A bilateral traction power supply system equivalent method and system considering compensation type devices

Abstract

The application relates to the technical field of electrified railway traction power supply, and provides a bilateral traction power supply system equivalent method and system considering compensation-type equipment. The method comprises the following steps: acquiring system topological relations, traction transformer parameters, real-time power demand of an energy storage system and a node admittance matrix of each part; determining a coefficient according to the real-time power demand of the energy storage system, establishing a comprehensive node admittance matrix of an energy storage-type traction substation; determining a compensation current according to a negative sequence current component of three-phase currents on a primary side of a center compensation traction substation, and establishing a whole node admittance matrix of the center compensation traction substation; and combining parallel operation relations of each traction substation and the system topological relations to form a whole node admittance matrix of the system. The application can simultaneously consider the functions of the energy storage system and the negative sequence compensation equipment in the equivalent model, improves the accuracy of equivalent modeling of the bilateral traction power supply system, and provides a model basis for power flow, power supply capacity and energy consumption analysis.

Description

Technical Field

[0001] This application relates to the field of electrified railway traction power supply technology, specifically to an equivalent method and system for a bilateral traction power supply system considering compensating equipment. Background Technology

[0002] As electric locomotives and EMUs develop towards high speed and heavy load, the limitations of traditional single-sided out-of-phase traction power supply methods in terms of power supply capacity, regenerative braking energy utilization, and phase-crossing operation are becoming increasingly apparent. To improve traction power supply capacity and train operating conditions, double-sided traction power supply systems are gaining attention. These systems typically involve multiple traction substations jointly supplying power to the traction network and can be equipped with energy storage devices and negative sequence compensation devices to meet the needs of traction load power supply, power quality improvement, and regenerative braking energy utilization.

[0003] Compared to traditional traction power supply systems, bilateral traction power supply systems involve parallel power supply relationships between multiple traction substations. Furthermore, the operation of energy storage devices and negative-sequence compensation devices alters the electrical characteristics of their respective traction substations, making the voltage and current relationships between different parts of the system more complex. Existing equivalent methods for traction power supply systems are mostly geared towards traditional traction power supply systems with relatively fixed structures and operating modes. For bilateral traction power supply systems that simultaneously include energy storage devices and negative-sequence compensation devices, it is difficult to accurately reflect the impact of different traction substations and their connected equipment on the system's electrical characteristics within a unified model.

[0004] Therefore, how to perform a unified and accurate mathematical equivalence on a bilateral traction power supply system that includes energy storage devices and negative sequence compensation devices has become a technical problem that needs to be solved when further analyzing the system's energy consumption, power quality, and power supply capacity. Summary of the Invention

[0005] This application aims to address the problems in the prior art by providing an equivalent method and system for a bilateral traction power supply system that considers compensating equipment, thereby improving the accuracy of equivalent modeling of the bilateral traction power supply system.

[0006] To achieve the above objectives, the first aspect of this application provides an equivalent method for a bilateral traction power supply system considering compensating equipment. The bilateral traction power supply system includes an external power source, a group of traction substations, a high-voltage transmission line connecting the external power source and the group of traction substations, and a traction network connected to the group of traction substations.

[0007] The traction substation group includes one centrally compensated traction substation and at least one energy storage traction substation. The centrally compensated traction substation includes a first single-phase traction transformer and a negative sequence compensation device connected to the primary AC bus of the centrally compensated traction substation. Each of the energy storage traction substations includes a second single-phase traction transformer and an energy storage system connected to the secondary side of the corresponding energy storage traction substation. The secondary output voltages of the centrally compensated traction substation and each of the energy storage traction substations are in phase and operate in parallel, and are respectively connected to the traction network. The method includes: Obtain the topological connection relationship of the bilateral traction power supply system, the turns ratio and impedance of the first single-phase traction transformer and each of the second single-phase traction transformers, the real-time power demand of each of the energy storage systems, and the node admittance matrix of the external power source, the high-voltage transmission line and the traction network; For each of the energy storage traction substations, a coefficient m is determined based on the real-time power demand of the corresponding energy storage system. The access currents at both ends of the energy storage system are set to negative m times the node current of the corresponding node on the secondary side of the energy storage traction substation. The energy storage system and the second single-phase traction transformer are considered as a whole. Based on the coefficient m and the turns ratio and impedance of the second single-phase traction transformer, the voltage and current relationship of each node of the energy storage traction substation is established, and the comprehensive node admittance matrix of the energy storage traction substation is obtained. Based on the turns ratio and impedance of the first single-phase traction transformer, the node voltage-current relationship of the first single-phase traction transformer is established. According to the node voltage-current relationship, the negative sequence current component of the three-phase current on the primary side of the central compensation traction substation before compensation is determined. According to the negative sequence current component, the three-phase compensation current output by the negative sequence compensation device is determined so that the negative sequence current component of the three-phase current on the primary side after compensation is zero. The negative sequence compensation device and the first single-phase traction transformer are regarded as a whole. Based on the node voltage-current relationship and the three-phase compensation current, the voltage-current relationship of each node of the central compensation traction substation is established, and the overall node admittance matrix of the central compensation traction substation is obtained. According to the parallel operation relationship, the overall node admittance matrix of the central compensation traction substation and the comprehensive node admittance matrix of each energy storage traction substation are combined to obtain the node admittance matrix of the traction substation group. Based on the aforementioned topological connections, the node admittance matrices of the external power source, the high-voltage transmission line, the traction substation group, and the traction network are integrated to obtain the overall system node admittance matrix, which serves as the overall mathematical equivalent model of the bilateral traction power supply system.

[0008] A second aspect of this application provides an equivalent system for a bilateral traction power supply system considering compensating equipment. The bilateral traction power supply system includes an external power source, a group of traction substations, a high-voltage transmission line connecting the external power source and the group of traction substations, and a traction network connected to the group of traction substations. The traction substation group includes one centrally compensated traction substation and at least one energy storage traction substation. The centrally compensated traction substation includes a first single-phase traction transformer and a negative sequence compensation device connected to the primary AC bus of the centrally compensated traction substation. Each of the energy storage traction substations includes a second single-phase traction transformer and an energy storage system connected to the secondary side of the corresponding energy storage traction substation. The secondary output voltages of the centrally compensated traction substation and each of the energy storage traction substations are in phase and operate in parallel, and are respectively connected to the traction network. The equivalent system includes: The parameter acquisition module is used to acquire the topological connection relationship of the bilateral traction power supply system, the turns ratio and impedance of the first single-phase traction transformer and each of the second single-phase traction transformers, the real-time power demand of each of the energy storage systems, and the node admittance matrix of the external power source, the high-voltage transmission line and the traction network. An equivalent module for energy storage traction substations is used to determine a coefficient m for each energy storage traction substation based on the real-time power demand of the corresponding energy storage system, set the access current at both ends of the energy storage system to be negative m times the node current of the corresponding node on the secondary side of the energy storage traction substation, and regard the energy storage system and the second single-phase traction transformer as a whole. Based on the coefficient m and the turns ratio and impedance of the second single-phase traction transformer, the voltage and current relationship of each node of the energy storage traction substation is established to obtain the comprehensive node admittance matrix of the energy storage traction substation. The equivalent module of the centrally compensated traction substation is used to establish the node voltage-current relationship of the first single-phase traction transformer based on the turns ratio and impedance of the first single-phase traction transformer, determine the negative sequence current component of the primary side three-phase current of the centrally compensated traction substation before compensation based on the node voltage-current relationship, and determine the three-phase compensation current output by the negative sequence compensation device based on the negative sequence current component, so that the negative sequence current component of the primary side three-phase current after compensation is zero; the negative sequence compensation device and the first single-phase traction transformer are regarded as a whole, and the voltage-current relationship of each node of the centrally compensated traction substation is established based on the node voltage-current relationship and the three-phase compensation current, so as to obtain the overall node admittance matrix of the centrally compensated traction substation; The equivalent module for the traction substation group is used to combine the overall node admittance matrix of the central compensation traction substation and the comprehensive node admittance matrix of each of the energy storage traction substations according to the parallel operation relationship, so as to obtain the node admittance matrix of the traction substation group. The system equivalent module is used to integrate the node admittance matrices of the external power source, the high-voltage transmission line, the traction substation group and the traction network according to the topological connection relationship, so as to obtain the overall system node admittance matrix, which serves as the overall mathematical equivalent model of the bilateral traction power supply system.

[0009] A third aspect of this application provides a terminal device, including a processor and a memory, wherein the memory stores a computer program that, when executed by the processor, implements the method described above.

[0010] A fourth aspect of this application provides a readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described method.

[0011] Compared with the prior art, this application has the following beneficial effects: By establishing the comprehensive node admittance matrix for energy storage-type traction substations and the overall node admittance matrix for center-compensated traction substations, and combining the parallel operation relationships of each traction substation with the topological connection relationships of the bilateral traction power supply system, a system-wide node admittance matrix is ​​formed. This allows the roles of both the energy storage system and the negative-sequence compensation equipment to be considered simultaneously in the system equivalent model, avoiding the loss of model information caused by only considering the characteristics of the traction transformer itself. This provides a model foundation for power flow analysis of the bilateral traction power supply system, as well as research on power quality, power supply capacity, energy consumption characteristics, and impact on external power sources. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a flowchart illustrating a method provided in an embodiment of this application; Figure 2 This is a schematic diagram of the topology of a bilateral traction power supply system provided in an embodiment of this application; Figure 3 This is a schematic diagram of the voltage and current relationship of an energy storage traction substation provided in one embodiment of this application; Figure 4This is a schematic diagram of the voltage and current relationship of a centrally compensated traction substation provided in an embodiment of this application; Figure 5 This is a schematic diagram of a chain circuit network structure provided in an embodiment of this application; Figure 6 This is a schematic diagram of the equivalent node admittance matrix of a bilateral traction power supply system provided in an embodiment of this application; Figure 7 This is a schematic diagram of the structure of a system provided in an embodiment of this application; Figure 8 This is a schematic diagram of the structure of a terminal device provided in an embodiment of this application. Detailed Implementation

[0014] To facilitate understanding of this application, the following description will be more comprehensive and detailed in conjunction with the accompanying drawings and preferred embodiments, but the scope of protection of this application is not limited to the following specific embodiments.

[0015] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of this application.

[0016] Please see Figure 1 One embodiment of this application provides an equivalent method for a bilateral traction power supply system that takes into account compensating equipment.

[0017] The dual-sided traction power supply system includes an external power source, a group of traction substations, high-voltage transmission lines connecting the external power source and the group of traction substations, and a traction network connected to the group of traction substations.

[0018] The traction substation group comprises one center-compensated traction substation (CTS) and multiple energy storage traction substations (TS1 to TSn). The center-compensated traction substation includes a first single-phase traction transformer and negative-sequence compensation equipment connected to the primary AC busbar of the center-compensated traction substation. Each energy storage traction substation includes a second single-phase traction transformer and an energy storage system connected to the secondary side of the corresponding energy storage traction substation. The secondary output voltages of the center-compensated traction substation and each energy storage traction substation are phase-synchronized and operate in parallel, and are connected to the traction network respectively.

[0019] External power supply is used to provide power to the bilateral traction power supply system. High-voltage transmission lines are used to connect the PCC point of the external power supply to the traction power supply system with each traction substation. The traction network is connected to the secondary side of each traction substation through feeders and supplies power to trains running on the traction network. Figure 2 The overall topology of the bilateral traction power supply system is shown.

[0020] The equivalent method for a bilateral traction power supply system considering compensating equipment includes the following steps: S102. Obtain the topological connection relationship of the bilateral traction power supply system, the turns ratio and impedance of the first single-phase traction transformer and each second single-phase traction transformer, the real-time power demand of each energy storage system, and the node admittance matrix of the external power supply, high-voltage transmission line and traction network.

[0021] In this step, the topology connection relationship includes at least the connection relationship between the external power source and each traction substation, the connection relationship between the primary side and the secondary side within each traction substation, and the connection relationship between the secondary side of each traction substation and the traction network.

[0022] The turns ratio and impedance of the first and second single-phase traction transformers are used to determine the voltage and current relationships between the nodes of the corresponding traction transformers. The real-time power demand of each energy storage system is used to determine the power demand of the corresponding energy storage system under its current operating conditions, and based on this, to determine the coefficients used in the equivalent process of the energy storage-type traction substation. .

[0023] External power sources, high-voltage transmission lines, and traction networks can be described using corresponding nodal admittance matrices. Specifically, existing power system modeling methods can be used to obtain the nodal admittance matrices, which can then be used as input for the subsequent construction of the overall system model.

[0024] S104. For each energy storage-type traction substation, determine the coefficient based on the real-time power demand of the corresponding energy storage system. ,coefficient This represents the proportional relationship between the input current of the energy storage system and the corresponding secondary-side node current. The input currents at both ends of the energy storage system are set as the negative values ​​of the node currents at the corresponding secondary-side nodes of the energy storage traction substation. The energy storage system and the second single-phase traction transformer are considered as a whole, based on a coefficient. In addition to the turns ratio and impedance of the second single-phase traction transformer, the voltage and current relationships of each node in the energy storage traction substation are established, and the comprehensive node admittance matrix of the energy storage traction substation is obtained.

[0025] In this step, the energy storage system's access current is introduced based on the existing node voltage-current relationship of the second single-phase traction transformer, so that the operating status of the energy storage system is reflected in the comprehensive node admittance matrix of the energy storage-type traction substation. Different energy storage-type traction substations determine the corresponding coefficients according to the real-time power demand of their respective energy storage systems. And obtain the corresponding comprehensive node admittance matrix.

[0026] Specifically, the energy storage system controller determines the energy storage system connection current based on real-time power demand and the current voltage and current at the connection point, and then determines a coefficient based on the proportional relationship between the energy storage system connection current and the secondary-side node current. .

[0027] S106. Based on the turns ratio and impedance of the first single-phase traction transformer, establish the node voltage and current relationship of the first single-phase traction transformer. Determine the negative sequence current component of the three-phase current on the primary side of the central compensation traction substation before compensation according to the node voltage and current relationship. Determine the three-phase compensation current output by the negative sequence compensation device according to the negative sequence current component so that the negative sequence current component of the three-phase current on the primary side after compensation is zero. Treat the negative sequence compensation device and the first single-phase traction transformer as a whole. Based on the node voltage and current relationship and the three-phase compensation current, establish the voltage and current relationship of each node of the central compensation traction substation to obtain the overall node admittance matrix of the central compensation traction substation.

[0028] In this step, the three-phase primary current formed after the first single-phase traction transformer is connected is obtained, and the negative sequence current component is determined. Then, the corresponding three-phase compensation current is output by the negative sequence compensation device. The compensation effect of the negative sequence compensation device and the electrical characteristics of the first single-phase traction transformer are reflected together in the overall node admittance matrix of the central compensation traction substation.

[0029] S108. According to the parallel operation relationship, the overall node admittance matrix of the central compensation traction substation and the comprehensive node admittance matrix of each energy storage traction substation are combined to obtain the node admittance matrix of the traction substation group.

[0030] In this step, based on the node number of each traction substation and the actual electrical connection relationship, the overall node admittance matrix of the central compensation traction substation and the comprehensive node admittance matrix of each energy storage traction substation are configured to the corresponding positions of the node admittance matrix of the traction substation group.

[0031] For the admittance terms corresponding to the same electrical node in different traction substations, the corresponding admittances are combined to obtain the traction substation group node admittance matrix that can uniformly describe the electrical characteristics of the central compensation traction substation and each energy storage traction substation.

[0032] Since the integrated node admittance matrix of the energy storage type traction substation already includes the influence of the energy storage system's operating status, and the overall node admittance matrix of the centrally compensated traction substation already includes the compensation effect of the negative sequence compensation device, the combined node admittance matrix of the traction substation group can simultaneously reflect the influence of the energy storage system and the negative sequence compensation device on the operating characteristics of the traction substation group.

[0033] S110. Based on the topological connection relationship, the node admittance matrices of the external power source, high-voltage transmission line, traction substation group and traction network are integrated to obtain the overall node admittance matrix of the system, which serves as the overall mathematical equivalent model of the bilateral traction power supply system.

[0034] In this step, each node is first uniformly numbered according to the topological connection relationship of the bilateral traction power supply system. Then, the node admittance matrices corresponding to the external power supply, high-voltage transmission line, traction substation group and traction network are configured to the corresponding positions in the overall node admittance matrix of the system.

[0035] For the common nodes between the external power supply and the high-voltage transmission line, the common nodes between the high-voltage transmission line and each traction substation, and the common nodes between each traction substation and the traction network, the corresponding admittance terms are integrated according to the corresponding electrical connection relationships to form the overall system node admittance matrix. . Figure 6 The process of constructing the overall node admittance matrix of the system is shown.

[0036] In this embodiment, by establishing the comprehensive node admittance matrix of the energy storage traction substation and the overall node admittance matrix of the centrally compensated traction substation, and then combining the parallel operation relationship of each traction substation and the topological connection relationship of the bilateral traction power supply system, a system-wide node admittance matrix is ​​formed. This allows the roles of the energy storage system and the negative-sequence compensation equipment to be considered simultaneously in the system equivalent model, avoiding the loss of model information caused by only considering the characteristics of the traction transformer itself. This provides a model foundation for power flow analysis of the bilateral traction power supply system, as well as for research on power quality, power supply capacity, energy consumption characteristics, and impact on external power sources.

[0037] In one embodiment, the node admittance matrix of the external power source, high-voltage transmission line, and traction network can be determined in the following manner.

[0038] For external power sources, equivalent characteristics can be derived from the electrical characteristics at the PCC point where the bilateral traction power supply system connects to the external power source. In a power system, short-circuit capacity and a reference voltage can be used to represent the power supply capacity and impedance characteristics presented by the power source. Let the short-circuit capacity of the bilateral traction power supply system connected to the external power source be... The reference voltage is When establishing the external power source model, only the electrical characteristics of the external power source at point PCC can be considered, ignoring the specific structure of the power plant, substation and transmission line upstream of point PCC, and the Norton equivalent circuit can be used to represent the external power source.

[0039] The three-phase node admittance matrix corresponding to the external power supply can be expressed as:

[0040] in, , and These represent the equivalent admittances of phases A, B, and C of the external power supply at point PCC, respectively. Therefore, the upstream power system can be simplified while preserving the electrical characteristics of the external power supply at point PCC.

[0041] For high-voltage transmission lines, a corresponding nodal admittance matrix can be established based on the line parameters and length. High-voltage transmission lines can be three-phase overhead transmission lines. Different conductors have different impedance and admittance parameters; the corresponding unit length parameters can be determined based on the specific conductor type, and the equivalent impedance matrix can be determined by combining this with the length of each section of the high-voltage transmission line. and equivalent admittance matrix .

[0042] Since the high-voltage transmission lines between the external power supply PCC point and each traction substation have a certain length, the influence of line distribution parameters can be considered, and a π-type equivalent circuit of a multi-conductor transmission line can be used to address the issue. The section of the high-voltage transmission line is described. The nodal admittance matrix of a high-voltage transmission line can be expressed as:

[0043] in,

[0044]

[0045] In the formula, Indicates the first The equivalent self-admittance matrix corresponding to a high-voltage transmission line segment. Indicates the first The equivalent mutual admittance matrix corresponding to a high-voltage transmission line segment. and These represent the equivalent impedance matrix and equivalent admittance matrix of the high-voltage transmission line segment, respectively.

[0046] Based on the actual connection relationships between each high-voltage transmission line segment and the external power supply and each traction substation, the self-admittance and mutual admittance of each high-voltage transmission line segment are configured to the corresponding nodes, thus forming the node admittance matrix of the high-voltage transmission line segment.

[0047] In one embodiment, the traction network may include multiple conductors such as catenary wires, contact wires, return wires, ground wires, rails, and protective conductors, and is connected to the secondary side of each traction substation via feeders. The traction network is used to provide electrical energy to trains whose positions change continuously along the track. Since the output voltage phases of the secondary sides of each traction substation are consistent, phase separation is not required between adjacent traction substations or at the outlet of the traction substation, allowing the traction network to maintain continuous power supply.

[0048] Specifically, a chain circuit can be used to model the traction network. The transverse sections, such as the train access point, the parallel line connection point, and the feeder-traction network connection point, are treated as different cross sections, and the traction network conductors between adjacent cross sections are treated as longitudinal connections, thereby dividing the traction network into multiple network segments connected sequentially. Figure 5 The corresponding chain circuit network structure is shown.

[0049] Let the nodal admittance matrices corresponding to each transverse section be as follows: , … The equivalent impedance matrices of the traction network conductors between adjacent cross-sections are respectively , … Then the admittance matrix of the traction network nodes can be expressed as:

[0050] in, Indicates the first The nodal admittance matrix formed by the transverse connecting parts such as trains, parallel lines, or feeders in each cross-section. Indicates the first The first cross-section and the first The equivalent impedance matrix of the traction network conductor between each cross section. The equivalent impedance matrix of each traction network conductor segment can be determined based on the impedance parameter per unit length of the traction network conductor and the corresponding segment length.

[0051] In this way, the train, feeder, and traction network conductors can be uniformly reflected in the traction network node admittance matrix. In the case of a train, when the train's position changes, the length of the lateral section where the train is located and the adjacent traction network segments also change accordingly. The corresponding node admittance matrix can be updated based on the changed network structure.

[0052] After obtaining the node admittance matrices of the external power source, high-voltage transmission lines, traction substation group and traction network, the overall node admittance matrix of the system can be further constructed according to the actual topological connection relationship of the bilateral traction power supply system.

[0053] Specifically, each electrical node in the bilateral traction power supply system is uniformly numbered, and the self-admittance terms corresponding to the external power supply, high-voltage transmission lines, traction substation group, and traction network are configured to the corresponding positions in the overall system node admittance matrix according to the node number. Based on the connection relationship formed by the high-voltage transmission lines, feeders, and traction network conductors, the corresponding mutual admittance terms are configured to the overall system node admittance matrix.

[0054] For the shared electrical nodes between the external power source and the high-voltage transmission line, between the high-voltage transmission line and each traction substation, and between each traction substation and the traction network, the admittance terms of the corresponding nodes are superimposed to form the overall system node admittance matrix. Therefore, the external power source, high-voltage transmission lines, traction substation group including energy storage system and negative sequence compensation equipment, and traction network can be uniformly represented in the same node admittance matrix.

[0055] In one embodiment, the primary AC bus of the centrally compensated traction substation is connected to the three-phase line of the external power supply, so that the centrally compensated traction substation is powered by the three-phase external power supply, and each energy storage traction substation draws power from the same two phases of the external power supply.

[0056] Specifically, the primary side of the centrally compensated traction substation is connected to the three-phase line of the external power supply, enabling the negative sequence compensation equipment installed on the primary side AC bus to perform negative sequence compensation according to the operating conditions of the three-phase current. The second single-phase traction transformer in each energy storage traction substation adopts the same two-phase power supply method, thereby maintaining the same phase relationship between the secondary side output voltages of each energy storage traction substation.

[0057] Through the above power supply method, the secondary output voltage phases of the central compensation traction substation and each energy storage traction substation are made consistent, allowing the secondary sides of each traction substation to be connected in parallel to the same traction network. The traction networks between adjacent traction substations can maintain electrical continuity, eliminating the need for electrical isolation through phase separation between adjacent traction substations and at the outlet of the traction substation, thus achieving continuous power supply between adjacent traction substations.

[0058] In this embodiment, by making the output voltage phase of the secondary side of each traction substation consistent, it is possible to provide conditions for each traction substation to supply power to the traction network in parallel, and it is also conducive to realizing bilateral power supply, so that different traction substations can share the traction load.

[0059] In one embodiment, the energy storage system includes an energy storage medium, a power electronic converter, and a transformer, wherein the power electronic converter is used to enable bidirectional energy flow between the energy storage medium and the traction power supply system.

[0060] The energy storage medium is used to store and release electrical energy, and can be energy storage devices such as lithium batteries and supercapacitors. The energy storage medium is connected to the secondary side of the energy storage traction substation via a power electronic converter and a transformer.

[0061] When the energy storage system is charging, the power electronic converter transfers electrical energy from the traction power supply system to the energy storage medium for storage. When the energy storage system is discharging, the power electronic converter transfers electrical energy from the energy storage medium to the traction power supply system. Therefore, the energy transfer direction of the energy storage system can be adjusted according to the actual operating requirements of the traction power supply system.

[0062] The real-time charging and discharging states of an energy storage system correspond to different real-time power demands. These real-time power demands can be further used to determine the coefficients in the equivalent model of an energy storage-type traction substation. This allows the operating status of the energy storage system to be reflected in the integrated node admittance matrix of the energy storage traction substation.

[0063] In this embodiment, by setting up an energy storage system capable of bidirectional energy transmission in the energy storage type traction substation, the energy storage type traction substation can be equipped with the ability to absorb and release electrical energy.

[0064] In one embodiment, establishing the integrated nodal admittance matrix of an energy storage traction substation includes the following process.

[0065] Please see Figure 3 The voltage and current of each node inside the energy storage traction substation are defined with the direction of the current flowing into the node as the positive direction.

[0066] in, , These represent the node voltages of the corresponding nodes on the primary side of the second single-phase traction transformer. , These represent the node voltages of the corresponding nodes on the secondary side of the second single-phase traction transformer; , These represent the node currents of the corresponding nodes on the primary side; , These represent the node currents on the secondary side of the second single-phase traction transformer when the energy storage system is not connected; , These represent the corresponding node currents on the secondary side after the energy storage system is connected; , These represent the current flowing into the energy storage system at both ends.

[0067] Without considering the connection of the energy storage system, based on the transformation ratio of the primary side to the secondary side of the second single-phase traction transformer. and impedance referred to the secondary side Establish the node voltage and current relationship between the primary and secondary nodes of the second single-phase traction transformer:

[0068] In the formula, This refers to the turns ratio of the primary side to the secondary side of the second single-phase traction transformer. This is the impedance of the second single-phase traction transformer referred to the secondary side.

[0069] Based on this, the access current of the energy storage system is introduced. A coefficient is determined according to the real-time power demand of the energy storage system. And according to the pre-defined positive current direction, the relationship between the current connected to both ends of the energy storage system and the corresponding secondary side node current is determined as follows:

[0070] Among them, coefficient This indicates the proportional relationship between the energy storage system's inlet current and the corresponding secondary-side node current. The negative sign indicates that, under the specified current reference direction, the reference direction of the energy storage system's inlet current is opposite to that of the corresponding secondary-side node current.

[0071] By combining the above connection current relationship with the node voltage and current relationship of the second single-phase traction transformer, the voltage and current relationship between each node of the energy storage traction substation is obtained:

[0072] Based on the above node voltage and current relationships, the comprehensive node admittance matrix of the energy storage traction substation can be determined as follows:

[0073] It should be noted that the above node voltage-current relationships and some matrix elements of the integrated node admittance matrix contain... When using the above expression form as the denominator, the following conditions must be met: .

[0074] In this embodiment, by establishing the relationship between the energy storage system's access current and the node voltage and current of the second single-phase traction transformer, the energy storage system and the second single-phase traction transformer can be described as a whole. When the real-time power demand of the energy storage system changes, the coefficients can be re-determined based on the corresponding power relationship. And update the integrated node admittance matrix of the energy storage traction substation so that the operating status of the energy storage system can be reflected in the overall mathematical equivalent model of the subsequent bilateral traction power supply system.

[0075] In one embodiment, the negative sequence compensation device includes a three-phase transformer and a three-phase static var generator (SVG).

[0076] Among them, the three-phase transformer connects the primary AC bus of the central compensation traction substation to the three-phase static var generator (SVG), enabling the three-phase SVG to be electrically connected to the primary three-phase AC bus via the three-phase transformer.

[0077] After the first single-phase traction transformer is connected to the primary AC bus, a negative sequence current component may be generated in the three-phase current of the primary side. The three-phase static var generator (SVG) controls the trigger signal of the power switching device according to the required three-phase compensation current, so that the three-phase static var generator (SVG) outputs the corresponding three-phase compensation current to the primary AC bus of the central compensation traction substation.

[0078] The power switching devices can be IGBTs. By controlling the trigger signals of each IGBT, the three-phase compensation current output by the three-phase static var generator (SVG) can be adjusted so that the compensation current corresponds to the negative sequence current formed after the first single-phase traction transformer is connected, thereby implementing negative sequence compensation for the three-phase current on the primary side of the central compensation traction substation.

[0079] In this embodiment, a three-phase static var generator (SVG) is connected to the primary AC bus of the centrally compensated traction substation via a three-phase transformer. The SVG outputs corresponding three-phase compensation current, which reduces the three-phase current imbalance caused by the connection of the first single-phase traction transformer. When negative-sequence full compensation is used, the negative-sequence current component in the primary three-phase current after compensation is made zero.

[0080] In one embodiment, establishing the overall node admittance matrix of a centrally compensated traction substation includes the following process.

[0081] Please see Figure 4 The voltage and current of each node inside the centrally compensated traction substation are defined with the direction of the current flowing into the node as the positive direction.

[0082] in, , , These represent the node voltages of phases A, B, and C on the primary side of the centrally compensated traction substation, respectively. , These represent the node voltages of the corresponding nodes on the secondary side of the first single-phase traction transformer. , This represents the branch current on the primary side of the first single-phase traction transformer when the negative sequence compensation equipment is not included. , , These represent the A-phase compensation current, B-phase compensation current, and C-phase compensation current output by the negative sequence compensation device, respectively. , , These represent the A-phase current, B-phase current, and C-phase current on the primary side of the centrally compensated traction substation after compensation.

[0083] Without considering the connection of negative sequence compensation equipment, the node voltage and current relationship between the primary and secondary nodes is established based on the turns ratio of the first single-phase traction transformer and its impedance referred to the secondary side. The first single-phase traction transformer can adopt the aforementioned node voltage and current model for single-phase traction transformers, where the turns ratio and impedance are the parameters corresponding to the first single-phase traction transformer.

[0084] Based on the above node voltage and current relationships, the relationship of the three-phase currents on the primary side after the first single-phase traction transformer is connected can be determined. The negative sequence current component in the three-phase current on the primary side is determined using the symmetrical component method.

[0085] make:

[0086] in, The base of the natural index is . It is the imaginary unit.

[0087] The required three-phase compensation current for the negative sequence compensation device is determined based on the primary current relationship. The negative sequence compensation current relationship is as follows:

[0088] In the formula, , , These represent the negative sequence current components corresponding to phases A, B, and C on the primary side before compensation. The negative sequence compensation device outputs the corresponding phase A compensation current for each of the aforementioned negative sequence current components. Phase B compensation current and C-phase compensation current .

[0089] like Figure 4 As shown, the compensated phase A current Phase B current and C-phase current satisfy:

[0090] For phases A and B, the compensated node current is determined by the branch current of the first single-phase traction transformer and the corresponding compensation current. For phase C, since the first single-phase traction transformer does not generate a corresponding phase C branch current, the compensated phase C current is determined by the phase C compensation current.

[0091] By combining the above three-phase compensation current relationship, the compensated three-phase current relationship, and the node voltage and current relationship of the first single-phase traction transformer, we can obtain the voltage and current relationships of each node in the centrally compensated traction substation:

[0092] In the formula, and In this embodiment, the turns ratio and impedance referred to the secondary side of the first single-phase traction transformer are used respectively.

[0093] Based on the relationship between the current column vector and the voltage column vector, the coefficient matrix can be determined as the overall node admittance matrix of the centrally compensated traction substation. Therefore, the negative-sequence compensation equipment and the first single-phase traction transformer are uniformly reflected in the same node admittance matrix.

[0094] In this embodiment, by determining the primary side negative sequence current component after the first single-phase traction transformer is connected, the corresponding three-phase compensation current is output by controlling the negative sequence compensation device. Then, the relationship between the three-phase current after compensation is combined with the relationship between the node voltage and current of the first single-phase traction transformer. This allows the establishment of an overall node admittance matrix that simultaneously reflects the effects of the first single-phase traction transformer and the negative sequence compensation device. This provides a foundation for the establishment of the node admittance matrix of the subsequent traction substation group and the overall node admittance matrix of the bilateral traction power supply system.

[0095] like Figure 7 As shown, this application also provides an equivalent system 300 for a bilateral traction power supply system considering compensating equipment. The bilateral traction power supply system includes an external power source, a group of traction substations, a high-voltage transmission line connecting the external power source and the group of traction substations, and a traction network connected to the group of traction substations. The traction substation group includes one centrally compensated traction substation and at least one energy storage traction substation. The centrally compensated traction substation includes a first single-phase traction transformer and a negative sequence compensation device connected to the primary AC bus of the centrally compensated traction substation. Each of the energy storage traction substations includes a second single-phase traction transformer and an energy storage system connected to the secondary side of the corresponding energy storage traction substation. The secondary output voltages of the centrally compensated traction substation and each of the energy storage traction substations are in phase and operate in parallel, and are respectively connected to the traction network. Equivalent systems include: The parameter acquisition module 302 is used to acquire the topological connection relationship of the bilateral traction power supply system, the turns ratio and impedance of the first single-phase traction transformer and each of the second single-phase traction transformers, the real-time power demand of each of the energy storage systems, and the node admittance matrix of the external power source, the high-voltage transmission line and the traction network. The equivalent module 304 for energy storage traction substations is used to determine a coefficient m for each energy storage traction substation based on the real-time power demand of the corresponding energy storage system, set the access current at both ends of the energy storage system to be negative m times the node current of the corresponding node on the secondary side of the energy storage traction substation, and regard the energy storage system and the second single-phase traction transformer as a whole. Based on the coefficient m and the turns ratio and impedance of the second single-phase traction transformer, the voltage and current relationship of each node of the energy storage traction substation is established to obtain the comprehensive node admittance matrix of the energy storage traction substation. The equivalent module 306 for the centrally compensated traction substation is used to establish the node voltage-current relationship of the first single-phase traction transformer based on the turns ratio and impedance of the first single-phase traction transformer; determine the negative sequence current component of the primary side three-phase current of the centrally compensated traction substation before compensation based on the node voltage-current relationship; and determine the three-phase compensation current output by the negative sequence compensation device based on the negative sequence current component, so that the negative sequence current component of the primary side three-phase current after compensation is zero; and consider the negative sequence compensation device and the first single-phase traction transformer as a whole, establish the voltage-current relationship of each node of the centrally compensated traction substation based on the node voltage-current relationship and the three-phase compensation current, and obtain the overall node admittance matrix of the centrally compensated traction substation. The equivalent module 308 for the traction substation group is used to combine the overall node admittance matrix of the central compensation traction substation and the comprehensive node admittance matrix of each energy storage traction substation according to the parallel operation relationship, so as to obtain the node admittance matrix of the traction substation group. The system equivalent module 310 is used to integrate the node admittance matrices of the external power source, the high-voltage transmission line, the traction substation group and the traction network according to the topological connection relationship, so as to obtain the overall system node admittance matrix, which serves as the overall mathematical equivalent model of the bilateral traction power supply system.

[0096] Each module in the above system can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of the computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0097] Furthermore, the central compensation traction substation is powered by the three-phase external power source, and each of the energy storage type traction substations draws power from the same two phases of the external power source, so that the secondary side output voltages of the central compensation traction substation and each of the energy storage type traction substations are in phase, and the traction network between adjacent traction substations is connected for power supply.

[0098] like Figure 8As shown, this application also provides a terminal device, including a processor 401 and a memory 402. The memory 402 stores a program or instructions that can run on the processor 401. When the program or instructions are executed by the processor 401, they implement the various steps of the above method embodiments and can achieve the same technical effect. To avoid repetition, they will not be described again here.

[0099] This application also provides a readable storage medium storing a program or instructions that, when executed by a processor, implement the various processes of the above-described method embodiments and achieve the same technical effects. To avoid repetition, these will not be described again here.

[0100] Among them, readable storage media include computer-readable storage media, such as computer read-only memory, random access memory, magnetic disk or optical disk, etc.

[0101] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0102] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a computer software product, which is stored in a storage medium (such as a read-only memory). The device includes a number of instructions in a ROM (random access memory), RAM (magnetic disk), or optical disk to cause a terminal to execute the methods described in the various embodiments of this application.

[0103] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. An equivalent method for a bilateral traction power supply system considering compensating equipment, characterized in that, The bilateral traction power supply system includes an external power source, a group of traction substations, a high-voltage transmission line connecting the external power source and the group of traction substations, and a traction network connected to the group of traction substations. The traction substation group includes one centrally compensated traction substation and at least one energy storage traction substation. The centrally compensated traction substation includes a first single-phase traction transformer and a negative sequence compensation device connected to the primary AC bus of the centrally compensated traction substation. Each of the energy storage traction substations includes a second single-phase traction transformer and an energy storage system connected to the secondary side of the corresponding energy storage traction substation. The secondary output voltages of the centrally compensated traction substation and each of the energy storage traction substations are in phase and operate in parallel, and are respectively connected to the traction network. The method includes: Obtain the topological connection relationship of the bilateral traction power supply system, the turns ratio and impedance of the first single-phase traction transformer and each of the second single-phase traction transformers, the real-time power demand of each of the energy storage systems, and the node admittance matrix of the external power source, the high-voltage transmission line and the traction network; For each of the energy storage traction substations, a coefficient m is determined based on the real-time power demand of the corresponding energy storage system. The access currents at both ends of the energy storage system are set to negative m times the node current of the corresponding node on the secondary side of the energy storage traction substation. The energy storage system and the second single-phase traction transformer are considered as a whole. Based on the coefficient m and the turns ratio and impedance of the second single-phase traction transformer, the voltage and current relationship of each node of the energy storage traction substation is established, and the comprehensive node admittance matrix of the energy storage traction substation is obtained. Based on the turns ratio and impedance of the first single-phase traction transformer, the node voltage-current relationship of the first single-phase traction transformer is established. According to the node voltage-current relationship, the negative sequence current component of the three-phase current on the primary side of the central compensation traction substation before compensation is determined. According to the negative sequence current component, the three-phase compensation current output by the negative sequence compensation device is determined so that the negative sequence current component of the three-phase current on the primary side after compensation is zero. The negative sequence compensation device and the first single-phase traction transformer are regarded as a whole. Based on the node voltage-current relationship and the three-phase compensation current, the voltage-current relationship of each node of the central compensation traction substation is established, and the overall node admittance matrix of the central compensation traction substation is obtained. According to the parallel operation relationship, the overall node admittance matrix of the central compensation traction substation and the comprehensive node admittance matrix of each energy storage traction substation are combined to obtain the node admittance matrix of the traction substation group. Based on the aforementioned topological connections, the node admittance matrices of the external power source, the high-voltage transmission line, the traction substation group, and the traction network are integrated to obtain the overall system node admittance matrix, which serves as the overall mathematical equivalent model of the bilateral traction power supply system.

2. The equivalent method for a bilateral traction power supply system considering compensating equipment according to claim 1, characterized in that, The central compensation traction substation is powered by the three-phase external power source, and each of the energy storage traction substations draws power from the same two phases of the external power source, so that the secondary output voltages of the central compensation traction substation and each of the energy storage traction substations are in phase, and the traction network between adjacent traction substations is connected for power supply.

3. The equivalent method for a bilateral traction power supply system considering compensating equipment according to claim 1, characterized in that, The energy storage system includes an energy storage medium, a power electronic converter, and a transformer. The power electronic converter is used to enable bidirectional energy flow between the energy storage medium and the traction power supply system.

4. The equivalent method for a bilateral traction power supply system considering compensating equipment according to claim 3, characterized in that, Establishing the comprehensive nodal admittance matrix of the energy storage traction substation includes: Taking the direction of the current flowing into the node as the positive direction, and without considering the connection of the energy storage system, the turns ratio of the second single-phase traction transformer is used. and impedance referred to the secondary side Establish the node voltage and current relationship between the primary and secondary nodes of the second single-phase traction transformer; The access current of the energy storage system is introduced, and according to: in, , These represent the corresponding node currents on the secondary side after the energy storage system is connected. , These represent the current supplied to both ends of the energy storage system; Determine the relationship between the current connected to both ends of the energy storage system and the corresponding secondary-side node current; Combining the aforementioned connection current relationship with the node voltage-current relationship of the second single-phase traction transformer, we obtain: in, and These represent the node currents at the corresponding nodes on the primary side of the second single-phase traction transformer. and These represent the node voltages of the corresponding nodes on the primary side of the second single-phase traction transformer. and These represent the node voltages of the corresponding nodes on the secondary side of the second single-phase traction transformer; This indicates the turns ratio of the primary side to the secondary side of the second single-phase traction transformer; Determine the comprehensive nodal admittance matrix of the energy storage traction substation. for: 。 5. The equivalent method for a bilateral traction power supply system considering compensating equipment according to claim 1, characterized in that, The negative sequence compensation device includes a three-phase transformer and a three-phase static var generator (SVG). The three-phase transformer is connected to the primary AC bus of the central compensation traction substation and the three-phase SVG. The three-phase SVG outputs the three-phase compensation current through the trigger signal of the control power switching device to perform negative sequence compensation on the primary three-phase current of the central compensation traction substation.

6. The equivalent method for a bilateral traction power supply system considering compensating equipment according to claim 5, characterized in that, Establishing the overall nodal admittance matrix of the centrally compensated traction substation includes: Taking the direction of the current flowing into the node as the positive direction, and without considering the connection of the negative sequence compensation device, the node voltage and current relationship between the primary side node and the secondary side node is established based on the first single-phase traction transformer. The negative sequence current component of the three-phase primary current after the first single-phase traction transformer is connected is determined using the symmetrical component method, and the corresponding A-phase compensation current is output by the negative sequence compensation device. Phase B compensation current and C-phase compensation current ; Compensated phase A current Phase B current and C-phase current satisfy: in, and These represent the branch currents of phase A and phase B on the primary side of the first single-phase traction transformer, respectively, without considering the operation of the negative sequence compensation device; By combining the compensated three-phase current relationship with the node voltage and current relationship of the first single-phase traction transformer, the voltage and current relationship of each node of the centrally compensated traction substation is obtained, and the overall node admittance matrix of the centrally compensated traction substation is determined.

7. An equivalent system for a bilateral traction power supply system considering compensating equipment, characterized in that, The bilateral traction power supply system includes an external power source, a group of traction substations, a high-voltage transmission line connecting the external power source and the group of traction substations, and a traction network connected to the group of traction substations. The traction substation group includes one centrally compensated traction substation and at least one energy storage traction substation. The centrally compensated traction substation includes a first single-phase traction transformer and a negative sequence compensation device connected to the primary AC bus of the centrally compensated traction substation. Each of the energy storage traction substations includes a second single-phase traction transformer and an energy storage system connected to the secondary side of the corresponding energy storage traction substation. The secondary output voltages of the centrally compensated traction substation and each of the energy storage traction substations are in phase and operate in parallel, and are respectively connected to the traction network. The equivalent system includes: The parameter acquisition module is used to acquire the topological connection relationship of the bilateral traction power supply system, the turns ratio and impedance of the first single-phase traction transformer and each of the second single-phase traction transformers, the real-time power demand of each of the energy storage systems, and the node admittance matrix of the external power source, the high-voltage transmission line and the traction network. An equivalent module for energy storage traction substations is used to determine a coefficient m for each energy storage traction substation based on the real-time power demand of the corresponding energy storage system, set the access current at both ends of the energy storage system to be negative m times the node current of the corresponding node on the secondary side of the energy storage traction substation, and regard the energy storage system and the second single-phase traction transformer as a whole. Based on the coefficient m and the turns ratio and impedance of the second single-phase traction transformer, the voltage and current relationship of each node of the energy storage traction substation is established to obtain the comprehensive node admittance matrix of the energy storage traction substation. The equivalent module of the centrally compensated traction substation is used to establish the node voltage-current relationship of the first single-phase traction transformer based on the turns ratio and impedance of the first single-phase traction transformer, determine the negative sequence current component of the primary side three-phase current of the centrally compensated traction substation before compensation based on the node voltage-current relationship, and determine the three-phase compensation current output by the negative sequence compensation device based on the negative sequence current component, so that the negative sequence current component of the primary side three-phase current after compensation is zero; the negative sequence compensation device and the first single-phase traction transformer are regarded as a whole, and the voltage-current relationship of each node of the centrally compensated traction substation is established based on the node voltage-current relationship and the three-phase compensation current, so as to obtain the overall node admittance matrix of the centrally compensated traction substation; The equivalent module for the traction substation group is used to combine the overall node admittance matrix of the central compensation traction substation and the comprehensive node admittance matrix of each of the energy storage traction substations according to the parallel operation relationship, so as to obtain the node admittance matrix of the traction substation group. The system equivalent module is used to integrate the node admittance matrices of the external power source, the high-voltage transmission line, the traction substation group and the traction network according to the topological connection relationship, so as to obtain the overall system node admittance matrix, which serves as the overall mathematical equivalent model of the bilateral traction power supply system.

8. The equivalent system of the bilateral traction power supply system considering compensating equipment according to claim 7, characterized in that, The central compensation traction substation is powered by the three-phase external power source, and each of the energy storage traction substations draws power from the same two phases of the external power source, so that the secondary output voltages of the central compensation traction substation and each of the energy storage traction substations are in phase, and the traction network between adjacent traction substations is connected for power supply.

9. A terminal device, characterized in that, It includes a processor and a memory, wherein the memory stores a computer program that, when executed by the processor, implements the equivalent method of the bilateral traction power supply system considering compensating equipment as described in any one of claims 1 to 6.

10. A readable storage medium, characterized in that, It stores a computer program that, when executed by a processor, implements the equivalent method of the bilateral traction power supply system considering compensating equipment as described in any one of claims 1 to 6.

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