Transformer over-temperature tripping maloperation prevention system

Abstract

A transformer over-temperature tripping anti-maloperation system relates to the technical field of transformers, and comprises a temperature discrimination unit and a tripping control unit, the temperature discrimination unit comprises a first temperature detector, a second temperature detector, a temperature measurement LCU and a voltage isolation relay; the first temperature detector and the second temperature detector are both used for detecting the temperature of the transformer iron core, and the first temperature detector and the second temperature detector are electrically connected with the temperature control box and the temperature measurement LCU respectively; the temperature measurement LCU is electrically connected with the voltage isolation relay through an over-temperature DO contact. The input end of the tripping control unit is electrically connected with the control contact loop, the output end of the tripping control unit is electrically connected with the transformer, and the control contact loop is formed by connecting a normally open contact of the voltage isolation relay, a high-temperature normally open contact of the temperature control box and an overhigh-temperature normally open contact of the temperature control box in series; the condition of tripping caused by inaccurate temperature judgment can be avoided.

Description

Technical Field

[0001] The utility model relates to the field of transformer technology, specifically to a transformer over-temperature tripping anti-maloperation system. Background Technology

[0002] Transformers are critical equipment in power systems, and their operating status directly affects the stability and reliability of the entire system. During continuous operation, transformers generate heat due to internal losses. If the temperature continues to rise without timely control, it will lead to overheating. Overheating not only accelerates the aging of insulation materials but can also cause serious safety accidents such as short circuits or even transformer burnout. Temperature protection systems can monitor the transformer temperature in real time and issue alarm signals or take appropriate measures before the temperature reaches dangerous levels, effectively preventing overheating damage.

[0003] Currently, transformer temperature protection is achieved through a combination of a platinum resistance thermometer, a transformer temperature control box, and non-electrical quantity protection devices. Specifically, the platinum resistance thermometer monitors the transformer core temperature in real time and transmits the temperature data to the transformer temperature control box. The temperature control box performs logical analysis based on preset values. Once it determines that the transformer temperature exceeds the over-temperature setpoint, it issues an over-temperature alarm signal and simultaneously activates the non-electrical quantity protection devices. Subsequently, the non-electrical quantity protection devices execute their tripping function, disconnecting the corresponding switches and thus disconnecting the transformer from the circuit.

[0004] However, this method has a potential risk of accidental activation in practical applications:

[0005] 1. Only one temperature-sensing platinum resistance thermometer is installed inside the transformer. When the temperature-sensing platinum resistance thermometer is open-circuited, the temperature it measures may rise abnormally and rapidly. In this case, the temperature control box may mistakenly activate the non-electrical quantity protection device, which in turn will perform an over-temperature protection action, causing the transformer to shut down and resulting in significant economic losses to the power system.

[0006] 2. The temperature protection trip logic mainly relies on the temperature control box. If the temperature control box itself malfunctions, its internal over-temperature trip contacts may also close accidentally, causing the non-electrical protection device to activate its over-temperature protection, resulting in the transformer being shut down erroneously.

[0007] 3. When the connection distance between the transformer and the non-electrical quantity protection device is long, abnormal phenomena such as operator error, system failure, DC grounding, and electromagnetic interference may interfere with the input signal of the non-electrical quantity protection device, causing the non-electrical quantity protection input to close erroneously. This erroneous action will also cause the temperature protection to activate, resulting in unnecessary transformer shutdown and reducing the reliability of system operation.

[0008] Therefore, we propose a system that can improve the accuracy of over-temperature tripping. Utility Model Content

[0009] The purpose of this invention is to provide a transformer over-temperature tripping prevention system, which can avoid tripping caused by inaccurate temperature judgment.

[0010] This utility model is achieved through the following technical solution:

[0011] A transformer over-temperature tripping anti-maloperation system includes a temperature discrimination unit and a tripping control unit. The temperature discrimination unit includes a first temperature sensor, a second temperature sensor, a temperature sensing LCU, and a voltage isolation relay. Both the first and second temperature sensors are used to detect the temperature of the transformer core, and the first and second temperature sensors are electrically connected to the temperature control box and the temperature sensing LCU, respectively. The temperature sensing LCU is electrically connected to the voltage isolation relay through an over-temperature DO contact.

[0012] The input terminal of the trip control unit is electrically connected to the control contact circuit, and the output terminal of the trip control unit is electrically connected to the transformer. The control contact circuit is composed of the normally open contact of the voltage isolation relay, the normally open contact of the temperature control box for high temperature, and the normally open contact of the temperature control box for excessive temperature, connected in series.

[0013] Furthermore, both the first and second temperature sensors are platinum resistance thermometers.

[0014] Furthermore, both the first and second temperature sensors are infrared temperature sensors.

[0015] Furthermore, both the first and second temperature sensors are fiber optic temperature sensors.

[0016] Furthermore, the temperature measurement LCU includes a temperature input module, a CPU, and a DO module, wherein the input pin of the temperature input module is electrically connected to the output pin of the second temperature sensor, the output pin of the temperature input module is electrically connected to the input pin of the CPU, and the output pin of the CPU is electrically connected to the DO module.

[0017] Furthermore, the trip control unit includes a non-electrical quantity protection device and a re-operating relay, wherein the control contact circuit is electrically connected to the input terminal of the re-operating relay; and the normally open contact of the re-operating relay is electrically connected to the input terminal of the non-electrical quantity protection device.

[0018] Furthermore, the non-electrical protection device is model number NARI RCS-985TW.

[0019] Furthermore, the model number of the temperature control box is LD-BK10-220EFCA.

[0020] The technical solution of this utility model has at least the following advantages and beneficial effects:

[0021] This utility model discloses a transformer over-temperature tripping prevention system, which uses two thermometers to detect the temperature of the transformer core, thereby increasing the redundancy of the transformer core temperature detection and effectively improving the accuracy of the transformer core temperature detection.

[0022] Using a voltage isolation relay can achieve voltage isolation between the low-voltage temperature discrimination unit and the high-voltage trip control unit, preventing strong electricity from interfering with or damaging weak signals, improving the safety of the system, and further ensuring the accuracy of temperature detection results. Accurate temperature detection results can prevent the trip control unit from malfunctioning. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of this utility model;

[0024] Figure 2 This is a schematic diagram of the temperature discrimination unit of this utility model;

[0025] Figure 3 This is a schematic diagram of the trip control unit of this utility model.

[0026] Reference numerals in the attached diagram: 1. First thermometer; 2. Second thermometer; 3. Temperature measuring LCU; 4. Voltage isolation relay; 5. Temperature control box; 6. Normally open contact of voltage isolation relay; 7. Normally open contact of temperature control box for high temperature; 8. Normally open contact of temperature control box for excessive temperature; 9. Re-operation relay; 10. Non-electrical protection device; 11. Transformer. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Example 1

[0029] As attached Figures 1-3As shown, a transformer over-temperature tripping anti-maloperation system includes a temperature discrimination unit and a tripping control unit. The temperature discrimination unit includes a first thermometer 1, a second thermometer 2, a temperature-sensing LCU3, and a voltage isolation relay 4. Both the first thermometer 1 and the second thermometer 2 are used to detect the temperature of the transformer core 11, and are electrically connected to the temperature control box 5 and the temperature-sensing LCU3, respectively. That is, the first thermometer 1 and the second thermometer 2 are installed at different locations on the transformer core 11, thereby increasing redundancy and enabling comprehensive monitoring of the transformer core 11. Temperature measurement ensures the accuracy of the measurement results. The temperature measuring LCU3 is electrically connected to the voltage isolation relay 4 through the over-temperature DO contact. The over-temperature DO contact is a normally open switch contact. When the temperature measuring LCU3 determines that the temperature measured by the second temperature sensor 2 is greater than the temperature threshold, it means that the core temperature of the transformer 11 measured by the second temperature sensor 2 is too high. Therefore, the temperature measuring LCU3 controls the over-temperature DO contact to close, thereby energizing the voltage isolation relay 4. Consequently, the normally open contact 6 of the voltage isolation relay also closes, realizing the transmission of control signals to the trip control unit.

[0030] Specifically, both the first thermometer 1 and the second thermometer 2 are platinum resistance thermometers, infrared thermometers, or fiber optic thermometers.

[0031] Among them, platinum resistance thermometers have excellent resistance-temperature linearity, with an accuracy of ±0.1℃, good long-term stability, and are suitable for long-term monitoring. They can directly contact the surface of the iron core or be embedded inside, and the measurement results reflect the true temperature, unaffected by surface emissivity or medium. They are suitable for oil-immersed transformers and can work stably in oil after sealing. The sensors are also relatively inexpensive and suitable for large-scale deployment.

[0032] However, it also has the disadvantages of complex installation: it requires contact with the iron core, which may require the transformer 11 to be shut down for installation, and it is intrusive to the structure; it is sensitive to electromagnetic interference: strong magnetic fields may affect the resistance of the wires or signal transmission, so shielding is required; it has a slow response time: the heat conduction delay leads to a long response time, which is not suitable for rapid temperature change scenarios; and it is a single-point measurement: it can only monitor local temperature, and multiple points need to be arranged to cover the entire iron core.

[0033] Infrared thermometers offer several advantages: no physical contact required, making them suitable for locations where sensor installation is difficult or for live detection; millisecond-level response, making them suitable for dynamic temperature monitoring; remote alignment with the iron core surface without requiring modifications to the transformer structure; and low cost per point, making them suitable for temporary or mobile monitoring.

[0034] However, oxidation, coatings, or stains on the iron core surface can change the emissivity, leading to measurement errors; oil mist, dust, or obstructions can hinder infrared radiation, making it difficult to apply inside oil-immersed transformers; it can only detect surface temperature and cannot reflect internal hot spots; and it requires regular calibration to maintain accuracy, resulting in poor long-term stability.

[0035] Fiber optic thermometers have excellent anti-electromagnetic interference capabilities. Since the optical signal is not affected by the strong magnetic field of the transformer, they are suitable for high-voltage and high-electromagnetic environments. A single fiber can cover multiple temperature measurement points, fiber optic gratings, or continuously monitor distributed systems, comprehensively reflecting the temperature distribution. Furthermore, the fiber is inherently insulated, eliminating the risk of electrical sparks, making it suitable for flammable and explosive environments. It is also corrosion-resistant and anti-aging, making it suitable for long-term stable monitoring.

[0036] However, fiber optic thermometers also have the disadvantage of complex installation, requiring fiber optic cables to be laid inside the iron core or windings, which is difficult to construct and may require custom design; in addition, the equipment and installation costs are significantly higher than those of platinum resistance thermometers and infrared thermometers; and while fiber optic gratings have a fast response, distributed optical fibers require a longer scanning time.

[0037] Therefore, staff need to select the appropriate temperature measuring device based on the actual scenario.

[0038] The input terminal of the trip control unit is electrically connected to the control contact circuit, and the output terminal of the trip control unit is electrically connected to the transformer 11. The control contact circuit is composed of the normally open contact 6 of the voltage isolation relay, the normally open contact 7 of the temperature control box (high temperature), and the normally open contact 8 of the temperature control box (over-high temperature).

[0039] The contacts in the contact circuit are connected in series. Therefore, only when the temperature signals received by the temperature control box 5 and the temperature measuring LCU3 both exceed their specified temperature thresholds will the normally open contacts corresponding to the temperature control box 5 and the voltage isolation relay 4 close, and the non-electrical protection device 10 will be energized to perform the action of shutting down the transformer 11.

[0040] It should be noted that the normally open high-temperature contact 7 and the normally open over-temperature contact 8 of the temperature control box represent the corresponding control contacts for two temperature thresholds. That is, when the temperature measured by the first thermometer 1 reaches the preset high-temperature threshold in the temperature control box 5, the temperature control box 5 will send an electrical signal to the high-temperature relay, thereby closing the normally open contact of the high-temperature relay, i.e., the normally open high-temperature contact 7 of the temperature control box; when the temperature measured by the first thermometer 1 reaches the preset over-temperature threshold in the temperature control box 5, the temperature control box 5 will send an electrical signal to the over-temperature relay, thereby closing the normally open contact of the over-temperature relay, i.e., the normally open over-temperature contact 8 of the temperature control box.

[0041] In addition, the non-electrical quantity protection device 10 is model NARI RCS-985TW. This non-electrical quantity protection device 10 adopts a fully enclosed chassis design, strictly separating strong and weak currents to reduce external interference and potential fault points. At the same time, anti-interference measures are also adopted in the software design to improve the anti-interference capability and external electromagnetic radiation standard of the device. It provides up to 25 inputs, supports rich signals and output contacts, and can meet the complex field application requirements. Moreover, it supports output configuration function, and each protection element can flexibly select the output to act, which facilitates the implementation of field applications and interlocking logic. In addition to basic non-electrical quantity protection, this system also provides temperature protection. That is, when the temperature measured by the first thermometer 1 and the second thermometer 2 both exceed the corresponding threshold, the non-electrical quantity protection device 10 starts to trip the transformer 11 and stop the operation of the transformer 11. It also supports various advanced application functions required for integrated automation, such as fault information recording and waveform information recording functions, which helps to improve the safety and stability of the power system. It also employs a high-performance hardware platform, including a high-speed digital signal processor (DSP), a large-scale logic gate array (FPGA), a parallel high-precision A / D converter, and a 32-bit microprocessor CPU, ensuring fast and accurate data processing capabilities.

[0042] Furthermore, the temperature control box 5, model LD-BK10-220EFCA, can accurately monitor and control the internal temperature of transformer 11, ensuring its operation within a safe range. It also features two protection levels: temperature alarm and over-temperature trip. When the temperature reaches a warning value (high temperature threshold), it can issue an alarm promptly. If the temperature further rises to a dangerous level (excessively high temperature threshold), it sends a control signal to the trip control unit. Additionally, the temperature control box 5 supports various types of temperature sensors, such as platinum resistance thermometers, infrared thermometers, or fiber optic thermometers, allowing for flexible adaptation to different application scenarios and improving measurement accuracy and response speed. It may also be equipped with an intelligent monitoring system that can display temperature data in real time and support remote monitoring and data transmission, facilitating maintenance personnel to promptly grasp the operating status of transformer 11.

[0043] Example 2

[0044] The temperature measurement LCU3 includes a temperature input module, a CPU, and a DO module. The input pin of the temperature input module is electrically connected to the output pin of the second temperature sensor 2, the output pin of the temperature input module is electrically connected to the input pin of the CPU, and the output pin of the CPU is electrically connected to the DO module.

[0045] It should be noted that the temperature input module is used to receive the temperature value detected by the second thermometer 2, while the CPU has a preset temperature threshold. Therefore, when the temperature value measured by the second thermometer 2 is higher than the temperature threshold, the CPU will output a control electrical signal to the DO module. The DO module is an intermediate relay. After receiving the electrical signal, the normally open contact of the intermediate relay, that is, the DO contact when the temperature is too high, will close.

[0046] In addition, the CPU is a Schneider 140CPU67160 PLC, the DO module is a 140DDO84300 model, and the temperature input module is a 140ARI03010 model. These three modules constitute the overall temperature measurement LCU, which realizes the function of receiving, judging and outputting control signals to the temperature value of the second temperature sensor 2.

[0047] Example 3

[0048] The trip control unit includes a non-electrical quantity protection device 10 and a re-operation relay 9, wherein the control contact circuit is electrically connected to the input terminal of the re-operation relay 9; the normally open contact of the re-operation relay 9 is electrically connected to the input terminal of the non-electrical quantity protection device 10; wherein the re-operation relay 9 is energized only after all circuits in the control contact circuit are closed, and then the normally open contact of the re-operation relay 9 closes to control the non-electrical quantity protection device 10 to start. By increasing the starting conditions of the non-electrical quantity protection device 10, the risk of false start of the non-electrical quantity protection device 10 can be effectively reduced.

[0049] In addition, the use of a high-power reclosing relay 9 ensures that the non-electrical protection device 10 is activated when the temperature is too high, and prevents it from being accidentally activated due to abnormal interference during operation, thus avoiding transformer tripping caused by temperature protection malfunction. Furthermore, the reclosing relay 9 can effectively cope with electromagnetic interference and abnormal operating conditions that may be encountered in the circuit, further improving the reliability of the system.

[0050] When implementing the transformer over-temperature tripping anti-maloperation system described in this utility model, all contacts in the contact control circuit of the tripping control unit will be fully closed only when the temperature value measured by the first thermometer 1 received by the temperature control box 5 is greater than the high temperature threshold and the excessively high temperature threshold, and the temperature value measured by the second thermometer 2 received by the temperature measuring LCU3 is greater than the temperature threshold. At this time, the non-electrical quantity protection unit will control the transformer 11 to trip, that is, stop the transformer 11 from working. By adding control conditions, the risk of maloperation during the control operation of the non-electrical quantity protection unit can be effectively reduced.

[0051] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A transformer over-temperature tripping anti-maloperation system, characterized in that: The system includes a temperature discrimination unit and a trip control unit. The temperature discrimination unit includes a first thermometer (1), a second thermometer (2), a temperature measuring LCU (3), and a voltage isolation relay (4). The first thermometer (1) and the second thermometer (2) are both used to detect the temperature of the core of the transformer (11). The first thermometer (1) and the second thermometer (2) are electrically connected to the temperature control box (5) and the temperature measuring LCU (3), respectively. The temperature measuring LCU (3) is electrically connected to the voltage isolation relay (4) through the over-temperature DO contact. The input terminal of the trip control unit is electrically connected to the control contact circuit, the output terminal of the trip control unit is electrically connected to the transformer (11), and the control contact circuit is composed of the normally open contact (6) of the voltage isolation relay, the normally open contact (7) of the temperature control box for high temperature, and the normally open contact (8) of the temperature control box for excessive temperature in series.

2. The transformer over-temperature tripping anti-maloperation system according to claim 1, characterized in that: Both the first thermometer (1) and the second thermometer (2) are platinum resistance thermometers.

3. The transformer over-temperature tripping anti-maloperation system according to claim 1, characterized in that: Both the first thermometer (1) and the second thermometer (2) are infrared thermometers.

4. The transformer over-temperature tripping anti-maloperation system according to claim 1, characterized in that: Both the first thermometer (1) and the second thermometer (2) are fiber optic thermometers.

5. The transformer over-temperature tripping anti-maloperation system according to claim 1, characterized in that: The temperature measurement LCU (3) includes a temperature input module, a CPU, and a DO module. The input pin of the temperature input module is electrically connected to the output pin of the second temperature sensor (2), the output pin of the temperature input module is electrically connected to the input pin of the CPU, and the output pin of the CPU is electrically connected to the DO module.

6. The transformer over-temperature tripping anti-maloperation system according to claim 5, characterized in that: The trip control unit includes a non-electrical quantity protection device (10) and a re-operation relay (9), wherein the control contact circuit is electrically connected to the input terminal of the re-operation relay (9); the normally open contact of the re-operation relay (9) is electrically connected to the input terminal of the non-electrical quantity protection device (10).

7. The transformer over-temperature tripping anti-maloperation system according to claim 6, characterized in that: The non-electrical protection device (10) is model number NARI RCS-985TW.

8. The transformer over-temperature tripping anti-maloperation system according to claim 1, characterized in that: The temperature control box (5) is model LD-BK10-220EFCA.

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