Network fault flexible reconfiguration control method of through traction power supply system and system thereof

Abstract

The application discloses a network fault flexible reconstruction control method and system of a through traction power supply system. When a fault occurs at an output or input port of a "two-phase-single-phase" conversion unit, based on a disconnection operation for controlling electric phase separation, physical decoupling of a fault traction station and a traction network is realized, and a local fault isolation area is constructed. Through switching of a control strategy or adjustment of a power instruction, the power supply system realizes adaptive reconstruction of a power supply path of the fault traction station, completes local island operation of the traction network, and after repair of the fault port is completed, the power supply system further executes a fault recovery process, and finally restores the system operation structure to a normal 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 application relates to the technical field of electrified railway power control, in particular to a network fault flexible reconstruction control method and system for a through traction power supply system. BACKGROUND

[0002] The through traction power supply system can cancel the electric phase separation link on the traction network while addressing power quality problems, realize uninterrupted power supply without phase separation on the entire traction network, balance the economy and reliability of system operation, and meet the development trend of future electrified railways.

[0003] In order to reduce equipment investment and reduce engineering transformation cost, a new type of through traction power supply system based on a "two-phase alternating current input-single-phase alternating current output" (hereinafter referred to as "two-phase-single-phase") variable unit is proposed in the prior art. As shown in Figure 1 , the system integrates a "two-phase-single-phase" variable unit on the basis of a 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 power supply.

[0004] However, due to the integration of a large number of active devices in the structure of the system, there is a risk of failure of each port during long-term operation. Once any port of the "two-phase-single-phase" variable unit fails, it may cause a decrease in the power support capacity of the traction network, an increase in the negative sequence current of the power grid, and even instability of the entire through system. Therefore, how to maintain the continuous power supply capacity of the system when any port fails is the key to ensuring the stable operation and sustainable development of the new type of through traction power supply system.

[0005] In the prior art, an application file with publication number CN115603312A proposes a hybrid through traction power supply device fault-tolerant operation control method based on multi-module cooperation, but this method only addresses single module failure and does not consider emergency recovery control under entire port failure; an application file with publication number CN115603311A proposes a hybrid through traction power supply system emergency control method based on multi-device cooperation, which adjusts the phase of the traction network voltage and coordinates the control of internal devices to realize emergency operation and fault recovery of the hybrid through traction power supply system under two-phase-single-phase variable unit failure emergency conditions. The implementation premise of this method is that the system still retains a clear voltage phase reference, and the healthy traction station has sufficient phase adjustment capability, which is suitable for operation recovery under single traction station failure or controllable phase scenarios. However, as shown in Figure 2 , 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 failed traction station (such as or The phase difference between the healthy traction station and the fault traction station may exist, the healthy traction station is difficult to determine the adjustment target of the output phase in the absence of a unified phase reference, and the phase synchronization mechanism is invalid; on the other hand, the output voltage phase of the traction station in a traditional phase supply mode is determined by the grid voltage and the traction transformer connection mode, and lacks adjustment ability, so that the overall phase of the traction network cannot be flexibly responded and dynamically coordinated according to the operating state. In the above case, when the power supply loop is switched through the tie switch, the voltage source phases are inconsistent, and then the circulating current, current impact or protection misoperation are caused, which seriously affects the safety and stability of the system. Therefore, in the scene of the unadjustable traction station or the multi- traction station joint fault in the system, the method is difficult to realize the effective coordination and safe and orderly recovery control of the traction network voltage phase. SUMMARY

[0006] Therefore, the present application provides a network fault flexible reconstruction control method and system for penetrating traction power supply system, which at least solves the problem that the prior art is difficult to realize effective fault control and flexible reconstruction of the power supply network when the phase of the traction station is not adjustable or the multi- traction station joint fault occurs.

[0007] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0008] The network fault flexible reconstruction control method for penetrating traction power supply system comprises the following steps:

[0009] Fault judgment: when the output port of the two-phase-single-phase conversion unit of the fault traction station is faulty, the flexible reconstruction control method of the output port fault is executed; when the input port of the two-phase-single-phase conversion unit of the fault traction station is faulty, the flexible reconstruction control method of the input port fault is executed; or

[0010] The flexible reconstruction control method of the output port fault comprises:

[0011] disconnecting the electric phase switch between the fault traction station and the adjacent healthy traction station and , closing the tie switch or , completing fault isolation; switching the control method of the corresponding input port, and switching back to the original control method after the fault output port is recovered, disconnecting the corresponding tie switch when the power flowing through the closed tie switch is reduced to 0, and closing and after completing system grid connection; ​​

[0012] The flexible reconfiguration control method of input port fault comprises:

[0013] On the basis of setting the active power adjustment of each port to 0, , and , disconnecting and , and closing the tie switch or the tie switch corresponding to the fault input port to complete fault isolation; after the fault input port is recovered, the input port is connected in the control mode under normal operation U dc , Q the power of is adjusted, and when the power flowing through the tie switch is reduced to 0, the tie switch or is disconnected, and and are closed after the system is connected.

[0014] Preferably, the specific content of the flexible reconfiguration control method of output port fault comprises:

[0015] (1) Fault isolation: disconnecting the electric phase breakers between the fault traction station and the adjacent healthy traction station and , and closing the tie switch or so that or is connected to the traction network;

[0016] (2) Control switching: switching the corresponding input port from U dc -Q control to P-Q control, that is, when the closed tie switch is , the corresponding input port is , and when the closed tie switch is , the corresponding input port is , and the active power reference value corresponding thereto is set to , wherein is the load power of the traction network, and the reactive power power instruction is set to 0;

[0017] (3) Control switching back: when the fault output port is recovered, switching back the control mode switched in step (2) to U dc -Q control;

[0018] (4) Power adjustment: setting Access the system via PQ control, and The active power reference value is adjusted to ;

[0019] (5) Network restoration: When the power flowing through the corresponding tie switch drops to 0, disconnect the corresponding tie switch;

[0020] (6) System grid connection: The phase-locked loop in the control system switches to track the voltage of the traction network at the non-faulty end, and then closes. and .

[0021] Preferably, the flexible reconfiguration control method for input port faults includes the following specific details:

[0022] ① , and The active power of each port is adjusted to 0;

[0023] ② Fault isolation: Disconnect and And close the contact switch corresponding to the fault input port. or contact switch ;

[0024] ③ Power adjustment: The output active power decreased to ;

[0025] ④ After the fault input port is restored, connect the original fault input port to... U dc -Q controls access and will The active power of the port is adjusted to ;

[0026] ⑤ Once the power flowing through the tie switch drops to 0, disconnect the tie switch closed in step ②.

[0027] ⑥ The phase-locked loop in the control system switches to track the voltage of the traction network at the non-faulty end, and then closes. and .

[0028] Preferably, the specific content of fault diagnosis includes:

[0029] When the input port of the two-phase to single-phase conversion unit is detected Or input port The power is normal, but the output port... If the power drops to 0, it is determined to be an output port fault, and the flexible reconfiguration control method for output port faults is executed.

[0030] When the input port of the two-phase to single-phase conversion unit is detected Or input port The output port suddenly dropped to 0. If the power output is still positive, and the fault is determined to be an input port fault, then the flexible reconfiguration control method for input port faults is executed.

[0031] Preferably, during the control switching process, the input port is enabled by an enable signal. Depend on U The DC-Q control is switched to PQ control, and the specific details include:

[0032] adjust The control enable signal enables the PI controller in the PQ control. E p =1, let U dc -Q control enables the PI controller. E u =0, setting the mode switching signal S =1.

[0033] Preferably, the flexible reconfiguration control method for input port faults first determines the specific input port of the fault before adjustment, i.e., determines the input port of the fault as... or .

[0034] In the preferred flexible reconfiguration control method for input port faults, the contact switch corresponding to the faulty input port is closed. or contact switch The specific content includes: if the input port If there is a fault, the connection will be closed. If the input port If there is a fault, the connection will be closed. .

[0035] The flexible reconfiguration control system for network faults in the traction power supply system includes: a fault diagnosis module, an output port fault adjustment module, and an input port fault adjustment module;

[0036] The fault diagnosis module is used to detect faults in the traction station. Output port of the two-phase to single-phase converter unit In case of a fault, an execution signal is sent to the fault adjustment module at the output port; when the traction station fails... The input port of the two-phase to single-phase converter unit or In case of a fault, an execution signal is sent to the fault adjustment module at the input port;

[0037] The output port fault adjustment module is configured to perform the following:

[0038] Disconnecting the fault traction station The electrical disconnection switch between the adjacent healthy traction station And Close the tie switch Or Complete fault isolation; switch the control method of the corresponding input port, and switch back to the original control method after the output port fault is recovered, disconnect the corresponding tie switch when the power flowing through the closed tie switch is reduced to 0, and close And After completing system grid connection;

[0039] The input port fault adjustment module is configured to perform the following:

[0040] Disconnect , And Adjust the active power of each port to 0 And , and close the tie switch Or tie switch corresponding to the fault input port to complete fault isolation; after the fault input port is recovered, the input port is connected in parallel with the U dc - Q Control mode under normal operating conditions, and the power of is adjusted, the tie switch Or is disconnected when the power flowing through the tie switch is reduced to 0, and And are closed after completing system grid connection.

[0041] According to the above technical solution, compared with the prior art, the present application provides a network fault flexible reconstruction control method and system for a through traction power supply system, which has the following advantages:

[0042] (1) The novel network fault flexible reconstruction control method for a through traction power supply system provided by the present application realizes the physical decoupling of the fault traction station and the traction network through the controlled opening and closing of the electrical disconnection switch between the substations, realizes the reconstruction of the power supply path of the fault traction station without phase synchronization, significantly improves the fault control response speed and power supply loop reconstruction ability of the system, and further realizes the coordinated operation and power support of multiple fault traction stations, breaking through the limitation of the adaptability of the existing method to single station faults, and having stronger system fault tolerance ability and engineering applicability;

[0043] ​(2) The network fault flexible reconstruction control method for the new through traction power supply system based on the original structure of the traction system, through the opening and closing control of the electric phase breaking switch and the tie switch and the adjustment of the control strategy, completes the whole process of fault splitting, path switching and system topology rollback, without introducing redundant devices or additional power resources, and has good engineering economy and promotion adaptability;

[0044] (3) The network fault flexible reconstruction control method for the new through traction power supply system can maintain 100% power supply output of the fault traction station under input / output multi-type fault working conditions, realizes continuous power supply of the traction network, and suppresses the generation of negative sequence current on the public power grid side, so that the new through traction power supply system has high reliability and excellent power supply quality guarantee capability under complex fault conditions. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0046] Figure 1 It is a simplified structure diagram of the through traction power supply system;

[0047] Figure 2 It is a multi-traction station joint fault schematic diagram of the through traction power supply system;

[0048] Figure 3 It is a power flow schematic diagram under the port fault condition of the through traction power supply system; Figure 3 (a) is a power flow schematic diagram under the output port fault condition of the two-phase-single-phase converter; Figure 3 (b) is a power flow schematic diagram under the input port fault condition of the two-phase-single-phase converter;

[0049] Figure 4 It is a network fault flexible reconstruction control method flow schematic diagram of the through traction power supply system provided by the present application;

[0050] Figure 5 It is a control switching principle diagram provided by the embodiment of the present application;

[0051] Figure 6 It is a control switching flow diagram provided by the embodiment of the present application;

[0052] Figure 7 It is an output port fault simulation waveform diagram provided by the embodiment of the present application; Figure 7 (a) is the input power of each port of the two-phase-single-phase converter;Figure 7 (b) two-phase output power of the traction transformer and load side power; Figure 7 (c) traction network voltage U; Figure 7 (d) three-phase current of the public grid side; Figure 7 (e) three-phase current amplitude of the public grid side; Figure 7 (f) DC side voltage of the two-phase-single-phase converter.

[0053] Figure 8 input port fault simulation waveform diagram provided for the embodiment of the present application; Figure 8 (a) input power of each port of the two-phase-single-phase converter; Figure 8 (b) two-phase output power of the traction transformer and load side power; Figure 8 (c) traction network voltage; Figure 8 (d) three-phase current of the public grid side; Figure 8 (e) three-phase current amplitude of the public grid side; Figure 8 (f) DC side voltage of the two-phase-single-phase converter. DETAILED DESCRIPTION

[0054] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. 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 protection scope of the present application.

[0055] The present application provides a network fault flexible reconstruction control method for a through traction power supply system, as shown in the following steps: Figure 4

[0056] Fault judgment: when the output port of the two-phase-single-phase conversion unit of the fault traction station is faulty, the flexible reconstruction control method for output port fault is executed; when the input port of the two-phase-single-phase conversion unit of the fault traction station is faulty, the flexible reconstruction control method for input port fault is executed;

[0057] The flexible reconstruction control method for output port fault includes:

[0058] disconnecting the electric phase break switch between the fault traction station and the adjacent healthy traction station and closing the tie switch or ​​​​Complete fault isolation; switch the control method of the corresponding input port, and then switch the control method of the faulty output port. After restoration, switch back to the original control method. When the power flowing through the closed tie switch drops to 0, open the corresponding tie switch and close it again after the system is fully connected to the grid. and In the event of an output port failure, the system power flow is as follows: Figure 3 As shown in (a);

[0059] Flexible reconfiguration control methods for input port failures include:

[0060] In , and With the active power of each port adjusted to 0, disconnect. and And close the contact switch corresponding to the fault input port. or contact switch Complete fault isolation; after the faulty input port is restored, return the input port to its normal operating state. U dc - Q Control method for grid connection, and for Perform power adjustment; once the power flowing through the tie switch drops to zero, disconnect the tie switch. or And close the loop after the system is connected to the grid. and In the event of an input port failure, the system power flow is as follows: Figure 3 As shown in (b).

[0061] It should be noted that:

[0062] Health Input Port See the principle of control mode switching. Figure 5 ,in, This is the actual voltage on the DC side. Provide a reference value for the DC-side voltage. This represents the actual active power. A reference value is given for active power. This represents the actual reactive power. The reactive power setpoint, for U dc - Q Active current reference value in control mode. for P - Q Active current reference value in control mode. This is the active current reference value after mode switching. Vqref and are d-axis and q-axis modulated reference voltages, respectively, is the switching mode signal, represents two-phase stationary coordinate system, dq represents two-phase rotating coordinate system.

[0063] In P - Q control mode, the PI controller enable signal E p =1, E u =0, the system will have active power deviation input to the active power PI controller, the active power PI controller outputs active current reference value ; if E p =0, the active power PI controller output is zeroed. In U dc - Q control mode, the PI controller enable signal E p =0, E u =1, the deviation of DC voltage square input to the DC voltage PI controller outputs active current reference value , and through the second notch filter, used to filter out the twice fundamental frequency component, so as to avoid the frequency disturbance into the current reference value, improve the stability of DC voltage control; if E u =0, the DC voltage PI controller output is zeroed. The reactive power deviation is always generated by the reactive power PI controller .

[0064] The mode switching signal S decides the source, S =0 selects , S =1 selects . The selected and input current inner loop controller to generate and , and after the coordinate transformation from rotating coordinate system dq to stationary coordinate system , it is sent to the PWM module to drive the power converter to realize output control.

[0065] The smooth switching process is shown in Figure 6 .

[0066] To further implement the above technical solutions, the specific content of the flexible reconfiguration control method of the output port fault includes:

[0067] (1) Fault isolation: to avoid the fault traction station output voltage fluctuation causes disturbance to the adjacent traction station traction network segment, disconnects the electrical phase switch between the fault traction station and the adjacent healthy traction station and ; to build a temporary power supply path to realize normal power supply of the fault traction station, close the tie switch or , merge into the traction network or ;

[0068] (2) Control switching: 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 to P-Q control, that is, when the closed tie switch is , the corresponding input port is , and when the closed tie switch is , the corresponding input port is , and the active power reference value of the corresponding input port is set to , wherein is the load power of the traction network, and the reactive power command is set to 0;

[0069] (3) Control switching back: when the fault output port is restored, the control mode switched in step (2) is switched back to U dc -Q control;

[0070] (4) Power adjustment: after the output port is repaired and has the ability to re-enter, the port is connected to the system with P-Q control strategy, and the active power reference value of is adjusted to in the normal operating state;

[0071] (5) Network structure recovery: when the power flowing through the corresponding tie switch is reduced to 0, the corresponding tie switch is disconnected;

[0072] (6) System grid connection: switch the phase-locked loop in control to track the non-fault end traction network voltage, and then close and .

[0073] To further implement the above technical solution, the specific content of the flexible reconfiguration control method for input port faults includes:

[0074] ① To suppress transient power surges during the tie-off closing process, before closing the tie-off switch, [the following is done:] , and The active power of each port is adjusted to 0;

[0075] ② Fault isolation: To avoid faults at the traction station output end Voltage fluctuations cause disturbances to the traction network of adjacent traction substations, requiring disconnection. and To establish a temporary power supply path and ensure normal power supply to the faulty traction station, the connecting switch is closed according to the fault input port. or contact switch ;

[0076] ③ Power Adjustment: To avoid uneven power distribution on the secondary side of the traction transformer, resulting in negative sequence current on the grid side, the following measures will be taken: The output active power decreased to The remaining The power is provided by the healthy phase of the secondary side of the traction transformer through the interconnecting switch;

[0077] ④ After the fault input port is restored, connect the original fault input port to... U dc -Q controls access and will The active power of the port is adjusted to ;

[0078] ⑤ To avoid power surges, disconnect the connecting switch closed in step ② after the power flowing through it drops to 0.

[0079] ⑥ To avoid current surges and circulating current problems caused by phase differences, The phase-locked loop in the control system switches to track the voltage of the traction network at the non-faulty end, and then closes. and .

[0080] To further implement the above technical solution, the specific content of fault diagnosis includes:

[0081] When the input port of the two-phase to single-phase conversion unit is detected Or input port The power is normal, but the output port... If the power drops to 0, it is determined to be an output port fault, and the flexible reconfiguration control method for output port faults is executed.

[0082] When the input port of the two-phase to single-phase conversion unit is detected Or input port The output port suddenly dropped to 0. If the power output is still positive, and the fault is determined to be an input port fault, then the flexible reconfiguration control method for input port faults is executed.

[0083] To further implement the above technical solution, during the control switching process, an enable signal is used to control the input port. Depend on U The DC-Q control is switched to PQ control, and the specific details include:

[0084] adjust The control enable signal enables the PI controller in the PQ control. E p =1, let U dc -Q control enables the PI controller. E u =0, setting the mode switching signal S =1.

[0085] To further implement the above technical solution, the flexible reconfiguration control method for input port faults first determines the specific input port of the fault before adjustment, that is, determines the input port of the fault as... or .

[0086] To further implement the above technical solution, in the process of the flexible reconfiguration control method for input port faults, the corresponding closed contact switch is closed according to the faulty input port. or contact switch The specific content includes: if the input port If there is a fault, the connection will be closed. If the input port If there is a fault, the connection will be closed. .

[0087] The flexible reconfiguration control system for network faults in the traction power supply system includes: a fault diagnosis module, an output port fault adjustment module, and an input port fault adjustment module;

[0088] The fault diagnosis module is used to detect faults in the traction station. Output port of the two-phase to single-phase converter unit In case of a fault, an execution signal is sent to the fault adjustment module at the output port; when the traction station fails... The input port of the two-phase to single-phase converter unit or In case of a fault, an execution signal is sent to the fault adjustment module at the input port;

[0089] The output port fault handling module is used to perform the following:

[0090] Disconnect the faulty traction station Electrical phase-splitter between adjacent health traction stations and Close the contact switch or Complete fault isolation; switch the control method of the corresponding input port, and then switch the control method of the faulty output port. After restoration, switch back to the original control method. When the power flowing through the closed tie switch drops to 0, open the corresponding tie switch and close it again after the system is fully connected to the grid. and ;

[0091] The input port fault handling module is used to perform the following:

[0092] In , and With the active power of each port adjusted to 0, disconnect. and And close the contact switch corresponding to the fault input port. or contact switch Complete fault isolation; after the faulty input port is restored, return the input port to its normal operating state. U dc - Q Control method for grid connection, and for Perform power adjustment; once the power flowing through the tie switch drops to zero, disconnect the tie switch. or And close the loop after the system is connected to the grid. and .

[0093] The invention will be further illustrated below through simulation experiments:

[0094] A fault condition model of the input / output port of a novel through-type traction power supply system was built in the MATLAB / Simulink simulation platform to verify the effectiveness of the network fault flexible reconfiguration control method for the through-type traction power supply system proposed in this invention. The simulation parameters are shown in Table 1.

[0095] ;

[0096] (1) Verification of flexible reconfiguration control method for output port faults;

[0097] The simulation conditions for the flexible reconfiguration control method for output port failure are shown in Table 2. The system operates normally during the 0-0.2s period; at 0.2s, the output port... Failure, immediately start the flexible reconfiguration control method of output port failure, 0.6s complete failure control; 0.6-0.8s system maintains normal operation of failure control method. 1.0s output port Repair, start the flexible reconfiguration control method of output port failure, 1.2s complete failure recovery, 1.2-1.4s system is in normal operation state.

[0098] ;

[0099] The failure control and failure recovery simulation waveforms of the flexible reconfiguration control method of output port failure are shown in Figure 7 . As can be seen from Figure 7 (a)-(f), during 0-0.2 s, the system is in normal operation state, the substation traction network voltage is stable, with an amplitude of 38.89 kV, as shown in Figure 7 (c). The output port continues to supply power to the traction load, and the output power is 10 MW, i.e. P load =10 MW, as shown in Figure 7 (a), the input power , of the two-phase input port and are both 5 MW power. At this time, the DC side voltage is stable at 50 kV, as shown in Figure 7 (d), the network side current has no abnormal fluctuation of positive sequence component and zero sequence component , and the negative sequence component is 0, as shown in Figure 7 (e).

[0100] At 0.2 s, the output port suddenly fails, and the output power drops to 0, as shown in Figure 7 (a), the system immediately executes the flexible reconfiguration control method of output port failure, and the electric phase separation switch is opened. Since the electric phase separation switch and the tie switch both need 0.2 s of action time, the traction network voltage will temporarily drop, as shown in Figure 7 (c). The tie switch is closed at 0.4 s, and the healthy phase of the traction transformer is connected to the system to continuously supply power to the traction network. During this stage, the load power is completely borne by the traction transformer side, as shown in Figure 7 (b), resulting in that the two-phase output power of the traction transformer Three-phase AC current on the public grid side , , Temporary fluctuations may occur, such as Figure 7 As shown in (d), the negative order component increases, as... Figure 7 As shown in (e), the system enters an asymmetric operating state.

[0101] At 0.4 s, the input port Switch to P-Q control. Adjust the port during the 0.4-0.6 s interval. Input power up to -5MW, after adjustment The power on the secondary side of the traction transformer is evenly distributed. The negative sequence current on the public power grid side gradually decreases to 0, such as Figure 7 As shown in (e). From 0.6 to 1.0 s, the system maintains normal operation under fault control conditions. Throughout this process, the DC side voltage... Maintain stability, such as Figure 7 As shown in (f).

[0102] The system detected the output port after running for 0.8 seconds. The repair has been completed and the system is capable of reconnecting. The system has initiated the fault recovery control method. Within 0.8 seconds, the port... Smooth switching of PQ control to U dc -Q control, while also controlling the port Connect using PQ control mode and set its output power reference value to be [value missing]. During the period of 0.8–1.0 s, the port Output power increased from 0 MW to 10 MW, input port and Power synchronization transitioned from 0 MW to +5 MW, and the system reverted to the original "two-phase power sharing – single-phase power supply" mode, such as... Figure 7 As shown in (a). When the system runs for 1.0s, the port... Power stabilized, the power transmission of the tie switch dropped to 0, and the control system disconnected the tie switch. Then, at 1.0s, the port... The phase-locked loop in the control system switches to traction network voltage tracking mode and closes the phase-splitter switch at 1.2 seconds. and Due to the inertia inherent in the power recovery process, a short-term unevenness in the output power of the traction transformer's secondary side may occur, leading to... This causes 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 As shown in (e).

[0103] 1.2–1.4 s, the system operation structure, control logic and power distribution are all restored to normal state. Transformer secondary side power is maintained As shown in Figure 7 (b), the traction network output is stable, and the three-phase current remains symmetrical, as shown in Figure 7 (d), the negative sequence current rapidly decreases, as shown in Figure 8 (e), the DC side voltage remains constant, as shown in Figure 8 (f).

[0104] (2) Verification of flexible reconstruction control method for input port fault;

[0105] The simulation conditions of the flexible reconstruction control method for input port fault are shown in Table 3: the system is normally operated during 0-0.2 s; at 0.2 s, the output port (port fault can adopt the same logic) fails, the system immediately starts the fault management strategy in the flexible reconstruction control method for input port fault, and completes fault management at 0.6 s; maintains normal operation in fault management state during 0.6-0.8 s. At 0.8 s, the input port is repaired, the fault recovery strategy is started and completed at 1.2 s, and the system is in normal operation state during 1.2-1.4 s.

[0106] ;

[0107] The fault management and fault recovery simulation waveforms of the flexible reconstruction control method for input port fault are shown in Figure 8 . As can be seen from Figure 8 (a)-(f), the system is normally operated during 0-0.2 s, the substation voltage of the traction network is 38.89 kV, as shown in Figure 8 (c), the traction transformer secondary side transmits equal power to the two-phase-single-phase transformation unit, i.e. as shown in Figure 8 (b). The output port stably supplies power to the traction network, and the output power is 10 MW, at this time, the input port , input power and are all 5 MW, as shown in Figure 8 (a), the system three-phase current , , is symmetrical, as shown in Figure 8 (d), the current negative sequence component close to zero, such as Figure 8 (e) shows that the DC side voltage is stably maintained at 50 kV, such as Figure 8 (f) shows.

[0108] At 0.2 s, the input port fails, and the output port power is reduced to 0. The system immediately starts the fault control strategy in the flexible reconfiguration control method of the input port failure. The output port power is adjusted instantaneously, and since the port fails completely, the port output power is completely supported by the transformer side alone, that is, , the uneven distribution of two-phase power on the secondary side of the traction transformer causes a certain negative sequence current to exist on the public grid side, as shown in Figure 8 (e). At the fault moment of 0.2 s, the system adjusts the power of each port to 0 and opens the electric phase separation switches and , and then closes the tie switch at 0.4 s. During 0.2-0.4 s, since the power supply loop has not been completely reconfigured before the tie switch is closed, the port experiences a short-term power drop with the port . During 0.4-0.6 s, the output power of the port is adjusted from 10 MW to 5 MW, and , the two-phase input of the traction transformer is gradually balanced, as shown in Figure 8 (a), and the system negative sequence current rapidly decreases, as shown in Figure 8 (e). During 0.6-0.8 s, the system continues to operate in the fault control state normal operation. The traction grid voltage remains stable, as shown in Figure 8 (c), the power supply capability of the port is maintained, the DC side voltage is undisturbed, as shown in Figure 8 (f).

[0109] At 0.8 s, the input port is repaired, the port is connected to U dc the grid in the -Q control mode, and then the output power of the port is gradually adjusted to the rated value of 10 MW, and the original power supply loop of the system gradually recovers, the tie switch is opened at 1.0 s, and the electric phase separation switches and in the substation are closed at 1.2 s. During the entire fault recovery process, the DC side voltage is stable, as shown in Figure 8(f) shows that only short negative sequence current exists during the power adjustment process, as ​ (e) shows. At 1.0 s, the output side power increases to 10 MW to supply power for the traction load, and after stabilization , the system negative sequence current is suppressed, as ​ (e) shows.

[0110] The present application proposes a network fault flexible reconstruction control method for a through traction power supply system. Based on the existing structure of the traction system, the topological switching of the physical traction and power supply path of the fault traction station and the traction network is realized through the opening and closing operation of the electric phase breaking switch and the tie switch, and the fast power supply loop reconstruction under the fault state is completed through the adjustment of the control strategy and the setting of the power instruction. The proposed method has good adaptability and scalability, and can cover multiple fault conditions, including single site input port fault, single site output port fault and multiple site input port / output port joint fault and other typical situations. Not only does it effectively guarantee the fault recovery and power supply safety of the through traction system, but it also significantly suppresses the negative sequence current on the grid side and improves the overall power quality level. The technical method has high economic efficiency, engineering realizability and popularization value, and provides key technical support for the practicality and engineering of future through traction power supply systems.

[0111] The above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A network fault flexible reconfiguration control method of a through traction power supply system, characterized by, The method comprises the following steps: Fault diagnosis: When a faulty traction station Output port of the two-phase to single-phase converter unit In the event of a fault, a flexible reconfiguration control method for the output port fault is implemented; when the traction station fails... The input port of the two-phase to single-phase converter unit or In case of a fault, a flexible reconfiguration control method for input port faults will be implemented; The flexible reconstruction control method of output port fault comprises: Disconnecting faulted traction substation Electrical phase breakers between adjacent healthy traction substations And Closing tie switches Or Completes fault isolation; switches control method of corresponding input port and switches back to original control method after recovery of faulted output port Disconnects corresponding tie switch when power flowing through closed tie switch reduces to zero and closes And After completion of system reintegration The flexible reconstruction control method of input port fault comprises: In , and With the active power of each port adjusted to 0, disconnect. and And close the contact switch corresponding to the fault input port. or contact switch Complete fault isolation; after the faulty input port is restored, return the input port to its normal operating state. U dc - Q Control method for grid connection, and for Perform power adjustment; once the power flowing through the tie switch drops to zero, disconnect the tie switch. or And close the loop after the system is connected to the grid. and .

2. The network fault flexible reconfiguration control method of the through-traction power supply system according to claim 1, characterized in that, The specific content of the flexible reconstruction control method of output port fault comprises: (1) Fault isolation: Disconnect the faulty traction station Electrical phase-splitter between adjacent health traction stations and Close the contact switch or ,make or Integrate into the traction network; (2) Control switching: the corresponding input port is switched from U dc Q control to P-Q control, i.e. when the closed tie switch is , the corresponding input port is , when the closed tie switch is , the corresponding input port is , and the corresponding active power reference value is set to , wherein is the load power of the traction network, and the reactive power command is set to 0; (3) Controlling the switching back: when the output port which has failed recovers, switching back the control mode in step (2) to U dc -Q control; (4) power adjustment: the access system with P-Q control, and the active power reference value of is adjusted to (5) Mesh recovery: when the power flowing through the corresponding tie switch is reduced to 0, the corresponding tie switch is disconnected; (6) System grid connection: closing PLL in control is switched to track non-faulted end traction network voltage, then closing and .

3. The network fault flexible reconfiguration control method of the through-train power supply system according to claim 1, characterized in that, The specific content of the flexible reconstruction control method of input port fault comprises: , and active power adjustment of each port to 0;​ ② fault isolation: open and and according to the fault input port corresponding closing tie switch or tie switch ; iii. Power adjustment: the output active power of the power supply is reduced to ; and iv. Power adjustment: the output active power of the power supply is reduced to ; and ④ After the fault input port is recovered, the original fault input port is replaced by U dc -Q controls access, and replaces the active power of the port with ; (5) When the power flowing through the tie switch is reduced to 0, the tie switch closed in step 2 is disconnected; (6) Will The phase-locked loop in the control is switched to track the non-fault end traction network voltage, and then the and .

4. The network fault flexible reconfiguration control method of the through-traction power supply system according to claim 1, characterized in that, The specific content of fault judgment comprises: When detecting that the input port of the two-phase-single-phase conversion unit or the input port normal power, and the output port power drop is 0, it is determined that the output port is faulty, and the flexible reconstruction control method of the output port fault is executed; When detecting that the input port of the two-phase-single-phase conversion unit or the input port suddenly drops to 0, while the output port still outputs power, it is judged that the input port is faulty, and the flexible reconstruction control method for input port fault is executed.

5. The network fault flexible reconfiguration control method of the through-train power supply system according to claim 1, characterized in that, In the process of controlling the switching, the input port by U switching from dc-Q control to P-Q control, which includes the following details: adjusting control enable signal, enabling the PI controller in the P-Q control E p =1, enabling the PI controller in the P-Q control U dc control enable signal, enabling the PI controller in the P-Q control E u =0, enabling the mode switching signal S =1.

6. The network fault flexible reconfiguration control method of the through-train power supply system according to claim 1, characterized in that, The flexible reconfiguration control method of input port fault judges the specific input port of the fault before adjustment, that is, judges whether the input port of the fault is or .

7. The network fault flexible reconfiguration control method of the through-train power supply system according to claim 1, characterized in that, In the process of flexible reconfiguration control method of input port fault, according to the specific content of the fault input port corresponding to the closed tie switch Or tie switch Includes: if the input port Fault then close , if the input port Fault then close .

8. The network fault flexible reconfiguration control system of the through traction power supply system, based on the network fault flexible reconfiguration control method of the through traction power supply system according to any one of claims 1-7, characterized in that, Comprise: The fault judgment module, the output port fault adjustment module and the input port fault adjustment module; a fault determination module for sending an execution signal to the output port fault adjustment module when the output port of the two-phase-single-phase conversion unit of the traction station faults ; and sending an execution signal to the input port fault adjustment module when the input port of the two-phase-single-phase conversion unit of the traction station faults or ; The output port fault adjustment module is used for executing the following content: Disconnecting faulted traction substation Electrical phase breakers between adjacent healthy traction substations And Closing tie switches Or Completing fault isolation; switching control method of corresponding input port and switching back to original control method after recovery of faulted output port Disconnecting corresponding tie switch after power flowing through closed tie switch reduces to 0 and closing And After completing system grid connection; The input port fault adjustment module is used for executing the following content: In , and With the active power of each port adjusted to 0, disconnect. and And close the contact switch corresponding to the fault input port. or contact switch Complete fault isolation; After the fault input port is recovered, the input port is in normal operation state U dc - Q The control mode is connected to the grid, and the power is adjusted When the power flowing through the tie switch is reduced to 0, the tie switch is disconnected Or And close And After the system is connected to the grid.

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