Long-distance protection system for main transformer
Through the main transformer long-distance protection system, fault signal transmission is achieved by using differential protection devices connected by optical fiber communication, which solves the problem that current transformers are difficult to meet requirements in long-distance scenarios and reduces equipment costs and production cycles.
Patent Information
- Application Number
- CN202422457415.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-10
- Publication Date
- 2025-10-10
- Estimated Expiration
- 2034-10-10
AI Technical Summary
In long-distance scenarios, protective current transformers are difficult to meet requirements, and existing technologies require customization and are costly.
A main transformer long-distance protection system is adopted, including a transformer, a main transformer differential protection device, a first line optical fiber differential protection device and a second line optical fiber differential protection device. The transmission of fault tripping signals and control of circuit breakers are achieved through optical fiber communication connections.
The protection range is shortened in long-distance scenarios, the current transformer parameters are easy to select, and the equipment cost and production cycle are reduced.
Smart Images
Figure CN223428152U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of main transformer protection, in particular to a long-distance protection system for a main transformer. Background Art
[0002] The main transformer in a substation system is a key device for voltage conversion in transmission and distribution systems. It can reduce or increase voltage to meet the requirements of different voltage levels. Main transformer protection is a crucial device for ensuring safe transformer operation and preventing accidents from escalating. It selectively eliminates various internal and external faults that may occur in the transformer, preventing them from escalating.
[0003] In a typical 110kV substation layout, the control cable installation distance generally does not exceed 200 meters. Commonly used control cables generally cover this distance and meet the impedance and voltage drop requirements of the secondary circuit. In a specific scenario, some control cables are installed over a distance of approximately 1000 meters. In this long-distance scenario, the secondary load of the protective current transformer is large, making it difficult to verify the secondary induced potential of the current transformer to meet the requirements. When selecting a current transformer, if the performance parameters of the current transformer are improved, it is difficult to find a suitable match in the current market. Customization is required from the manufacturer, which results in long product development and production cycles and high equipment costs.
[0004] The above content is only used to assist in understanding the technical solution of the present invention and does not constitute an admission that the above content is prior art. Utility Model Content
[0005] The main purpose of the utility model is to provide a long-distance protection system for a main transformer, aiming to solve the technical problem in the prior art that current transformers for protection in long-distance scenarios are difficult to meet the requirements.
[0006] To achieve the above objectives, the technical solution of the utility model proposes a long-distance protection system for a main transformer.
[0007] To achieve the above object, the present invention provides a main transformer long-distance protection system, which includes: a transformer, a main transformer differential protection device, a first line optical fiber differential protection device, and a second line optical fiber differential protection device;
[0008] The high-voltage side current loop of the main transformer differential protection device is connected to the high-voltage side current transformer of the transformer, the low-voltage side current loop of the main transformer differential protection device is connected to the low-voltage side current transformer of the transformer, the first line optical fiber differential protection device is communicatively connected to the main transformer differential protection device, and the first line optical fiber differential protection device and the second line optical fiber differential protection device are connected via optical fiber communication;
[0009] The main transformer differential protection device is configured to generate a fault trip signal when a short circuit fault is detected, and input the fault trip signal to the first line optical fiber differential protection device;
[0010] The first line optical fiber differential protection device is used to send the fault trip signal to the second line optical fiber differential protection device through optical fiber, driving the outlet of the second line optical fiber differential protection device to trip the high-voltage side circuit breaker of the transformer.
[0011] Optionally, the high-voltage side current transformer includes: an independent current transformer and a bushing current transformer;
[0012] The independent current transformer and the bushing current transformer are arranged between the high-voltage side of the transformer and the high-voltage busbar, the independent current transformer is arranged close to the high-voltage busbar, and the bushing current transformer is arranged close to the high-voltage side of the transformer;
[0013] The high-voltage side current loop of the main transformer differential protection device is connected to the bushing current transformer;
[0014] The first line optical fiber differential protection device is connected to the bushing current transformer, and the second line optical fiber differential protection device is connected to the independent current transformer.
[0015] Optionally, when both the first line optical fiber differential protection device and the second line optical fiber differential protection device detect a short circuit fault, the outlet of the first line optical fiber differential protection device trips the low-voltage side circuit breaker of the transformer, and the outlet of the second line optical fiber differential protection device trips the high-voltage side circuit breaker of the transformer.
[0016] Optionally, when the second line optical fiber differential protection device detects a short circuit fault but does not detect a short circuit fault, a backup tripping signal is sent to the first line optical fiber differential protection device via optical fiber, driving the first line optical fiber differential protection device outlet to trip the low-voltage side circuit breaker of the transformer.
[0017] Optionally, the main transformer long-distance protection system further includes: a high-voltage side backup protection device;
[0018] The high-voltage side current loop of the high-voltage side backup protection device is connected to the bushing current transformer, and the high-voltage side backup protection device is also communicatively connected to the first line optical fiber differential protection device.
[0019] Optionally, the main transformer long-distance protection system further includes: a low-voltage side backup protection device;
[0020] The low-voltage side current loop of the low-voltage side backup protection device is connected with a low-voltage side current transformer of the transformer, and the low-voltage side backup protection device is further communicatively connected with the main transformer differential protection device.
[0021] Optionally, the high-voltage side backup protection device, the low-voltage side backup protection device, the main transformer differential protection device and the first line optical fiber differential protection device are all arranged in a transformer protection cabinet.
[0022] The laying distance of the control cable of the secondary wiring of the bushing current transformer from the transformer protection cabinet is within a preset parameter range.
[0023] Optionally, a transformer low-break circuit breaker operation box is further arranged in the transformer protection cabinet.
[0024] Optionally, the second line optical fiber differential protection device is arranged in a high-voltage side protection cabinet.
[0025] The laying distance of the control cable of the secondary wiring of the independent current transformer from the high-voltage side protection cabinet is within a preset parameter range.
[0026] Optionally, a transformer high-break circuit breaker operation box is further arranged in the high-voltage side protection cabinet.
[0027] The main transformer long-distance protection system comprises a transformer, a main transformer differential protection device, a first line optical fiber differential protection device and a second line optical fiber differential protection device; a high-voltage side current loop of the main transformer differential protection device is connected with a high-voltage side current transformer of the transformer, a low-voltage side current loop of the main transformer differential protection device is connected with a low-voltage side current transformer of the transformer, the first line optical fiber differential protection device is communicatively connected with the main transformer differential protection device, and the first line optical fiber differential protection device and the second line optical fiber differential protection device are communicatively connected through an optical fiber; the main transformer differential protection device is configured to generate a fault trip signal when detecting occurrence of a short-circuit fault, and open the fault trip signal into the first line optical fiber differential protection device; the first line optical fiber differential protection device is configured to send the fault trip signal to the second line optical fiber differential protection device through the optical fiber, and drive the second line optical fiber differential protection device to trip the high-voltage side circuit breaker of the transformer. The protection range of the main transformer differential protection is reduced from a high-voltage bus to a high-voltage side bushing, and the protection requirement of a lead wire from the bus to the high-voltage side bushing of the transformer is completed by the two sets of line optical fiber current differential protection devices, so that the performance parameters of the current transformer are easy to select. BRIEF DESCRIPTION OF DRAWINGS
[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings described in the following only constitute some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained according to the structures shown in the drawings without creative labor.
[0029] Figure 1 It is a structure schematic view of the first embodiment of the long distance protection system of the main transformer of the present application.
[0030] Figure 2 It is a typical configuration schematic view of the protection current transformer of the main transformer in the prior art.
[0031] Figure 3 It is a structure schematic view of the second embodiment of the long distance protection system of the main transformer of the present application.
[0032] Figure 4 It is a secondary wiring diagram of the high-voltage side breaker in the second embodiment of the long distance protection system of the main transformer of the present application.
[0033] Figure 5 It is a secondary wiring diagram of the low-voltage side breaker in the second embodiment of the long distance protection system of the main transformer of the present application.
[0034] The implementation, functional features and advantages of the present application will be further described with reference to the drawings in combination with the embodiments. DETAILED DESCRIPTION
[0035] It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.
[0036] The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments only constitute some of the embodiments of the present application, and are not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.
[0037] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between the components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly.
[0038] In addition, the descriptions of "first," "second," etc. in this utility model are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this utility model.
[0039] Reference Figure 1 , Figure 1 This is a structural diagram of the first embodiment of the long-distance protection system for main transformers of the present invention. The present invention proposes the first embodiment of the long-distance protection system for main transformers.
[0040] In this embodiment, the main transformer long-distance protection system includes: a transformer 10, a main transformer differential protection device 20, a first line optical fiber differential protection device 30, and a second line optical fiber differential protection device 40. The high-voltage side current loop of the main transformer differential protection device is connected to the high-voltage side current transformer of the transformer, the low-voltage side current loop of the main transformer differential protection device is connected to the low-voltage side current transformer 101 of the transformer, the first line optical fiber differential protection device is communicatively connected to the main transformer differential protection device, and the first line optical fiber differential protection device and the second line optical fiber differential protection device are connected via optical fiber communication.
[0041] It should be noted that a main transformer differential protection device can be an electrical device that protects the main transformer of a power system. It can determine whether the main transformer has a fault by detecting the difference in current between the two sides of the main transformer and perform corresponding protective actions based on the judgment result. A fiber optic differential protection device can be an electrical device that provides differential protection for fiber optic communication systems. It can determine fault conditions by detecting differential optical power, thereby implementing signal switching and protection.
[0042] Furthermore, the high-voltage side current transformer includes: an independent current transformer 102 and a bushing current transformer 103; the independent current transformer and the bushing current transformer are arranged between the high-voltage side of the transformer and the high-voltage busbar, with the independent current transformer being arranged close to the high-voltage busbar and the bushing current transformer being arranged close to the high-voltage side of the transformer; the high-voltage side current loop of the main transformer differential protection device is connected to the bushing current transformer; the first line optical fiber differential protection device is connected to the bushing current transformer, and the second line optical fiber differential protection device is connected to the independent current transformer. A high-voltage side circuit breaker 201 is also arranged between the independent current transformer 102 and the bushing current transformer 103, and a low-voltage side circuit breaker 202 is arranged between the low-voltage side current transformer 101 and the low-voltage busbar. In the event of a transformer short circuit, the main transformer differential protection device and the two sets of line optical fiber differential protection devices can both control the side circuit breakers to trip to prevent the fault from expanding.
[0043] It should be understood that, taking a 110kV substation as an example, in a typical layout, the distance between the main transformer, 110kV distribution device, 10kV distribution device and main control room does not exceed 100 meters, and the laying distance of the control cable does not exceed 200 meters. Commonly used control cables (such as ZRA-KVVP2 / 22) can generally cover the above-mentioned control cable laying distance and meet the impedance and voltage drop requirements of the circuit. Figure 2 , Figure 2 This is a typical configuration diagram of the current transformer for main transformer protection in the prior art. Among them, in the more special long-distance protection scenario, the second-phase booster station does not have an independent main control room, and the transformer protection cabinet is arranged in the second-phase 10kV distribution device room; the second-phase booster transformer is connected to the first-phase 110kV bus, and its high-voltage primary equipment is arranged in the first-phase booster plant. The laying distance of the cable between the booster transformer protection device and the 110kV distribution device may reach about 1000 meters. The parameters of the current transformer for high-voltage side protection are: 5P40, 20VA, 600-1200 / 1A. The parameters of the current transformer for low-voltage side protection are: 5P10, 20VA, 4000 / 1A. The calculation formula for calculating the secondary load of the current transformer can be referred to:
[0044] Z b =ΣK rc Z r +K lc R1+R c
[0045] Among them, Z b is the secondary load of the current transformer, K rc is the relay impedance conversion factor, which can be 1; Z ris the relay current coil impedance, which can be 0.5; K lc is the connection wire impedance conversion coefficient, which can be 2 (single-phase short circuit); R1 is the connection wire resistance, which can be calculated according to the cable length and the conductance coefficient of the cable, and the connection wire resistance on the high-voltage side is 4.39Ω; R c is the contact resistance, which can be 0.1Ω.
[0046] Further, the secondary limit potential of the high-voltage side current transformer can be calculated, and the calculation formula is:
[0047] E al =K alf I sr (R ct +R b )
[0048] wherein K alf is the accurate limit coefficient, which can be 40; I sr is the rated secondary current, which can be 1A; R ct is the current transformer secondary winding resistance, which can be 6Ω; R b is the current transformer rated load, which can be 10Ω (intermediate tap). The calculated secondary limit potential E al is 640V.
[0049] At the same time, the current transformer secondary induced potential can be calculated according to the calculation formula:
[0050] E a ' l =KK pcf I sr (R ct +R b ')
[0051] wherein K is the given transient coefficient, which can be 2; K pcf is the protection verification coefficient, which can be 66.67; I sr is the rated secondary current, which can be 1A; R b ′ is the actual secondary load of the current transformer, which can be 9.37Ω. The calculated secondary limit potential E al ′ is 2049.33V.
[0052] It should be understood that according to the calculation result, the high-voltage side protection current transformer is 600 / 1A when the ratio is E al (640V)<E al'(2049.33V) does not meet the requirements. The secondary induced potential test fails, even if the rated load of the current transformer is increased to 15VA and the cross section of the connecting wire is increased to 6mm 2 If the performance parameters of the current transformer are further improved, it will need to be customized from the manufacturer, which will be very costly.
[0053] In the main transformer long-distance protection system of this embodiment, the main transformer differential protection device can be used to generate a fault trip signal when a short-circuit fault is detected, and input the fault trip signal into the first line optical fiber differential protection device; the first line optical fiber differential protection device is used to send the fault trip signal to the second line optical fiber differential protection device via optical fiber, driving the second line optical fiber differential protection device outlet to trip the high-voltage side circuit breaker of the transformer. This reduces the protection range of the main transformer differential protection from the 110kV busbar to the high-voltage side, while the rapid protection and backup protection requirements from the 110kV busbar to the high-voltage side bushing lead of the main transformer are met by the 110kV line optical fiber current differential protection device. This meets the parameter requirements of the current transformers on both sides of the main transformer, and mainstream manufacturers in the current market can find matching products, saving site construction costs.
[0054] Reference Figure 3 , Figure 3 This is a schematic diagram of the structure of the second embodiment of the main transformer long-distance protection system of the present invention. Based on the first embodiment of the main transformer long-distance protection system described above, the second embodiment of the main transformer long-distance protection system of the present invention is proposed. The diagram includes a circuit breaker (CB), a DS, and an ES.
[0055] The main transformer long-distance protection system may further include: a high-voltage side backup protection device (high backup protection in the figure), wherein the high-voltage side current loop of the high-voltage side backup protection device is connected to the bushing current transformer, and the high-voltage side backup protection device is also communicatively connected to the first line optical fiber differential protection device. The main transformer long-distance protection system may further include: a low-voltage side backup protection device (low backup protection in the figure); wherein the low-voltage side current loop of the low-voltage side backup protection device is connected to the low-voltage side current transformer of the transformer, and the low-voltage side backup protection device is also communicatively connected to the main transformer differential protection device.
[0056] It should be understood that the high-voltage side backup protection device, the low-voltage side backup protection device, the main transformer differential protection device and the first line optical fiber differential protection device are all arranged in a transformer protection cabinet; the transformer protection cabinet and the control cable of the secondary wiring of the bushing current transformer are in a 10kV distribution room within a preset parameter range. The second line optical fiber differential protection device is arranged in a high-voltage side protection cabinet; the high-voltage side protection cabinet and the control cable of the secondary wiring of the independent current transformer are in a main control room within a preset parameter range. The preset parameter range can be a distance that ensures that the parameters of the current transformer can meet the verification requirements, and the specific calculation can be performed according to the actual situation of the substation, and the specific calculation method can refer to the above formula, which is not limited here. For example, the preset parameter range can be set within 150 meters, that is, the distance between the control cables of the secondary wiring of the current transformers on both sides of the main transformer, and the control cables of the AC voltage loop, the circuit breaker control loop, the signal loop and other secondary circuits is within 150 meters.
[0057] Further, a transformer low breaker operation box is further arranged in the transformer protection cabinet, and the first line optical fiber differential protection device can open the tripping outlet into the tripping loop of the transformer low breaker operation box to trip the transformer low side breaker after receiving the tripping signal. The high-voltage side protection cabinet is further provided with a transformer high breaker operation box, and the second line optical fiber differential protection device can open the tripping outlet into the tripping loop of the transformer high breaker operation box to trip the transformer high side breaker after receiving the tripping signal.
[0058] Referring to Figure 4 , Figure 4 is a secondary wiring diagram of the transformer high side breaker tripped in the second embodiment of the main transformer long distance protection system of the utility model. In the figure, the serial number 0xxx is the opening and closing node of the device, and 2-1QDxx is the interface terminal. When a short-circuit fault occurs in the detection range of the main transformer differential protection device, the differential protection, non-electric quantity protection, high backup protection and low backup protection act to trip the transformer low side breaker; at the same time, another set of tripping outlet is opened into the "remote trip" of the first line optical fiber current differential protection device (10kV distribution room), and the first line optical fiber differential protection device receives the "remote trip" opening and sends the tripping signal to the second line optical fiber differential protection device (main control room) through optical fiber communication. The second line optical fiber differential protection device receives the tripping signal and exports to trip the main transformer high side breaker.
[0059] Further, referring to Figure 5 , Figure 5This is a secondary wiring diagram of the low-voltage side circuit breaker in the second embodiment of the long-distance protection system for the main transformer of the present invention. Serial number 11xx in the figure is the input node of the device, and 2-1CDxx is the interface terminal. In one possible implementation, when a short circuit fault occurs in the lead from the 110kV busbar to the high-voltage side bushing of the main transformer, the first line optical fiber differential protection device and the second line optical fiber differential protection device both detect the short circuit fault and perform protection actions. The outlet of the first line optical fiber differential protection device (10kV distribution room) trips the low-voltage side circuit breaker of the transformer, and the outlet of the second line optical fiber differential protection device (main control room) trips the high-voltage side circuit breaker of the transformer.
[0060] In another possible implementation, when the second-line optical fiber differential protection device does not detect a short-circuit fault, the second-line optical fiber differential protection device only detects a short-circuit fault and performs backup protection action, sending a backup tripping signal to the first-line optical fiber differential protection device via an optical fiber, driving the first-line optical fiber differential protection device outlet to trip the low-voltage side circuit breaker of the transformer.
[0061] The main transformer long-distance protection system of this embodiment replaces the typical solution by adding two sets of line optical fiber current differential protection devices and adjusting the configuration of the current transformer secondary winding, thereby avoiding the situation in the typical solution where it is difficult to match the transformer products on the market.
[0062] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification and drawings under the utility model concept, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.
Claims
1. A main transformer long distance protection system, characterized in that: The main transformer long-distance protection system includes: a transformer, a main transformer differential protection device, a first line optical fiber differential protection device, and a second line optical fiber differential protection device; The high-voltage side current loop of the main transformer differential protection device is connected to the high-voltage side current transformer of the transformer, the low-voltage side current loop of the main transformer differential protection device is connected to the low-voltage side current transformer of the transformer, the first line optical fiber differential protection device is communicatively connected to the main transformer differential protection device, and the first line optical fiber differential protection device and the second line optical fiber differential protection device are connected via optical fiber communication; The main transformer differential protection device is configured to generate a fault trip signal when a short circuit fault is detected, and input the fault trip signal to the first line optical fiber differential protection device; The first line optical fiber differential protection device is used to send the fault trip signal to the second line optical fiber differential protection device through optical fiber, driving the outlet of the second line optical fiber differential protection device to trip the high-voltage side circuit breaker of the transformer.
2. The main transformer long-distance protection system according to claim 1, characterized in that: The high-voltage side current transformer includes: an independent current transformer and a bushing current transformer; The independent current transformer and the bushing current transformer are arranged between the high-voltage side of the transformer and the high-voltage busbar, the independent current transformer is arranged close to the high-voltage busbar, and the bushing current transformer is arranged close to the high-voltage side of the transformer; The high-voltage side current loop of the main transformer differential protection device is connected to the bushing current transformer; The first line optical fiber differential protection device is connected to the bushing current transformer, and the second line optical fiber differential protection device is connected to the independent current transformer.
3. The main transformer long-distance protection system according to claim 2, characterized in that: When both the first line optical fiber differential protection device and the second line optical fiber differential protection device detect a short circuit fault, the outlet of the first line optical fiber differential protection device trips the low-voltage side circuit breaker of the transformer, and the outlet of the second line optical fiber differential protection device trips the high-voltage side circuit breaker of the transformer.
4. The main transformer long-distance protection system according to claim 2, characterized in that: When the second line optical fiber differential protection device detects a short circuit fault but the second line optical fiber differential protection device does not detect a short circuit fault, a backup tripping signal is sent to the first line optical fiber differential protection device through an optical fiber, driving the first line optical fiber differential protection device outlet to trip the low-voltage side circuit breaker of the transformer.
5. The main transformer long-distance protection system according to claim 2, characterized in that: The main transformer long-distance protection system further includes: a high-voltage side backup protection device; The high-voltage side current loop of the high-voltage side backup protection device is connected to the bushing current transformer, and the high-voltage side backup protection device is also communicatively connected to the first line optical fiber differential protection device.
6. The main transformer long-distance protection system according to claim 5, characterized in that: The main transformer long-distance protection system further includes: a low-voltage side backup protection device; The low-voltage side current loop of the low-voltage side backup protection device is connected to the low-voltage side current transformer of the transformer, and the low-voltage side backup protection device is also communicatively connected to the main transformer differential protection device.
7. The main transformer long-distance protection system according to claim 6, characterized in that: The high-voltage side backup protection device, the low-voltage side backup protection device, the main transformer differential protection device and the first line optical fiber differential protection device are all arranged in the transformer protection cabinet; The laying distance between the transformer protection cabinet and the control cable of the secondary connection of the bushing current transformer is within a preset parameter range.
8. The main transformer long-distance protection system according to claim 7, characterized in that: A transformer lowering circuit breaker operating box is also provided in the transformer protection cabinet.
9. The main transformer long-distance protection system according to claim 8, characterized in that: The optical fiber differential protection device of the second line is arranged in the high-voltage side protection cabinet; The laying distance between the high-voltage side protection cabinet and the control cable of the secondary connection of the independent current transformer is within a preset parameter range.
10. The main transformer long-distance protection system according to claim 9, characterized in that: The high-voltage side protection cabinet is also provided with a variable-height circuit breaker operation box.