A fault location method and system for electrified railway at power supply mode

Abstract

The application discloses a fault distance measurement method and system for an electrified railway AT power supply mode, relates to the technical field of fault distance measurement, determines whether load current is contained in fault current according to impedance angle, and calculates fault current without containing load current; that is, the mixed load current is removed in the fault current calculation process, so that the accuracy of the fault current is ensured; the fault type is judged based on the self-coupling variable absorption current direction characteristics, so that the fault type judgment error caused when the fault occurs at the end section of the traction network is avoided, the fault type identification accuracy is greatly improved, and the fault distance measurement precision is improved.

Description

Technical Field

[0001] This invention relates to the field of fault location technology, and specifically to a fault location method and system for AT power supply mode in electrified railways. Background Technology

[0002] Currently, heavy-haul freight railways operate at high density with frequent electric locomotive operations. Many heavy-haul freight railways employ AT (Automatic Transmission) power supply systems to enhance traction power capacity. To ensure uninterrupted current draw during brief voltage fluctuations in the traction grid, freight electric locomotives typically have their circuit breaker undervoltage protection delay settings set to 1 second. This relatively long undervoltage protection delay means that the locomotive may still be drawing current during traction grid faults. Since the fault current includes a load current component, this can increase the error in fault location calculations. To improve traction grid power supply capacity, heavy-haul freight railways generally use a "AT-connected substations, parallel substations" power supply method, such as... Figure 2 As shown, in this operating mode, when a traction network fault occurs, the fault location system typically uses the up and down T-line currents and F-line currents (I0) of the substation. T1 I F1 I T2 I F2 The fault type is determined because the traction network contains autotransformers. When the fault occurs at the end of the traction network, the fault type is incorrectly determined. Combined with the fact that the fault current contains a load current component and the fault type is incorrectly determined, the error in fault distance calculation will increase. Summary of the Invention

[0003] The technical problem to be solved by this invention is that the fault current obtained by existing fault location methods contains load current components, and the fault type is determined based on the current of the substation, which increases the error in fault location calculation. The purpose of this invention is to provide a fault location method and system for AT power supply mode of electrified railways. By removing load current from the fault data and determining the fault type based on the current direction characteristics of the autotransformer, the method avoids the situation of incorrect fault type determination when the fault occurs at the end of the traction network, and solves the problem of large fault location calculation error.

[0004] This invention is achieved through the following technical solution:

[0005] This solution provides a fault location method for AT power supply in electrified railways, including the following steps:

[0006] Step 1: Identify traction network faults based on voltage and power frequency changes, and initiate fault location and recording of fault data;

[0007] Step 2: Calculate the impedance angle of the traction network at the time of the fault based on the fault data, determine whether the fault current includes the load current based on the impedance angle, and calculate the fault current that does not include the load current.

[0008] Step 3: Determine the fault type based on the direction characteristics of the current draw-up in the fault data;

[0009] Step 4: Perform fault calculation based on the fault type and the fault current excluding load current.

[0010] The working principle of this solution is as follows: The locomotive's undervoltage protection has a long delay, meaning the locomotive is still drawing current even when the traction network fails. Traditional fault location methods obtain fault currents containing load current components, which increases the error in fault location calculations. This solution provides a fault location method for electrified railways using AT power supply. It determines whether the fault current includes load current based on impedance angle and calculates the fault current that does not include load current; that is, it removes the mixed load current during the fault current calculation process to ensure the accuracy of the fault current. Traditional fault location methods are based on the up and down T-line currents and F-line currents (I... T1 I F1 I T2 I F2 To determine the fault type, since the traction network contains autotransformers, when a fault occurs at the end of the traction network, it can lead to incorrect fault type identification. Combined with the fact that the fault current contains a load current component and the fault type identification error, the error in fault location calculation will increase. This solution determines the fault type based on the current direction characteristics of the autotransformer to avoid the fault type identification error that occurs when the fault occurs at the end of the traction network, thus greatly improving the accuracy of fault type identification and the precision of fault location.

[0011] Meanwhile, when a fault occurs in the traction network, the voltage of the traction network drops sharply from the normal state to the fault state, and the voltage fluctuates greatly within a short period of time. This solution uses the voltage power frequency change to more accurately identify traction network faults. When a traction network fault occurs, it is started with the voltage change (voltage power frequency change) to detect the fault more sensitively.

[0012] A further optimized solution is a method for identifying traction network faults based on voltage frequency changes, which includes the following process:

[0013] Collect the uplink T-line voltage U of substations, AT stations, and sectioning stations within the traction network power supply range. Ts and the downlink T-line voltage U Tx ;

[0014] Fault location is initiated when all substations, AT stations, and section stations meet the judgment criteria.

[0015] The judgment expression is: and

[0016] U set For the setting voltage, U Ts(-2T) and U Tx(-2T) This represents the upward T-line voltage and the downward T-line voltage at 2T moments before the fault.

[0017] A further optimization scheme is proposed, wherein the fault data includes:

[0018] The voltage U of the down-line T in the substation T1 Upward T-line voltage U T2 Downward T-line protection current I T1 and Downward F-line protection current I F1 Upward T-line protection current I T2 and the protection current I of the upward F line F2 Downward suction current I at1 and upward absorption current I at2 ;

[0019] Downlink T-line voltage U within AT station T3 Upward T-line voltage U T4 Downward absorption current I at3 and upward absorption current I at4 ;

[0020] Downlink T-line voltage U within the partitioned area T5 Upward T-line voltage U T6 Downward absorption current I at5 and upward absorption current I at6 The aforementioned downstream and upstream currents are both currents on the autotransformer.

[0021] The further optimized solution is that step two includes the following sub-steps:

[0022] S21, calculate the downlink fault impedance Z1 and uplink fault impedance Z2 of the substation, and determine the traction network impedance angle θ2;

[0023]

[0024]

[0025] in, Represents vector values; Indicates the uplink feeder current. Uplink feeder current;

[0026] S32, Determine the impedance angle θ at the moment of traction network failure. gz ;

[0027] S33, determine whether the impedance angle at the traction network fault moment satisfies: θ gz <k * traction network impedance angle θ2; where k is the reliability coefficient;

[0028] If so, the fault current contains load current; otherwise, the fault current does not contain load current.

[0029] The further optimized solution is that the calculation method of the fault current without load current is:

[0030] For the fault current containing load current: the fault current I gz = I TF - I TF(-2T) ;

[0031] For the fault current without load current: the fault current I gz = I TF ;

[0032] where I TF is the protection current at the fault moment, and I TF(-2T) is the current at 2T moments before the fault, generally 40 ms before the fault.

[0033] This solution can accurately identify whether the fault current contains load current, so as to eliminate the load current through the power frequency variation algorithm when the fault current contains load current.

[0034] The further optimized solution is that the method for obtaining the impedance angle at the traction network fault moment is:

[0035] Determine the load impedance angle θ1 of the traction network during normal operation according to the locomotive load characteristics, and determine the fault impedance angle θ2 when the traction network fails and the locomotive stops drawing current according to the traction network parameters; jointly determine the fault impedance angle θ3 when the traction network fails and the locomotive still draws current according to the traction network parameters and the locomotive load characteristics, and determine the impedance angle θ at the traction network fault moment according to the traction network impedance relationship gz .

[0036] Under the power supply mode of "AT substation disconnected, section substation paralleled", when a T-R fault occurs in the traction network, the direction of the suction current near the fault point is flowing into the autotransformer; when a F-R fault occurs in the traction network, the direction of the suction current near the fault point is flowing out of the autotransformer; when a T-F fault occurs in the traction network, the autotransformer is bypassed and the suction current is basically 0 in theory. According to the above characteristics, the further optimized solution is that step three includes the following process:

[0037] A. When the downlink suction current I at1 , the uplink suction current I at2 , the downlink suction current I at3 , the uplink suction current I at4 , the downlink suction current Iat5 and upward absorption current I at6 If all values ​​are less than the "TF fault judgment current" setting, then the fault type is TF fault.

[0038] B, find the current drawn up by the current I in the current drawdown. at1 Upward current I at2 Downward suction current I at3 Upward current I at4 Downward suction current I at5 and upward absorption current I at6 The maximum pull-up current I in at_max and

[0039] When the downward current I is drawn at1 Upward current I at2 Downward suction current I at3 Upward current I at4 Downward suction current I at5 and upward absorption current I at6 Any value greater than the "TF fault judgment current" setting and When the fault type is determined to be TR fault;

[0040] When the downward current I is drawn at1 Upward current I at2 Downward suction current I at3 Upward current I at4 Downward suction current I at5 and upward absorption current I at6 Any value greater than the "TF fault judgment current" setting and The fault type is determined to be FR fault.

[0041] This solution also provides a fault location system for AT power supply mode in electrified railways, which implements the above-mentioned fault location method, including: an identification and start-up module, a first calculation module, a judgment module, and a second calculation module;

[0042] The identification and activation module is used to identify traction network faults based on voltage and power frequency changes, and to activate fault ranging and record fault data.

[0043] The first calculation module is used to calculate the impedance angle of the traction network at the time of the fault based on the fault data, determine whether the fault current includes the load current based on the impedance angle, and calculate the fault current that does not include the load current.

[0044] The judgment module is used to determine the fault type based on the characteristics of the current absorption direction in the fault data.

[0045] The second calculation module is used to perform fault calculations based on the fault type and the fault current that does not include the load current.

[0046] A further optimized solution is that the identification and activation module includes a fault location device. Fault location devices are installed in substations, AT stations, and sections within the traction network power supply range, and the fault location devices are connected together through a fault location channel.

[0047] A further optimized solution involves storing the ranging data measured by the fault location device in the fault location device itself using the Comtrde standard waveform recording format. Simultaneously, the fault location device installed in the substation is equipped with a fault recall function. When a brief interruption of the ranging channel prevents the data from being uploaded, the ranging data in the fault waveform recording can be retrieved multiple times through the fault recall function of the substation's fault location device. The railway traction power supply system is a single-phase load, which can generate significant electromagnetic interference to communication lines along the line, especially during traction network faults, where the impact on communication lines is greatest. When the traction network fails, interference with communication lines causes abnormalities in the fault location channel within the faulty section, preventing data exchange and causing malfunctions in the fault location system, increasing the distance calculation error. To ensure that the fault location data is not lost during brief interruptions of the fault location channel due to electromagnetic interference, this solution stores the ranging data in the fault location device using the Comtrde standard waveform recording format.

[0048] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0049] This invention provides a fault location method and system for AT power supply in electrified railways; it determines whether the fault current includes load current based on impedance angle and calculates the fault current that does not include load current; that is, the load current is removed during the fault current calculation process to ensure the accuracy of the fault current; it judges the fault type based on the current direction characteristics of the autotransformer to avoid the situation of incorrect fault type judgment when the fault occurs at the end of the traction network, which greatly improves the accuracy of fault type identification and the precision of fault location. Attached Figure Description

[0050] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0051] Figure 1 A schematic diagram of a fault location method for AT power supply in electrified railways;

[0052] Figure 2 Connection diagram of power supply method for traction network AT to be disconnected and paralleled in the zone;

[0053] Figure 3 This is a graph showing the relationship between traction network impedance and traction network fault impedance.

[0054] Figure 4 This is a schematic diagram of the fault location device assembly. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0056] Example 1

[0057] This embodiment provides a fault location method for AT power supply in electrified railways, such as... Figure 1 As shown, the steps include:

[0058] Step 1: Identify traction network faults based on voltage and power frequency changes, and initiate fault location and recording of fault data;

[0059] The method for identifying traction network faults based on voltage frequency changes includes the following steps: collecting the upstream T-line voltage U of substations, AT stations, and sectioning stations within the traction network power supply range. Ts and the downlink T-line voltage U Tx Fault location is initiated when the substation, AT station, and sectioning station all meet the judgment criteria.

[0060] The judgment expression is: and

[0061] U set For the setting voltage, U Ts(-2T) and U Tx(-2T) This represents the upward T-line voltage and the downward T-line voltage at 2T moments before the fault.

[0062] like Figure 2 As shown, the fault data includes:

[0063] The voltage U of the down-line T in the substation T1 Upward T-line voltage U T2 Downward T-line protection current I T1 and Downward F-line protection current I F1 Upward T-line protection current I T2 and the protection current I of the upward F line F2 Downward suction current I at1 and upward absorption current Iat2 ;

[0064] The voltage U of the downlink T-line within the AT substation T3 , the voltage U of the uplink T-line T4 , the downlink pickup current I at3 and the uplink pickup current I at4 ;

[0065] The voltage U of the downlink T-line within the section post T5 , the voltage U of the uplink T-line T6 , the downlink pickup current I at5 and the uplink pickup current I at6 .

[0066] Step 2: Calculate the impedance angle at the fault moment of the traction network based on the fault data, determine whether the fault current contains load current according to the impedance angle, and calculate the fault current without load current; Step 2 specifically includes the following sub-steps:

[0067] S21, calculate the downlink fault impedance Z1 and the uplink fault impedance Z2 of the substation, and determine the impedance angle θ2 of the traction network;

[0068]

[0069]

[0070] where represents the vector value; represents the uplink feeder current, the uplink feeder current;

[0071] S32, determine the impedance angle θ at the fault moment of the traction network gz ;

[0072] S33, judge whether the impedance angle at the fault moment of the traction network satisfies: θ gz < k * the impedance angle θ2 of the traction network; where k is the reliability coefficient;

[0073] If so, the fault current contains load current, otherwise the fault current does not contain load current.

[0074] The calculation method of the fault current without load current is:

[0075] For the fault current containing load current: the fault current I gz = I TF - I TF(-2T) ;

[0076] For the fault current without load current: the fault current I gz = I TF ;

[0077] Among them I TF For the protection current during a fault, I TF(-2T) This represents the current at 2T before the fault.

[0078] The method for obtaining the impedance angle at the moment of traction network failure is as follows:

[0079] The relationship between traction network impedance and traction network fault impedance is as follows: Figure 3 As shown, the load impedance angle θ1 during normal operation of the traction network is determined based on the locomotive load characteristics; the fault impedance angle θ2 when the locomotive stops drawing current due to a traction network fault is determined based on the traction network parameters; the fault impedance angle θ3 when the locomotive continues to draw current due to a traction network fault is determined based on both the traction network parameters and the locomotive load characteristics; and the impedance angle θ at the moment of the traction network fault is determined based on the traction network impedance relationship. gz .

[0080] Step 3: Determine the fault type based on the characteristics of the current absorption direction in the fault data;

[0081] Step three includes the following process:

[0082] A, when the current I is drawn in from the current downstream. at1 Upward current I at2 Downward suction current I at3 Upward current I at4 Downward suction current I at5 and upward absorption current I at6 If all values ​​are less than the "TF fault judgment current" setting, then the fault type is TF fault.

[0083] B, find the current drawn up by the current I in the current drawdown. at1 Upward current I at2 Downward suction current I at3 Upward current I at4 Downward suction current I at5 and upward absorption current I at6 The maximum pull-up current I in at_max and

[0084] When the downward current I is drawn at1 Upward current I at2 Downward suction current I at3 Upward current I at4 Downward suction current I at5 and upward absorption current I at6 Any value greater than the "TF fault judgment current" setting and When the fault type is determined to be TR fault;

[0085] When the downward current I is drawnat1 Upward current I at2 Downward suction current I at3 Upward current I at4 Downward suction current I at5 and upward absorption current I at6 Any value greater than the "TF fault judgment current" setting and The fault type is determined to be FR fault.

[0086] Step 4: Perform fault calculation based on the fault type and the fault current excluding load current.

[0087] Example 2

[0088] This embodiment provides a fault location system for AT power supply mode in electrified railways, which implements the fault location method described in the previous embodiment, and includes: an identification and start-up module, a first calculation module, a judgment module, and a second calculation module;

[0089] The identification and activation module is used to identify traction network faults based on voltage and power frequency changes, and to activate fault ranging and record fault data.

[0090] The first calculation module is used to calculate the impedance angle of the traction network at the time of the fault based on the fault data, determine whether the fault current includes the load current based on the impedance angle, and calculate the fault current that does not include the load current.

[0091] The judgment module is used to determine the fault type based on the characteristics of the current absorption direction in the fault data.

[0092] The second calculation module is used to perform fault calculations based on the fault type and the fault current that does not include the load current.

[0093] The identification and activation module includes a fault location device, such as... Figure 4 As shown, fault location devices 1-3 are installed in substations, AT stations, and sections within the traction network power supply range, and each fault location device is connected together through a fault location channel.

[0094] The ranging data measured by the fault ranging device is stored in the fault ranging device in the Comtrde standard waveform recording format. At the same time, the fault ranging device installed in the substation is equipped with a fault recall function. When the ranging channel is briefly interrupted and the ranging data cannot be uploaded, the ranging data in the fault waveform recording can be recalled multiple times through the "fault recall" function of the substation fault ranging device.

[0095] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fault location method for AT power supply mode in electrified railways, characterized in that, Including the following steps: Step 1: Identify traction network faults based on voltage and power frequency changes, and initiate fault location and recording of fault data; The method for identifying traction network faults based on voltage frequency variations includes the following process: Collect the uplink T-line voltage U of substations, AT stations, and sectioning stations within the traction network power supply range. Ts and the voltage of the downlink T-line ; Fault location is initiated when all substations, AT stations, and section stations meet the judgment criteria. The judgment expression is: and ; in For setting voltage, and This represents the upward T-line voltage and the downward T-line voltage at 2T moments before the fault. The fault data includes: Downlink T-line voltage in the substation Upward T-line voltage Downward T-line protection current and downlink F-line protection current Upward T-line protection current and the protection current of the upward F line Downward current absorption and upward current absorption ; Downlink T-line voltage within AT station Upward T-line voltage Downward current absorption and upward current absorption ; Downlink T-line voltage within the section Upward T-line voltage Downward current absorption and upward current absorption ; Step 2: Calculate the impedance angle of the traction network at the time of the fault based on the fault data, determine whether the fault current includes load current based on the impedance angle, and calculate the fault current that does not include load current; specifically, this includes the following sub-steps: S21, calculate the downlink fault impedance Z1 and uplink fault impedance Z2 of the substation, and determine the traction network impedance angle. ; ； ； in, Represents vector values; Indicates the downlink feeder current. Uplink feeder current; S32, Determine the impedance angle at the moment of traction network fault. ; S33, Determine if the impedance angle is satisfied at the moment of traction network fault: ;in The reliability coefficient; If so, the fault current includes the load current; otherwise, the fault current does not include the load current. Step 3: Determine the fault type based on the characteristics of the current absorption direction in the fault data; Step 4: Perform fault calculation based on the fault type and the fault current excluding load current.

2. The fault location method for AT power supply mode in electrified railways according to claim 1, characterized in that, The method for calculating fault current excluding load current is as follows: For fault currents that include load currents: fault current ; For fault currents that do not include load currents: Fault current ; in To protect against current during a fault, This represents the current at 2T before the fault.

3. The fault location method for AT power supply mode in electrified railways according to claim 1, characterized in that, The method for obtaining the impedance angle at the moment of traction network failure is as follows: Determine the load impedance angle of the traction network during normal operation based on the locomotive load characteristics. The fault impedance angle is determined based on the traction network parameters when the locomotive stops drawing current due to a traction network fault. The fault impedance angle is determined based on traction network parameters and locomotive load characteristics when the locomotive continues to draw current despite a traction network fault. Determine the impedance angle at the moment of traction network failure based on the impedance relationship of the traction network. .

4. The fault location method for AT power supply mode in electrified railways according to claim 1, characterized in that, Step 3 Includes the following processes: A, when the current is drawn in from the downstream side. Upward current absorption Downward current absorption Upward current absorption Downward current absorption and upward current absorption If all values ​​are less than the "TF fault judgment current" setting, then the fault type is TF fault. B, find the current drawn in the current row. Upward current absorption Downward current absorption Upward current absorption Downward current absorption and upward current absorption Maximum pull-up current and ; When the current is drawn down Upward current absorption Downward current absorption Upward current absorption Downward current absorption and upward current absorption Any value greater than the "TF fault judgment current" setting and When the fault type is determined to be TR fault, the fault type is determined to be TR fault. When the current is drawn down Upward current absorption Downward current absorption Upward current absorption Downward current absorption and upward current absorption Any value greater than the "TF fault judgment current" setting and The fault type is determined to be FR fault.

5. A fault location system for AT power supply mode in electrified railways, characterized in that, The method for implementing the fault location method according to any one of claims 1-4 includes: an identification and activation module, a first calculation module, a judgment module, and a second calculation module; The identification and activation module is used to identify traction network faults based on voltage and power frequency changes, and to activate fault ranging and record fault data. The first calculation module is used to calculate the impedance angle of the traction network at the time of the fault based on the fault data, determine whether the fault current includes the load current based on the impedance angle, and calculate the fault current that does not include the load current. The judgment module is used to determine the fault type based on the characteristics of the current absorption direction in the fault data. The second calculation module is used to perform fault calculations based on the fault type and the fault current that does not include the load current.

6. A fault location system for AT power supply mode in electrified railways according to claim 5, characterized in that, The identification and activation module includes a fault location device. Fault location devices are installed in substations, AT stations, and sections within the traction network power supply range, and the fault location devices are connected together through a fault location channel.

7. A fault location system for AT power supply mode in electrified railways according to claim 6, characterized in that, The ranging data measured by the fault ranging device is stored in the fault ranging device in the Comtrde standard waveform recording format. At the same time, the fault ranging device installed in the substation is equipped with a fault recall function. When the ranging channel is briefly interrupted and the ranging data cannot be uploaded, the ranging data in the fault waveform can be recalled multiple times through the fault recall function of the substation fault ranging device.

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