Load flow calculation method and system for alternating-current in-phase traction power supply system

Abstract

The embodiment of the invention provides a load flow calculation method and system for an alternating-current in-phase traction power supply system, and belongs to the technical field of rail transit power supply. The method comprises the following steps: establishing a traction substation equivalent circuit model based on a compensation current of a cophase power supply device and an electrical quantity constraint relation of a traction transformer; combining the node voltage model of the traction substation with the node admittance relationship of the chain circuit, and performing regularization processing to obtain a regularized load flow calculation model; establishing a mapping relation of compensation current of the in-phase power supply device, and coupling external power supply parameters into the mapping relation to obtain to-be-updated compensation current; and in the iteration process, the compensation current and the injection current of each node are updated according to the node voltage until the convergence condition is met, and then a load flow calculation result is output. According to the scheme, the problem of efficient solving of load flow calculation of the traction power supply system containing the in-phase power supply device is effectively solved, and the method can be applied to capacity configuration and operation optimization design of the in-phase power supply device in different operation scenes.

Description

Technical Field

[0001] This invention relates to the field of rail transit power supply technology, specifically to a power flow calculation method and a power flow calculation system for an AC in-phase traction power supply system. Background Technology

[0002] As the sole power source for electrified railway trains, the traction power supply system plays a crucial role in ensuring the safe, high-speed, and stable operation of railways.

[0003] The current traction power supply system faces power quality issues, primarily negative sequence current, and phase separation problems. Excessive negative sequence current can lead to additional losses and overheating in generators, reduced transformer capacity utilization, and malfunctions in relay protection devices. To address the negative sequence problem, electrified railways frequently rotate the phase sequence of traction substations connected to the power system, and also install phase separation at the outlet of traction substations and at the sectioning points between adjacent traction substations. These phase separations are de-energized areas; when trains pass through these phase separations, they may experience overvoltage leading to equipment damage, traction loss causing train stoppages, and braking loss leading to brake failure. Furthermore, the presence of phase separation prevents energy interconnection between adjacent power supply arms, making it difficult for trains operating in different power supply arm sections to fully utilize the regenerative braking energy of trains under braking conditions, resulting in a significant waste of green energy.

[0004] Connecting in-phase power supply devices to the traction power supply system can eliminate negative sequence problems and issues caused by phase separation at the traction substation outlet. It also enables energy interconnection between adjacent power supply arms, improving the utilization rate of regenerative braking energy. Furthermore, it can increase the traction network voltage and enhance the system's power supply capacity. However, connecting in-phase power supply devices to the traction power supply system will cause changes in the system's power flow distribution, affecting the system's operating boundaries and characteristics, necessitating analysis and evaluation through appropriate power flow calculations.

[0005] Power flow calculation is an important tool for assessing the power supply capacity and optimizing the operation of traction power supply systems. Traditional power flow calculation methods mainly focus on modeling and solving regular traction networks and traction substations, without considering the efficient solution of irregular networks caused by the integration of external power grids and in-phase power supply devices. The diversity and complexity of external power sources, as well as the diversity of in-phase power supply device integration schemes, will exacerbate the challenges faced by existing methods in terms of multi-topology compatibility and computational efficiency.

[0006] Against this backdrop, there is an urgent need for a power flow calculation method that reflects the coupling relationship between the in-phase power supply device and the external power source, traction transformers with different wiring methods, and traction network, while significantly reducing the number of iterations and computation time, so as to achieve efficient and accurate unified modeling and integration of external power grid, traction transformer, traction network, and in-phase power supply device into the chain circuit calculation framework. Summary of the Invention

[0007] The purpose of this invention is to provide a power flow calculation method and system for AC in-phase traction power supply systems, so as to at least solve the problems of irregular traction power supply network structure and difficulty in unified modeling and efficient calculation of power flow after the connection of in-phase power supply devices.

[0008] To achieve the above objectives, the first aspect of the present invention provides a power flow calculation method for an AC in-phase traction power supply system. The method includes: establishing an equivalent circuit model of the traction substation based on the compensation current of the in-phase power supply device and the electrical quantity constraints of the traction transformer; dividing the transmission line, feeder, and traction network into smaller power supply units using different numbered sections to construct a unified chain circuit model of the transmission line, feeder, and traction network; combining the node voltage model of the traction substation with the node admittance relationship of the chain circuit model to form an irregular power flow unified iterative node voltage model; and performing regularization processing on the irregular power flow unified iterative node voltage model to obtain a regularized power flow calculation model; establishing a mapping relationship for the compensation current of the in-phase power supply device based on the current supplied by the traction bus to the feeder, the target value of the three-phase voltage imbalance, and the target value of the power factor; and coupling external power supply parameters and node quantities of the chain circuit into the mapping relationship to obtain the compensation current to be updated; solving the regularized power flow calculation model using a matrix decomposition method; updating the compensation current and the injected current at each node according to the node voltage during the iteration process until the convergence condition is met, and then outputting the power flow calculation result.

[0009] Optionally, an equivalent circuit model of the traction substation is established based on the constraint relationship between the compensation current of the in-phase power supply device and the electrical quantities of the traction transformer. This includes: extracting the primary side port quantities based on the three-phase voltage and three-phase current parameters of the primary side of the traction transformer; calculating the secondary side port quantities based on the impedance parameters, port voltage parameters, and port connection angles of the secondary side of the traction transformer; after equivaling the compensation current of the in-phase power supply device to a controlled current source injected into the port, combining the primary side port quantities, secondary side port quantities, and controlled current source according to the electrical connection relationship to obtain the equivalent circuit model of the traction substation.

[0010] Optionally, the transmission lines, feeders, and traction networks can be divided into smaller power supply units using different numbered sections to construct a unified chain circuit model for the transmission lines, feeders, and traction networks. This includes: dividing the transmission lines, feeders, and traction networks into smaller power supply units using different numbered sections; sequentially dividing the node sets of each section according to the section numbers of the transmission lines, feeders, and traction networks; generating corresponding node admittance matrices based on the line electrical parameters of each node set; connecting the node admittance matrices of each section in section order to form a segmented admittance structure for the chain circuit; and using the segmented admittance structure as a whole as the chain circuit model.

[0011] Optionally, the irregular power flow unified iterative node voltage model is regularized to obtain a regularized power flow calculation model, including: identifying cross-section node coupling relationships in the irregular power flow unified iterative node voltage model; equivalently replacing the cross-section node quantities in the identified node coupling relationships with node quantities within the same cross section; rearranging the node quantities obtained from the equivalent replacement to generate a node admittance matrix structure in the form of a strip matrix, and using this strip matrix node admittance matrix structure as the regularized power flow calculation model.

[0012] Optionally, a mapping relationship for the compensation current of the in-phase power supply device is established based on the current supplied by the traction bus to the feeder, the target value of the three-phase voltage imbalance, and the target value of the power factor. This includes: calculating the current supplied by the traction bus to the feeder based on the node voltage and current electrical quantities corresponding to the feeder and the traction network; calculating the three-phase voltage imbalance constraint at the point of common coupling based on the target value of the three-phase voltage imbalance; calculating the power constraint at the traction bus based on the target value of the power factor; and combining the current supplied by the traction bus to the feeder, the three-phase voltage imbalance constraint, and the power constraint according to the mapping rules to form a mapping relationship for determining the compensation current of the in-phase power supply device.

[0013] Optionally, the current acquisition rule for the traction bus to the feeder is as follows: voltage and current information of the nodes at the connection between the traction bus and the feeder are acquired, and the nodes are merged into segments according to the cross-section to form the feeder current input for compensating the current mapping relationship; the rule for determining the target value of the three-phase voltage imbalance is as follows: the range of three-phase voltage imbalance at the common coupling point is determined based on the initial distribution of node voltages in the power flow calculation model; a target value for three-phase voltage imbalance compensation is selected within the range of the three-phase voltage imbalance and the preset allowable value of three-phase voltage imbalance; the rule for determining the target value of the power factor is as follows: the actual power components at the traction bus are decomposed into active and reactive components, and a target value representing the desired power distribution of the traction bus is determined according to the preset power factor limit interval, which serves as the power input for compensating the current mapping relationship.

[0014] Optionally, the regularized power flow calculation model is solved using a matrix decomposition method, including: converting the regularized power flow calculation model into a strip matrix structure; performing decomposition operations on the strip matrix according to the matrix decomposition rules to obtain the node voltages; and writing the obtained node voltages into the iterative process to update the compensation current of the in-phase power supply device and the injection current of the chain circuit nodes.

[0015] Optionally, during the iteration process, the compensation current and the injected current at each node are updated based on the node voltage, including: writing the solved node voltages and currents of the feeder and traction network range into the compensation current mapping relationship to regenerate the compensation current of the in-phase power supply device; simultaneously, performing node-by-node calculations on the solved node voltages and the node admittance data corresponding to each cross-section of the chain circuit to generate node injected currents representing the actual injection situation of each node in the chain circuit; and using the compensation current and node injected currents as inputs for the next solution of the regularized power flow calculation model to form a continuous iterative update chain.

[0016] A second aspect of this invention provides a power flow calculation system for an AC in-phase traction power supply system. The system includes: an initialization unit for establishing an equivalent circuit model of the traction substation based on the compensation current of the in-phase power supply device and the electrical quantity constraints of the traction transformer; and a model construction unit for dividing the transmission lines, feeders, and traction network into smaller power supply units using different numbered sections, constructing a unified chain circuit model of the transmission lines, feeders, and traction network, combining the node voltage model of the traction substation with the node admittance relationship of the chain circuit model, and forming a unified irregular power flow. The system iterates through node voltage models and regularizes irregular power flow by unifying the iterative node voltage models to obtain a regularized power flow calculation model. A mapping construction unit is used to establish a mapping relationship between the compensation current of the in-phase power supply device and the target values ​​of the three-phase voltage imbalance and power factor, based on the current supplied by the traction bus to the feeder, the target value of the three-phase voltage imbalance, and the target value of the power factor. External power supply parameters and node quantities of the chain circuit are coupled into the mapping relationship to obtain the compensation current to be updated. An output unit is used to solve the regularized power flow calculation model using matrix decomposition. During the iteration process, the compensation current and the injected current at each node are updated based on the node voltage until the convergence condition is met, at which point the power flow calculation results are output.

[0017] On the other hand, the present invention provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the above-described power flow calculation method for an AC in-phase traction power supply system.

[0018] Through the above technical solution, this invention constructs an equivalent circuit model of the traction substation using the compensation current of the in-phase power supply device, enabling the electrical relationship between the in-phase power supply device and the traction transformer to be incorporated into the power flow calculation framework in a unified form. By establishing a chain circuit model through the cross-sectional division of transmission lines, feeders, and the traction network, and combining the traction substation node voltage model with the node admittance relationship of the chain circuit, the traction power supply network containing the in-phase power supply device can be solved for power flow in a unified iterative structure. Furthermore, irregular power flow structures are regularized, transforming the power flow calculation process into a regularized model solvable using a fixed matrix structure. The compensation current mapping relationship, constructed based on the traction bus current, the target value of the three-phase voltage imbalance, and the target value of the power factor, allows the compensation current of the in-phase power supply device to be dynamically updated with changes in node voltage. The matrix decomposition method is used to update node voltage, compensation current, and node injection current during iteration, enabling the power flow solution to be completed within a unified model, yielding power flow results usable for traction system analysis and operation control.

[0019] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart of the steps of a power flow calculation method for an AC in-phase traction power supply system provided in one embodiment of the present invention; Figure 2 This is a schematic diagram of a train power supply system provided in one embodiment of the present invention; Figure 3 This is a schematic diagram of dynamic power flow calculation using a unified iterative solution method provided by one embodiment of the present invention; Figure 4 This is a system structure diagram of the power flow calculation system of the AC in-phase traction power supply system provided in one embodiment of the present invention. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0022] Figure 1 This is a flowchart illustrating the steps of a power flow calculation method for an AC in-phase traction power supply system according to one embodiment of the present invention. Figure 1As shown, this invention provides a power flow calculation method for an AC in-phase traction power supply system, the method comprising: Step S10: Establish an equivalent circuit model of the traction substation based on the compensation current of the in-phase power supply device and the electrical quantity constraint relationship of the traction transformer.

[0023] Specifically, the primary side port quantities are obtained based on the three-phase voltage and three-phase current parameters of the primary side of the traction transformer; the secondary side port quantities are calculated based on the impedance parameters, port voltage parameters, and port connection angles of the secondary side of the traction transformer; after the compensation current of the same-phase power supply device is equivalent to the controlled current source injected into the port, the primary side port quantities, secondary side port quantities, and controlled current source are combined according to the electrical connection relationship to obtain the equivalent circuit model of the traction substation.

[0024] In this embodiment of the invention, based on the three-phase voltage and three-phase current parameters of the primary side of the traction transformer, the voltage and current quantities at the primary side ports are extracted respectively, so that the ports in the model have an electrical characterization consistent with the actual primary side operating state. Subsequently, the secondary side port quantities are calculated based on the impedance parameters, port voltage parameters, and port connection angles of the secondary side of the traction transformer, and the turns ratio, phase angle, and impedance distribution are incorporated into the formation process of the secondary side port quantities, so that the secondary side exhibits port characteristics that can be used for power flow solution in the equivalent model. After the primary side port quantities and secondary side port quantities are determined, the compensation current generated by the in-phase power supply device is equivalently injected into the secondary side ports of the traction transformer as a controlled current source, so that the in-phase power supply device can participate in the node voltage solution as an independent injection unit in the model. Finally, the primary side port quantities, secondary side port quantities, and controlled current sources are combined according to the electrical connection relationship of the traction substation, thereby obtaining an equivalent circuit model of the traction substation that can be directly incorporated into the unified iterative framework of power flow.

[0025] Through the aforementioned equivalent modeling process, the traction substation no longer relies on the step-by-step expansion of the actual transformer structure in the power flow solution. Instead, it enters the overall power flow calculation framework in the form of unified port quantities and controlled current sources. This approach allows the compensation current of the in-phase power supply device to directly participate in the node voltage model, while clarifying the coupling relationship between the primary side, secondary side, and compensation current. This provides a consistent and computable electrical foundation for subsequent chain circuit combinations, regularized power flow model construction, and iterative solutions.

[0026] In one specific implementation, such as Figure 2This invention provides a schematic diagram of a train power supply system structure applying the power flow calculation method for an AC in-phase traction power supply system proposed in this invention. The diagram illustrates the electrical connections between the external power grid, the traction transformer, and the in-phase power supply device. The external power grid supplies power to the traction network through the traction transformer, including Scott connection, Vv connection, Vx connection, and YNvd connection, to adapt to the phase sequence and power supply requirements of the traction network. The traction transformer transmits current to the traction network through the traction bus, forming the train power supply path. The in-phase power supply device on the right side of the schematic diagram is connected to the traction bus via a controlled current source, and its compensation current... With traction transformer TT port M current Together, they work on the traction network to maintain the traction network voltage within the specified range and mitigate the three-phase voltage imbalance problem at the point of common coupling. The overall structure reflects the coordinated relationship between the external power grid, traction transformers, traction network, and in-phase power supply devices in the traction power supply system, providing a clear electrical topology for subsequent compensation and power flow calculations.

[0027] In-phase power supply devices include converters α and β , converter α and β The compensation current is expressed as and ,in, I Cα and These are the compensation currents. The magnitude and power factor angle; I Cβ and These are the compensation currents. The magnitude and power factor angle; Ψ M and Ψ N For the secondary side port of traction transformer TT M and N The port wiring angle. Utilizing compensation current. and Converter α and β Equivalent to being connected to the secondary side port of the traction transformer TT M and N A controlled current source.

[0028] Step S20: Divide the transmission line, feeder and traction network into smaller power supply units using different numbered sections, construct a unified chain circuit model of the transmission line, feeder and traction network, combine the node voltage model of the traction substation with the node admittance relationship of the chain circuit model to form an irregular power flow unified iterative node voltage model, and perform regularization processing on the irregular power flow unified iterative node voltage model to obtain a regularized power flow calculation model.

[0029] Specifically, the transmission lines, feeders, and traction networks are divided into smaller power supply units using different numbered sections. A chain circuit model is constructed according to the section numbers of the transmission lines, feeders, and traction networks, including: dividing the node sets of each section sequentially according to the section numbers of the transmission lines, feeders, and traction networks; generating corresponding node admittance matrices based on the line electrical parameters of each node set; connecting the node admittance matrices of each section in section order to form a segmented admittance structure of the chain circuit; and using the segmented admittance structure as a whole as the chain circuit model.

[0030] Furthermore, the irregular power flow unified iterative node voltage model is regularized to obtain a regularized power flow calculation model, including: identifying cross-section node coupling relationships in the irregular power flow unified iterative node voltage model; equivalently replacing the cross-section node quantities in the identified node coupling relationships with node quantities within the same cross section; rearranging the node quantities obtained from the equivalent replacement to generate a node admittance matrix structure in the form of a strip matrix, and using this strip matrix structure as the regularized power flow calculation model.

[0031] Construct a current compensation device with in-phase power supply and The nodal voltage model of the traction substation (TS) is derived, and a chain circuit is used to uniformly model the transmission lines, feeders, and traction network, thereby obtaining a unified iterative voltage model for power flow calculation of the AC in-phase traction power supply system. In one specific implementation, the following steps are included: 1) Set the secondary side port of the traction transformer TT M and N The currents flowing through are respectively and The current supplied by the traction bus to the feeder is ,in, I LM and They are currents The magnitude and power factor angle. Current. and The relationship between them is: (1) S2: Set the three-phase currents A, B, and C on the primary side of the traction transformer TT to be... and To form a current matrix ; Traction transformer TT secondary side port M and N The ratio of k M and k N Current and The relationship between them is: (2) S3: Set the TT port of the traction transformer M and N The self-impedances are respectively Z M and Z N The mutual impedance between the two is Z MN , forming an impedance matrix The three-phase voltage on the primary side of the traction transformer TT. and With port M and N Between voltages and The relationship between them is: (3) S4: Definition Ma and Mb For port M The two terminals, with corresponding terminal voltages are and ; Na and Nb For port N The two terminals have corresponding terminal voltages of and .Voltage , With voltage The relationship between them is: (4) S5: Traction transformer TT terminal Ma , Mb , Na and Nb Injection current and Represented as: (5) S6: Combining equations (1) to (5), we obtain the node voltage model of the traction substation containing the compensation current of the in-phase power supply device as follows: (6) S7: Considering the changes in train position and power over time, using numbers 1~ n 1, n 1+1~ n 2 and n 2+1~ n Multiple fixed and dynamic locomotive sections in section 3 divide the transmission lines, feeders, and traction network into several power supply units, constructing a unified chain circuit model for the transmission lines, feeders, and traction network, denoted as chain circuits 1, 2, and 3, respectively. The external power source is located in section 1, and the traction substation, consisting of the traction transformer TT and the in-phase power supply device, is located in section 3. n 1 and n Between 1 and 1. Based on equation (6), the unified iterative node voltage equation for calculating irregular power flow, consisting of an external power source with arbitrary topology, a traction substation, and a traction network, is established as follows: (7) In the formula, I T1 and U T1 This represents the injected current and node voltage matrix of the nodes contained in chain circuits 1 and 2; I T2 , I T3 , I T4 , I T5 and U T2 , U T3 , U T4 , U T5 These are cross-sections of chain circuit 3. n 2+1~ n 2+ m 1-1, n 2+ m 1, n 2+ m 1+1, n 2+ m 1+2~ n 3. A node current and voltage matrix consisting of the included nodes; where, m 1 is an auxiliary quantity; for example, the first section of the chain circuit 3 is numbered 21. n 2=20), I T3 Located at section 30 ( n 2+ m 1=30, m 1=10); using numbers 1~n 1. n 1+1~ n 2 and n 2+1~ n Multiple sections of section 3 divide the transmission line, feeder, and traction network into several power supply units, constructing a unified chain circuit model for the transmission line, feeder, and traction network, denoted as chain circuits 1, 2, and 3 respectively; sections 1~ n 1 corresponds to chain circuit 1. n 1+1~ n 2 corresponds to chain circuit 2. n 2+1~ n 3 corresponds to chain circuit 3; Y Tlm Denotes the corresponding nodal admittance matrix, 1≤ l ≤5, 1≤ m ≤5.

[0032] To achieve the node admittance matrix in equation (7) Y Tlm Standardization, I T3 and I T4 Included U T1 use I T1 , Y T13 and Y T14 If we express it as: (8) In the formula, ; ;Δ Y T33 =Δ A 3 Y T13 ;Δ Y T34 =Δ A 3 Y T14 ;Δ Y T43 =Δ A 4 Y T13 ;Δ Y T44 =Δ A 4 Y T14 .

[0033] Substituting equation (8) into equation (7), we obtain the regularized node voltage model as follows: (9) Equation (9) can be simplified to equation (10), where, Y T0 A striped regular matrix: (10) By equivalently replacing the cross-sectional node quantities and rearranging the row and column structure of the node voltage model, the complex topology, which originally included external power sources, multiple transmission lines, feeders, and traction networks, can be transformed into a regularized matrix form with strip-like characteristics. This regularized matrix corresponds one-to-one with the node admittance relationships of each section in the chain circuit, enabling power flow solutions to be performed on the entire traction power supply network under a unified matrix structure.

[0034] Based on this, the present invention further abstracts the network structure into a chain circuit model formed by the continuous connection of several cross-sections, and divides the transmission line, feeder, and traction network into node sets respectively using the cross-section number as an index, thereby generating their respective node admittance matrices and combining them sequentially to form a segmented admittance structure of the chain circuit. Combined with the aforementioned traction substation node voltage model, an irregular power flow unified iterative node voltage model covering the entire traction power supply network can be formed.

[0035] Subsequently, by identifying the node coupling relationships across the cross-section in the irregular model and converting them into the number of nodes within the same cross-section through equivalent substitution, a regularized power flow calculation model in the form of a strip matrix can be further constructed, enabling power flow solutions to be performed within a structured and decomposable matrix framework.

[0036] Step S30: Establish a mapping relationship for the compensation current of the same-phase power supply device based on the current supplied by the traction bus to the feeder, the target value of the three-phase voltage imbalance, and the target value of the power factor, and couple the external power supply parameters into the mapping relationship to obtain the compensation current to be updated.

[0037] Specifically, a mapping relationship for the compensation current of the in-phase power supply device is established based on the current supplied by the traction bus to the feeder, the target value of the three-phase voltage imbalance, and the target value of the power factor. This includes: calculating the current supplied by the traction bus to the feeder based on the node voltage and current electrical quantities corresponding to the feeder and the traction network; calculating the three-phase voltage imbalance constraint at the point of common coupling based on the target value of the three-phase voltage imbalance; calculating the power constraint at the traction bus based on the target value of the power factor; and combining the current supplied by the traction bus to the feeder, the three-phase voltage imbalance constraint, and the power constraint according to the mapping rules to form a mapping relationship for determining the compensation current of the in-phase power supply device.

[0038] In this embodiment of the invention, the current acquisition rule provided by the traction bus to the feeder is as follows: voltage and current are acquired at the node quantities at the connection between the traction bus and the feeder, and the node quantities are merged into segments according to the sectional division to form the feeder current input quantity used to compensate the current mapping relationship; the determination rule of the three-phase voltage imbalance target value is as follows: the three-phase voltage imbalance range at the common coupling point is determined based on the initial distribution of node voltages in the power flow calculation model; a three-phase voltage imbalance compensation target value is selected within the range of the three-phase voltage imbalance and the preset allowable value of the three-phase voltage imbalance; the determination rule of the power factor target value is as follows: the actual power components at the traction bus are decomposed into active and reactive components, and a target value representing the expected power distribution of the traction bus is determined according to the preset power factor limit interval, so as to serve as the power input quantity in the compensation current mapping relationship.

[0039] In this embodiment of the invention, the compensation current of the in-phase power supply device is often determined by multiple operating variables, thus requiring the construction of a mapping relationship that can be adjusted according to changes in network conditions. The core inputs to this mapping relationship come from three parts: the current supplied by the traction bus to the feeder, the target value of the three-phase voltage imbalance, and the target value of the power factor. These three reflect the feeder load, the three-phase voltage imbalance at the point of common coupling, and the reactive power regulation demand at the traction bus, respectively. By organizing these inputs into calculable nodal quantities, basic data is provided for the generation of the compensation current. The goal of this part is to obtain a type of compensation current that can be continuously updated during the iterative process, ensuring that the compensation current remains consistent with the network conditions during power flow solutions.

[0040] Feeder current processing is typically the first step. This part involves acquiring voltage and current information at the nodes where the traction bus connects to the feeder to obtain basic current information on the feeder side. The feeder current is then used as an input to a mapping relationship to reflect the actual load state of the feeder in the current iteration. This type of processing is usually well-structured and can be directly applied to chain networks of different sizes.

[0041] For the target value of three-phase voltage imbalance, the range of three-phase voltage imbalance at the common coupling point is determined based on the initial distribution of node voltages in the power flow calculation model; and a target value for three-phase voltage imbalance compensation is selected within the range of three-phase voltage imbalance and the preset allowable value of three-phase voltage imbalance.

[0042] The target power factor value is determined by combining the range of the ratio of the active to reactive components of the feeder current at the traction bus and the range of the preset power factor compensation target value. This target power factor is then written into a mapping relationship to form a third type of input quantity, used for generating the compensation current.

[0043] The three types of input quantities mentioned above are combined to form a compensation current mapping relationship. The combination process typically uses the regularized node quantities as indices, writing the feeder current, the target value of the three-phase voltage imbalance, and the target value of the power factor into the mapping rules with a fixed structure. This mapping rule is not dependent on a specific network size and can be applied to traction power supply lines of different sizes. Through this combination, a type of compensation current matching the network state can be obtained, allowing the compensation current to be repeatedly written into the power flow model during the iteration process, forming a closed-loop relationship with the updated node voltage and node injected current.

[0044] In one specific implementation, the feeder current is utilized. and Three-phase voltage imbalance compensation target value ε U and power factor compensation target value The compensation current of the in-phase power supply device in equation (6).

[0045] Step S40: Solve the regularized power flow calculation model using the matrix decomposition method. During the iteration process, update the compensation current and the injected current of each node based on the node voltage until the convergence condition is met, and then output the power flow calculation results.

[0046] Specifically, the matrix decomposition method is used to solve the regularized power flow calculation model, including: converting the regularized power flow calculation model into a matrix structure; performing decomposition operations on the matrix structure according to the matrix decomposition rules to obtain the node voltages; and writing the obtained node voltages into the iterative process to update the compensation current of the in-phase power supply device and the injection current of the chain circuit nodes.

[0047] Furthermore, during the iteration process, the compensation current and the injected current of each node are updated based on the node voltage, including: writing the solved node voltage and current of the feeder and traction network range into the compensation current mapping relationship to regenerate the compensation current of the in-phase power supply device; simultaneously, performing node-by-node calculations on the solved node voltage and the node admittance data corresponding to each cross section of the chain circuit to generate the node injection current used to represent the actual injection situation of each node in the chain circuit; and using the compensation current and node injection current as input quantities for the next solution of the regularized power flow calculation model to form a continuous iterative update chain.

[0048] In this embodiment of the invention, the regularized node voltage model exhibits a relatively regular structure, facilitating further numerical operations. Converting this structure into matrix form is a fundamental step, requiring only dimensional adjustment and data loading based on row and column indices. In large-scale traction power supply models, this conversion maintains the coupling relationships between nodes, thus helping to preserve the integrity of the calculation.

[0049] The choice of matrix decomposition is based on model size and coupling distribution. Regularized nodal voltage models often exhibit piecewise connectivity in their matrices, making common decomposition methods such as LU or improved decomposition strategies suitable. The goal of the decomposition operation is to obtain the nodal voltage vectors, which are derived from a single inversion or piecewise back substitution. Such methods are well-established in traction system power flow analysis, thus requiring no additional algorithmic structure within this framework. The obtained nodal voltages provide stable input for subsequent steps and establish the basic coordinates for the iterative process.

[0050] After the node voltage enters the iterative chain, several physical quantities need to be reconstructed. The current transfer characteristics from the traction bus to the feeder are quantified at this stage, generating node quantities on the feeder side. These node quantities are then written into the compensation current mapping relationship to update the compensation current of the in-phase power supply unit. Changes in the compensation current are usually closely related to the node voltage and current distribution, and this mapping mechanism takes into account both the imbalance and power factor objectives, thus making the update logic relatively compact.

[0051] The node injection current update process for chain circuits is relatively straightforward. Each cross section has an associated node admittance matrix, and the corresponding node voltage is obtained by multiplying the node current by the associated matrix item by item. Since the connection between cross sections in the model is relatively clear, node-by-node calculations can maintain high structural consistency. The updated injection current will be re-substituted into the matrix model in the next solution round, ensuring the continuity of the power flow model.

[0052] The compensation current and the node injection current together constitute the input for the next round of solution. The goal of continuous iteration is to find a stable state of voltage and current matching, and the convergence condition is usually set based on the electrical quantities to be solved. When the condition is met, the iteration process naturally terminates, and the power flow results can be output. This iterative framework maintains the coordination relationship between various parts of the traction power supply system and avoids local electrical quantities deviating from the actual range during the calculation process.

[0053] In one specific implementation, the cross-sections of the feeders and traction network, represented by the chain circuit, are renumbered using the traction bus as the dividing point. The cross-sections included in the feeder are numbered by... n 1+1~ n 2 becomes N 1+1~ N 2. The section numbering included in the traction net is determined by... n 2+1~ n 3 becomes N 2+1~ N 3. The feeder current is calculated using the nodal injection current, nodal voltage, and admittance parameters of the feeder and traction network. for: (11) In the formula, YL11 For cross-section N Admittance matrix consisting of 1+1 nodes; Y L22 For cross-section N 1+2~ N Admittance matrix consisting of 3 nodes; Y L21 and Y L22 The node admittance matrix is ​​formed by nodes between different cross-sections; I L2 For cross-section N 1+2~ N A current matrix consisting of injected currents at three nodes; U L1 For cross-section N A voltage matrix consisting of 1+1 nodes.

[0054] Set short-circuit capacity as S d The phase angle of the negative sequence current after compensation is θ , and For current The active and reactive components, and For current The active and reactive components, and For current The active and reactive components. In terms of current... Three-phase voltage imbalance compensation target value ε U and the target value of power factor compensation cos φ 0 represents the current component I Cαp , I Cαq , I Cβp and I Cβq for: (12) In the formula, ; ; ; ; ; ; U A for The modulus.

[0055] The unified iterative solution for AC in-phase traction power supply systems includes the following steps: 1) Construct an equivalent circuit model of a traction substation with in-phase power supply devices, and obtain a regularized unified iterative node voltage model for power flow calculation according to equation (10).

[0056] 2) Determine the target values ​​for three-phase voltage imbalance and power factor compensation. ε U and The value of short-circuit capacity S d The phase angle of the compensated negative sequence current is θ ε The value of is determined. Parameter initialization is performed, with a total of iterations. K , No. k The initial value for the next iteration is 1, and the node voltage matrix in equation (7) is determined. The initial value is .

[0057] 3) Based on node voltage Update # k The traction network section during the next iteration N 1+2~ N 3. Included node injection current matrix The value of .

[0058] 4) Update the first according to equation (9) k The value of the current supplied by the traction bus to the feeder in the next iteration Based on this, update the first equation according to equation (12). k The current of the in-phase power supply device during the next iteration and And thus update the first k The injected current matrix of each node in the next iteration The value of .

[0059] 5) Solve equation (10) using the LU decomposition method to obtain the first... k The node voltage matrix after the next iteration is: .

[0060] 6) Convergence determination. If ( λ For convergence accuracy) and k ≦ K If so, proceed to step 2). or k > K Proceed to step 7).

[0061] 7) End, and output the calculation results such as the voltage of each node, the current of each feeder, and the convergence amount of each iteration.

[0062] Preferably, by changing the connection angle of the TT transformer port, traction power supply schemes composed of different connection transformers and in-phase power supply devices, as well as the incoming phase sequence of different external power sources, can be simulated in the same model. The aforementioned traction transformers with different connections include Scott connection transformers, Vv connection transformers, Vx connection transformers, and YNvd connection transformers.

[0063] In this embodiment, by changing the short-circuit capacity S d The magnitude of the value is used to simulate the impact of external power supply parameters on the traction power supply system under the same model.

[0064] In this embodiment, the compensation target values ​​of three-phase voltage imbalance and power factor are used to evaluate the compensation effect of three-phase voltage imbalance and power factor under different in-phase power supply device access schemes, and to study the capacity configuration of in-phase power supply devices.

[0065] In this embodiment, the traction network can be supplied directly, supplied directly with a return line, or supplied via AT power supply.

[0066] In one specific implementation, such as Figure 3 This diagram illustrates a dynamic power flow calculation method using a unified iterative approach. The overall process begins with parameter initialization, including the operating parameters of the in-phase power supply unit, the equivalent quantities of the traction transformer, and the node admittance data of the chain circuit. After initialization, the node voltages are initially estimated based on the external power supply voltage and the traction bus status, establishing reference values ​​for subsequent iterations. In the iterative solution phase, the compensation current of the in-phase power supply unit is first updated based on the current node voltage. This update is based on the compensation current mapping relationship, which includes the three-phase voltage imbalance, the target power factor, and the traction bus feeder current, thus providing a corrected value for the compensation current. Subsequently, the node injection currents of each section of the chain circuit are calculated item by item according to the node admittance matrix, forming the input quantities for a new round of power flow model. The regularized power flow calculation model uses matrix decomposition to solve for the node voltages. LU decomposition or other numerical strategies adapted to strip structures can be used to ensure solution efficiency and convergence stability. After obtaining the node voltages, it is determined whether the deviation between the current iteration and the previous iteration meets the preset convergence threshold. If the conditions are not met, the updated compensation current and node injection current are written into the next iteration and the solution is repeated; if the conditions are met, the power flow calculation results are output, including node voltage distribution, injection current distribution and power characteristics of the traction system.

[0067] Figure 4 This is a system structure diagram of the power flow calculation system for an AC in-phase traction power supply system provided in one embodiment of the present invention. (See diagram below.) Figure 4As shown, this invention provides a power flow calculation system for an AC in-phase traction power supply system. The system includes: an initialization unit for establishing an equivalent circuit model of the traction substation based on the compensation current of the in-phase power supply device and the electrical quantity constraints of the traction transformer; and a model construction unit for dividing the transmission lines, feeders, and traction network into smaller power supply units using different numbered sections, constructing a unified chain circuit model of the transmission lines, feeders, and traction network, combining the node voltage model of the traction substation with the node admittance relationship of the chain circuit model to form a unified iterative node voltage model for irregular power flows, and processing irregular power flows. The flow uniform iterative node voltage model is regularized to obtain a regularized power flow calculation model; the mapping construction unit is used to establish the mapping relationship of the compensation current of the same phase power supply device based on the current provided by the traction bus to the feeder, the target value of the three-phase voltage imbalance, and the target value of the power factor, and couples the external power supply parameters and the node quantities of the chain circuit into the mapping relationship to obtain the compensation current to be updated; the output unit is used to solve the regularized power flow calculation model using the matrix decomposition method, and updates the compensation current and the injected current of each node according to the node voltage during the iteration process until the convergence condition is met and the power flow calculation result is output.

[0068] The present invention also provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the above-described power flow calculation method for an AC in-phase traction power supply system.

[0069] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a microcontroller, chip, or processor to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, portable hard drive, read-only memory, random access memory, magnetic disk, or optical disk.

[0070] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details described above. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe the various possible combinations.

[0071] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the embodiments of the present invention, they should also be regarded as the content disclosed by the embodiments of the present invention.

Claims

1. A power flow calculation method for an AC homopolar traction power supply system, characterized by, The method comprises: establishing an equivalent circuit model of the traction substation based on a compensation current of the in-phase power supply device and an electrical quantity constraint relationship of the traction transformer; dividing the power transmission line, the feeder line and the traction network into smaller power supply units by using different numbered sections, constructing a unified power transmission line, feeder line and traction network chain circuit model, combining a node voltage model of the traction substation with a node admittance relationship of the chain circuit model to form an irregular power flow unified iterative node voltage model, and performing regularizing processing on the irregular power flow unified iterative node voltage model to obtain a regularized power flow calculation model; establishing a mapping relationship of the compensation current of the in-phase power supply device according to a current provided by the traction bus to the feeder line, a target value of three-phase voltage unbalance degree and a target value of power factor, and coupling external power supply parameters into the mapping relationship to obtain a compensation current to be updated; solving the regularized power flow calculation model by using a matrix decomposition method, updating the compensation current and the injection current of each node in the iterative process until the convergence condition is met, and outputting a power flow calculation result.

2. The method of claim 1, wherein, The method for establishing an equivalent circuit model of the traction substation based on a compensation current of the in-phase power supply device and an electrical quantity constraint relationship of the traction transformer comprises: extracting a primary side port quantity according to three-phase voltage and three-phase current parameters of the primary side of the traction transformer; calculating a secondary side port quantity according to impedance parameters, port voltage parameters and port wiring angles of the secondary side of the traction transformer; combining the primary side port quantity, the secondary side port quantity and the controlled current source equivalent to the compensation current of the in-phase power supply device according to an electrical connection relationship to obtain the equivalent circuit model of the traction substation.

3. The method of claim 1, wherein, The method for dividing the power transmission line, the feeder line and the traction network into smaller power supply units by using different numbered sections, constructing a unified power transmission line, feeder line and traction network chain circuit model comprises: dividing the power transmission line, the feeder line and the traction network into smaller power supply units by using different numbered sections, and sequentially dividing node sets of each section according to section numbers of the power transmission line, the feeder line and the traction network; generating a corresponding node admittance matrix according to line electrical parameters of each node set; connecting sectional admittance structures of the chain circuit model by connecting node admittance matrices of each section according to section sequences, and taking the sectional admittance structures as a whole as the chain circuit model.

4. The method of claim 1, wherein, The method for performing regularizing processing on the irregular power flow unified iterative node voltage model to obtain a regularized power flow calculation model comprises: identifying a node coupling relationship across sections in the irregular power flow unified iterative node voltage model; equivalently replacing node quantities across sections in the identified node coupling relationship with node quantities inside the same section; rearranging the node quantities obtained by the equivalent replacement to generate a node admittance matrix structure in a strip matrix form, and taking the node admittance matrix structure in the strip matrix form as the regularized power flow calculation model.

5. The method of claim 1, wherein, The method for establishing a mapping relationship of the compensation current of the in-phase power supply device according to a current provided by the traction bus to the feeder line, a target value of three-phase voltage unbalance degree and a target value of power factor comprises: calculating the current provided by the traction bus to the feeder line according to node voltage and current electrical quantities corresponding to the feeder line and the traction network. According to the three-phase voltage unbalance degree target value, a three-phase voltage unbalance degree constraint at the point of common coupling is calculated; According to the power factor target value, a power constraint at the traction bus is calculated; The current provided by the traction bus to the feeder, the three-phase voltage unbalance degree constraint, and the power constraint are combined according to a mapping rule to form a mapping relationship for determining the compensation current of the co-phase power supply device.

6. The method of claim 5, wherein, The collection rule of the current provided by the traction bus to the feeder is: Voltage and current information of node quantities at a connection between the traction bus and the feeder are collected, and section merging is performed on the node quantities according to section division to form feeder current input quantities for the compensation current mapping relationship; The determination rule of the three-phase voltage unbalance degree target value is: A three-phase voltage unbalance degree range at the point of common coupling is determined based on an initial distribution of node voltages in a power flow calculation model; and a three-phase voltage unbalance degree compensation target value for compensation is selected within the three-phase voltage unbalance degree range and a preset three-phase voltage unbalance degree allowable value range; The determination rule of the power factor target value is: Actual power components at the traction bus are decomposed into active component and reactive component, and a target value for representing expected power distribution of the traction bus is determined according to a preset power factor limited interval, to serve as a power input quantity in the compensation current mapping relationship.

7. The method of claim 1, wherein, A matrix decomposition method is used to solve the regularized power flow calculation model, including: The regularized power flow calculation model is converted into a matrix structure; A decomposition operation is performed on the matrix structure according to a matrix decomposition rule to obtain node voltages; The obtained node voltages are substituted into an iteration process to update the compensation current of the co-phase power supply device and the node injection current of the chain circuit.

8. The method of claim 1, wherein, The compensation current and the node injection current are updated according to the node voltages during the iteration process, including: The node voltages and currents in the feeder and traction network range solved are substituted into the compensation current mapping relationship to regenerate the compensation current of the co-phase power supply device; Meanwhile, the node voltages and the node admittance data corresponding to each section of the chain circuit are operated node by node to generate node injection currents for representing actual injection conditions of each node in the chain circuit; The compensation current and the node injection current are taken as input quantities for solving the regularized power flow calculation model in the next time, to form a continuous iteration update chain.

9. A power flow calculation system for an AC, phase-locked traction power supply system, characterized in that The system includes: An initial unit configured to establish an equivalent circuit model of a traction substation based on an electrical quantity constraint relationship between a compensation current of a co-phase power supply device and a traction transformer; A model construction unit configured to divide a power transmission line, a feeder, and a traction network into smaller power supply units by using different numbered sections, to construct a unified power transmission line, feeder, and traction network chain circuit model, to combine a node voltage model of the traction substation and a node admittance relationship of the chain circuit model to form an irregular power flow unified iteration node voltage model, and to regularize the irregular power flow unified iteration node voltage model to obtain a regularized power flow calculation model. The mapping construction unit is configured to establish a mapping relationship of the compensation current of the phase-to-phase power supply device according to the current provided by the traction bus to the feeder, the target value of the three-phase voltage unbalance degree and the target value of the power factor, and to couple the external power supply parameters into the mapping relationship to obtain the compensation current to be updated. The output unit is configured to solve the regularized power flow calculation model by using a matrix decomposition method, to update the compensation current and the injection current of each node according to the node voltage in an iteration process, and to output the power flow calculation result until a convergence condition is met.

10. A computer-readable storage medium, characterized in that, The computer readable storage medium stores instructions, which, when executed on a computer, cause the computer to perform the power flow calculation method of the alternating current phase-to-phase traction power supply system according to any one of claims 1-8.

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