Network fault flexible reconstruction control method for through traction power supply system and system thereof

Abstract

The invention discloses a network fault flexible reconstruction control method and system for a through traction power supply system, and the method comprises the steps: achieving the physical comprehension of a fault traction station and a traction network, and constructing a local fault isolation region based on the disconnection operation of a control electric split phase when an output or input port of a two-phase-single-phase conversion unit breaks down; the power supply system realizes self-adaptive reconstruction of a power supply path of the fault traction station through switching of a control strategy or adjustment of a power instruction, and local island operation of the traction network is completed; after the fault port is repaired, the power supply system further executes a fault recovery process, and finally, a system operation structure is recovered to a conventional mode before the fault; the system comprises a fault judgment module, an output port fault adjustment module and an input port fault adjustment module, and is used for realizing the method.

Description

Technical Field

[0001] The present invention relates to the technical field of electric railway power control, and in particular to a method and system for flexible reconfiguration control of network faults in a through-train traction power supply system. Background Art

[0002] The through-type traction power supply system can eliminate the electrical phase separation link on the traction network while solving power quality problems, realizing phase-free and uninterrupted power supply for the entire traction network. It can take into account the economy and reliability of system operation and is in line with the future development trend of electrified railways.

[0003] In order to reduce equipment investment and engineering transformation costs, a new through-type traction power supply system based on a "two-phase AC input-single-phase AC output" (hereinafter referred to as "two-phase-single-phase") conversion unit has been proposed in the prior art. Figure 1 As shown, the system integrates a "two-phase-to-single-phase" conversion unit on the basis of the traditional traction station to form a flexible connection interface between the traction transformer and the traction network, thereby realizing efficient and reliable full-line through-type power supply.

[0004] However, due to the large number of active components integrated into this system, there is a risk of failure at various ports during long-term operation. A failure at any port in the "two-phase to single-phase" conversion unit could cause a decrease in the traction network's power support capacity, an increase in negative sequence currents in the grid, and even instability of the entire through-line system. Therefore, maintaining the system's ability to provide continuous power in the event of a failure at any port is crucial to ensuring the stable operation and sustainable development of the new through-line traction power supply system.

[0005] In the prior art, an application document with publication number CN115603312A proposed a fault-tolerant operation control method for a hybrid through-type traction power supply device based on multi-module collaboration, but this method only targets single module failures and does not consider emergency recovery control under the failure of the entire port; an application document with publication number CN115603311A proposed an emergency management and control method for a hybrid through-type traction power supply system based on multi-device collaboration. This method adjusts the voltage phase of the traction network and coordinates the control of the internal devices to achieve emergency operation and fault recovery of the hybrid through-type traction power supply system under the emergency condition of a two-phase-single-phase conversion unit failure. The premise for the implementation of this method is that a clear voltage phase reference is still retained in the system, and the healthy traction station has sufficient phase adjustment capabilities, which is suitable for operation recovery under single traction station failure or controllable phase scenarios. However, if Figure 2 As shown, this method has obvious limitations: on the one hand, when multiple traction stations fail simultaneously in the system, the healthy ports of the traction transformers retained in each faulty traction station (such as or ) may have a phase difference between them. In the absence of a unified phase reference, it is difficult for a healthy traction station to determine the adjustment target of its output phase, resulting in the failure of the phase synchronization mechanism. On the other hand, some traction stations use the traditional same-phase power supply method, and their output voltage phase is determined by the grid voltage and the connection method of the traction transformer. They lack adjustment capabilities, resulting in the inability of the overall phase of the traction network to respond flexibly and dynamically coordinate according to the operating status. In the above situation, when switching the power supply circuit through the interconnecting switch, it is easy to cause inconsistent voltage source phases, which in turn causes circulating currents, current shocks or protection malfunctions, seriously affecting the safety and stability of the system. Therefore, this method is difficult to achieve effective coordination and safe and orderly recovery control of the traction network voltage phase in scenarios where there are unadjustable traction stations or multiple traction stations with joint failures in the system. Summary of the Invention

[0006] In view of this, the present invention provides a network fault flexible reconstruction control method and system for a through-traction power supply system, which is used to at least solve the problem in the prior art that when there is a phase-unadjustable traction station or a joint failure of multiple traction stations, the system is difficult to achieve effective fault control and flexible reconstruction of the power supply network.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: A method for flexible reconfiguration control of a network fault in a through-train traction power supply system includes the following steps: Fault diagnosis: When the fault traction station Output port of the two-phase to single-phase conversion unit When a fault occurs, the flexible reconstruction control method for the output port fault is executed; when the fault traction station The input port of the two-phase to single-phase conversion unit or In case of a fault, a flexible reconfiguration control method for input port fault is executed; Flexible reconfiguration control methods for output port failures include: Disconnect the faulty traction station Electrical phase-splitting switch between adjacent health traction stations and , close the tie switch or , complete fault isolation; switch the control method of the corresponding input port, and After recovery, switch back to the original control method. When the power flowing through the closed tie switch is reduced to 0, open the corresponding tie switch and close it after the system is connected to the grid. and ; Flexible reconfiguration control methods for input port failures include: In the 、 and The active power of each port is adjusted to 0, and then disconnect and , and close the tie switch according to the fault input port or contact switch , complete the fault isolation; after the fault input port is restored, the input port will be in normal operating state U dc - Q Control mode is connected to the grid and Perform power adjustment. When the power flowing through the tie switch is reduced to 0, disconnect the tie switch. or , and closed after the system is connected to the grid and .

[0008] Preferably, the specific contents of the flexible reconfiguration control method for output port failure include: (1) Fault isolation: disconnect the faulty traction station Electrical phase-splitting switch between adjacent health traction stations and , close the tie switch or ,make or Incorporate into the traction network; (2) Control switching: Change the corresponding input port from U dc -Q control switches to PQ control, that is, when the closed tie switch is The corresponding input port is , when the closed contact switch is The corresponding input port is , and set its corresponding active power reference value as ,in, is the load power of the traction network, and the reactive power command is set to 0; (3) Control switchback: When the output port fails After recovery, switch the control mode after switching in step (2) back to U dc -Q control; (4) Power adjustment: Use PQ to control access to the system and The active power reference value is adjusted to ; (5) Network recovery: When the power flowing through the corresponding tie switch drops to 0, disconnect the corresponding tie switch; (6) System grid connection: The phase-locked loop in the control switches to track the voltage of the traction network at the non-fault end and then closes and .

[0009] Preferably, the specific contents of the flexible reconstruction control method for input port failure include: ① 、 and The active power of each port is adjusted to 0; ②Fault isolation: disconnect and , and close the tie switch according to the fault input port or contact switch ; ③Power adjustment: The output active power is reduced to ; ④After the fault input port is restored, the original fault input port is U dc -Q controls access and The active power of the port is adjusted to ; ⑤ When the power flowing through the tie switch is reduced to 0, open the tie switch closed in step ②; ⑥ General The phase-locked loop in the control switches to track the voltage of the traction network at the non-fault end and then closes and .

[0010] Preferably, the specific contents of the fault judgment include: When the input port of the two-phase to single-phase conversion unit is detected or input port The power is normal, and the output port If the power drops to 0, it is determined to be an output port failure, and the flexible reconfiguration control method for output port failure is executed; When the input port of the two-phase to single-phase conversion unit is detected or input port The output port is 0 If power is still output, it is determined that the input port is faulty, and a flexible reconstruction control method for input port fault is executed.

[0011] Preferably, during the control switching process, the input port is enabled by the enable signal. Depend on U The dc-Q control switches to PQ control, which includes: adjust Control enable signal, which enables the PI controller in PQ control E p =1, let U dc -Q control PI controller enable signal E u =0, mode switching signal S =1.

[0012] Preferably, the flexible reconstruction control method for input port failure is to determine the specific input port of the failure before adjusting, that is, to determine whether the input port of the failure is or .

[0013] Preferably, in the process of the flexible reconstruction control method for input port fault, the tie switch is closed according to the fault input port. or contact switch The specific contents include: If the input port Closed if fault occurs , if the input port Closed if fault occurs .

[0014] A flexible reconfiguration control system for network faults in the traction power supply system, including a fault judgment module, an output port fault adjustment module, and an input port fault adjustment module; Fault diagnosis module, used when fault traction station Output port of the two-phase to single-phase conversion unit When a fault occurs, an execution signal is sent to the output port fault adjustment module; when the fault traction station The input port of the two-phase to single-phase conversion unit or In case of a fault, an execution signal is sent to the input port fault adjustment module; The output port fault conditioning module is used to perform the following: Disconnect the faulty traction station Electrical phase-splitting switch between adjacent health traction stations and , close the tie switch or , complete fault isolation; switch the control method of the corresponding input port, and After recovery, switch back to the original control method. When the power flowing through the closed tie switch is reduced to 0, open the corresponding tie switch and close it after the system is connected to the grid. and ; The input port fault conditioning module is used to perform the following: In the 、 and The active power of each port is adjusted to 0, and then disconnect and , and close the tie switch according to the fault input port or contact switch , complete the fault isolation; after the fault input port is restored, the input port will be in normal operating state U dc - Q Control mode is connected to the grid and Perform power adjustment. When the power flowing through the tie switch is reduced to 0, disconnect the tie switch. or , and closed after the system is connected to the grid and .

[0015] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a flexible network fault reconfiguration control method and system for a traction power supply system, which has the following beneficial effects: (1) The novel network fault flexible reconstruction control method of the through-line traction power supply system involved in the present invention realizes the physical decoupling of the faulty traction station and the traction network through the controlled opening and closing of the electrical phase-splitting switches between substations, and realizes the reconstruction of the power supply path of the faulty traction station without the need for phase synchronization, which significantly improves the system's fault control response speed and power supply circuit reconstruction capability. Furthermore, the proposed method can realize the coordinated operation and power support of multiple faulty traction stations, breaking through the limitations of existing methods on adaptability to single-station faults, and having stronger system fault tolerance and engineering applicability. (2) The flexible network fault reconstruction control method for the new through-type traction power supply system of the present invention is based on the original structure of the traction system. By controlling the opening and closing of the electrical phase switches and the tie switches and adjusting the control strategy, the method completes the entire process of fault separation, path switching and system topology fallback. It does not require the introduction of redundant devices or additional power resources and has good engineering economy and promotion adaptability. (3) The flexible network fault reconstruction control method for the new through-type traction power supply system involved in the present invention can maintain 100% power output of the faulty traction station under the input / output multi-type fault conditions, thereby realizing continuous power supply to the traction network; and suppress the generation of negative sequence current on the public power grid side, so that the new through-type traction power supply system can have high reliability and excellent power supply quality assurance capabilities under complex fault conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 To simplify the structural diagram of the through traction power supply system; Figure 2 This is a schematic diagram of a joint fault at multiple traction stations in the through-train traction power supply system; Figure 3 This is a schematic diagram of power flow in the event of a fault in the through-line traction power supply system port; Figure 3 (a) Schematic diagram of power flow in the case of a fault at the output port of a two-phase to single-phase converter; Figure 3 (b) Schematic diagram of power flow in the case of a fault at the input port of a two-phase to single-phase converter; Figure 4 A schematic flow chart of a method for flexible reconfiguration of a network fault-related traction power supply system provided by the present invention; Figure 5 A control switching principle diagram provided for an embodiment of the present invention; Figure 6 A control switching flow chart provided for an embodiment of the present invention; Figure 7 Output port fault simulation waveform diagram provided by the embodiment of the present invention; Figure 7 (a) is the input power of each port of the two-phase to single-phase converter; Figure 7 (b) is the two-phase output power of the traction transformer and the load side power; Figure 7 (c) is the traction network voltage U; Figure 7 (d) Three-phase current on the public grid side; Figure 7 (e) is the amplitude of the three-sequence current on the public grid side; Figure 7 (f) is the DC side voltage of the two-phase to single-phase converter.

[0018] Figure 8 Input port fault simulation waveform diagram provided by the embodiment of the present invention; Figure 8 (a) is the input power of each port of the two-phase to single-phase converter; Figure 8 (b) is the two-phase output power of the traction transformer and the load side power; Figure 8 (c) is the traction network voltage; Figure 8 (d) Three-phase current on the public grid side; Figure 8 (e) is the amplitude of the three-sequence current on the public grid side; Figure 8 (f) is the DC side voltage of the two-phase to single-phase converter. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0020] The present invention provides a method for controlling network faults in a traction power supply system. Figure 4 As shown, the following steps are included: Fault diagnosis: When the fault traction station Output port of the two-phase to single-phase conversion unit When a fault occurs, the flexible reconstruction control method for the output port fault is executed; when the fault traction station The input port of the two-phase to single-phase conversion unit or In case of a fault, a flexible reconfiguration control method for input port fault is executed; Flexible reconfiguration control methods for output port failures include: Disconnect the faulty traction station Electrical phase-splitting switch between adjacent health traction stations and , close the tie switch or , complete fault isolation; switch the control method of the corresponding input port, and After recovery, switch back to the original control method. When the power flowing through the closed tie switch is reduced to 0, open the corresponding tie switch and close it after the system is connected to the grid. and ; In the case of output port failure, the system power flow is as follows Figure 3 (a) Flexible reconfiguration control methods for input port failures include: In the 、 and The active power of each port is adjusted to 0, and then disconnect and , and close the tie switch according to the fault input port or contact switch , complete the fault isolation; after the fault input port is restored, the input port will be in normal operating state U dc - Q Control mode is connected to the grid and Perform power adjustment. When the power flowing through the tie switch is reduced to 0, disconnect the tie switch. or , and closed after the system is connected to the grid and , the system power flow in the case of input port failure is as follows Figure 3 (b)

[0021] It should be noted that: Health input port Control mode switching principle see Figure 5 ,in, is the actual voltage on the DC side, Given a reference value for the DC side voltage, is the actual active power, is the reference value for active power, is the actual reactive power, is the reactive power given value, for U dc - Q Active current reference value in control mode, for P - Q Active current reference value in control mode, is the active current reference value after mode switching, is the reactive current reference value after mode switching, and are the d-axis and q-axis modulation reference voltages, is the switching mode signal, represents a two-phase stationary coordinate system, dq Represents a two-phase rotating coordinate system.

[0022] exist P - Q In control mode, the PI controller enables the signal E p =1, E u =0, the system will have active power deviation Input active power PI controller, active power PI controller output active current reference value ;like E p =0, the active power PI controller output is set to zero. U dc - Q In control mode, the PI controller enables the signal E p =0, E u=1, deviation of DC voltage squared Input DC voltage PI controller outputs active current reference value , and passes through the secondary notch filter to filter out twice the fundamental frequency component, thereby preventing the frequency disturbance from entering the current reference value and improving the stability of DC voltage control; if E u =0, the DC voltage PI controller output is set to zero. Reactive power deviation The reactive power generated is always processed by the PI controller .

[0023] Mode switching signal S Decide The source, S =0Select , S =1Select . Selected and Input current inner loop controller generates and , and from the rotating coordinate system dq to the stationary coordinate system After the coordinate transformation, it is sent to the PWM module to drive the power converter to achieve output control.

[0024] Smooth switching process see Figure 6 .

[0025] To further implement the above technical solution, the specific contents of the flexible reconfiguration control method for output port failure include: (1) Fault isolation: To avoid faults at the output end of the traction station Voltage drop fluctuations cause disturbances to the traction network sections of adjacent traction stations, disconnecting the faulty traction station. Electrical phase-splitting switch between adjacent health traction stations and ; To build a temporary power supply path to achieve normal power supply to the faulty traction station, close the tie switch or ,make or Incorporate into the traction network; (2) Control switching: In order to actively adjust the power injected into the traction network by the input port, the corresponding input port is switched from U dc -Q control switches to PQ control, that is, when the closed tie switch is The corresponding input port is , when the closed contact switch is The corresponding input port is , and set its corresponding active power reference value as ,in, is the load power of the traction network, and the reactive power command is set to 0; (3) Control switchback: When the output port fails After recovery, switch the control mode after switching in step (2) back to U dc -Q control; (4) Power adjustment: at the output port After the repair is completed and the port is able to be reconnected, Access the system with PQ control strategy and The active power reference value is adjusted to the normal operating state ; (5) Network structure recovery: When the flow passes through the corresponding contact switch After the power is reduced to 0, the corresponding tie switch is disconnected; (6) System grid connection: The phase-locked loop in the control switches to track the voltage of the traction network at the non-fault end and then closes and .

[0026] To further implement the above technical solution, the specific contents of the flexible reconfiguration control method for input port failure include: ① In order to suppress the transient power impact during the tie-breaker closing process, before closing the tie-breaker, 、 and The active power of each port is adjusted to 0; ② Fault isolation: To avoid faults at the output end of the traction station Voltage drop fluctuations cause disturbances to the traction network sections of adjacent traction stations, disconnecting and ; To build a temporary power supply path to achieve normal power supply to the faulty traction station, close the tie switch according to the fault input port or contact switch ; ③Power adjustment: To avoid the negative sequence current on the grid side caused by uneven power on the secondary side of the traction transformer, The output active power is reduced to , the remaining The power is provided by the healthy phase on the secondary side of the traction transformer through the tie switch; ④After the fault input port is restored, the original fault input port is U dc -Q controls access and The active power of the port is adjusted to ; ⑤ To avoid power shock, when the power flowing through the tie switch drops to 0, open the tie switch closed in step ②; ⑥ To avoid current shock and circulating current problems caused by phase difference, The phase-locked loop in the control switches to track the voltage of the traction network at the non-fault end and then closes and .

[0027] In order to further implement the above technical solution, the specific contents of fault diagnosis include: When the input port of the two-phase to single-phase conversion unit is detected or input port The power is normal, and the output port If the power drops to 0, it is determined to be an output port failure, and the flexible reconfiguration control method for output port failure is executed; When the input port of the two-phase to single-phase conversion unit is detected or input port The output port is 0 If power is still output, it is determined that the input port is faulty, and a flexible reconstruction control method for input port fault is executed.

[0028] In order to further implement the above technical solution, during the control switching process, the input port is realized by enabling the signal Depend on U The dc-Q control switches to PQ control, which includes: adjust Control enable signal, which enables the PI controller in PQ control E p =1, let U dc -Q control PI controller enable signal E u =0, mode switching signal S =1.

[0029] In order to further implement the above technical solution, the flexible reconstruction control method for input port failure is to first determine the specific input port of the fault before adjusting, that is, to determine whether the input port of the fault is or .

[0030] In order to further implement the above technical solution, in the process of flexible reconstruction control method of input port fault, the tie switch corresponding to the fault input port is closed. or contact switch The specific contents include: If the input port Closed if fault occurs , if the input port Closed if fault occurs .

[0031] A flexible reconfiguration control system for network faults in the traction power supply system, including a fault judgment module, an output port fault adjustment module, and an input port fault adjustment module; Fault diagnosis module, used when fault traction station Output port of the two-phase to single-phase conversion unit When a fault occurs, an execution signal is sent to the output port fault adjustment module; when the fault traction station The input port of the two-phase to single-phase conversion unit or In case of a fault, an execution signal is sent to the input port fault adjustment module; The output port fault conditioning module is used to perform the following: Disconnect the faulty traction station Electrical phase-splitting switch between adjacent health traction stations and , close the tie switch or , complete fault isolation; switch the control method of the corresponding input port, and After recovery, switch back to the original control method. When the power flowing through the closed tie switch is reduced to 0, open the corresponding tie switch and close it after the system is connected to the grid. and ; The input port fault conditioning module is used to perform the following: In the 、 and The active power of each port is adjusted to 0, and then disconnect and , and close the tie switch according to the fault input port or contact switch , complete the fault isolation; after the fault input port is restored, the input port will be in normal operating state U dc - Q Control mode is connected to the grid and Perform power adjustment. When the power flowing through the tie switch is reduced to 0, disconnect the tie switch. or , and closed after the system is connected to the grid and .

[0032] The present invention will be further described below through simulation experiments: A novel input / output port fault condition model of the through-type traction power supply system was constructed in the MATLAB / Simulink simulation platform to verify the effectiveness of the flexible network fault reconstruction control method for the through-type traction power supply system proposed in this invention. The simulation parameters are shown in Table 1.

[0033] ; (1) Verification of flexible reconfiguration control method for output port faults; The simulation conditions of the flexible reconfiguration control method for output port faults are shown in Table 2. During the period 0-0.2s, the system operates normally; at 0.2s, the output port When a fault occurs, the flexible reconstruction control method for the output port fault is immediately activated, and the fault control is completed in 0.6 seconds; the system maintains normal operation of the fault control method for 0.6-0.8 seconds. Repair, start the output port fault recovery control method, complete the fault recovery in 1.2s, and the system is in normal operation in 1.2-1.4s.

[0034] ; The fault control and fault recovery simulation waveforms of the flexible reconfiguration control method for output port faults are shown in Figure 7 .Depend on Figure 7 From (a) to (f), we can see that during the period 0–0.2 s, the system is in normal operation and the substation Traction network voltage Stable, with an amplitude of 38.89 kV, such as Figure 7 (c) Output port Continuously supply power to the traction load and output power is 10 MW, that is P load =10 MW, e.g. Figure 7 (a) shows the two-phase input port 、 Input power and The power is 5 MW. At this time, the DC side voltage Stable at 50kV, such as Figure 7 As shown in (d), the grid-side current has no positive sequence component and zero sequence component Abnormal fluctuations, and the negative sequence component is 0, such as Figure 7 (e) shown.

[0035] At 0.2 s, the output port Sudden failure, output power Reduced to 0, such as Figure 7 As shown in (a), the system immediately executes the flexible reconstruction control method for output port faults and disconnects the phase-splitting switch. Since both the phase-splitting switch and the tie switch require 0.2 s to operate, the traction network voltage will temporarily drop, as shown in Figure 7 (c) The contactor is closed at 0.4s, switching the healthy phase of the traction transformer to The system is connected to the traction grid to continuously supply power. At this stage, the load power is completely supplied by the traction transformer. Side responsibility, such as Figure 7 (b) shows that the two-phase output power of the traction transformer , three-phase AC current on the public grid side 、 、 Temporary fluctuations such as Figure 7 As shown in (d), the negative sequence component rises, such as Figure 7 As shown in (e), the system enters an asymmetric operating state.

[0036] At 0.4 s, the input port Switch to P–Q control. During 0.4-0.6 s, adjust the port Input power to -5 MW, adjusted , traction transformer secondary side power sharing , the negative sequence current on the public grid side gradually decreases to 0, such as Figure 7 (e) As shown in Figure 5. 0.6-1.0 s, the system maintains normal operation in the fault control state. During the whole process, the DC side voltage Keep stable, such as Figure 7 (f) shown.

[0037] When the system runs to 0.8 s, the output port is detected The system has completed the repair and has the ability to reconnect, and the system starts the fault recovery control method. In 0.8s, the port The PQ control switches smoothly to U dc -Q control, while the port Connect in PQ control mode and set its output power reference value to During 0.8-1.0 s, the port Output power increases from 0 MW to 10 MW, input port and The power synchronization transitions from 0 MW to +5 MW, and the system returns to the original "two-phase power sharing - single-phase power supply" mode, such as Figure 7 (a). When the system runs to 1.0s, the port The power returns to normal, the transmission power of the tie switch drops to 0, and the control system disconnects the tie switch. Then at 1.0s, the port The phase-locked loop in the control switches to the traction network voltage tracking mode and closes the phase-splitting switch at 1.2 s. and Due to the inertia of the power recovery process, the output power of the secondary side of the traction transformer will be uneven for a short time, resulting in , causing transient fluctuations in the three-phase current, such as Figure 7 As shown in (d), a temporary negative sequence current is generated on the grid side, such as Figure 7 (e) shown.

[0038] 1.2–1.4 s, the system operation structure, control logic and power distribution all returned to normal. The secondary side power of the transformer is maintained ,like Figure 7 As shown in (b), the traction network output is stable and the three-phase current remains symmetrical, as shown in Figure 7 As shown in (d), the negative sequence current decreases rapidly, as Figure 7 (e) shows that the DC side voltage Keep constant, such as Figure 7 (f) shown.

[0039] (2) Verification of flexible reconfiguration control method for input port faults; The simulation conditions of the flexible reconstruction control method for input port faults are shown in Table 3: the system operates normally during 0-0.2s; the output port (port The same logic can be used for faults) When a fault occurs, the system immediately starts the fault control strategy in the flexible reconstruction control method of the input port fault and completes the fault control in 0.6 seconds; it maintains the fault control state and operates normally for 0.6-0.8 seconds. The repair was completed, the fault recovery strategy was initiated, and fault recovery was completed in 1.2 seconds. The system was in normal operation for 1.2-1.4 seconds.

[0040] ; The fault control and fault recovery simulation waveforms of the flexible reconfiguration control method for input port faults are shown in Figure 8 .Depend on Figure 8 From (a) to (f), we can see that during the period 0–0.2 s, the system operates normally and the substation Traction network voltage is 38.89 kV, such as Figure 8 As shown in (c), the secondary side of the traction transformer transmits equal power to the two-phase to single-phase conversion unit, that is, like Figure 8 (b) Output port Stable power supply to the traction network, output power is 10 MW. At this time, the input port 、 Input power and Both are 5 MW, such as Figure 8 (a) shows the three-phase current of the system. 、 、 Symmetrical, such as Figure 8 As shown in (d), the negative sequence component of the current Close to zero, such as Figure 8 (e) shows that the DC side voltage Maintained stably at 50 kV, such as Figure 8 (f) shown.

[0041] At 0.2 s, the input port Fault, Reduced to 0. The system immediately starts the fault control strategy in the flexible reconstruction control method for input port failure. At the moment of adjusting the output port power, due to the port Complete failure, The output power of the port is completely determined by the transformer The side is powered separately, i.e. ,The uneven distribution of the two-phase power on the secondary side of the traction transformer leads to a certain negative sequence current on the public grid side, such as Figure 8 (e) At the 0.2 s fault instant, the system adjusts the power of each port to 0 and disconnects the electrical phase switch. and Then, the tie switch is closed at 0.4 s. During the period of 0.2–0.4 s, the power supply circuit was not completely reconstructed before the tie switch was closed, resulting in the port With port A short power drop occurs. During the 0.4-0.6s period, the port The output power is adjusted from 10MW to 5MW, and , the two-phase input of the traction transformer gradually becomes balanced, such as Figure 8 As shown in (a), the system negative sequence current decreases rapidly, as shown in Figure 8 (e) As shown. During the period of 0.6–0.8 s, the system continued to operate normally in the fault control state. During this process, the traction network voltage remained stable, as shown in Figure 8 (c) shows that the port is maintained Power supply capability, DC side voltage No disturbance, such as Figure 8 (f) shown.

[0042] At 0.8s, the input port Repair, port by U dc -Q control mode is connected to the grid, and then the port is gradually adjusted The output power reaches the rated value of 10MW, the original power supply circuit of the system gradually recovers, and the contact switch is disconnected at 1.0s. , and at 1.2s the partition is closed and the phase is divided and The DC side voltage during the entire fault recovery process Stable, such as Figure 8 As shown in (f), there is only a short-term negative sequence current during the power adjustment process, such as Figure 8 (e) As shown. At 1.0s, the output side power Increase to 10MW to supply power to traction load, and after stabilization , the system negative sequence current is suppressed, such as Figure 8 (e) shown.

[0043] The present invention proposes a flexible reconstruction control method for network faults in a through-type traction power supply system. Based on the existing structure of the traction system, the physical disassembly of the faulty traction station and the traction network and the topological switching of the power supply path are achieved through the opening and closing operations of the electrical phase-splitting switch and the connecting switch. The rapid reconstruction of the power supply circuit under the fault state is further completed by adjusting the control strategy and setting the power instruction. The proposed method has good adaptability and scalability, and can cover multiple types of fault conditions, including typical situations such as single-site input port fault, single-site output port fault, and multi-site input port / output port combined fault. It not only effectively guarantees the fault recovery and power supply safety of the through-type traction system, but also significantly suppresses the negative sequence current on the grid side and improves the overall power quality level. This technical method has high economic efficiency, engineering feasibility and promotion value, and provides key technical support for the practical application and engineering of future through-type traction power supply systems.

[0044] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A flexible reconfiguration control method for network faults in a traction power supply system, characterized in that: The following steps are involved: Fault diagnosis: When the fault traction station Output port of the two-phase to single-phase conversion unit When a fault occurs, the flexible reconstruction control method for the output port fault is executed; when the fault traction station The input port of the two-phase to single-phase conversion unit or In case of a fault, a flexible reconfiguration control method for input port fault is executed; Flexible reconfiguration control methods for output port failures include: Disconnect the faulty traction station Electrical phase-splitting switch between adjacent health traction stations and , close the tie switch or , complete fault isolation; switch the control method of the corresponding input port, and After recovery, switch back to the original control method. When the power flowing through the closed tie switch is reduced to 0, open the corresponding tie switch and close it after the system is connected to the grid. and ; Flexible reconfiguration control methods for input port failures include: In the 、 and The active power of each port is adjusted to 0, and then disconnect and , and close the tie switch according to the fault input port or contact switch , complete the fault isolation; after the fault input port is restored, the input port will be in normal operating state U dc - Q Control mode is connected to the grid and Perform power adjustment. When the power flowing through the tie switch is reduced to 0, disconnect the tie switch. or , and closed after the system is connected to the grid and .

2. The method for flexible reconfiguration control of network faults in a through-traffic power supply system according to claim 1, characterized in that: The specific contents of the flexible reconfiguration control method for output port failure include: (1) Fault isolation: disconnect the faulty traction station Electrical phase-splitting switch between adjacent health traction stations and , close the tie switch or ,make or Incorporate into the traction network; (2) Control switching: Change the corresponding input port from U dc -Q control switches to PQ control, that is, when the closed tie switch is The corresponding input port is , when the closed contact switch is The corresponding input port is , and set its corresponding active power reference value as ,in, is the load power of the traction network, and the reactive power command is set to 0; (3) Control switchback: When the output port fails After recovery, switch the control mode after switching in step (2) back to U dc -Q control; (4) Power adjustment: Use PQ to control access to the system and The active power reference value is adjusted to ; (5) Network recovery: When the power flowing through the corresponding tie switch drops to 0, disconnect the corresponding tie switch; (6) System grid connection: The phase-locked loop in the control switches to track the voltage of the traction network at the non-fault end and then closes and .

3. The method for flexible reconfiguration control of network faults in a through-traffic power supply system according to claim 1, characterized in that: The specific contents of the flexible reconfiguration control method for input port faults include: ① 、 and The active power of each port is adjusted to 0; ②Fault isolation: disconnect and , and close the tie switch according to the fault input port or contact switch ; ③Power adjustment: The output active power is reduced to ; ④After the fault input port is restored, the original fault input port is U dc -Q controls access and The active power of the port is adjusted to ; ⑤ When the power flowing through the tie switch is reduced to 0, open the tie switch closed in step ②; ⑥ General The phase-locked loop in the control switches to track the voltage of the traction network at the non-fault end and then closes and .

4. The method for flexible reconfiguration control of network faults in a through-traffic power supply system according to claim 1, characterized in that: The specific contents of fault diagnosis include: When the input port of the two-phase to single-phase conversion unit is detected or input port The power is normal, and the output port If the power drops to 0, it is determined to be an output port failure, and the flexible reconfiguration control method for output port failure is executed; When the input port of the two-phase to single-phase conversion unit is detected or input port The output port is 0 If power is still output, it is determined that the input port is faulty, and a flexible reconstruction control method for input port fault is executed.

5. The method for flexible reconfiguration control of network faults in a through-traffic power supply system according to claim 1, characterized in that: During the control switching process, the input port is enabled by the enable signal. Depend on U The dc-Q control switches to PQ control, which includes: adjust Control enable signal, which enables the PI controller in PQ control E p =1, let U dc -Q control PI controller enable signal E u =0, mode switching signal S =1.

6. The method for flexible reconfiguration control of network faults in a through-traffic power supply system according to claim 1, characterized in that: Flexible reconstruction control method for input port fault Before adjustment, first determine the specific input port of the fault, that is, determine whether the input port of the fault is or .

7. The method for flexible reconfiguration control of network faults in a through-line traction power supply system according to claim 1, characterized in that: In the process of flexible reconfiguration control method for input port fault, the tie switch is closed according to the fault input port. or contact switch The specific contents include: If the input port Closed if fault occurs , if the input port Closed if fault occurs .

8. A network fault flexible reconfiguration control system for a traction power supply system, based on a network fault flexible reconfiguration control method for a traction power supply system according to any one of claims 1 to 7, characterized in that: include: Fault judgment module, output port fault adjustment module and input port fault adjustment module; Fault diagnosis module, used when fault traction station Output port of the two-phase to single-phase conversion unit When a fault occurs, an execution signal is sent to the output port fault adjustment module; when the fault traction station The input port of the two-phase to single-phase conversion unit or In case of a fault, an execution signal is sent to the input port fault adjustment module; The output port fault conditioning module is used to perform the following: Disconnect the faulty traction station Electrical phase-splitting switch between adjacent health traction stations and , close the tie switch or , complete fault isolation; switch the control method of the corresponding input port, and After recovery, switch back to the original control method. When the power flowing through the closed tie switch is reduced to 0, open the corresponding tie switch and close it after the system is connected to the grid. and ; The input port fault conditioning module is used to perform the following: In the 、 and The active power of each port is adjusted to 0, and then disconnect and , and close the tie switch according to the fault input port or contact switch , complete fault isolation; After the faulty input port is restored, the input port will be in normal operation. U dc - Q Control mode is connected to the grid and Perform power adjustment. When the power flowing through the tie switch is reduced to 0, disconnect the tie switch. or , and closed after the system is connected to the grid and .

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