output side current of the rectifier unit 118 to decrease. When the DC output side current of the rectifier unit 118 is less than the specified output current second threshold, it indicates that the AC power grid voltage 110 has recovered to an acceptable normal level, and the risk of generating circulating current is reduced. Furthermore, the controller 128 can periodically reduce the DC side voltage of the bidirectional converter 120. In each cycle, the controller 128 gradually reduces the DC side voltage of the bidirectional converter 120 by a specified amplitude, and counts the number of voltage reductions until the number of voltage reductions is equal to the number of voltage increases. By making the number of increases and decreases in voltage equal, the controller 128 can ensure that the DC side voltage of the bidirectional converter 120 gradually returns to the initial level, avoiding instability of the rail transit power supply system 100 due to voltage drops. Furthermore, by counting the number of voltage increases and voltage decreases, the controller 128 can effectively manage the voltage adjustment process and improve the overall performance of the rail transit power supply system 100.

[0057] An embodiment of the present application also provides a control method for a rail transit power supply system, the control method comprising: monitoring the DC output side current of a rectifier unit in the rail transit power supply system and monitoring the DC side current of a bidirectional converter in the rail transit power supply system; and when it is determined that a circulating current exists between the rectifier unit and the bidirectional converter based on the DC output side current of the rectifier unit and the DC side current of the bidirectional converter, controlling to increase the DC side voltage of the bidirectional converter.

[0058] The specific functions and effects of each step in the control method of the rail transit power supply system can be explained with reference to the aforementioned embodiments and will not be repeated here.

[0059] In some embodiments, the control method of the rail transit power supply system is applied to a controller. The controller can implement the functions described in the above embodiments by executing the control method of the rail transit power supply system. Specifically, the control method of the rail transit power supply system can refer to the above embodiments and will not be described in detail.

[0060] An embodiment of the present application further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the control method of the rail transit power supply system as described in the above embodiment is implemented.

[0061] An embodiment of the present application also provides a computer program product, and when the computer program software is executed by a processor, the control method of the rail transit power supply system as described in the above embodiment is implemented.

[0062] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. can transmit electrical signals or data to each other.

[0063] It should be understood that the specific examples in this article are only intended to help those skilled in the art to better understand the embodiments of the present application, rather than to limit the scope of the present invention.

[0064] It can be understood that in the various embodiments of the present application, the size of the serial number of each process does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0065] It can be understood that the various embodiments described in this application can be implemented individually or in combination, and the embodiments of this application are not limited to this.

[0066] It can be understood that the processor of the embodiment of the present application can be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method implementation can be completed by the hardware integrated logic circuit or software instructions in the processor. The above processor can be a general processor, a digital signal processor (DigitalSignal Processor, DSP), an application-specific integrated circuit (Application Specific Integrated Circuit, ASIC), a field programmable gate array (Field Programmable Gate Array, FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiment of the present application can be implemented or executed. The general processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in the embodiment of the present application can be directly embodied as a hardware decoding processor to perform, or the hardware and software modules in the decoding processor are combined and executed. The software module can be located in a mature storage medium in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.

[0067] It is understood that the storage medium in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (programmable ROM, PROM), an erasable programmable read-only memory (erasablePROM, EPROM), an electrically erasable programmable read-only memory (EEPROM) or a flash memory. The volatile memory may be a random access memory (RAM). It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0068] Unless otherwise stated, all technical and scientific terms used in the embodiments of the present application are the same as the meanings generally understood by those skilled in the art of the technical field of the present application. The terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the scope of the present application. The term "and / or" used in the present application includes any and all combinations of one or more related listed items. The singular forms "a kind of", "above" and "the" used in the embodiments of the present application and the appended claims are also intended to include majority forms, unless the context clearly indicates other meanings.

[0069] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0070] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0071] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0072] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0073] The above is only a specific embodiment of the present application, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A rail transit power supply system, characterized in that: include: A rectifier unit and a bidirectional converter connected in parallel between the AC bus and the DC contact network; A controller is used to monitor the DC output side current of the rectifier unit and the DC side current of the bidirectional converter; when it is determined that there is a circulating current between the rectifier unit and the bidirectional converter based on the DC output side current of the rectifier unit and the DC side current of the bidirectional converter, the DC side voltage of the bidirectional converter is controlled to be increased.

2. The rail transit power supply system according to claim 1, characterized in that: According to the DC output side current of the rectifier unit and the DC side current of the bidirectional converter, determining that there is a circulating current between the rectifier unit and the bidirectional converter includes: The DC side current direction of the bidirectional converter is from the DC contact network into the bidirectional converter, and the DC side current is greater than the specified energy-feed starting current threshold of the bidirectional converter, and the DC output side current of the rectifier unit is greater than the specified output current first threshold.

3. The rail transit power supply system according to claim 2, characterized in that: The controller controls the bidirectional converter to increase the DC side voltage of the bidirectional converter until the controller determines that there is no circulating current between the rectifier unit and the bidirectional converter.

4. The rail transit power supply system according to claim 3, characterized in that: The controller considers that there is no circulating current between the rectifier unit and the bidirectional converter, including: The DC side current direction of the bidirectional converter is from the bidirectional converter to the DC contact network, and the DC side current is not less than 0; or, The DC output side current of the rectifier unit is not greater than a specified output current second threshold value; wherein the specified output current second threshold value is not greater than the specified output current first threshold value.

5. The rail transit power supply system according to claim 3, characterized in that: The controller controls the bidirectional converter to periodically increase the DC side voltage of the bidirectional converter until it is determined that there is no circulating current between the rectifier unit and the bidirectional converter; wherein the controller controls the DC side voltage of the bidirectional converter to increase by a specified amplitude in each cycle.

6. The rail transit power supply system according to claim 5, characterized in that: The controller statistically controls the number of voltage increases of the DC side voltage of the bidirectional converter; When the DC output side current of the rectifier unit is less than the second threshold value of the specified output current, the controller controls the periodic reduction of the DC side voltage of the bidirectional converter, reducing the specified amplitude each time until the number of voltage reductions of the DC side voltage of the bidirectional converter is equal to the number of voltage increases.

7. A control method for a rail transit power supply system, characterized in that: include: Monitoring the DC output side current of the rectifier unit in the rail transit power supply system and monitoring the DC side current of the bidirectional converter in the rail transit power supply system; When it is determined that there is a circulating current between the rectifier unit and the bidirectional converter based on the DC output side current of the rectifier unit and the DC side current of the bidirectional converter, the DC side voltage of the bidirectional converter is controlled to be increased.

8. The method according to claim 7, characterized in that According to the DC output side current of the rectifier unit and the DC side current of the bidirectional converter, determining that there is a circulating current between the rectifier unit and the bidirectional converter includes: The DC side current direction of the bidirectional converter is from the DC contact network into the bidirectional converter, and the DC side current is greater than the specified energy-feed starting current threshold of the bidirectional converter, and the DC output side current of the rectifier unit is greater than the specified output current first threshold.

9. The method according to claim 7, characterized in that: The method further comprises: The step of controlling and increasing the DC side voltage of the bidirectional converter comprises: controlling and increasing the DC side voltage of the bidirectional converter until the controller determines that there is no circulating current between the rectifier unit and the bidirectional converter.

10. The method according to claim 9, characterized in that The controller considers that there is no circulating current between the rectifier unit and the bidirectional converter, including: The DC side current direction of the bidirectional converter is from the bidirectional converter to the DC contact network, and the DC side current is not less than 0; or, The DC output side current of the rectifier unit is not greater than a specified output current second threshold value; wherein the specified output current second threshold value is not greater than the specified output current first threshold value.

11. The method according to claim 9, characterized in that The step of controlling and increasing the DC side voltage of the bidirectional converter comprises: The bidirectional converter is controlled to periodically increase the DC side voltage of the bidirectional converter until it is determined that there is no circulating current between the rectifier unit and the bidirectional converter; wherein the DC side voltage of the bidirectional converter is controlled to increase by a specified amplitude in each cycle.

12. The method according to claim 11, characterized in that The method further comprises: Statistically controlling the number of voltage increases for increasing the DC side voltage of the bidirectional converter; When the DC output side current of the rectifier unit is less than the second threshold value of the specified output current, the DC side voltage of the bidirectional converter is controlled to be periodically reduced, each time by the specified amplitude, until the number of voltage reductions of the DC side voltage of the bidirectional converter is equal to the number of voltage increases.

13. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the control method of the rail transit power supply system as described in any one of claims 7 to 12 is implemented.

14. A computer program product, characterized in that When the computer program product is executed by a processor, the control method of the rail transit power supply system as described in any one of claims 7 to 12 is implemented.

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