Rail transit traction power supply system model and simulation model of variable line resistance thereof

Abstract

The application provides a rail transit traction power supply system model and a simulation model of variable line resistance thereof, and comprises a variable resistance simulation module connected with an electrical port input end in the rail transit traction power supply system, a line current output signal being output according to an electrical port input signal and a line current in the rail transit traction power supply system, and the current signal being output to an electrical port output end; a line voltage module connected in parallel at two ends of the variable resistance simulation module, used for outputting a voltage signal according to the electrical port input signal and the current signal; a delay module connected in series with the line voltage module, used for performing delay processing on the voltage signal and outputting a delay voltage signal, and the voltage signal being processed by a transfer function in the delay module; and a current calculation module connected in series with the delay module, used for determining a current source instruction according to the delay voltage signal and a train impedance. The algebraic loop problem caused by the large-scale variable line resistance is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of rail transit traction power supply, in particular to a rail transit traction power supply system model and a simulation model of variable line resistance thereof. BACKGROUND

[0002] In the simulation of the rail transit traction power supply system, there are generally three forms of equivalent models of variable line resistance: multi-section switch switching method, equivalent current source model and equivalent voltage source model, wherein the multi-section switch switching method has the disadvantages of discontinuous line resistance value and introduction of a large number of switches, which seriously affects the simulation speed, the equivalent current source model has the disadvantage of algebraic loop problem, and the equivalent voltage source model has the disadvantage of algebraic loop problem and poor system stability in the case of large current fluctuation.

[0003] For the algebraic loop problem introduced by the variable line resistance, there are currently three main solutions to the algebraic loop problem, including the solving algorithm provided by Simulink, the transformation method and the disassembly method. Among them, the solving algorithm provided by Simulink is suitable for very short algebraic loops and can converge in small-scale cases. However, due to the large scale of the traction power supply simulation of the whole line, this method cannot converge. The transformed simulation model of the transformation method can only realize homomorphic simulation, which may no longer be consistent with the original physical meaning or physical structure. The disassembly method cannot solve large-scale algebraic loop problems and can only solve specific algebraic loops, which cannot solve the algebraic loop problem caused by the variable line resistance.

[0004] Therefore, how to solve the algebraic loop problem caused by large-scale variable line resistance has become a technical problem to be solved by technical personnel in the field and a focus of research. SUMMARY

[0005] In order to solve the problems in the prior art, the present application provides a rail transit traction power supply system model and a simulation model of variable line resistance thereof.

[0006] The application provides a simulation model of a variable line resistance in a rail transit traction power supply system.

[0007] The simulation model of the variable line resistance in the rail transit traction power supply system is established, the variable line resistance is simulated by using a current source equivalent model, and the robustness is higher, and the stability can be maintained in a model with large current fluctuation.

[0008] In the first implementation manner of the first aspect, the current calculation module comprises: a calculation submodule configured to determine an initial current source instruction according to the delayed voltage signal and the train impedance; and a current limiting submodule configured to determine the current source instruction as a preset upper limit value when the initial current source instruction is greater than the preset upper limit value, and determine the current source instruction as a preset lower limit value when the initial current source instruction is less than the preset lower limit value.

[0009] The line resistance is very small when the train is very close to the substation, and the line resistance is 0 when the train reaches the substation. Since the current source instruction value is obtained by dividing the voltage difference by the resistance value, the smaller the resistance is, the greater the current is. It is found in simulation that if the current instruction value is greater than the maximum current of the original line, the entire simulation model cannot converge. Therefore, the preset upper and lower limits are mainly set to prevent simulation divergence and ensure simulation convergence.

[0010] With reference to the first aspect, in a second implementation of the first aspect, the simulation model of the variable line resistance in the rail transit traction power supply system further comprises: a parallel resistance connected in parallel between the two sides of the variable resistance simulation module, and the resistance value of the parallel resistance is determined according to the simulation step of the simulation model of the variable line resistance.

[0011] The beneficial effect is that: a fixed resistance is connected in parallel between the two ends of the variable resistance simulation module, so as to improve the stability of the simulation system and effectively prevent the error caused by the direct series connection of the two current sources. When the delay and voltage fluctuate, the fluctuation value of the current command is larger than the accurate current, which is easy to cause the system to diverge. However, the parallel resistance can shunt the current source, so that the overall current flowing through the line is smaller. Even if the fluctuation causes the current command value to be larger, the current flowing through the line is within the range that will not diverge, so it is less likely to diverge, and the robustness is stronger.

[0012] The second aspect of the application provides a rail transit traction power supply system model, comprising at least one train module, each train module being connected in series, and a controllable resistance module being connected between each two train modules. The train module comprises: a first variable line resistance model, a second variable line resistance model, a fixed resistance, and a train model. The first variable line resistance model and the second variable line resistance model are connected in series with each other, and the first variable line resistance model and the second variable line resistance model are simulation models of variable line resistance in the rail transit traction power supply system. The fixed resistance is connected in parallel between the output end of the first variable line resistance model and the output end of the second variable line resistance model. The train model is connected in parallel between the output end of the controllable resistance module and the output end of the first variable line resistance model.

[0013] The beneficial effect is that: the application establishes a rail transit traction power supply system model, uses a current source equivalent model to simulate the variable line resistance, and has stronger robustness and can maintain stability in a model with large current fluctuation. The delay module is added to the model to eliminate the algebraic loop. In the embodiment of the application, the delay module performs delay processing on the voltage signal through a transfer function. The transfer function includes a time constant, and the delay time can be adjusted by adjusting the time constant. In different scale simulation models, different time constants can be selected according to different simulation steps, so as to adjust the delay time. The simulation model of the variable line resistance can be applied to different scale rail transit traction power supply system simulation models. The delay module in the embodiment of the application also has a low-pass filtering effect, which is used to remove high-frequency interference signals in the high-voltage signal.

[0014] With reference to the second aspect, in a first implementation of the second aspect, the rail transit traction power supply system model further comprises: a controllable parallel resistance branch, the controllable parallel resistance branch is connected in parallel with the train module and moves with the train module, and the controllable parallel resistance branch is connected in series with the variable resistance simulation module.

[0015] The beneficial effect is that after the system adds a time delay link, when the train ends traction, the train has no path to absorb current, and the current source on the line will delay a beat, and there will be current, which will cause energy to accumulate rapidly on the line, resulting in the voltage of the supporting capacitor rising and falling slowly. The controllable parallel resistance branch absorbs the delayed traction energy.

[0016] In combination with the first embodiment of the second aspect, in the second embodiment of the second aspect, a switch signal judgment module is connected in series at one end of the controllable parallel resistance branch, the controllable parallel resistance branch and the switch signal judgment module are connected in parallel across the circuit breaker and the filter capacitor, and the filter capacitor is connected in parallel with the train power module.

[0017] In combination with the second embodiment of the second aspect, in the third embodiment of the second aspect, the switch signal judgment module comprises:

[0018] a first switch signal judgment submodule for outputting a first switch signal according to the train power output; and a second switch signal judgment submodule for outputting a second switch signal according to the substation voltage, the no-load voltage, and the first switch signal.

[0019] In combination with the third embodiment of the second aspect, in the fourth embodiment of the second aspect, the judgment process of the first switch signal judgment submodule is that if the train power is less than 10 KW, the first switch signal is on; and if the train power is greater than or equal to 10 KW, the first switch signal is 0, and 0 means no output.

[0020] In combination with the third embodiment of the second aspect or the fourth embodiment of the second aspect, in the fifth embodiment of the second aspect, the judgment process of the second switch signal judgment submodule is that if the first switch signal is on, the second switch signal judgment submodule does not judge, and the controllable parallel resistance branch is on; and if the first switch signal is 0, the second switch signal judgment submodule judges the relationship between the substation output voltage and the no-load voltage to obtain the second switch signal.

[0021] In combination with the fifth embodiment of the second aspect, in the sixth embodiment of the second aspect, if the substation output voltage is less than the no-load voltage, the second switch signal is off, and the controllable parallel resistance branch is off; and if the substation output voltage is greater than or equal to the no-load voltage, the second switch signal is 0. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the description of the specific embodiments or the prior art. Obviously, the drawings described below are some embodiments of the present application.

[0023] Figure 1A simulation model structure schematic diagram of a variable line resistance in a rail transit traction power supply system provided by an embodiment of the present application is shown.

[0024] Figure 2 A rail transit traction power supply system schematic diagram provided by an embodiment of the present application is shown.

[0025] Figure 3 A rail transit traction power supply system circuit topology schematic diagram provided by an embodiment of the present application is shown.

[0026] Figure 4 A train model-parallel resistance branch structure schematic diagram provided by an embodiment of the present application is shown.

[0027] Figure 5 A switch signal judgment logic schematic diagram in a rail transit traction power supply system model provided by an embodiment of the present application is shown. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0029] In the description of the present application, it should be noted that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0030] An embodiment of the present application provides a simulation model of a variable line resistance in a rail transit traction power supply system, as shown in the figure, comprising the following modules: Figure 1

[0031] The variable resistance simulation module 101 is connected with an electrical port input end in the rail transit traction power supply system, outputs a current signal to an electrical port output end according to an electrical port input signal and a line current in the rail transit traction power supply system.

[0032] In an optional embodiment, the variable resistance simulation module 101 adopts a current source equivalent model.

[0033] In an optional embodiment, Figure 1 The electrical port + in the above formula is an input end, Figure 1 The electrical port - in the above formula is an output end, Figure 1 The controllable current source - in the above formula simulates a line current, which is the variable resistance simulation module 101 in the embodiment of the present application.

[0034] ​The line voltage module 102 is connected in parallel across the variable resistance analog module 101, and is configured to output a voltage signal according to the appliance end input signal and the current signal.

[0035] The delay module 103 is connected in series with the line voltage module, and is configured to output a delay voltage signal by delaying the voltage signal.

[0036] In an optional embodiment, the transfer function is G(s)=1 / (1+Ts), where G(s) represents the delay voltage signal, T is the time constant, s is the Laplace transform, and j is a complex variable. , where j is the imaginary axis in the complex variable, is the frequency of the signal.

[0037] In an optional embodiment, the greater the time constant T, the greater the delay, and the stability of the system also increases.

[0038] In an optional embodiment, the selection of the time constant T is related to the simulation step length of the model. In a fixed step simulation, the smaller the step length, the smaller the time constant T.

[0039] In an optional embodiment, according to simulation experience, in a full-line subway simulation, the value of the time constant T is selected to be between 0 and 10.

[0040] The current calculation module 4 is connected in series with the delay module 103, and is configured to determine the current source command according to the delay voltage signal and the train impedance.

[0041] In the embodiment of the application, a simulation model of the variable line resistance in the rail transit traction power supply system is established, and the variable line resistance is simulated using a current source equivalent model, which has stronger robustness and can remain stable in a model with large current fluctuations. The delay module 103 is added to the model to eliminate algebraic loops. In the embodiment of the application, the delay module 103 delays the voltage signal by a transfer function, which includes a time constant. By adjusting the time constant, the delay time can be adjusted. In different scale simulation models, different time constants can be selected according to different simulation step lengths, so as to adjust the delay time. The simulation model of the variable line resistance can be applied to different scale rail transit traction power supply system simulation models. The delay module 103 in the embodiment of the application also has a low-pass filtering effect, which is used to remove high-frequency interference signals in the high-voltage signal.

[0042] In an optional embodiment, the current calculation module 104 comprises: a calculation submodule 111 for determining an initial current source instruction according to the delay voltage signal and the train impedance; a current limiting submodule 112 for determining the current source instruction as a preset upper limit value when the initial current source instruction is greater than the preset upper limit value, and determining the current source instruction as a preset lower limit value when the initial current source instruction is less than the preset lower limit value.

[0043] In an optional embodiment, the current source instruction is obtained by dividing the delay voltage signal by the train impedance, and the smaller the train impedance, the greater the current source instruction.

[0044] In an optional embodiment, it is found in simulation that if the current instruction value is greater than the maximum current of the original line, the entire simulation model cannot converge, and therefore, the current limiting submodule is arranged in the embodiment to prevent simulation divergence and ensure simulation convergence.

[0045] In an optional embodiment, the preset upper limit value and the preset lower limit value are respectively the current when two trains are simultaneously at maximum traction and maximum braking and the current flows to the single-sided converter station.

[0046] In an optional embodiment, as shown in Figure 1 The simulation model of the variable line resistance in the rail transit traction power supply system further comprises a parallel resistance connected in parallel with the variable resistance simulation module 101, and the resistance value of the parallel resistance is determined according to the simulation step of the simulation model of the variable line resistance.

[0047] In an optional embodiment, the parallel resistance is connected in parallel with the variable resistance simulation module 101, which affects the total line resistance value, and the greater the parallel resistance, the smaller the influence on the resistance value after parallel connection, and the smaller the influence on the simulation accuracy, and the higher the system simulation accuracy.

[0048] In an optional embodiment, the selection of the parallel resistance value is related to the simulation step of the model, and in fixed-step simulation, the greater the step, the smaller the parallel resistance, because the smaller the step, the higher the simulation accuracy, the smaller the measurement error of the voltage fluctuation, and the smaller the deviation value of the calculated current source instruction, and the parallel resistance demand is not so strong, and can be set to be greater, and vice versa.

[0049] In an optional embodiment, according to experience, the parallel resistance value is selected between 1 and 1000.

[0050] As shown in Figure 2 The rail transit traction power supply system model provided by the embodiment of the present application corresponds to the rail transit traction power supply system as shown in Figure 2 As shown in Figure 3 The rail transit traction power supply system model provided by the embodiment of the present application corresponds to the rail transit traction power supply system as shown in Figure 2 As shown in

[0051] At least one train module 301, each train module 301 is connected in series, and a controllable resistance module is connected between each two train modules.

[0052] In an optional embodiment, Figure 3 The two train modules are train module 301 and train module 302, Figure 3 The three controllable resistance modules are controllable resistance module 303, controllable resistance module 304 and controllable resistance module 305.

[0053] In an optional embodiment, each controllable resistance module includes a diode, a controllable resistance and a voltage source.

[0054] The train module 301 includes a first variable line resistance model, a second variable line resistance model, a fixed resistance and a train model.

[0055] In Figure 3 In the embodiment, for the train module 301, The first variable line resistance model, The second variable line resistance model, The fixed resistance, and the train model is Veh1.

[0056] The first variable line resistance model and the second variable line resistance model are connected in series, and the first variable line resistance model and the second variable line resistance model are simulation models of the variable line resistance in the rail transit traction power supply system provided in the embodiment.

[0057] The fixed resistance is connected in parallel between the output end of the first variable line resistance model and the output end of the second variable line resistance model.

[0058] The train model is connected in parallel between the output end of the controllable resistance module and the output end of the first variable line resistance model.

[0059] In the embodiment of the present application, the simulation model of the variable line resistance in the rail transit traction power supply system is established, and the current source equivalent model is used to simulate the variable line resistance, which has stronger robustness and can remain stable in the model with large current fluctuation. The delay module 103 is added to the model to eliminate the algebraic loop. In the embodiment of the present application, the delay module 103 performs delay processing on the voltage signal through a transfer function, the time constant is included in the transfer function, and the delay time can be adjusted by adjusting the time constant. In different scale simulation models, different time constants can be selected according to different simulation steps, so as to adjust the delay time, so that the simulation model of the variable line resistance can be applicable to different scale rail transit traction power supply system simulation models. The delay module 103 in the embodiment of the present application also has a low-pass filtering effect to remove high-frequency interference signals in the high-voltage signal.

[0060] In an optional embodiment, the rail transit traction power supply system model further includes a controllable parallel resistance branch, the controllable parallel resistance branch is connected in parallel with the train module and moves with the train module, and the controllable parallel resistance branch is connected in series with the variable resistance simulation module.

[0061] In the embodiment shown in FIG. 5, Figure 3 In the embodiment shown in FIG. 5, the controllable parallel resistance branch is connected in parallel with the train model Veh1 and the train model Veh2.

[0062] In an optional embodiment, Figure 4 The energy discharge resistance is the controllable parallel resistance branch in the embodiment of the present application.

[0063] In an optional embodiment, in Figure 4 In addition to the energy discharge resistance and the switch signal, the remaining parts jointly constitute the train model, that is, the Veh1 or Veh2 in Figure 3

[0064] In an optional embodiment, after the system adds the delay link, when the train ends traction, the train has no path to absorb current, the current source on the line will delay for one beat, and there will still be current, which will cause energy to accumulate rapidly on the line, resulting in the voltage of the supporting capacitor rising and falling slowly. At this time, the controllable parallel resistance branch is connected in parallel on the train branch to absorb the delayed traction energy.

[0065] In an optional embodiment, the control strategy of the parallel resistance branch is: when the train ends traction, the switch is turned on to absorb energy; when the line voltage approaches the no-load voltage, the switch is turned off to stop absorbing energy.

[0066] In an optional embodiment, as shown in FIG. 5, the switch signal judgment module includes:

[0067] ​The first switch signal judging sub-module 501 is used for outputting a first switch signal according to the train power.

[0068] The second switch signal judging sub-module 502 is used for outputting a second switch signal according to the substation voltage, the no-load voltage and the first switch signal.

[0069] In an optional embodiment, as shown in Figure 5 the judging process of the first switch signal judging sub-module 501 is as follows:

[0070] If the train power is less than 10KW, the first switch signal is on.

[0071] If the train power is greater than or equal to 10KW, the first switch signal is 0, and the meaning of 0 is no output.

[0072] In an optional embodiment, as shown in Figure 5 the judging process of the second switch signal judging sub-module 502 is as follows:

[0073] If the first switch signal is on, the second switch signal judging sub-module 502 does not judge, and the controllable parallel resistance branch is on.

[0074] If the first switch signal is 0, the second switch signal judging sub-module 502 judges the relationship between the substation output voltage and the no-load voltage, and obtains the second switch signal.

[0075] In an optional embodiment, as shown in Figure 5 If the substation output voltage is less than the no-load voltage, the second switch signal is off, and the controllable parallel resistance branch is off.

[0076] If the substation output voltage is greater than or equal to the no-load voltage, the second switch signal is 0.

[0077] Obviously, the above embodiments are merely examples for clearly illustrating but not limiting the implementation. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the implementation is not required or can not be exhausted. The obvious changes or variations derived from the above still fall within the protection scope of the present application.

Claims

1. A simulation model of variable line resistance in a rail transit traction power supply system, characterized in that, include: A variable resistance simulation module is connected to the electrical port input terminal of the rail transit traction power supply system. Based on the electrical port input signal and the line current in the rail transit traction power supply system, it outputs a current signal to the electrical port output terminal. The variable resistance simulation module adopts a current source equivalent model. A line voltage module is connected in parallel across the variable resistor analog module and is used to output a voltage signal based on the input signal from the electrical port and the current signal. A delay module, connected in series with the line voltage module, is used to delay the voltage signal and output a delayed voltage signal. The delay module uses a transfer function to delay the voltage signal, and this transfer function includes a time constant, which is determined based on the simulation step size of the simulation model of the variable line resistance. The delay module also removes high-frequency interference signals from the voltage signal; the larger the time constant, the greater the delay. A current calculation module, connected in series with the delay module, is used to determine the current source command based on the delayed voltage signal and the train impedance. The current calculation module includes: a calculation submodule, used to determine the initial current source command based on the delayed voltage signal and the train impedance; and a current limiting submodule, which determines the current source command as the preset upper limit value when the initial current source command is greater than the preset upper limit value, and determines the current source command as the preset lower limit value when the initial current source command is less than the preset lower limit value. The simulation model of the variable line resistance in the rail transit traction power supply system also includes a parallel resistor connected in parallel on both sides of the variable resistance simulation module. The resistance value of the parallel resistor is determined according to the simulation step size of the simulation model of the variable line resistance.

2. A model of a rail transit traction power supply system, characterized in that, It includes at least one train module, with each train module connected in parallel and a controllable resistor module connected between every two train modules. The train module includes: a first variable line resistance model, a second variable line resistance model, a fixed resistor, and a train model. The first variable line resistance model and the second variable line resistance model are connected in series, and the first variable line resistance model and the second variable line resistance model are simulation models of variable line resistance in the rail transit traction power supply system as described in claim 1. The fixed resistor is connected in parallel across the output terminals of the first variable line resistance model and the second variable line resistance model. The train model is connected in parallel at both ends of the output terminal of the controllable resistor module and the output terminal of the first variable line resistor model.

3. The rail transit power supply system model according to claim 2, characterized in that, The rail transit traction power supply system model also includes: A controllable parallel resistor branch is connected in parallel with the train module. As the train module moves, the controllable parallel resistor branch is connected in series with the variable resistor simulation module.

4. The rail transit power supply system model according to claim 3, characterized in that, One end of the controllable parallel resistor branch is connected in series with a switch signal judgment module. The controllable parallel resistor branch and the switch signal judgment module are connected in parallel across the circuit breaker and the filter capacitor. The filter capacitor is connected in parallel with the train power module.

5. The rail transit power supply system model according to claim 4, characterized in that, The switch signal determination module includes: The first switch signal judging sub-module is configured to output a first switch signal according to the train power; The second switch signal judging sub-module is configured to output a second switch signal according to the substation voltage, the no-load voltage and the first switch signal.

6. The rail transit power supply system model according to claim 5, characterized in that, The judging process of the first switch signal judging sub-module is as follows: If the train power is less than 10 KW, the first switch signal is on; If the train power is greater than or equal to 10 KW, the first switch signal is 0, and the 0 means no output.

7. The rail transit power supply system model according to claim 5 or 6, characterized in that, The judging process of the second switch signal judging sub-module is as follows: If the first switch signal is on, the second switch signal judging sub-module does not judge, and the controllable parallel resistance branch is on; If the first switch signal is 0, the second switch signal judging sub-module judges the relationship between the substation output voltage and the no-load voltage, and obtains the second switch signal.

8. The rail transit traction power supply system model of claim 7, wherein, If the substation output voltage is less than the no-load voltage, the second switch signal is off, and the controllable parallel resistance branch is off; If the substation output voltage is greater than or equal to the no-load voltage, the second switch signal is 0.

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