Track traffic main substation transformer backup protection setting matching device

Abstract

A rail transit main substation transformer backup protection setting matching device comprises a first main transformer and a second main transformer. The first main transformer and the second main transformer are both connected with a transformer backup protection device; the first main transformer is connected with a first 35kV bus, and is respectively connected with a first 35kV incoming cabinet, a first 35kV PT cabinet and a first 35kV outgoing cabinet through the first 35kV bus; the second main transformer is connected with a second 35kV bus and is respectively connected with a second 35kV incoming cabinet, a second 35kV PT cabinet and a second 35kV outgoing cabinet through the second 35kV bus; the first 35kV wire inlet cabinet and the second 35kV wire inlet cabinet are provided with 35kV wire inlet circuit breakers. The first 35kV bus and the second 35kV bus are connected through a segmentation cabinet, and a 35kV segmentation circuit breaker is arranged in the segmentation cabinet. According to the utility model, a unified setting device is formed by optimizing a main wiring mode and an operation mode and defining a setting matching scheme, so that the power supply reliability is improved.

Description

Technical Field

[0001] The utility model belongs to a setting coordination scheme for backup protection of transformer in rail transit main substation, and forms a setting coordination scheme with guiding significance, specifically, it is an application research on the setting coordination scheme for backup protection of main transformer applicable to rail transit main substation with 35kV main connection form of single busbar segmented connection. Background Art

[0002] The plan for a certain city's rail transit main substation before 2023 is: high-voltage side voltage 110kV, line transformer group wiring, low-voltage side voltage 35kV, single busbar wiring, and no 35kV segmentation. After 2023, it is required to increase the segmentation of 35kV and adopt single busbar segmentation wiring, so that the two sections of 35kV busbar can be connected, and the 110kV line transformer group wiring form remains unchanged. Due to the increase of 35kV segmentation, the main transformer backup protection outlet and its delay need to be adjusted accordingly. The main substation supplies power to the next level of positive line switch station through cable lines, and the switch station supplies power to rectifier transformers, distribution transformers, etc. through cable lines. Usually, the voltage level of 110kV and below adopts remote backup mode, and the layer-by-layer differential coordination will cause the main transformer backup protection delay to reach about 2s. Excessive delay is not conducive to equipment stability and does not meet the protection speed requirements. The 35kV segmentation has been added, and its setting coordination problem needs to be considered. If the level differential coordination is increased, the setting coordination will be difficult.

[0003] The main transformer electrical quantity protection of the main substation includes a double-set configuration scheme with main protection and backup protection combined in one, and a single-set configuration scheme with main protection and backup protection separated. Different configuration schemes have different setting and coordination principles. Unclear setting and coordination schemes will cause confusion to operation and maintenance personnel, which is not conducive to their operation and maintenance work on the equipment. Utility Model Content

[0004] The technical problem to be solved by the utility model is: how to meet the delay requirement of main transformer backup protection and take into account the setting delay of the protection of the lower switch, and provide a backup protection setting coordination device for the transformer of the rail transit main substation.

[0005] In order to achieve the above object, the utility model is realized by the following technical solutions:

[0006] A transformer backup protection setting coordination device for a rail transit main transformer substation includes a first main transformer and a second main transformer; and the first main transformer and the second main transformer are both connected to a transformer backup protection device;

[0007] The first main transformer is connected to the No. 1 35kV busbar, and is connected to the No. 1 35kV incoming line cabinet, the No. 1 35kV PT cabinet and the No. 1 35kV outgoing line cabinet through the No. 1 35kV busbar;

[0008] The second main transformer is connected to the No. 2 35kV busbar, and is connected to the No. 2 35kV incoming cabinet, the No. 2 35kV PT cabinet and the No. 2 35kV outgoing cabinet through the No. 2 35kV busbar;

[0009] The No. 1 35kV incoming line cabinet and the No. 2 35kV incoming line cabinet are equipped with 35kV incoming line circuit breakers;

[0010] The No. 1 35kV busbar and the No. 2 35kV busbar are connected via a sectionalizing cabinet, and a 35kV sectionalizing circuit breaker is arranged in the sectionalizing cabinet;

[0011] The first main transformer and the second main transformer are provided with transformer backup protection devices, whose overcurrent protection outlets can trip the 35kV section circuit breaker, the 35kV incoming line circuit breaker of the transformer, and the high-voltage side circuit breaker of the transformer;

[0012] The No. 1 35kV outgoing line cabinet and the No. 2 35kV outgoing line cabinet are both provided with circuit breakers, and the output ends of the No. 1 35kV outgoing line cabinet and the No. 2 35kV outgoing line cabinet are both connected to the next level main line switch station of the rail transit;

[0013] Both No. 1 35kV outgoing line cabinet and No. 2 35kV outgoing line cabinet are provided with overcurrent section I and overcurrent section II. The outlets of overcurrent section I and overcurrent section II are 35kV section circuit breakers or the circuit breakers of the cabinet on the low-voltage side of the main transformer.

[0014] The transformer backup protection device consists of two sets of main and rear combined protection devices.

[0015] The transformer backup protection device consists of a single set of differential protection, non-electrical quantity protection, high backup protection and low backup protection.

[0016] Compared with the prior art, the utility model has the following beneficial effects: by optimizing the main wiring form and operation mode, clarifying the setting coordination plan, and forming a unified setting device, it is conducive to unified operation and maintenance, forming operation and maintenance standardization, reducing the workload of operation and maintenance and debugging, and reducing the possibility of errors in setting and adjusting set values, thereby improving power supply reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the main wiring diagram of the rail transit main substation;

[0018] Figure 2 This is the first set of structural diagrams for transformer backup protection devices;

[0019] Figure 3 This is the second set of structural diagrams for the transformer backup protection device. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0021] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0022] GB / T 50062-2008, Design Specification for Relay Protection and Automatic Devices of Power Installations, states that “4.0.6 External interphase short-circuit protection shall comply with the following provisions: 1. For single-side power supply double-winding transformers and three-winding transformers, interphase short-circuit backup protection should be installed on each side; non-power supply side protection may have two or three time limits; power supply side protection may have one time limit. 4 When there is no dedicated busbar protection on the low-voltage side of the transformer, and the high-voltage side interphase short-circuit backup protection is not sensitive enough to the low-voltage side bus interphase short circuit, interphase short-circuit backup protection should be configured on the low-voltage side.”

[0023] Article interpretation: Article 4.0.6, on the non-power side of the rail transit main substation, that is, the low-voltage side of the main transformer, the low-voltage side is protected by overcurrent protection, and the sectional circuit breaker is tripped by different time limits. The high-voltage side protection is not sensitive enough to the low-voltage side bus fault, and the low-voltage side is required to be equipped with backup protection, but it is not required to install two sets of protection. The reverse inference can be understood as when the high-voltage side protection meets the sensitivity requirements for the low-voltage side bus fault, the high-voltage side overcurrent can be coordinated with the low-voltage side overcurrent protection to the low-voltage side bus.

[0024] "3kV~110kV Power Grid Relay Protection Device Operation Setting Regulations" DL / T 584-2017 mentions "5.2.2 3kV~110kV power grid relay protection generally follows the remote backup principle, that is, when the relay protection installed at the circuit breaker near the fault point or the circuit breaker itself fails to operate, the relay protection at the upper level circuit breaker on the power supply side can operate to clear the fault.

[0025] 5.2.3 If there is no bus differential protection on the low-voltage side of the transformer, the relay protection setting value of the high-voltage line on the power supply side should strive to have sufficient sensitivity to the low-voltage bus. If there is no sufficient sensitivity, the protection configuration should comply with the following provisions:

[0026] a) If the sensitivity coefficient of the overcurrent protection on the high-voltage side of the transformer to the low-voltage bus meets the regulations, the overcurrent protection configured on the low-voltage side circuit breaker and the high-voltage side circuit breaker of the transformer will become the main protection and backup protection of the low-voltage bus. In this case, these two sets of overcurrent protection are required to be provided by different protection devices (or protection units).

[0027] b) If the sensitivity coefficient of the overcurrent protection on the high-voltage side of the transformer to the low-voltage bus does not meet the regulations, two sets of completely independent overcurrent protection should be configured on the low-voltage side circuit breaker of the transformer as the main protection and backup protection of the low-voltage bus. In this case, the two sets of overcurrent protection are required to be connected to different windings of the current transformer, powered by different DC fuses, and act on the low-voltage side circuit breaker and the high-voltage side circuit breaker (or the circuit breakers on each side of the transformer) with different time limits. "

[0028] Interpretation of the clauses: Clause 5.2.2: 3kV~110kV power grid relay protection generally follows the principle of remote backup. The word "generally" is used, but it does not limit the remote backup or the combination of remote and remote coordination. Higher requirements reduce the economy and improve the protection reliability and simplify the selective coordination problem; Clause 5.2.3-a): When the high-voltage side protection meets the sensitivity requirements for low-voltage side bus faults, both the high-voltage and low-voltage sides are equipped with overcurrent protection that can protect the low-voltage side bus. Since the low-voltage side bus is protected, there is a requirement to trip the low-voltage side section circuit breaker in combination with different operating modes. The purpose is to reduce the scope of the fault impact; Clause 5.2.3-b): The high-voltage side protection is not sensitive enough to the low-voltage side bus fault. When two sets of completely independent protections are installed on the low-voltage side, only the low-voltage side overcurrent protection can be used to protect the low-voltage side bus.

[0029] "Technical Code for Relay Protection and Safety Automatic Devices" GB / T 14285-2023 mentions "5.3.3.3 The backup protection for phase-to-phase short-circuit faults has a time-delay tripping of the corresponding circuit breaker, which acts to reduce the scope of the fault impact (such as tripping the busbar circuit breaker, section circuit breaker), tripping the circuit breaker on this side, and tripping the circuit breakers on each side of the transformer. a) For single-side power supply double-winding transformers and three-winding transformers, the backup protection time limit on the power supply side acts to trip the circuit breakers on each side of the transformer; the backup protection on the non-power supply side has two or three time limits, which act to reduce the scope of the fault impact, trip the circuit breaker on this side, and trip the circuit breakers on each side of the transformer; 5.3.3.5 If there is no dedicated busbar protection for the busbar connected to the low-voltage side of the transformer, in order to improve the reliability of removing the low-voltage side busbar fault, it is advisable to configure two sets of overcurrent protection on the low-voltage side of the transformer, and the input current is taken from different current transformer secondary circuits. "

[0030] Article interpretation: Article 5.3.3.3- a) states that on the non-power side of the rail transit main substation, i.e. the low-voltage side of the main transformer, the low-voltage side is protected by overcurrent protection and the first time limit tripping section circuit breaker. Article 5.3.3.5 states that it is recommended to install two sets of independent backup protection on the low-voltage side.

[0031] Based on the above analysis, the following conclusions are drawn: When there is no dedicated busbar protection on the low-voltage side of the transformer, its busbar needs to be protected by two sets of protection. When the high-voltage side protection is sensitive enough to the low-voltage side busbar fault, it can be the main transformer high backup + main transformer low backup protection to the low-voltage side busbar; when the high-voltage side protection is not sensitive enough to the low-voltage side busbar fault, it is necessary to set up two independent main transformer low backup protection to complete the protection of the low-voltage side busbar. Referring to the latest regulations, it is recommended to configure two independent main transformer low backup protections on the low-voltage side.

[0032] The 35kV busbar of the rail transit main substation is usually not equipped with a dedicated busbar protection device. The 35kV busbar is within the protection range of the main transformer backup protection. Under the current minimum operation mode, the system short-circuit capacity can basically ensure that the high backup and low backup protection settings of the main transformer set according to the regulations and specifications are sensitive enough to the 35kV busbar interphase short-circuit fault. In the current power grid, the system's short-circuit capacity is further increased, which can ensure the sensitivity of the main transformer high backup and low backup protection to the 35kV busbar interphase short-circuit.

[0033] like Figure 1 As shown, a transformer backup protection setting coordination device for a rail transit main substation includes a first main transformer 1 and a second main transformer 6; and the first main transformer 1 and the second main transformer 6 are both connected to a transformer backup protection device;

[0034] The first main transformer 1 is connected to the No. 1 35kV busbar 3, and is respectively connected to the No. 1 35kV incoming line cabinet 2, the No. 1 35kV PT cabinet 4 and the No. 1 35kV outgoing line cabinet 5 through the No. 1 35kV busbar 3;

[0035] The second main transformer 6 is connected to the second 35kV busbar 7, and is respectively connected to the second 35kV incoming line cabinet 8, the second 35kV PT cabinet 9 and the second 35kV outgoing line cabinet 10 through the second 35kV busbar 7;

[0036] The first 35kV busbar 3 and the second 35kV busbar 7 are connected via a segmentation cabinet 11, and a 35kV segmentation circuit breaker 12 is arranged in the segmentation cabinet 11;

[0037] The No. 1 35kV incoming line cabinet 2 and the No. 2 35kV incoming line cabinet 8 are both provided with a 35kV incoming line circuit breaker 14;

[0038] The first main transformer 1 and the second main transformer 6 are provided with a transformer backup protection device, whose overcurrent protection outlet can trip the 35kV section circuit breaker 12, the 35kV incoming line circuit breaker 14 of the transformer, and the high-voltage side circuit breaker of the transformer;

[0039] The first 35kV outgoing line cabinet 5 and the second 35kV outgoing line cabinet 10 are both provided with a circuit breaker 13, and the output ends of the first 35kV outgoing line cabinet 5 and the second 35kV outgoing line cabinet 10 are both connected to the next level main line switch station of the rail transit;

[0040] Both the No. 1 35kV outgoing line cabinet 5 and the No. 2 35kV outgoing line cabinet 10 are provided with an overcurrent section I and an overcurrent section II, and the outlets of the overcurrent section I and the overcurrent section II are tripped by circuit breakers 13 in the cabinets.

[0041] The working principle of the utility model is:

[0042] like Figure 1 As shown in the figure, the normal operation mode of the rail transit main substation is that two main transformers each carry a section of 35kV busbar, and the 35kV section circuit breaker 12 is in the open position; there is also an operation mode in which one main transformer carries two sections of 35kV busbars. Since the power supply company does not allow the 110kV electromagnetic ring network to be created through the rail transit main substation, when the operation mode is adjusted, one main transformer needs to be stopped, and then the 35kV section circuit breaker 12 is closed. When the operation mode is adjusted, the main transformer backup protection setting value is not adjusted, so its setting value needs to consider the above two operation modes.

[0043] Below, the protection selectivity coordination setting scheme is analyzed for different operating modes.

[0044] When the two main transformers are in the operation mode of each carrying a section of 35kV bus, the 35kV section circuit breaker 12 is in the open position, and its protection will not be activated, and there is no problem of coordination between the main transformer backup protection and the 35kV section protection; when in the process of adjusting the operation mode, for example, the first main transformer 1 is in operation → the second main transformer 6 is shut down → the 35kV section circuit breaker 12 is closed, at this time, the coordination problem between the first main transformer backup protection and the 35kV section protection is involved, and the 35kV section protection is put into charging protection. The 35kV section protection serves as the main protection of the 35kVⅡ bus, and the backup protection device of the first main transformer serves as its backup protection. After the busbar charging is completed, since the first main transformer backup protection device can protect all busbars and meet the upper and lower level difference coordination with the 35kV outgoing line, the main transformer backup protection and the 35kV outgoing line protection form upper and lower level coordination, that is, the main transformer backup protection device is the remote backup of the 35kV outgoing line protection, so it exits the 35kV segment protection and reduces the level difference coordination time of the intermediate link. In order to reduce the scope of the fault impact, the main transformer backup protection device will exit the 35kV segment circuit breaker 12 with the minimum action time. In order to reduce the possibility of error in adjusting the set value, the main transformer backup protection set value is not adjusted with the operation mode, that is, no matter which operation mode, the main transformer backup protection will exit the 35kV segment circuit breaker.

[0045] like Figure 1 As shown in the figure, the power supply company requires that the backup protection delay of the main transformer of the rail transit main substation should not exceed 2.4s. In order to meet its requirements, the backup protection delay of the main transformer is usually limited to about 2.0s; the minimum delay of No. 1 35kV outgoing line cabinet 5 and No. 2 35kV outgoing line cabinet 10 is: 1.2s for overcurrent stage I and 1.4s for overcurrent stage II. The sensitivity of the setting values ​​of overcurrent stage I and overcurrent stage II both meet the requirements.

[0046] like Figure 2 , Figure 3 As shown in the figure, it is a schematic diagram of the arrangement of the transformer backup protection device, where Figure 2 The transformer backup protection device is composed of two sets of main and rear combined protection devices, which are usually used in smart substations. Its non-electrical protection is integrated in the smart terminal equipment, which is not shown in this figure; Figure 3 The transformer backup protection device consists of a single set of differential protection, non-electrical quantity protection, high backup protection and low backup protection, and is usually used in conventional substations.

[0047] Below, the protection selectivity coordination setting schemes of different protection configuration schemes are analyzed one by one.

[0048] Considering that the 0.2s time difference coordination has been widely used in the distribution network and has been proven to be mature in practice, the time difference of the utility model is coordinated according to 0.2s.

[0049] like Figure 2As shown, each set of main-rear combined protection device has complete differential protection, high backup protection, and low backup protection functions. At this time, the low-voltage side backup protection of each set of protection is used as the main protection for 35kV bus phase-to-phase short circuit, and the low-voltage side backup protection is used as its backup protection, while taking into account the selective coordination of 35kV outgoing line protection. Two sections of low backup overcurrent protection are set in the No. 1 35kV outgoing line cabinet 5 and the No. 2 35kV outgoing line cabinet 10, each with 2 time limits. Among them, the first time limit of the overcurrent section I is 1.4s, the outlet trips the 35kV section circuit breaker 12, the second time limit is 1.6s, the outlet trips the 35kV incoming line circuit breaker 14; the first time limit of the overcurrent section II is 1.6s, the outlet trips the 35kV section circuit breaker 12, the second time limit is 1.8s, and the outlet trips the 35kV incoming line circuit breaker 14. If the transformer backup protection devices fail to trip the 35kV section circuit breaker 12, considering that the possibility of both sets of protection failing to operate at the same time is small, the greatest possibility is that the circuit breaker fails to operate. Therefore, the high backup protection will no longer trip the 35kV section circuit breaker, and only set the overcurrent stage I to trip both sides of the main transformer after a time limit of 2.0s to simplify the protection setting coordination.

[0050] like Figure 3 The figure shows the high backup protection and low backup protection of a single set of configurations. At this time, both high / low backup protections need to protect the 35kV busbar, and at the same time, the selective coordination of the 35kV outgoing line protection must be taken into account. The low backup overcurrent protection is set to 2 sections, each with 2 time limits. Among them, the first time limit of the overcurrent section I is 1.4s, the outlet trips the 35kV section circuit breaker 12, the second time limit is 1.6s, and the outlet trips the 35kV incoming line circuit breaker 14; the first time limit of the overcurrent section II is 1.6s, the outlet trips the 35kV section circuit breaker 12, the second time limit is 1.8s, and the outlet trips the 35kV incoming line circuit breaker 14. The high backup protection is only set to the overcurrent section I, the first time limit is 1.8s, the outlet trips the 35kV section circuit breaker, the second time limit is 2.0s, and the outlet trips each side of the main transformer.

[0051] Comparing the above setting coordination devices, the dual configuration scheme of main protection and backup protection combined into one has the following advantages over the single configuration scheme of main protection and backup protection separated: the dual configuration scheme of main and backup protection combined into one has dual sets of high backup protection and low backup protection, and the dual sets of low backup protection for 35kV bus phase short circuit is close to the principle of near backup coordination, and the high backup is used as far backup protection, forming a coordination scheme combining near backup + far backup, while the single high backup protection and low backup protection configuration scheme can only realize the far backup coordination scheme; the dual configuration scheme of main and backup combined into one has a higher degree of integration than the single configuration scheme of main and backup separated, simplifies the secondary line, and is conducive to operation and maintenance. Therefore, the protection configuration scheme is further unified, and both the intelligent station and the conventional station adopt the configuration scheme of dual sets of electrical quantity protection devices combined into one, and the configuration scheme of single sets of protection devices separated into main and backup is abandoned.

[0052] The above is only a preferred embodiment of the present invention. It should be pointed out that those skilled in the art can make several changes and improvements without departing from the overall concept of the present invention, and these should also be regarded as the protection scope of the present invention.

Claims

1. A backup protection setting coordination device for transformers in rail transit main substations, characterized in that: It comprises a first main transformer (1) and a second main transformer (6); and both the first main transformer (1) and the second main transformer (6) are connected to a transformer backup protection device; The first main transformer (1) is connected to a No. 1 35 kV busbar (3), and is respectively connected to a No. 1 35 kV incoming line cabinet (2), a No. 1 35 kV PT cabinet (4) and a No. 1 35 kV outgoing line cabinet (5) through the No. 1 35 kV busbar (3); The second main transformer (6) is connected to the No. 2 35kV busbar (7), and is respectively connected to the No. 2 35kV incoming line cabinet (8), the No. 2 35kV PT cabinet (9) and the No. 2 35kV outgoing line cabinet (10) through the No. 2 35kV busbar (7); The No. 1 35kV incoming line cabinet (2) and the No. 2 35kV incoming line cabinet (8) are provided with a 35kV incoming line circuit breaker (14); The first 35 kV busbar (3) and the second 35 kV busbar (7) are connected via a segmentation cabinet (11), and a 35 kV segmentation circuit breaker (12) is arranged in the segmentation cabinet (11); The first main transformer (1) and the second main transformer (6) are provided with a transformer backup protection device, whose overcurrent protection outlet can trip a 35 kV section circuit breaker (12), a 35 kV incoming line circuit breaker (14) of the transformer, and a high-voltage side circuit breaker of the transformer; The No. 1 35kV outgoing line cabinet (5) and the No. 2 35kV outgoing line cabinet (10) are both provided with circuit breakers (13), and the output ends of the No. 1 35kV outgoing line cabinet (5) and the No. 2 35kV outgoing line cabinet (10) are both connected to the next level main line switch station of the rail transit; Both the No. 1 35kV outgoing line cabinet (5) and the No. 2 35kV outgoing line cabinet (10) are provided with an overcurrent section I and an overcurrent section II. The outlets of the overcurrent section I and the overcurrent section II are tripped by a 35kV section circuit breaker (12) or a circuit breaker (13) of the cabinet on the low-voltage side of the main transformer.

2. A backup protection setting coordination device for a rail transit main substation transformer according to claim 1, characterized in that: The transformer backup protection device consists of two sets of main and rear combined protection devices.

3. A backup protection setting coordination device for a rail transit main substation transformer according to claim 1, characterized in that: The transformer backup protection device consists of a single set of differential protection, non-electrical quantity protection, high backup protection and low backup protection.

Images