Droop control method, control device and traction power supply system for traction power supply system

Abstract

The application provides a droop control method of a traction power supply system, a control device and the traction power supply system, and relates to the technical field of power supply. The traction power supply system comprises power supply devices of multiple stations; at least one station is a first station, and the remaining stations comprise at least one of a second station and a third station; the power supply device of the first station comprises a rectifier unit; the power supply device of the second station comprises a bidirectional converter unit; the power supply device of the third station comprises a rectifier unit and a bidirectional converter unit connected in parallel; the method comprises the following steps: acquiring a line loss inter-station droop pressure drop and a load droop pressure drop of the bidirectional converter unit; determining a total droop pressure drop based on the line loss inter-station droop pressure drop and the load droop pressure drop; and performing droop control on the bidirectional converter unit based on the total droop pressure drop, so that the bidirectional converter unit simulates the droop characteristics of the rectifier unit. The application can avoid cross-station power supply, and thus can avoid or reduce rail potential corrosion and line loss caused by cross-station power supply.

Description

Technical Field

[0001] This application relates to the field of power supply technology, and in particular to a droop control method, control equipment and traction power supply system for a traction power supply system. Background Technology

[0002] In urban rail transit traction power supply systems, 24-pulse rectifier units are typically used to supply power to the traction network, utilizing the inherent droop characteristics of these units to achieve natural load distribution. However, these rectifier units only have unidirectional rectification capabilities and cannot absorb the regenerative energy generated during train braking, resulting in energy waste.

[0003] To address these issues, related technologies have introduced bidirectional converter units with energy feedback capabilities into traction power supply systems. However, bidirectional converter units have voltage regulation characteristics, meaning their output DC voltage is typically stable at a fixed value, while rectifier units exhibit droop characteristics, with their output voltage decreasing as the load increases. Therefore, if one station is powered by a rectifier unit and the other by a bidirectional converter unit, cross-station power supply can easily occur, leading to rail potential corrosion and line losses. Summary of the Invention

[0004] This application provides a sag control method, control equipment, and traction power supply system for a traction power supply system, in order to solve the problems of rail potential corrosion and line loss caused by cross-station power supply in existing traction power supply systems.

[0005] In a first aspect, embodiments of this application provide a droop control method for a traction power supply system, the traction power supply system including power supply devices for multiple stations; wherein at least one station is a first station, and the remaining stations include at least one of a second station and a third station; the power supply device for the first station includes a rectifier unit; the power supply device for the second station includes a bidirectional converter unit; the power supply device for the third station includes a rectifier unit and a bidirectional converter unit connected in parallel; the method includes: Obtain the inter-station line loss droop voltage drop and load droop voltage drop corresponding to the bidirectional converter unit; The total droop voltage drop of the bidirectional converter unit is determined based on the droop voltage drop due to inter-station line loss and the load droop voltage drop. Based on the total droop voltage drop, droop control is applied to the bidirectional converter unit to simulate the droop characteristics of the rectifier unit.

[0006] In one possible implementation, obtaining the load droop voltage drop corresponding to the bidirectional converter unit includes: Obtain the actual DC current and actual load status of the bidirectional converter unit; Determine the droop factor of the bidirectional converter unit based on the actual load conditions; Determine the load factor based on the type of the site where the bidirectional converter unit is located; The load droop voltage drop of the bidirectional converter unit is determined based on the load factor, actual DC current, and droop factor.

[0007] In one possible implementation, the load factor is determined based on the type of site where the bidirectional converter unit is located, including: If the type of the site where the bidirectional converter unit is located is the second site, then the load factor is determined to be 0; If the bidirectional converter unit is located at a site of type 3, then the load factor is determined to be greater than 0.

[0008] In one possible implementation, obtaining the actual load state of the bidirectional converter unit includes: If the actual DC current is less than or equal to the first preset current, or if the actual power of the bidirectional converter is less than or equal to the first preset power, then the actual load state of the bidirectional converter is determined to be the first load state. If the actual DC current is greater than the first preset current and less than or equal to the second preset current, or if the actual power is greater than the first preset power and less than or equal to the second preset power, then the actual load state of the bidirectional converter unit is determined to be the second load state. If the actual DC current is greater than the second preset current, or the actual power is greater than the second preset power, then the actual load state of the bidirectional converter unit is determined to be the third load state. Wherein, the first preset current is less than the second preset current, and the first preset power is less than the second preset power.

[0009] In one possible implementation, the actual load state includes a first load state, a second load state, or a third load state. The first load state corresponds to the first droop coefficient, the second load state corresponds to the second droop coefficient, and the third load state corresponds to the third droop coefficient.

[0010] In one possible implementation, the first droop coefficient is 0; The second and third droop coefficients are determined by fitting the output voltage-output current curves of the rectifier unit under the same actual load conditions.

[0011] In one possible implementation, obtaining the inter-station line loss droop voltage drop corresponding to the bidirectional converter unit includes: Determine whether the adjacent site of the bidirectional converter unit is the first site; If both adjacent stations of the bidirectional converter unit are the first station, the inter-station line loss droop voltage drop corresponding to the bidirectional converter unit is determined based on the larger of the distances between the bidirectional converter unit and the two adjacent stations and the line loss coefficient. If one of the adjacent stations of the bidirectional converter unit is the first station, then the inter-station line loss droop voltage drop corresponding to the bidirectional converter unit is determined based on the distance between the bidirectional converter unit and the adjacent station and the line loss coefficient.

[0012] In one possible implementation, at least one neighboring station of the second station is the first station, and / or, at least one neighboring station of the third station is the first station.

[0013] Secondly, embodiments of this application provide a droop control device for a traction power supply system. The traction power supply system includes power supply devices for multiple stations; wherein at least one station is a first station, and the remaining stations include at least one of a second station and a third station; the power supply device for the first station includes a rectifier unit; the power supply device for the second station includes a bidirectional converter unit; and the power supply device for the third station includes a rectifier unit and a bidirectional converter unit connected in parallel; the device includes: The acquisition module is used to acquire the inter-station line loss droop voltage drop and load droop voltage drop corresponding to the bidirectional converter unit; The total droop voltage drop determination module is used to determine the total droop voltage drop of the bidirectional converter unit based on the droop voltage drop of the inter-station line loss and the load droop voltage drop. The droop control module is used to control the droop of the bidirectional converter unit based on the total droop voltage drop, so that the bidirectional converter unit can simulate the droop characteristics of the rectifier unit.

[0014] Thirdly, embodiments of this application provide a control device, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the droop control method of the traction power supply system as described in the first aspect or any possible implementation of the first aspect.

[0015] Fourthly, embodiments of this application provide a traction power supply system, including power supply devices for multiple stations; Wherein, at least one station is a first station, and the remaining stations include at least one of a second station and a third station; the power supply device of the first station includes a rectifier unit; the power supply device of the second station includes a bidirectional converter unit and a control device as described in the third aspect; the power supply device of the third station includes a rectifier unit and a bidirectional converter unit connected in parallel, and a control device as described in the third aspect. The bidirectional converter unit is controlled by the corresponding control equipment.

[0016] Fifthly, embodiments of this application provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the droop control method of the traction power supply system as described in the first aspect or any possible implementation thereof.

[0017] In a sixth aspect, embodiments of this application provide a computer program product, including a computer program that, when executed by a processor, implements the droop control method of the traction power supply system as described in the first aspect or any possible implementation of the first aspect.

[0018] In this embodiment, for a traction power supply system that includes both rectifier units and bidirectional converter units, droop control is applied to the bidirectional converter units to simulate the droop characteristics of rectifier units. This results in the bidirectional converter units and rectifier units outputting DC voltages with the same or similar characteristics. Specifically, when determining the total droop voltage drop of the bidirectional converter units, both inter-station line loss droop voltage drop and load droop voltage drop are considered. This allows droop control based on the total droop voltage drop to eliminate the voltage difference between the bidirectional converter unit's location and its adjacent locations, avoiding cross-station power supply. This, in turn, avoids or reduces rail potential corrosion and line losses caused by cross-station power supply. Furthermore, by considering the inter-station line loss droop voltage drop, load distribution between adjacent locations can be optimized, bringing the power supply boundary closer to the midpoint between the two locations. This reduces long-distance current transmission, significantly reducing overall system line losses and improving system power supply efficiency. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the traction power supply system provided in the embodiments of this application; Figure 2 This is a flowchart illustrating the implementation of the droop control method for the traction power supply system provided in this application embodiment; Figure 3 This is a schematic diagram of the voltage-current curves of the rectifier unit and the bidirectional converter unit provided in the embodiments of this application; Figure 4 This is a schematic diagram of the droop control device of the traction power supply system provided in the embodiments of this application; Figure 5 This is a schematic diagram of the control device provided in the embodiments of this application. Detailed Implementation

[0021] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the following description will be provided in conjunction with the accompanying drawings and specific embodiments.

[0023] See Figure 1 This illustrates a schematic diagram of the traction power supply system provided in an embodiment of this application. Figure 1 As shown, the traction power supply system includes power supply devices for multiple stations; wherein, at least one station is a first station, and the remaining stations include at least one of a second station and a third station; the power supply device 21 of the first station includes a rectifier unit 24; the power supply device 22 of the second station includes a bidirectional converter unit 25; and the power supply device 23 of the third station includes a rectifier unit 24 and a bidirectional converter unit 25 connected in parallel.

[0024] The AC side of the power supply device at each station is connected to the AC power grid 10, and the DC side of the power supply device at each station is connected to the traction network 30.

[0025] The rectifier unit 24 is used to convert alternating current (AC) to direct current (DC) and can only be used for unidirectional energy transfer. The rectifier unit 24 can be a 24-pulse rectifier unit or other types of rectifier units; no specific restrictions are made here. The rectifier unit 24 has a droop characteristic, meaning its output voltage decreases as the output current increases.

[0026] The bidirectional converter unit 25 can be used to convert AC power to DC power, and vice versa, enabling bidirectional energy transmission. This application does not limit the specific structure of the bidirectional converter unit 25; any feasible structure is acceptable.

[0027] In this embodiment, the power supply stations are divided into three categories: a first station, a second station, and a third station. The power supply unit 21 of the first station includes a rectifier unit 24 but does not include a bidirectional converter unit 25. The power supply unit 22 of the second station includes a bidirectional converter unit 25 but does not include a rectifier unit 24. The power supply unit 23 of the third station includes both a rectifier unit 24 and a bidirectional converter unit 25, which are connected in parallel. The number of first stations is greater than or equal to one, and the total number of second and third stations is greater than or equal to one.

[0028] The remaining stations mentioned above refer to all stations in the traction power supply system except for the first station. These remaining stations can all be the second station, all be the third station, or a combination of both.

[0029] For example, for all stations in the entire system, some stations may be the first station and the remaining stations may be the second station; some stations may be the first station and the remaining stations may be the third station; some stations may be the first station, some stations may be the second station, and all remaining stations may be the third station.

[0030] For the first and last stations, there is only one adjacent station; for stations that are neither the first nor the last station, there are two adjacent stations.

[0031] In some possible implementations, at least one neighboring station of the second station is the first station, and / or, at least one neighboring station of the third station is the first station.

[0032] In this embodiment of the application, for a site that includes a bidirectional converter unit 25, at least one of its adjacent sites is a first site, that is, a site that includes a rectifier unit 24 but does not include a bidirectional converter unit 25.

[0033] It should be noted that, in Figure 1 In this designation, each rectifier unit 24 is represented by the same designation, and each bidirectional converter unit 25 is represented by the same designation. However, the rectifier units 24 at different sites are different rectifier units 24, but their structures can be the same; similarly, the bidirectional converter units 25 at different sites are different bidirectional converter units 25, but their structures can be the same.

[0034] For the power supply equipment at each site, in addition to the aforementioned rectifier unit 24 and / or bidirectional converter unit 25, other necessary devices may be included, such as transformers, etc., without specific limitations. This application embodiment does not specifically limit the number of rectifier units 24 and / or bidirectional converter units 25 included in the power supply equipment at each site. For example, the power supply equipment 21 at the first site may include one rectifier unit 24, two rectifier units 24 connected in parallel, or even more rectifier units 24 connected in parallel. The power supply equipment 22 at the second site may include one bidirectional converter unit 25, two bidirectional converter units 25 connected in parallel, or even more bidirectional converter units 25 connected in parallel. The power supply equipment 23 at the third site may include one rectifier unit 24 and one bidirectional converter unit 25 connected in parallel, or even more rectifier units 24 and more bidirectional converter units 25 connected in parallel. For example, the power supply unit 21 of the first site includes two rectifier units 24 connected in parallel, the power supply unit 22 of the second site includes two bidirectional converter units 25 connected in parallel, and the power supply unit 23 of the third site includes one rectifier unit 24 and one bidirectional converter unit 25 connected in parallel; or, the power supply unit 21 of the first site includes one rectifier unit 24, the power supply unit 22 of the second site includes one bidirectional converter unit 25, and the power supply unit 23 of the third site includes one rectifier unit 24 and one bidirectional converter unit 25 connected in parallel; and so on.

[0035] If a power supply unit at a certain site includes at least two rectifier units 24, then each rectifier unit 24 can operate simultaneously, or only some of the rectifier units 24 can operate, with the remaining rectifier units 24 serving as redundant backup units. Similarly, if a power supply unit at a certain site includes at least two bidirectional converter units 25, then each bidirectional converter unit 25 can operate simultaneously, or only some of the bidirectional converter units 25 can operate, with the remaining bidirectional converter units 25 serving as redundant backup units.

[0036] In the aforementioned traction power supply system, if two adjacent stations are designated as Station 1 and Station 2, or Station 1 and Station 3, meaning one station's power supply unit consists only of a rectifier unit while the other station's includes a bidirectional converter unit, the drooping characteristic of the rectifier unit causes its output voltage to decrease as the output current increases. Conversely, the bidirectional converter unit has voltage stabilization characteristics, maintaining a constant output voltage. This difference in output voltage between the two adjacent stations leads to cross-station power supply, where the station with the higher output voltage transmits current through the traction network's rails to the station with the lower output voltage, causing rail corrosion and line losses. Furthermore, the difference in output voltage between stations means that when vehicles travel between them, the power supply boundary is closer to the station with the lower output voltage. This increases the length of the power supply line to the station with the higher output voltage, leading to increased line losses and reduced power supply efficiency.

[0037] To address the aforementioned issues, this application provides a droop control method for a traction power supply system.

[0038] See Figure 2 The diagram illustrates the implementation flowchart of the droop control method for the traction power supply system provided in the embodiments of this application.

[0039] The traction power supply system includes power supply devices for multiple stations; at least one station is a first station, and the remaining stations include at least one of a second station and a third station; the power supply device for the first station includes a rectifier unit; the power supply device for the second station includes a bidirectional converter unit; and the power supply device for the third station includes a rectifier unit and a bidirectional converter unit connected in parallel.

[0040] For a detailed description of the traction power supply system, please refer to the aforementioned embodiments, which will not be repeated here.

[0041] See Figure 2 The sag control method of the traction power supply system is described in detail below: In S201, obtain the inter-station line loss droop voltage drop and load droop voltage drop corresponding to the bidirectional converter unit.

[0042] This application embodiment focuses on droop control of bidirectional converter units in a traction power supply system, where each bidirectional converter unit can be controlled by a corresponding control device.

[0043] This application describes a single bidirectional converter unit. However, the method provided in this application can be used to control each bidirectional converter unit in the traction power supply system.

[0044] Among them, the droop voltage drop due to line loss between stations can be understood as the voltage drop required for bidirectional converter units based on the line loss between adjacent stations.

[0045] Load droop voltage drop can be understood as the voltage drop that needs to be determined based on the load conditions of the bidirectional converter unit.

[0046] This application does not impose specific restrictions on the means of obtaining the inter-station line loss droop voltage drop and load droop voltage drop corresponding to the bidirectional converter unit; any feasible means are acceptable.

[0047] In S202, the total droop voltage drop of the bidirectional converter unit is determined based on the droop voltage drop due to inter-station line loss and the load droop voltage drop.

[0048] The embodiments of this application comprehensively consider the inter-station line loss droop voltage drop and the load droop voltage drop of the bidirectional converter unit to determine its total droop voltage drop.

[0049] The total droop voltage drop of the bidirectional converter unit is the sum of the inter-station line loss droop voltage drop and the load droop voltage drop of the bidirectional converter unit.

[0050] In S203, based on the total droop voltage drop, droop control is performed on the bidirectional converter unit to make the bidirectional converter unit simulate the droop characteristics of the rectifier unit.

[0051] This application embodiment controls the droop of the bidirectional converter unit by using the total droop voltage drop, thereby enabling the bidirectional converter unit to simulate the droop characteristics of the rectifier unit, so that the output voltages of the two units have the same droop characteristics, avoiding cross-site power supply and reducing power supply efficiency.

[0052] In some possible implementations, the above-mentioned droop control of the bidirectional converter unit based on the total droop voltage drop may include: Obtain the reference DC voltage of the bidirectional converter unit; The reference DC voltage after droop is determined based on the reference DC voltage and the total droop voltage drop; The actual DC voltage of the bidirectional converter unit is controlled based on the reference DC voltage after drooping.

[0053] In this embodiment, the reference DC voltage of the bidirectional converter unit is its regulated voltage under normal conditions, which is usually a fixed value. Its value can be the output voltage value of the rectifier unit when it is unloaded, or it can be determined to other values ​​according to actual needs. No specific restrictions are made here.

[0054] The reference DC voltage of the bidirectional converter is obtained by subtracting its total droop voltage drop from its reference DC voltage. The actual DC voltage of the bidirectional converter is then controlled to be the droop-down reference DC voltage. Controlling the actual DC voltage of the bidirectional converter based on the droop-down reference DC voltage is a mature technology in this field and will not be elaborated further.

[0055] To ensure the stability of the traction power supply system, the technical solution provided in this application is a transitional solution between the traditional power supply scheme in which the power supply equipment of each station only includes rectifier units and does not include bidirectional converter units, and the future power supply scheme in which the power supply equipment of each station only includes bidirectional converter units and does not include rectifier units.

[0056] This application addresses a traction power supply system that includes both rectifier units and bidirectional converter units. By implementing droop control on the bidirectional converter units, the droop characteristics of the bidirectional converter units are simulated, resulting in DC voltages with similar or identical output characteristics to the rectifier units. Specifically, when determining the total droop voltage drop of the bidirectional converter units, both inter-station line loss droop voltage drop and load droop voltage drop are considered. This allows droop control based on the total droop voltage drop to eliminate the voltage difference between the station where the bidirectional converter unit is located and adjacent stations, avoiding cross-station power supply. This, in turn, avoids or reduces rail potential corrosion and line losses caused by cross-station power supply. Furthermore, by considering the inter-station line loss droop voltage drop, load distribution between adjacent stations can be optimized, bringing the power supply boundary closer to the midpoint between the two stations. This reduces long-distance current transmission, significantly reducing overall system line losses and improving system power supply efficiency.

[0057] Specifically, if a power supply unit at a certain station includes a rectifier and a bidirectional converter connected in parallel, while the power supply unit at its adjacent station only includes a rectifier, then when a vehicle is running between these two stations, the station with the higher output voltage typically supplies power to the vehicle. However, if one station (referred to as station A) is powered by both a rectifier and a bidirectional converter, while the other station (referred to as station B) is powered only by a rectifier, then under the same load, the output current of the rectifier at station A is lower than that at station B. Based on the droop characteristic of rectifiers, the output voltage of the rectifier at station A is higher than that at station B. Without considering the droop voltage drop due to line losses between stations, the power supply distance at station A is longer than that at station B. In other words, the power supply boundary is not located in the middle of the two stations, which increases line losses and reduces system power supply efficiency. In this embodiment, considering the voltage drop due to line loss between stations, the output voltage of the bidirectional converter unit at station A will be lower than the output voltage of the rectifier unit at the same station. At this time, the rectifier unit will carry the entire load or most of the load. As the load increases, the output voltage of the rectifier unit will also decrease. When it drops to the output voltage of the bidirectional converter unit, a balance between the rectifier units and the bidirectional converter units within the station can be achieved. Simultaneously, due to the decrease in the output voltage of station A, the power supply boundary between station A and station B will move closer to station A, approaching or becoming the midpoint between the two stations. This reduces line loss, improves the system's power supply efficiency, and also achieves voltage balance between station A and station B, avoiding cross-station power supply. This prevents rail potential corrosion and line loss caused by cross-station power supply, further improving the system's power supply efficiency.

[0058] The same applies to situations where the power supply equipment of a certain site includes bidirectional converter units, and the power supply equipment of its adjacent sites only includes rectifier units. The same effect can be achieved, so I will not elaborate further.

[0059] The foregoing embodiments are an introduction to the overall implementation process of the droop control method of the traction power supply system. The specific implementation process of each step is further described below.

[0060] In some embodiments, obtaining the load droop voltage drop corresponding to the bidirectional converter unit in S201 includes: Obtain the actual DC current and actual load status of the bidirectional converter unit; Determine the droop factor of the bidirectional converter unit based on the actual load conditions; Determine the load factor based on the type of the site where the bidirectional converter unit is located; The load droop voltage drop of the bidirectional converter unit is determined based on the load factor, actual DC current, and droop factor.

[0061] The actual DC current of the bidirectional converter unit is its actual DC side current. The actual load condition of the bidirectional converter unit is its actual DC side load condition. The type of the site where the bidirectional converter unit is located is either a second site or a third site.

[0062] Rectifier units exhibit droop characteristics, but the changes in their output voltage and output current are not linear. Therefore, in this embodiment, the load conditions can be divided into multiple load states, and the interval corresponding to each load state can be considered a linear interval, corresponding to a droop coefficient. The droop coefficient can be considered as the amount by which the voltage needs to decrease for every 1A increase in current under the corresponding load state. Based on this, this embodiment can determine the corresponding droop coefficient based on the actual load state of the bidirectional converter unit.

[0063] In some possible implementations, a correspondence between load states and droop coefficients can be pre-stored, and the droop coefficient corresponding to the actual load state can be determined based on this correspondence.

[0064] For a power supply station containing parallel-connected rectifier units and bidirectional converter units (i.e., the third station), to achieve current sharing between the rectifier units and bidirectional converter units within the station, the load droop voltage drop obtained by multiplying the droop factor by the actual DC current is sufficient. However, for a power supply station containing only bidirectional converter units and no rectifier units (i.e., the second station), current sharing within the station is not required; therefore, its load droop voltage drop can be 0. To implement the control scheme in both cases, this application embodiment determines the final load droop voltage drop through a load factor. The load factor is determined based on whether the bidirectional converter units are connected in parallel with rectifier units, that is, based on whether the station containing the bidirectional converter units is the third station, or whether it is the third station or the second station. Finally, the load droop voltage drop of the bidirectional converter units is determined based on the load factor, the actual DC current, and the droop factor.

[0065] The load droop voltage drop of the bidirectional converter unit is the product of the load factor, the actual DC current, and the droop factor.

[0066] In this embodiment, the power supply configurations of the sites are diverse. Using a uniform load droop voltage drop might not be applicable to all sites. For example, for the second site, its power supply includes bidirectional converters but not rectifiers. The bidirectional converters do not need to share current with the rectifiers, and the load droop voltage drop is mainly used to achieve current sharing with the rectifiers in the same site. Therefore, for the second site, the product of the droop coefficient and the actual DC current is not needed as the load droop voltage drop. However, for the third site, current sharing is required. Based on this, this embodiment determines the load droop voltage drop by comprehensively considering the actual DC current, the actual load state, and the site type. This allows for refined and scenario-specific adaptation of load droop control, improving control flexibility and applicability under different transitional configurations.

[0067] In some embodiments, determining the load factor based on the type of the site where the bidirectional converter unit is located includes: If the type of the site where the bidirectional converter unit is located is the second site, then the load factor is determined to be 0; If the bidirectional converter unit is located at a site of type 3, then the load factor is determined to be greater than 0.

[0068] As mentioned earlier, the load factor can be determined based on the type of the site where the bidirectional converter unit is located. If the site is a type 2 site, meaning it only includes bidirectional converter units, then no in-site current sharing is required, and its load factor can be 0, meaning the load droop voltage drop can be 0. If the site is a type 3 site, meaning it includes both bidirectional converter units and rectifier units, then in-site current sharing is required, and its load factor is a value greater than 0. For example, it can be a value greater than 0 and less than or equal to 1, typically 1.

[0069] This application provides a clear and reasonable method for determining the load factor in the aforementioned embodiments. The decision to enable the load current droop effect is based on whether the power supply equipment at the site includes parallel rectifier units, i.e., whether the site is a second or third site. Specifically, when the site is a second site, the load factor is set to 0. This means that in this scenario, load droop based on the droop factor and actual DC current can be ignored, focusing on solving the problem of cross-site line loss compensation. When the site is a third site, the load factor (greater than 0) is enabled to ensure current sharing among parallel devices within the site. This differentiated approach makes the droop control strategy more targeted and practical for engineering, effectively matching the internal needs of different sites.

[0070] In some possible implementations, if the bidirectional converter unit is located at a second-type site, the load factor can be 0 or close to 0, meaning the load droop drop can be 0 or a small value. If the bidirectional converter unit is located at a third-type site, the load factor is determined to be greater than 0. For example, a small dividing line value can be used for differentiation. If the bidirectional converter unit is located at a second-type site, the load factor is determined to be between 0 and this dividing line value (inclusive of 0 and the dividing line value). If the bidirectional converter unit is located at a third-type site, the load factor is determined to be between the dividing line value and 1 (exclusive of the dividing line value, inclusive of 1). The dividing line value is greater than 0 and less than 1. The specific value of the load factor for different types can be determined by combining the inter-site line loss droop drop, ensuring that the total droop drop meets the goals of non-inter-site power supply and optimal power supply efficiency.

[0071] In some embodiments, obtaining the actual load status of the bidirectional converter unit includes: If the actual DC current is less than or equal to the first preset current, or if the actual power of the bidirectional converter is less than or equal to the first preset power, then the actual load state of the bidirectional converter is determined to be the first load state. If the actual DC current is greater than the first preset current and less than or equal to the second preset current, or if the actual power is greater than the first preset power and less than or equal to the second preset power, then the actual load state of the bidirectional converter unit is determined to be the second load state. If the actual DC current is greater than the second preset current, or the actual power is greater than the second preset power, then the actual load state of the bidirectional converter unit is determined to be the third load state. Wherein, the first preset current is less than the second preset current, and the first preset power is less than the second preset power.

[0072] In this embodiment, the actual load state of the bidirectional converter can be determined based on the actual DC current of the bidirectional converter, or it can be determined based on the actual power of the bidirectional converter. The actual power refers to the actual power on its DC side.

[0073] Specifically, if the actual DC current is less than or equal to the first preset current, the actual load state of the bidirectional converter unit is determined to be the first load state; if the actual DC current is greater than the first preset current and less than or equal to the second preset current, the actual load state of the bidirectional converter unit is determined to be the second load state; if the actual DC current is greater than the second preset current, the actual load state of the bidirectional converter unit is determined to be the third load state. Alternatively, if the actual power of the bidirectional converter unit is less than or equal to the first preset power, the actual load state of the bidirectional converter unit is determined to be the first load state; if the actual power is greater than the first preset power and less than or equal to the second preset power, the actual load state of the bidirectional converter unit is determined to be the second load state; if the actual power is greater than the second preset power, the actual load state of the bidirectional converter unit is determined to be the third load state.

[0074] Since the actual DC current of the bidirectional converter unit is related to its actual power, the first preset power is the power corresponding to the first preset current, and the second preset power is the power corresponding to the second preset current.

[0075] The load conditions of the bidirectional converter unit under different load states are as follows: first load state < second load state < third load state. For example, the first load state can be an unloaded or lightly loaded state, the second load state can be a medium load state, and the third load state can be a heavy load state, and so on.

[0076] It should be noted that the embodiments of this application divide the load state into three categories, but in practical applications, it can be divided into more categories. The more detailed the division, the higher the accuracy, but the more complex the calculation. Therefore, this application takes into account both accuracy and calculation efficiency and divides the load state into three categories.

[0077] In some embodiments, the actual load state includes a first load state, a second load state, or a third load state. The first load state corresponds to the first droop coefficient, the second load state corresponds to the second droop coefficient, and the third load state corresponds to the third droop coefficient.

[0078] In some embodiments, the first droop coefficient is 0; The second and third droop coefficients are determined by fitting the output voltage-output current curves of the rectifier unit under the same actual load conditions.

[0079] In the embodiments of this application, different load states correspond to different droop coefficients.

[0080] The first droop coefficient corresponding to the first load state is 0, meaning the load droop voltage drop under the first load state is 0. In this case, droop control of the bidirectional converter unit is only based on the droop voltage drop due to inter-station line loss. Under no-load or light-load conditions, the current is smaller, and the current sharing requirements for the rectifier unit and bidirectional converter unit are lower. Therefore, the first droop coefficient can be set to 0, and droop control of the bidirectional converter unit is only based on the droop voltage drop due to inter-station line loss.

[0081] The second droop coefficient corresponding to the second load state and the third droop coefficient corresponding to the third load state can be the absolute values ​​of the slopes obtained by linearly fitting the output voltage-output current curves of the rectifier unit under the same load state.

[0082] This application's embodiments map different load states to different droop coefficients. The corresponding droop coefficient can be determined based on the actual load state, making the equivalent output characteristic of the bidirectional converter unit appear as a broken line composed of multiple segments with different slopes. This piecewise linearization describes the simulated object (i.e., the rectifier unit) more accurately than a single slope, allowing droop control to more precisely fit the droop characteristics of the rectifier unit across the entire load range. This results in a smoother and more realistic simulation effect in hybrid systems, optimizing the system's dynamic and steady-state performance under different load levels.

[0083] In some embodiments, at least one neighboring station of the second station is the first station, and / or, at least one neighboring station of the third station is the first station.

[0084] In this embodiment of the application, for a site containing a bidirectional converter unit, at least one of its adjacent sites is the first site.

[0085] For stations that are both the first and last stations, there is only one adjacent station. For stations that are intermediate stations (i.e., neither the first nor the last station), there are two adjacent stations.

[0086] If the stations containing bidirectional converter units are the first and last stations, then their adjacent stations are one, and that station is the first station. If the stations containing bidirectional converter units are intermediate stations, then one of their two adjacent stations is the first station, or both of their adjacent stations are the first stations.

[0087] The method provided in this application embodiment can be applied to traction power supply systems where at least one adjacent station of the second station is the first station, and / or at least one adjacent station of the third station is the first station. For traction power supply systems with other structures, although the method provided in this application embodiment can also be used for control, it may not be the optimal solution, and other better technical solutions may exist. For example, for a traction power supply system containing only bidirectional converter units, more flexible control of the bidirectional converter units can be adopted.

[0088] In some embodiments, obtaining the inter-station line loss droop voltage drop corresponding to the bidirectional converter unit includes: Determine whether the adjacent site of the bidirectional converter unit is the first site; If both adjacent stations of the bidirectional converter unit are the first station, the inter-station line loss droop voltage drop corresponding to the bidirectional converter unit is determined based on the larger of the distances between the bidirectional converter unit and the two adjacent stations and the line loss coefficient. If one of the adjacent stations of the bidirectional converter unit is the first station, then the inter-station line loss droop voltage drop corresponding to the bidirectional converter unit is determined based on the distance between the bidirectional converter unit and the adjacent station and the line loss coefficient.

[0089] In this embodiment of the application, if both adjacent stations of the bidirectional converter unit are the first station, the distances between the bidirectional converter unit and its two adjacent stations are obtained, and the larger of the two distances is taken. The product of the line loss coefficient, the larger value and the line resistance per unit length is taken as the inter-station line loss droop voltage drop corresponding to the bidirectional converter unit.

[0090] If one of the adjacent stations of the bidirectional converter unit is the first station, the distance between the bidirectional converter unit and the adjacent station is directly obtained, and the product of the line loss coefficient, the distance and the line resistance per unit length is used as the inter-station line loss droop voltage drop corresponding to the bidirectional converter unit.

[0091] Here, the resistance per unit length refers to the resistance per unit length of the transmission line used to transmit electrical energy between two stations. This transmission line can be a steel rail or any other suitable transmission line.

[0092] The line loss coefficient is greater than 0 and less than or equal to 1. Normally, the line loss coefficient is set to 1. However, when considering both inter-station line loss droop and load droop, the line loss coefficient can be flexibly set to ensure that the total droop meets the goals of non-inter-station power supply and optimal power supply efficiency.

[0093] This application provides a method for determining the droop voltage drop of inter-station line losses. By distinguishing between one or both sides of the bidirectional converter unit as the first station and selecting the most unfavorable (farthest) line for compensation, the output voltage of the DC side of the bidirectional converter unit can be actively reduced, causing the load current to be provided more by the first station closer to the train. This substantially pushes the optimal power supply boundary point to the midpoint between the two stations, minimizes the overall line loss, improves system efficiency, and avoids cross-station power supply.

[0094] In a specific application scenario, such as Figure 3 As shown, Figure 3 The output voltage-output current curves of the rectifier units included in the power supply equipment at the same site are given, as well as the voltage-current curves of the DC side of the bidirectional converter unit after droop control.

[0095] exist Figure 3 In the first load state, when the actual DC current is 0-300A or the actual power is 0-500kW, the corresponding first droop coefficient is 0. At this time, the DC side voltage of the bidirectional converter is lower than the output voltage of the rectifier unit, and the rectifier unit mainly supplies power, while the bidirectional converter unit does not produce power.

[0096] When the actual DC current is between 300A and 1200A or the actual power is between 500kW and 2MW, it is in the second load state, and the corresponding second droop coefficient is 0.083. The DC side voltage of the bidirectional converter unit is between 1635V and 1560V. During this stage, the bidirectional converter unit begins to share the traction network power.

[0097] When the actual DC current exceeds 1200A or the actual power exceeds 2MW, it is in the third load state, with a corresponding third droop factor of 0.0058. The DC side voltage range of the bidirectional converter unit is 1560V-1546V. During this stage, the bidirectional converter unit and the rectifier unit share the current. When the DC side voltage is below 1550V, the load is mainly carried by the bidirectional converter unit, which can reduce the power supply loss across stations.

[0098] The aforementioned droop coefficients can be fine-tuned according to the actual situation.

[0099] It should be understood that the sequence number of each step in the above embodiments does not imply 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 this application.

[0100] The following are device embodiments of this application. For details not described in detail, please refer to the corresponding method embodiments described above.

[0101] Figure 4 A schematic diagram of the droop control device of the traction power supply system provided in an embodiment of this application is shown. For ease of explanation, only the parts related to the embodiment of this application are shown, and are described in detail below: The traction power supply system includes power supply units for multiple stations; wherein at least one station is a first station, and the remaining stations include at least one of a second station and a third station; the power supply unit for the first station includes a rectifier unit; the power supply unit for the second station includes a bidirectional converter unit; and the power supply unit for the third station includes a rectifier unit and a bidirectional converter unit connected in parallel. Figure 4As shown, the droop control device 4 of the traction power supply system includes: an acquisition module 41, a total droop voltage drop determination module 42, and a droop control module 43.

[0102] The acquisition module 41 is used to acquire the inter-station line loss droop voltage drop and load droop voltage drop corresponding to the bidirectional converter unit; The total droop voltage drop determination module 42 is used to determine the total droop voltage drop of the bidirectional converter unit based on the droop voltage drop of the inter-station line loss and the load droop voltage drop. The droop control module 43 is used to control the droop of the bidirectional converter unit based on the total droop voltage drop, so that the bidirectional converter unit can simulate the droop characteristics of the rectifier unit.

[0103] In one possible implementation, the acquisition module 41 acquires the load droop voltage drop corresponding to the bidirectional converter unit, including: Obtain the actual DC current and actual load status of the bidirectional converter unit; Determine the droop factor of the bidirectional converter unit based on the actual load conditions; Determine the load factor based on the type of the site where the bidirectional converter unit is located; The load droop voltage drop of the bidirectional converter unit is determined based on the load factor, actual DC current, and droop factor.

[0104] In one possible implementation, in the acquisition module 41, the load factor is determined based on the type of the site where the bidirectional converter unit is located, including: If the type of the site where the bidirectional converter unit is located is the second site, then the load factor is determined to be 0; If the bidirectional converter unit is located at a site of type 3, then the load factor is determined to be greater than 0.

[0105] In one possible implementation, the acquisition module 41 acquires the actual load status of the bidirectional converter unit, including: If the actual DC current is less than or equal to the first preset current, or if the actual power of the bidirectional converter is less than or equal to the first preset power, then the actual load state of the bidirectional converter is determined to be the first load state. If the actual DC current is greater than the first preset current and less than or equal to the second preset current, or if the actual power is greater than the first preset power and less than or equal to the second preset power, then the actual load state of the bidirectional converter unit is determined to be the second load state. If the actual DC current is greater than the second preset current, or the actual power is greater than the second preset power, then the actual load state of the bidirectional converter unit is determined to be the third load state. Wherein, the first preset current is less than the second preset current, and the first preset power is less than the second preset power.

[0106] In one possible implementation, the actual load state includes a first load state, a second load state, or a third load state. The first load state corresponds to the first droop coefficient, the second load state corresponds to the second droop coefficient, and the third load state corresponds to the third droop coefficient.

[0107] In one possible implementation, the first droop coefficient is 0; The second and third droop coefficients are determined by fitting the output voltage-output current curves of the rectifier unit under the same actual load conditions.

[0108] In one possible implementation, the acquisition module 41 acquires the inter-station line loss droop voltage drop corresponding to the bidirectional converter unit, including: Determine whether the adjacent site of the bidirectional converter unit is the first site; If both adjacent stations of the bidirectional converter unit are the first station, the inter-station line loss droop voltage drop corresponding to the bidirectional converter unit is determined based on the larger of the distances between the bidirectional converter unit and the two adjacent stations and the line loss coefficient. If one of the adjacent stations of the bidirectional converter unit is the first station, then the inter-station line loss droop voltage drop corresponding to the bidirectional converter unit is determined based on the distance between the bidirectional converter unit and the adjacent station and the line loss coefficient.

[0109] In one possible implementation, at least one neighboring station of the second station is the first station, and / or, at least one neighboring station of the third station is the first station.

[0110] Figure 5 This is a schematic diagram of the control device provided in an embodiment of this application. Figure 5 As shown, the control device 5 in this embodiment includes a processor 50 and a memory 51. The memory 51 stores a computer program 52. When the processor 50 executes the computer program 52, it implements the steps in the various method embodiments described above. Alternatively, when the processor 50 executes the computer program 52, it implements the functions of each module / unit in the various device embodiments described above.

[0111] For example, the computer program 52 may be divided into one or more modules / units, which are stored in the memory 51 and executed by the processor 50 to complete the present application. The one or more modules / units may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program 52 in the control device 5.

[0112] The control device 5 may include, but is not limited to, a processor 50 and a memory 51. Those skilled in the art will understand that... Figure 5 This is merely an example of control device 5 and does not constitute a limitation on control device 5. It may include more or fewer components than shown, or combine certain components, or different components. For example, control device 5 may also include input / output devices, network access devices, buses, etc.

[0113] The processor 50 can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0114] The memory 51 can be an internal storage unit of the control device 5, such as a hard disk or RAM of the control device 5. The memory 51 can also be an external storage device of the control device 5, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the control device 5. Furthermore, the memory 51 can include both internal and external storage units of the control device 5. The memory 51 is used to store the computer program 52 and other programs and data required by the control device 5. The memory 51 can also be used to temporarily store data that has been output or will be output.

[0115] For the sake of simplicity and clarity, only the above-described functional modules / units are used as examples. In practical applications, the functions described above can be assigned to different functional modules / units as needed. These modules / units can be implemented in hardware, software, or a combination of both.

[0116] This application also provides a traction power supply system, including power supply devices for multiple stations; Wherein, at least one station is a first station, and the remaining stations include at least one of a second station and a third station; the power supply device of the first station includes a rectifier unit; the power supply device of the second station includes a bidirectional converter unit and the aforementioned control equipment; the power supply device of the third station includes a rectifier unit and a bidirectional converter unit connected in parallel, as well as the aforementioned control equipment. The bidirectional converter unit is controlled by the corresponding control equipment.

[0117] For details regarding the traction power supply system, please refer to the content in the foregoing embodiments, which will not be repeated here.

[0118] This application also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the methods described in the above-described method embodiments.

[0119] This application also provides a computer program product, including a computer program. When the computer program is executed by a processor, it implements the methods in the above-described method embodiments.

[0120] Computer programs include computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. Computer-readable media can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0121] In the above embodiments, the descriptions of each embodiment have their own emphasis. Parts not detailed or described in a particular embodiment can be referred to in the relevant descriptions of other embodiments. Unless otherwise specified or in conflict with logic, the terminology and / or descriptions between different embodiments are consistent and can be referenced interchangeably. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0122] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A droop control method for a traction power supply system, characterized in that, The traction power supply system includes power supply devices for multiple stations; wherein at least one station is a first station, and the remaining stations include at least one of a second station and a third station; the power supply device for the first station includes a rectifier unit; the power supply device for the second station includes a bidirectional converter unit; the power supply device for the third station includes a rectifier unit and a bidirectional converter unit connected in parallel; the method includes: Obtain the inter-station line loss droop voltage drop and load droop voltage drop corresponding to the bidirectional converter unit; The total droop voltage drop of the bidirectional converter unit is determined based on the inter-station line loss droop voltage drop and the load droop voltage drop. Based on the total droop voltage drop, droop control is performed on the bidirectional converter unit to make the bidirectional converter unit simulate the droop characteristics of the rectifier unit. The inter-station line loss droop voltage drop is the voltage that the bidirectional converter needs to droop, determined based on the distance between the station where the bidirectional converter is located and its adjacent stations and the line loss coefficient. The load droop voltage drop is the voltage that the bidirectional converter needs to droop, determined based on the actual load condition of the bidirectional converter.

2. The sag control method for the traction power supply system according to claim 1, characterized in that, Obtaining the load droop voltage drop corresponding to the bidirectional converter unit includes: Obtain the actual DC current and actual load status of the bidirectional converter unit; Based on the actual load conditions, the droop coefficient of the bidirectional converter unit is determined; The load factor is determined based on the type of the site where the bidirectional converter unit is located; The load droop voltage drop of the bidirectional converter unit is determined based on the load factor, the actual DC current, and the droop factor.

3. The sag control method for the traction power supply system according to claim 2, characterized in that, The determination of the load factor based on the type of the site where the bidirectional converter unit is located includes: If the type of the site where the bidirectional converter unit is located is the second site, then the load factor is determined to be 0; If the type of the site where the bidirectional converter unit is located is a third site, then the load factor is determined to be greater than 0.

4. The sag control method for the traction power supply system according to claim 2, characterized in that, Obtaining the actual load status of the bidirectional converter unit includes: If the actual DC current is less than or equal to the first preset current, or if the actual power of the bidirectional converter is less than or equal to the first preset power, then the actual load state of the bidirectional converter is determined to be the first load state. If the actual DC current is greater than the first preset current and less than or equal to the second preset current, or if the actual power is greater than the first preset power and less than or equal to the second preset power, then the actual load state of the bidirectional converter unit is determined to be the second load state. If the actual DC current is greater than the second preset current, or the actual power is greater than the second preset power, then the actual load state of the bidirectional converter unit is determined to be the third load state. Wherein, the first preset current is less than the second preset current, and the first preset power is less than the second preset power.

5. The sag control method for the traction power supply system according to claim 2, characterized in that, The actual load state includes a first load state, a second load state, or a third load state; The first load state corresponds to the first droop coefficient, the second load state corresponds to the second droop coefficient, and the third load state corresponds to the third droop coefficient.

6. The sag control method for the traction power supply system according to claim 5, characterized in that, The first droop coefficient is 0; The second droop coefficient and the third droop coefficient are determined based on the fitting of the output voltage-output current curves of the rectifier unit under the same actual load conditions.

7. The sag control method for the traction power supply system according to claim 1, characterized in that, Obtaining the inter-station line loss droop voltage drop corresponding to the bidirectional converter unit includes: Determine whether the adjacent station of the bidirectional converter unit is the first station; If both adjacent stations of the bidirectional converter unit are the first station, then the inter-station line loss droop voltage drop corresponding to the bidirectional converter unit is determined based on the larger of the distances between the bidirectional converter unit and the two adjacent stations and the line loss coefficient. If one of the adjacent stations of the bidirectional converter unit is the first station, then the inter-station line loss droop voltage drop corresponding to the bidirectional converter unit is determined based on the distance between the bidirectional converter unit and the adjacent station and the line loss coefficient.

8. The sag control method for the traction power supply system according to any one of claims 1 to 7, characterized in that, At least one neighboring station of the second station is the first station, and / or at least one neighboring station of the third station is the first station.

9. A control device, characterized in that, It includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the sag control method of the traction power supply system as described in any one of claims 1 to 8.

10. A traction power supply system, characterized in that, Includes power supply equipment for multiple sites; Wherein, at least one station is a first station, and the remaining stations include at least one of a second station and a third station; the power supply device of the first station includes a rectifier unit; the power supply device of the second station includes a bidirectional converter unit and the control device as described in claim 9; the power supply device of the third station includes a rectifier unit and a bidirectional converter unit connected in parallel, and the control device as described in claim 9. The bidirectional converter unit is controlled by the corresponding control equipment.

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