Fault isolation and protection method for railway power supply system

Abstract

The invention discloses a protection and fault isolation method for a railway power supply system, and the method comprises the steps: firstly collecting instantaneous current signals at a self-closing line and a through line connected with a power distribution station in the railway power supply system, at a self-closing line and a through line in each box transformer substation, and at a primary side and a secondary side of a transformer; and then calculating the phasor of the instantaneous current signal, finally calculating the current phasor, and comparing the calculation result with threshold values epsilon and M to judge whether the corresponding electrical equipment of the railway power supply system has a fault or not. And the fault information is transmitted to a power distribution substation, and then the power distribution substation issues a corresponding instruction to perform fault isolation. According to the invention, the fault part can be quickly and effectively isolated when the railway power supply system breaks down, fault extension is prevented, and normal power supply is recovered, so that the reliability and the safety of the system are improved.

Description

Technical Field

[0001] The present invention relates to the field of fault isolation and protection of railway power supply systems, and particularly to a protection and fault isolation method applicable to railway power supply systems using load switches. Background Art

[0002] In modern railway power supply systems, load switches are common and crucial electrical devices mainly used to connect and disconnect power lines. Load switches can not only control power during normal operation but also quickly cut off the power supply in case of faults, thus playing a role in protecting equipment and lines. The reliability and safety of railway power supply systems are crucial for ensuring the normal operation of trains. In such systems, once a fault (such as a short circuit, overload, or equipment failure) occurs, it is necessary to quickly disconnect the faulty part to protect the other parts of the system.

[0003] However, the traditional fault isolation and protection methods for railway power systems mainly rely on manual inspections, which require checking the specific locations of faults in the lines one by one and then isolating the faults. Due to the increased complexity of the system caused by the use of load switches, the manual inspection method is time-consuming and laborious, and cannot isolate and protect faults in a timely manner when faults occur, resulting in the stability and safety of the system being affected. Therefore, based on the existing systems, it is urgent to propose a protection and fault isolation method applicable to railway power supply systems using load switches to improve the reliability and safety of the system. Summary of the Invention

[0004] Aiming at the above existing problems, the present invention aims to ensure that when a fault occurs in a railway power supply system, the faulty part can be quickly and effectively isolated, the fault can be prevented from spreading, and normal power supply can be restored, thereby improving the reliability and safety of the system and ensuring the continuity and stability of railway transportation. The present invention provides a protection and fault isolation method applicable to railway power supply systems using load switches.

[0005] To achieve the above object, the present invention provides a fault isolation and protection method for a railway power supply system, including the following steps:

[0006] S1, number the box transformers in the railway power supply system. In the k-th box transformer, respectively and real-time collect the three-phase instantaneous current signals of the auto closed line, the through line, and each side of the transformer connected to the through line according to different connection situations;

[0007] S2, calculate the corresponding current phasors according to the collected instantaneous currents;

[0008] S3. Calculate the power parameters of the box-type substation, compare them with the set threshold values, determine whether a fault has occurred in the box-type substation, and if a fault has occurred, transmit the fault information to the distribution substation.

[0009] S4. According to different fault locations, the distribution substation disconnects and closes the relevant circuit breakers and load switches in the corresponding order.

[0010] Further, in step S1, when k = 1, the three-phase instantaneous current signals of the automatic block line connected to the distribution substation are collected in real time: The three-phase instantaneous current signals of the automatic block line connected to the (k + 1)-th box-type substation are collected in real time: The three-phase instantaneous current signals of the primary side of the transformer connected to the automatic block line are collected in real time: The three-phase instantaneous current signals of the secondary side of the transformer connected to the automatic block line are collected in real time: The three-phase instantaneous current signals of the through line connected to the distribution substation are collected in real time: The three-phase instantaneous current signals of the through line connected to the (k + 1)-th box-type substation are collected in real time: The three-phase instantaneous current signals of the primary side of the transformer connected to the through line are collected in real time: The three-phase instantaneous current signals of the secondary side of the transformer connected to the through line are collected in real time:

[0011] Further, in step S1, inside the k-th box-type substation of the railway power supply system, when N > k > 1, the three-phase instantaneous current signals of the automatic block line connected to the (k - 1)-th box-type substation are collected in real time: The three-phase instantaneous current signals of the automatic block line connected to the (k + 1)-th box-type substation are collected in real time: The three-phase instantaneous current signals of the primary side of the transformer connected to the automatic block line are collected in real time: The three-phase instantaneous current signals of the secondary side of the transformer connected to the automatic block line are collected in real time: The three-phase instantaneous current signals of the through line connected to the (k - 1)-th box-type substation are collected in real time: The three-phase instantaneous current signals of the through line connected to the (k + 1)-th box-type substation are collected in real time: The three-phase instantaneous current signals of the primary side of the transformer connected to the through line are collected in real time: The three-phase instantaneous current signals of the secondary side of the transformer connected to the through line are collected in real time:

[0012] Furthermore, in step S1, in the kth box-type transformer of the railway power supply system, when k=N, the three-phase instantaneous current signal of the self-closing line connected to the N-1th box-type transformer is collected in real time: Real-time acquisition of three-phase instantaneous current signals on the primary side of the transformer connected to the self-closing line: Real-time acquisition of three-phase instantaneous current signals on the secondary side of the transformer connected to the self-closing line: Real-time collection of three-phase instantaneous current signals of the through-line connected to the N-1th box-type transformer: Real-time acquisition of three-phase instantaneous current signals on the primary side of the transformer connected to the through-line: Real-time acquisition of three-phase instantaneous current signals on the secondary side of the transformer connected to the through-line: At the same time, the three-phase instantaneous current signal of the self-closing line connected to the power distribution station is collected in real time: I 9-A ,I 9-B ,I 9-C ; Real-time collection of three-phase instantaneous current signals at the through-line connected to the power distribution station: I 10-A ,I 10-B ,I 10-C .

[0013] Furthermore, it is characterized in that, in step S2, the current phasor is obtained according to the instantaneous current calculation:

[0014] The busbar flow direction is specified as the positive direction.

[0015] Further, in step S3, the following formula is used to calculate

[0016]

[0017] If satisfied One of them, and satisfies If one of them occurs, it is determined that the self-closing busbar in the k-th box-type transformer fails; otherwise, it is determined that the self-closing busbar in the k-th box-type transformer does not fail.

[0018] Further, in step S3, the following formula is used to calculate

[0019]

[0020] If satisfied If it meets one of them, it is determined that the transformer connected to the non - through line in the k - th distribution transformer substation has a fault; otherwise, it is determined that the transformer connected to the non - through line in the k - th distribution transformer substation has no fault.

[0021] Further, in step S3, it is calculated by the following formula

[0022]

[0023] If it meets one of the conditions and meets one of the conditions, it is determined that the through - line busbar in the k - th distribution transformer substation has a fault; otherwise, it is determined that the through - line busbar in the k - th distribution transformer substation has no fault.

[0024] Further, in step S3, it is calculated by the following formula

[0025]

[0026] If it meets one of them, it is determined that the transformer connected to the through - line in the k - th distribution transformer substation has a fault; otherwise, it is determined that the transformer connected to the through - line in the k - th distribution transformer substation has no fault.

[0027] Further, in step S3, it is calculated by the following formula

[0028]

[0029] If it meets one of them, and meets one of them, it is determined that the non - through line between the first distribution transformer substation and the substation has a fault; otherwise, it is determined that the non - through line between the first distribution transformer substation and the substation has no fault.

[0030] Further, in step S3, it is calculated by the following formula

[0031]

[0032] If it meets one of the conditions and meets one of them, it is determined that the through - line between the first distribution transformer substation and the substation has a fault; otherwise, it is determined that the through - line between the first distribution transformer substation and the substation has no fault.

[0033] Further, in step S3, the current phasor in the (k + 1)-th distribution transformer substation is transmitted to the k - th distribution transformer substation, and it is calculated by the following formula:

[0034]

[0035] If one of the following conditions is satisfied and one of the following conditions is satisfied then it is determined that the automatic closing line between the k-th and (k + 1)-th distribution transformers fails; otherwise, it is determined that the automatic closing line between the k-th and (k + 1)-th distribution transformers does not fail.

[0036] Further, in step S3, it is calculated by the following formula

[0037]

[0038] If one of the following conditions is satisfied and one of the following conditions is satisfied then it is determined that the through line between the k-th and (k + 1)-th distribution transformers fails; otherwise, it is determined that the through line between the k-th and (k + 1)-th distribution transformers does not fail.

[0039] Further, in step S4, the substation performs fault isolation according to the fault information, specifically

[0040] S41. If the automatic closing line busbar in the k-th distribution transformer fails, first disconnect the circuit breaker QF2 of the automatic closing line in the substation, then disconnect the load switch QS k1 connected to the automatic closing line in the k-th distribution transformer k2 , and finally close the circuit breaker QF2 of the automatic closing line in the substation;

[0041] S42. If the transformer connected to the automatic closing line in the k-th distribution transformer fails, disconnect the circuit breaker QF k1 on the primary side of the transformer connected to the automatic closing line in the k-th distribution transformer;

[0042] S43. If the through line busbar in the k-th distribution transformer fails, first disconnect the circuit breaker QF1 of the through line in the substation, then disconnect the load switch QS k3 connected to the through line in the k-th distribution transformer k4 , and finally close the circuit breaker QF1 of the through line in the substation;

[0043] S44. If the transformer connected to the through line in the k-th distribution transformer fails, disconnect the circuit breaker QF k2 on the primary side of the transformer connected to the through line in the k-th distribution transformer;

[0044] S45. If a fault occurs in the auto - closing line between the first distribution transformer substation and the power distribution substation, first disconnect the circuit breaker QF2 of the auto - closing line in the power distribution substation, and then disconnect the load switch QS of the auto - closing line connecting the first distribution transformer substation and the power distribution substation. 11 and QS 12 ;

[0045] S46. If a fault occurs in the through - line between the first distribution transformer substation and the power distribution substation, first disconnect the circuit breaker QF1 of the through - line in the power distribution substation, and then disconnect the load switch QS of the through - line connecting the first distribution transformer substation and the power distribution substation. 13 and QS 14 ;

[0046] S47. If a fault occurs in the auto - closing line between the k - th and (k + 1)-th distribution transformer substations, first disconnect the circuit breaker QF2 of the auto - closing line in the power distribution substation, then disconnect the load switches QS at both ends of the faulty auto - closing line. k2 and QS (k+1)1 , and finally close the circuit breaker of the auto - closing line in the power distribution substation;

[0047] S48. If a fault occurs in the through - line between the k - th and (k + 1)-th distribution transformer substations, first disconnect the circuit breaker QF1 of the through - line in the power distribution substation, then disconnect the load switches QS at both ends of the faulty through - line. k4 and QS (k+1)3 , and finally close the circuit breaker of the through - line in the power distribution substation.

[0048] Furthermore, in S2, the threshold ε is taken as 0.01 times the rated current, and the threshold M is set according to the actual working conditions.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] 1. Precise fault judgment: By collecting the three - phase instantaneous current signals at multiple key positions in the railway power supply system (such as at the auto - closing line and through - line connecting to the power distribution substation, the auto - closing line and through - line in each distribution transformer substation, and each side of the transformer), calculating the current phasor and power parameters, and then comparing with the set thresholds, the fault location can be accurately judged, covering faults of different equipment in the distribution transformer substation, faults between different distribution transformer substations, and faults of the lines between the distribution transformer substation and the power distribution substation.

[0051] 2. Quick isolation and repair: According to the fault information, the power distribution substation can quickly disconnect and close the relevant circuit breakers and load switches in the corresponding order, quickly isolate the faulty part, which helps to restore normal power supply and reduce the fault influence time. The quick and accurate fault isolation effectively prevents the expansion of the fault, avoids the fault from affecting other parts of the system, ensures the stable operation of the railway power supply system, guarantees the normal operation of the train, and improves the reliability and safety of the system, which is crucial for the continuity and stability of railway transportation.

[0052] 3. This method is applicable to railway power supply systems using load switches and is generally applicable to railway power supply networks of different scales and layouts. Whether in a system with a large or small number of box transformers, fault handling can be carried out through numbering and corresponding calculation and judgment logics. Compared with the traditional manual inspection method for fault isolation and protection, this invention does not require a large amount of manpower to check for faults one by one, saving labor costs and time costs, improving the efficiency of fault handling, and reducing power outage time and economic losses caused by faults. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings and other embodiments can be obtained. In the drawings:

[0054] Figure 1 It is a simplified schematic diagram of a railway power supply system using a load switch.

[0055] Figure 2 It is a flowchart of the protection and fault isolation method for a railway power supply system. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0056] The following will further describe in detail the specific embodiments of the present invention in conjunction with the accompanying drawings and embodiments. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0057] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or groups.

[0058] For the sake of simplicity of the drawings, only the parts related to the present invention are schematically shown in each drawing, and they do not represent their actual structures as products. In addition, for the sake of simplicity and easy understanding of the drawings, in some drawings, components with the same structure or function are only schematically shown for one of them, or only one of them is marked. In this article, "one" not only means "only this one" but also means "more than one" situation.

[0059] It should also be further understood that the term "and / or" used in the specification and appended claims of this application refers to any combination and all possible combinations of one or more of the related listed items, and includes these combinations.

[0060] In the embodiments shown in the drawings, the indication of directions (such as up, down, left, right, front and back) is used to explain that the structures and movements of various components of the present invention are not absolute but relative. When these components are in the positions shown in the drawings, these descriptions are appropriate. If the descriptions of the positions of these components change, the indication of these directions also changes accordingly.

[0061] In addition, in the description of the present application, the terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0062] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific embodiments of the present invention will be described below with reference to the drawings.

[0063] Figure 1 A simplified schematic diagram of a railway power supply system using a load switch. The distribution substation is on the left and is connected to k box transformers through the single-track line and the through line. The value of k increases sequentially starting from the distribution substation. When k is equal to 1, position 1 represents the single-track line connection point in the first box transformer to the distribution substation, and position 5 represents the through line connection point in the first box transformer to the distribution substation; when k is greater than 1, position 1 represents the single-track line connection point in the kth box transformer to the (k - 1)th box transformer, and position 5 represents the through line connection point in the kth box transformer to the (k - 1)th box transformer; in any box transformer, position 2 represents the single-track line connection point in the kth box transformer to the (k + 1)th box transformer, position 3 represents the primary side of the transformer connected to the single-track line in the kth box transformer, position 4 represents the secondary side of the transformer connected to the single-track line in the kth box transformer, position 6 represents the through line connection point in the kth box transformer to the (k + 1)th box transformer, position 7 represents the primary side of the transformer connected to the through line in the kth box transformer, position 8 represents the secondary side of the transformer connected to the through line in the kth box transformer; position 9 represents the single-track line connection point to the distribution substation, and position 10 represents the through line connection point to the distribution substation; the figure includes the circuit breaker QF2 on the single-track line connected in the distribution substation and the circuit breaker QF1 at the through line connection point in the distribution substation; in the kth box transformer in the figure, there are two load switches QS k1 、QS k2 、two load switches QS k3 、QS k4 connected to the through line, the transformer PT k1 connected to the single-track line busbar, the transformer PT k2 connected to the through line busbar, the circuit breaker QF k1 connected to the primary side of the transformer PT k1 、the circuit breaker QF k2 connected to the primary side of the transformer PT k2 .

[0064] Figure 2 It is a flowchart of a protection and fault isolation method applicable to a railway power supply system using load switches, including the following steps:

[0065] Step 1: Data acquisition

[0066] S11. Number the box-type transformers in the railway power supply system. Starting from the box-type transformer connected to the distribution substation, they are numbered as: 1, 2, 3, … k; where the maximum value of k is N;

[0067] S12. In the k-th box-type transformer of the railway power supply system, when k = 1, real-time collect the three-phase instantaneous current signals of the automatic block line connected to the distribution substation: Real-time collect the three-phase instantaneous current signals of the automatic block line connected to the (k + 1)-th box-type transformer: Real-time collect the three-phase instantaneous current signals of the primary side of the transformer connected to the automatic block line: Real-time collect the three-phase instantaneous current signals of the secondary side of the transformer connected to the automatic block line: Real-time collect the three-phase instantaneous current signals of the through line connected to the distribution substation: Real-time collect the three-phase instantaneous current signals of the through line connected to the (k + 1)-th box-type transformer: Real-time collect the three-phase instantaneous current signals of the primary side of the transformer connected to the through line: Real-time collect the three-phase instantaneous current signals of the secondary side of the transformer connected to the through line: Among them, the subscript 1 represents the instantaneous current signal at position 1, the subscript 2 represents the instantaneous current signal at position 2, the subscript 3 represents the instantaneous current signal at position 3, the subscript 4 represents the instantaneous current signal at position 4, the subscript 5 represents the instantaneous current signal at position 5, the subscript 6 represents the instantaneous current signal at position 6, the subscript 7 represents the instantaneous current signal at position 7, and the subscript 8 represents the instantaneous current signal at position 8; the subscripts A, B, and C represent the instantaneous current signals of phase A, phase B, and phase C at this position.

[0068] S13. In the k-th box-type transformer of the railway power supply system, when N > k > 1, real-time collect the three-phase instantaneous current signals of the automatic block line connected to the (k - 1)-th box-type transformer: Real-time collect the three-phase instantaneous current signals of the automatic block line connected to the (k + 1)-th box-type transformer: Real-time collect the three-phase instantaneous current signals of the primary side of the transformer connected to the automatic block line: Real-time collect the three-phase instantaneous current signals of the secondary side of the transformer connected to the automatic block line: Real-time collect the three-phase instantaneous current signals of the through line connected to the (k - 1)-th box-type transformer: Real-time collect the three-phase instantaneous current signals of the through line connected to the (k + 1)-th box-type transformer: Collect the three-phase instantaneous current signals on the primary side of the transformer connected to the through line in real time: Collect the three-phase instantaneous current signals on the secondary side of the transformer connected to the through line in real time:

[0069] S14. In the k-th distribution transformer substation in the railway power supply system, when k = N, collect the three-phase instantaneous current signals of the auto closed line connected to the (N - 1)-th distribution transformer substation in real time: Collect the three-phase instantaneous current signals on the primary side of the transformer connected to the auto closed line in real time: Collect the three-phase instantaneous current signals on the secondary side of the transformer connected to the auto closed line in real time: Collect the three-phase instantaneous current signals of the through line connected to the (N - 1)-th distribution transformer substation in real time: Collect the three-phase instantaneous current signals on the primary side of the transformer connected to the through line in real time: Collect the three-phase instantaneous current signals on the secondary side of the transformer connected to the through line in real time:

[0070] S15. Collect the three-phase instantaneous current signals at the auto closed line connected to the distribution substation: I 9-A 、I 9-B 、I 9-C ; Collect the three-phase instantaneous current signals at the through line connected to the distribution substation: I 10-A 、I 10-B 、I 10-C ; Among them, the subscript 9 represents the instantaneous current signal at position 9, and the subscript 10 represents the instantaneous current signal at position 10;

[0071] Step 2: Calculate the current phasor

[0072] Calculate the current phasor based on the instantaneous current:

[0073] Specify that the direction from the bus to the line is the positive direction;

[0074] Step 3: Fault detection

[0075] S31. Calculate through the following formula If it satisfies One of the conditions and satisfies One of the conditions therein, then it is determined that a fault has occurred on the auto closed line bus in the k-th distribution transformer substation, otherwise it is determined that no fault has occurred on the auto closed line bus in the k-th distribution transformer substation; among them, Represents the sum of the A-phase currents at the auto closed line bus in the k-th distribution transformer substation, Represents the sum of the B-phase currents at the auto closed line bus in the k-th distribution transformer substation, represents the sum of the C-phase current at the self-closing busbar in the k-th box-type transformer;

[0076]

[0077]

[0078] S32, calculated by the following formula If satisfied If one of the conditions is met, it is judged that the transformer connected to the self-closing line in the k-th box-type transformer is faulty, otherwise it is judged that the transformer connected to the self-closing line in the k-th box-type transformer is not faulty; wherein, It represents the sum of the phase A current at the transformer connected to the self-closing line in the k-th box-type transformer. represents the sum of the phase B current at the transformer connected to the self-closing line in the k-th box-type transformer. represents the sum of the C-phase currents at the transformer connected to the self-closing line in the k-th box-type transformer;

[0079]

[0080] S33, calculated by the following formula If satisfied One of the conditions and meets If one of the conditions is met, it is determined that the through-line busbar in the k-th box-type transformer has a fault, otherwise it is determined that the through-line busbar in the k-th box-type transformer has not a fault; wherein, represents the sum of the phase A current at the through-line busbar in the kth box-type transformer. represents the sum of the phase B current at the through-line busbar in the kth box-type transformer. represents the sum of the C-phase current at the through-line busbar in the k-th box-type transformer;

[0081]

[0082] S34, calculated by the following formula If satisfied If one of the conditions is met, it is judged that the transformer connected to the through-line in the k-th box-type transformer is faulty, otherwise it is judged that the transformer connected to the through-line in the k-th box-type transformer is not faulty; wherein, represents the A-phase current and the current at the transformer connected to the through-line in the k-th box-type transformer. represents the sum of the phase B current at the transformer connected to the through-line in the kth box-type transformer and represents the sum of the C-phase currents at the transformer connected to the through-line in the k-th box-type transformer;

[0083]

[0084] S35, calculated by the following formula If satisfied One of the conditions is satisfied If one of the conditions is satisfied, it is determined that the non - through line between the first distribution transformer substation and the power distribution substation has failed; otherwise, it is determined that the non - through line between the first distribution transformer substation and the power distribution substation has not failed. Among them, represents the sum of the A - phase currents at the non - through line between the first distribution transformer substation and the power distribution substation, represents the sum of the B - phase currents at the non - through line between the first distribution transformer substation and the power distribution substation, represents the sum of the C - phase currents at the non - through line between the first distribution transformer substation and the power distribution substation;

[0085]

[0086] S36. Calculate through the following formula If satisfied One of the conditions is satisfied and If one of the conditions is satisfied, it is determined that the through line between the first distribution transformer substation and the power distribution substation has failed; otherwise, it is determined that the through line between the first distribution transformer substation and the power distribution substation has not failed. Among them, represents the sum of the A - phase currents at the through line between the first distribution transformer substation and the power distribution substation, represents the sum of the B - phase currents at the through line between the first distribution transformer substation and the power distribution substation, represents the sum of the C - phase currents at the through line between the first distribution transformer substation and the power distribution substation;

[0087]

[0088] S37. Transmit the current phasor in the (k + 1) - th distribution transformer substation to the k - th distribution transformer substation and calculate through the following formula: If satisfied One of the conditions is satisfied and If one of the conditions is satisfied, it is determined that the non - through line between the k - th and (k + 1) - th distribution transformer substations has failed; otherwise, it is determined that the non - through line between the k - th and (k + 1) - th distribution transformer substations has not failed. Among them, represents the sum of the A - phase currents at the non - through line between the k - th and (k + 1) - th distribution transformer substations, represents the sum of the B - phase currents at the non - through line between the k - th and (k + 1) - th distribution transformer substations, represents the sum of the C - phase currents at the non - through line between the k - th and (k + 1) - th distribution transformer substations;

[0089]

[0090] S38. Calculate through the following formula If satisfied One of the conditions is satisfied and If one of the conditions is met, it is determined that a fault has occurred in the through line between the k-th and (k + 1)-th distribution transformers; otherwise, it is determined that no fault has occurred in the through line between the k-th and (k + 1)-th distribution transformers. Among them, represents the sum of the A-phase currents at the through line between the k-th and (k + 1)-th distribution transformers, represents the sum of the B-phase currents at the through line between the k-th and (k + 1)-th distribution transformers, represents the sum of the C-phase currents at the through line between the k-th and (k + 1)-th distribution transformers;

[0091]

[0092] S39. If a fault occurs in the railway power supply system, the fault information is transmitted to the distribution substation.

[0093] As a preferred embodiment, in step 3, the threshold ε is taken as 0.01 times the rated current, and the threshold M is set according to the actual working conditions.

[0094] Step 4: The distribution substation performs fault isolation according to the fault information

[0095] S41. If a fault occurs in the busbar of the self-closed line in the k-th distribution transformer, first disconnect the circuit breaker QF2 of the self-closed line in the distribution substation, and then disconnect the load switch QS connected to the self-closed line in the k-th distribution transformer k1 and QS k2 , and finally close the circuit breaker QF2 of the self-closed line in the distribution substation;

[0096] S42. If a fault occurs in the transformer connected to the self-closed line in the k-th distribution transformer, disconnect the circuit breaker QF on the primary side of the transformer connected to the self-closed line in the k-th distribution transformer k1 ;

[0097] S43. If a fault occurs in the busbar of the through line in the k-th distribution transformer, first disconnect the circuit breaker QF1 of the through line in the distribution substation, and then disconnect the load switch QS connected to the through line in the k-th distribution transformer k3 and QS k4 , and finally close the circuit breaker QF1 of the through line in the distribution substation;

[0098] S44. If a fault occurs in the transformer connected to the through line in the k-th distribution transformer, disconnect the circuit breaker QF on the primary side of the transformer connected to the through line in the k-th distribution transformer k2 ;

[0099] S45. If a fault occurs in the self-closed line between the first distribution transformer and the distribution substation, first disconnect the circuit breaker QF2 of the self-closed line in the distribution substation, and then disconnect the load switches QS 11 and QS 12 ;

[0100] S46, if the through line between the first box transformer and the substation fails, first disconnect the circuit breaker QF1 of the through line in the substation, and then disconnect the load switch QS of the through line connecting the first box transformer and the substation. 13 With QS 14 ;

[0101] S47, if the self-closing line between the kth and k+1 box-type transformers fails, first disconnect the circuit breaker QF2 of the self-closing line in the distribution station, and then disconnect the load switches QS at both ends of the faulty self-closing line. k2 With QS (k+1)1 , and finally close the circuit breaker of the self-closing line in the distribution station;

[0102] S48. If a fault occurs in the through-line between the kth and k+1th box-type transformers, first disconnect the circuit breaker QF1 of the through-line in the distribution station, and then disconnect the load switches QS at both ends of the faulty through-line. k4 With QS (k+1)3 , and finally close the circuit breaker of the through line in the distribution station;

[0103] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A fault isolation and protection method for a railway power supply system, characterized in that: The following steps are involved: S1, numbering the box-type transformers in the railway power supply system, and collecting three-phase instantaneous current signals of the self-closing line, the through line and each side of the transformer connected to the through line in real time in the kth box-type transformer according to different connection conditions; S2, calculate the corresponding current phasor according to the collected instantaneous current; S3, calculating the power parameters of the box-type transformer and comparing them with the set threshold value to determine whether a fault occurs in the box-type transformer. If a fault occurs, the fault information is transmitted to the power distribution station; S4, according to different fault locations, the distribution station opens and closes the relevant circuit breakers and load switches in the corresponding order.

2. The fault isolation and protection method for a railway power supply system according to claim 1, characterized in that: In step S1, when k=1, the three-phase instantaneous current signal of the self-closing line connected to the power distribution station is collected in real time: Real-time acquisition of the three-phase instantaneous current signal of the self-closing line connected to the k+1th box-type transformer: Real-time acquisition of three-phase instantaneous current signals on the primary side of the transformer connected to the self-closing line: Real-time acquisition of three-phase instantaneous current signals on the secondary side of the transformer connected to the self-closing line: Real-time collection of three-phase instantaneous current signals of the through-line connected to the power distribution station: Real-time collection of three-phase instantaneous current signals of the through-line connected to the k+1th box-type transformer: Real-time acquisition of three-phase instantaneous current signals on the primary side of the transformer connected to the through-line: Real-time acquisition of three-phase instantaneous current signals on the secondary side of the transformer connected to the through-line:

3. The fault isolation and protection method for a railway power supply system according to claim 1, characterized in that: In step S1, in the kth box-type transformer of the railway power supply system, when N>k>1, the three-phase instantaneous current signal of the self-closing line connected to the k-1th box-type transformer is collected in real time: Real-time acquisition of the three-phase instantaneous current signal of the self-closing line connected to the k+1th box-type transformer: Real-time acquisition of three-phase instantaneous current signals on the primary side of the transformer connected to the self-closing line: Real-time acquisition of three-phase instantaneous current signals on the secondary side of the transformer connected to the self-closing line: Real-time collection of three-phase instantaneous current signals of the through-line connected to the k-1th box-type transformer: Real-time collection of three-phase instantaneous current signals of the through-line connected to the k+1th box-type transformer: Real-time acquisition of three-phase instantaneous current signals on the primary side of the transformer connected to the through-line: Real-time acquisition of three-phase instantaneous current signals on the secondary side of the transformer connected to the through-line:

4. The fault isolation and protection method for a railway power supply system according to claim 1, characterized in that: In step S1, in the kth box-type transformer of the railway power supply system, when k=N, the three-phase instantaneous current signal of the self-closing line connected to the N-1th box-type transformer is collected in real time: Real-time acquisition of three-phase instantaneous current signals on the primary side of the transformer connected to the self-closing line: Real-time acquisition of three-phase instantaneous current signals on the secondary side of the transformer connected to the self-closing line: Real-time collection of three-phase instantaneous current signals of the through-line connected to the N-1th box-type transformer: Real-time acquisition of three-phase instantaneous current signals on the primary side of the transformer connected to the through-line: Real-time acquisition of three-phase instantaneous current signals on the secondary side of the transformer connected to the through-line: At the same time, the three-phase instantaneous current signal of the self-closing line connected to the power distribution station is collected in real time: I 9-A ,I 9-B ,I 9-C ; Real-time collection of three-phase instantaneous current signals at the through-line connected to the power distribution station: I 10-A ,I 10-B ,I 10-C .

5. The fault isolation and protection method for a railway power supply system according to claim 1, characterized in that: In step S2, the current phasor is calculated based on the instantaneous current: The busbar flow direction is specified as the positive direction.

6. The fault isolation and protection method for a railway power supply system according to claim 1, characterized in that: In step S3, the following formula is used to calculate If satisfied One of them, and satisfies If one of them occurs, it is determined that the self-closing busbar in the k-th box-type transformer fails; otherwise, it is determined that the self-closing busbar in the k-th box-type transformer does not fail.

7. The fault isolation and protection method for a railway power supply system according to claim 1, characterized in that: In step S3, the following formula is used to calculate If satisfied If one of them is found, it is determined that the transformer connected to the self-closing line in the k-th box-type transformer is faulty; otherwise, it is determined that the transformer connected to the self-closing line in the k-th box-type transformer is not faulty.

8. The fault isolation and protection method for a railway power supply system according to claim 1, characterized in that: In step S3, the following formula is used to calculate If satisfied One of the conditions and meets If one of the conditions is met, it is determined that the through-line busbar in the k-th box-type transformer has a fault; otherwise, it is determined that the through-line busbar in the k-th box-type transformer has no fault.

9. The fault isolation and protection method for a railway power supply system according to claim 1, characterized in that: In step S3, the following formula is used to calculate If satisfied If one of them is found, it is determined that the transformer connected to the through-line in the k-th box-type transformer is faulty; otherwise, it is determined that the transformer connected to the through-line in the k-th box-type transformer is not faulty.

10. The fault isolation and protection method for a railway power supply system according to claim 1, characterized in that: In step S3, the following formula is used to calculate If satisfied One of them, and satisfies If one of them occurs, it is determined that the self-closing line between the first box-type transformer and the power distribution station fails; otherwise, it is determined that the self-closing line between the first box-type transformer and the power distribution station does not fail.

11. The fault isolation and protection method for a railway electric power supply system according to claim 1, characterized in that: In step S3, the following formula is used to calculate If satisfied One of the conditions and meets If one of them occurs, it is determined that the through-line between the first box-type transformer and the power distribution station fails; otherwise, it is determined that the through-line between the first box-type transformer and the power distribution station does not fail.

12. The fault isolation and protection method for a railway power supply system according to claim 1, characterized in that: In step S3, the current phasor in the k+1th box transformer is transmitted to the kth box transformer and calculated by the following formula: If satisfied One of the conditions is met If one of them is detected, it is determined that the self-closing line between the kth and k+1th box-type transformers is faulty; otherwise, it is determined that the self-closing line between the kth and k+1th box-type transformers is not faulty.

13. The fault isolation and protection method for a railway power supply system according to claim 1, characterized in that: In step S3, the following formula is used to calculate If satisfied One of the conditions and meets If one of them is detected, it is determined that the through-line between the kth and k+1th box-type transformers is faulty; otherwise, it is determined that the through-line between the kth and k+1th box-type transformers is not faulty.

14. The fault isolation and protection method for a railway power supply system according to claim 1, characterized in that: In step S4, S41, if the busbar of the self-closing line in the k-th box-type transformer fails, first disconnect the circuit breaker QF2 of the self-closing line in the distribution station, and then disconnect the load switch QS connected to the self-closing line in the k-th box-type transformer k1 With QS k2 , and finally close the circuit breaker QF2 of the self-closing line in the distribution station; S42: If the transformer connected to the self-closing line in the k-th box-type transformer fails, disconnect the circuit breaker QF on the primary side of the transformer connected to the self-closing line in the k-th box-type transformer. k1 ; S43, if the busbar of the through-line in the k-th box-type transformer fails, first disconnect the circuit breaker QF1 of the through-line in the distribution station, and then disconnect the load switch QS connected to the through-line in the k-th box-type transformer. k3 With QS k4 , and finally close the circuit breaker QF1 of the through line in the distribution station; S44. If the transformer connected to the through-line in the k-th box-type transformer fails, disconnect the circuit breaker QF on the primary side of the transformer connected to the through-line in the k-th box-type transformer. k2 ; S45, if the self-closing line between the first box-type transformer and the power distribution station fails, first disconnect the circuit breaker QF2 of the self-closing line in the power distribution station, and then disconnect the load switch QS of the self-closing line connecting the first box-type transformer and the power distribution station. 11 With QS 12 ; S46, if the through-line between the first box-type transformer and the substation fails, first disconnect the circuit breaker QF1 of the through-line in the substation, and then disconnect the load switch QS of the through-line connecting the first box-type transformer and the substation. 13 With QS 14 ; S47, if the self-closing line between the kth and k+1 box-type transformers fails, first disconnect the circuit breaker QF2 of the self-closing line in the distribution station, and then disconnect the load switches QS at both ends of the faulty self-closing line. k2 With QS (k+1)1 , and finally close the circuit breaker of the self-closing line in the distribution station; S48. If a fault occurs in the through-line between the kth and k+1th box-type transformers, first disconnect the circuit breaker QF1 of the through-line in the distribution station, and then disconnect the load switches QS at both ends of the faulty through-line. k4 With QS (k+1)3 , and finally close the circuit breaker of the through line in the distribution station.

15. The method for fault isolation and protection of a railway power supply system according to any one of claims 6 to 13, characterized in that: The threshold ε in S2 is 0.01 times the rated current, and the threshold M is set according to the actual working conditions.

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