Relay control method based on temperature induction

Abstract

The invention discloses a relay control method based on temperature induction. The relay control method comprises the following steps: acquiring electrical equipment protected by a relay to obtain a current current value; obtaining a current-time limit mapping relation; determining an initial countdown time limit corresponding to the current current value based on the current current value and a current-time limit mapping relation; acquiring the current working temperature of the relay to obtain a current temperature value; calculating a final countdown time limit based on the current temperature value and the initial countdown limit; and controlling the relay to trip based on the final countdown time limit. Therefore, the inverse time limit characteristic and the temperature protection are organically combined, more accurate, reasonable and efficient overcurrent protection can be carried out, and the adaptability of the system to a complex operation environment is enhanced.

Description

Technical Field

[0001] This application relates to the field of relay control, specifically to a relay control method based on temperature sensing. Background Technology

[0002] In the fields of power systems and industrial automation, relay protection is a core component ensuring the safe operation of electrical equipment and the reliability of the system. Overcurrent protection, as one of the most basic and widely used types of protection, operates promptly when an abnormally large current is detected in the circuit, cutting off the faulty circuit to prevent equipment damage and the escalation of accidents. Inverse-time protection is a typical form of overcurrent protection, its core characteristic being that the relay's operating time is inversely proportional to the current magnitude: the larger the current value, the shorter the operating time. This characteristic cleverly balances the equipment's ability to withstand short-term overloads with the need for rapid clearing of serious faults, allowing the equipment to continue operating under brief, non-destructive overloads while simultaneously responding quickly to serious faults that endanger equipment safety (such as short circuits), minimizing damage.

[0003] However, traditional inverse-time protection strategies are typically designed and implemented based on fixed It (current-time) characteristic curves. These curves perform well under standard laboratory conditions or specific ambient temperatures, but they do not fully account for the differences in operating temperature of electrical equipment (such as motors, transformers, cables, and relays) during actual operation due to factors such as changes in ambient temperature, load duration, and heat dissipation conditions.

[0004] Therefore, a new type of anti-time-limit protection scheme is needed. Summary of the Invention

[0005] One advantage of this application is that it provides a temperature-sensing-based relay control method, which can provide more accurate, reasonable and efficient overcurrent protection and enhance the system's adaptability to complex operating environments.

[0006] According to one aspect of this application, a relay control method based on temperature sensing is provided, comprising: Obtain the current value of the electrical equipment protected by the relay; Obtain the current-time mapping relationship; Determine the initial countdown timer corresponding to the current current value based on the current current value and the current-time mapping relationship; Obtain the current operating temperature of the relay to get the current temperature value; Calculate the final countdown time based on the current temperature value and the initial countdown limit; The relay trips based on the final countdown timer.

[0007] In one embodiment of the temperature-sensing-based relay control method according to this application, calculating the final countdown time limit based on the current temperature value and the preliminary countdown time limit includes: obtaining a correction coefficient corresponding to the current temperature; and calculating the final countdown time limit based on the current temperature value, the correction coefficient, and the preliminary countdown time limit, wherein the final countdown time limit is equal to the ratio of the preliminary countdown time limit to the correction coefficient corresponding to the current temperature value.

[0008] In one embodiment of the temperature-sensing-based relay control method according to this application, obtaining the correction coefficient corresponding to the current temperature includes: querying the correction coefficient corresponding to the current temperature based on a temperature-correction coefficient table.

[0009] In one embodiment of the temperature-sensing-based relay control method according to this application, obtaining the correction coefficient corresponding to the current temperature includes: calculating the correction coefficient corresponding to the current temperature based on a function of the correction coefficient with respect to temperature.

[0010] In one embodiment of the temperature-sensing-based relay control method according to this application, the functional relationship between temperature and correction coefficient conforms to the Arrhenius equation.

[0011] In one embodiment of the temperature-sensing-based relay control method according to this application, determining the preliminary countdown time limit corresponding to the current current value based on the current current value and the current-time limit mapping relationship includes: when the current value fluctuates between 1 times greater than or equal to the rated current value and less than 1.6 times the rated current value within the current preset time period, the preliminary countdown time limit corresponding to the maximum current value within the current preset time period is taken as the preliminary countdown time limit corresponding to the current current value.

[0012] In one embodiment of the temperature-sensing-based relay control method according to this application, the temperature-sensing-based relay control method further includes: in response to the current trip being the first trip, controlling the relay to close after a preset recovery time interval following the control relay trip.

[0013] In one embodiment of the temperature-sensing-based relay control method according to this application, the temperature-sensing-based relay control method further includes: responding to the time interval between the current trip and the previous trip being less than or equal to a preset trip time interval, and not controlling the relay to close after controlling the relay to trip.

[0014] In one embodiment of the temperature-sensing-based relay control method according to this application, the temperature-sensing-based relay control method further includes: in response to the time interval between the current trip and the previous trip being greater than a preset time, controlling the relay to close after a preset recovery time interval following the control relay trip.

[0015] According to another aspect of this application, a relay control method based on temperature sensing is proposed, comprising: Obtain the real-time current and operating temperature of the relay to get the real-time current value and operating temperature value; The degree of thermal damage is calculated based on the real-time current value and the operating temperature value. The relay trips based on the degree of thermal damage.

[0016] Compared with the prior art, this application has the following beneficial effects: First, this application combines traditional inverse-time overcurrent protection with real-time temperature sensing. By introducing a temperature correction coefficient or based on a thermal damage accumulation model, the operating time of the relay is dynamically adjusted. This makes the protection action no longer dependent on a fixed current-time curve, but can accurately reflect the actual withstand capability of the equipment under different thermal conditions, thereby achieving more accurate, intelligent, and efficient overcurrent protection and significantly enhancing the system's adaptability to complex operating environments.

[0017] Secondly, by monitoring temperature in real time and adjusting the protection strategy, this application effectively avoids equipment overheating damage caused by slow protection action in high-temperature environments, and unnecessary tripping caused by overly sensitive protection in low-temperature environments. This not only improves the continuity and reliability of power system operation, but also enhances the safety of electrical equipment and relays themselves.

[0018] Finally, the protection method based on the accumulation of thermal damage proposed in this application introduces a memory function into the relay, enabling full life-cycle health management based on the equipment's historical thermal load. This forward-looking protection strategy can maximize the use of the equipment's design life while ensuring safety, avoiding wasted lifespan due to overly conservative protection strategies or premature failure due to ignoring historical loads.

[0019] The further objectives and advantages of this application will become fully apparent from the following description and accompanying drawings. Attached Figure Description

[0020] The above and other objects, features, and advantages of this application will become more apparent from the more detailed description of the embodiments of this application in conjunction with the accompanying drawings. The drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0021] Figure 1 The illustration shows a flowchart of a temperature-sensing-based relay control method according to an embodiment of this application.

[0022] Figure 2 The illustration shows a flowchart of one step of a temperature-sensing-based relay control method according to an embodiment of this application.

[0023] Figure 3 Another flowchart of a temperature-sensing-based relay control method according to an embodiment of this application is illustrated. Detailed Implementation

[0024] Hereinafter, exemplary embodiments according to this application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein.

[0025] It is understood that the term "a" should be understood as "at least one" or "one or more," meaning that in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple. The term "a" should not be construed as a limitation on the quantity. "Multiple" means two or more.

[0026] While ordinal numbers such as “first,” “second,” etc., will be used to describe various components, there is no limitation on those components herein. The term is used only to distinguish one component from another; for example, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component, without departing from the teachings of this application. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0027] The terminology used herein is for the purpose of describing various embodiments only and is not intended to be limiting. As used herein, the singular form also includes the plural form, unless the context clearly indicates otherwise. It will also be understood that the terms “comprising” and / or “having” as used in this specification specify the presence of the described features, numbers, operations, components, elements or combinations thereof, without excluding the presence or addition of one or more other features, numbers, operations, components, elements or combinations thereof.

[0028] As mentioned above, traditional inverse-time protection strategies are typically designed and implemented based on preset It (current-time) characteristic curves. These curves perform well under standard laboratory conditions or specific ambient temperatures, but they do not fully account for the differences in operating temperature of electrical equipment (such as motors, transformers, cables, and relays) during actual operation due to factors such as changes in ambient temperature, load duration, and heat dissipation conditions.

[0029] The lifespan and thermal damage risk of insulation materials in electrical equipment are closely related to their operating temperature: the higher the temperature, the faster the insulation material ages, and its ability to withstand overcurrent surges decreases. This means that even with the same overcurrent, the potential thermal stress and damage to the electrical equipment at higher operating temperatures is far greater than at lower temperatures. Furthermore, the operating temperature of a relay affects its response speed. Therefore, a fixed inverse-time characteristic curve may not accurately reflect the true thermal capacity and thermal tolerance limits of electrical equipment or relays under different thermal conditions. This can lead to traditional inverse-time protection failing to cut off the power supply in time when the electrical equipment or relay is already operating at high temperatures or the ambient temperature is too high, ultimately causing overheating damage to the electrical equipment. Conversely, when the electrical equipment or relay is operating at low temperatures or the ambient temperature is low, the protection action may be too sensitive, leading to unnecessary tripping and affecting the continuity of system operation and production efficiency. In order to protect electrical equipment more precisely and improve the adaptability, accuracy and reliability of protection, it is necessary to break through the limitations of traditional fixed time-limit protection and develop an intelligent protection scheme that can sense the real-time thermal state of electrical equipment or relays and dynamically adjust the protection action time limit accordingly.

[0030] In theory, to address the thermal effects of electrical equipment or relays, the temperature of the protected equipment or relay can be directly detected using built-in or external temperature sensors. When the temperature reaches a preset danger threshold, an alarm or trip signal is triggered. While this solution provides basic temperature protection, it is essentially a constant-temperature protection system. In other words, this solution only makes a judgment at a fixed temperature point, without considering the combined effects of the degree and duration of current overload on the thermal effect, and it cannot dynamically adjust its operating time according to changes in current, thus lacking flexibility in dealing with complex overload scenarios.

[0031] Based on this, this application proposes a relay control method based on temperature sensing, which introduces a temperature variable into inverse-time protection to achieve an organic combination of inverse-time characteristics and temperature protection. The method includes: acquiring the current value of the electrical equipment protected by the relay; acquiring the current-time mapping relationship; determining the preliminary countdown timer corresponding to the current current value based on the current current value and the current-time mapping relationship; acquiring the current operating temperature of the relay to obtain the current temperature value; calculating the final countdown timer based on the current temperature value and the preliminary countdown timer; and controlling the relay to trip based on the final countdown timer.

[0032] Accordingly, such as Figures 1 to 2 As shown, a temperature-sensing-based relay control method according to an embodiment of this application is illustrated. Figure 1As shown, the relay control method based on temperature sensing includes: S1: obtaining the current value of the electrical equipment protected by the relay; S2: obtaining the current-time mapping relationship; S3: determining the preliminary countdown time limit corresponding to the current current value based on the current current value and the current-time mapping relationship; S4: obtaining the current operating temperature of the relay to obtain the current temperature value; S5: calculating the final countdown time limit based on the current temperature value and the preliminary countdown time limit; S6: controlling the relay to trip based on the final countdown time limit.

[0033] Specifically, in step S1, the current value of the electrical equipment protected by the relay is obtained. Specifically, in this application, in the inverse-time protection mechanism, obtaining the current flowing through the relay is the foundation and prerequisite of the entire protection process, and its importance is self-evident. The reason for needing to obtain the current flowing through the relay is that the core logic of overcurrent protection lies in judging whether an abnormality exists and the severity of the abnormality based on the magnitude of the current. The characteristics of inverse-time protection directly depend on the magnitude of the current value; that is, the larger the current, the shorter the theoretical operating time. Therefore, accurately determining the current flowing through the protected circuit is the key starting point for judging whether the electrical equipment is in an overload state and how long it needs to respond. Without accurate current data, all subsequent time-limit calculations, temperature corrections, and final tripping control will be impossible, and the protection function cannot be realized.

[0034] In step S2, the current-time mapping relationship is obtained. Specifically, as mentioned above, the essence of inverse-time protection lies in its unique operating characteristic curve: the larger the current, the shorter the relay operating time. This characteristic is not randomly generated, but is pre-designed and determined based on the characteristics of power system equipment, protection coordination requirements, and industry standards. The current-time mapping relationship is a key step in transforming engineering experience and standard specifications into executable logic, ensuring the standardization and predictability of protection functions.

[0035] Before a relay leaves the factory or during on-site configuration, engineers select and set the appropriate inverse-time characteristic curve based on the type of protected equipment, its rated parameters, and the protection coordination requirements of the power grid. These characteristic curves typically exist within the relay in two main forms: one is a tabular form, an embedded lookup table storing several typical current values ​​and their corresponding time limits; the other is a mathematical formula form, a preset inverse-time function formula that allows direct calculation of the corresponding time limit by inputting the current value. For example, relevant international and industry standards define a series of standard inverse-time characteristic curves, such as Standard Inverse, Very Inverse, and Extremely Inverse.

[0036] In one embodiment of this application, the current-time mapping relationship is represented in tabular form. Table 1 is a current-time mapping table that can represent the current-time mapping relationship.

[0037] Table 1

[0038] In step S3, a preliminary countdown timer corresponding to the current current value is determined based on the current current value and the current-time mapping relationship. Specifically, when the current current value is less than the rated value, the countdown does not begin. The rated current value varies depending on the operating environment; for example, in one example of this application, the rated current value is 50A. It should be understood that in other examples, the rated current value may be other values.

[0039] As shown in Table 1, the initial countdown timer is 3600 seconds when the current current value is greater than or equal to the rated current value and less than 1.2 times the rated current value; 1500 seconds when the current current value is greater than or equal to 1.2 times the rated current value and less than 1.4 times the rated current value; 900 seconds when the current current value is greater than or equal to 1.4 times the rated current value and less than 1.6 times the rated current value; 180 seconds when the current current value is greater than or equal to 1.6 times the rated current value and less than 2.0 times the rated current value; 2 seconds when the current current value is greater than or equal to 2.0 times the rated current value and less than 3.0 times the rated current value; and 0 seconds when the current current value is greater than 3.0 times the rated current value.

[0040] It is worth mentioning that, considering the accuracy of current measurement and the fluctuation of current values, a certain current value within a certain time period can be used as the current current value. In one example of this application, when the current value fluctuates between 1 / 2 and 1.6 times the rated current value within the current preset time period, the preliminary countdown time corresponding to the maximum current value within the current preset time period is used as the preliminary countdown time corresponding to the current current value. The current preset time period is determined according to the actual situation. For example, in application scenarios with high current fluctuation frequency, the current preset time period is short, such as 5 seconds, that is, the current preset time period is a time period of 5 seconds from the current time point.

[0041] In step S4, the current operating temperature of the relay is obtained to obtain the current temperature value. Specifically, the current operating temperature of the relay is the temperature of the environment in which the relay is located. If the ambient temperature of the relay is high, it may affect the performance and lifespan of the internal components of the relay, and even affect the stability of its protection characteristics. In particular, the temperature of the relay itself or its surrounding environment will affect the relay's response speed. Therefore, relying solely on the current magnitude to determine the protection time limit is insufficient. By sensing the relay's operating temperature in real time, important thermal information affecting protection decisions can be accurately grasped, thereby providing necessary data support for dynamically adjusting the protection action time limit based on the actual thermal state. This ensures that the protection action is closer to the actual tolerance capacity of the equipment, avoids misjudgments or protection lags caused by temperature factors, extends the operating life of the protected equipment and the relay itself, and improves the safety and reliability of the system.

[0042] The operating temperature of the relay is obtained by a temperature sensor integrated inside or adjacent to the relay body. Typically, the temperature sensing unit inside the relay contains a high-precision temperature sensor. These sensors can be thermistors, resistance temperature detectors, thermocouples, or more advanced semiconductor digital temperature sensors.

[0043] S5: Calculate the final countdown time based on the current temperature value and the preliminary countdown timer. Specifically, this application overcomes the limitations of traditional inverse-time protection that relies solely on the current-time curve, introducing a dynamic correction parameter related to the relay's operating temperature to achieve more accurate and adaptive overcurrent protection. Accordingly, as... Figure 2 As shown, step S5 includes: S51: obtaining the correction coefficient corresponding to the current temperature; S52: calculating the final countdown time based on the current temperature value, the correction coefficient, and the initial countdown time.

[0044] In step S51, the correction coefficient corresponding to the current temperature is obtained. In one embodiment of this application, the preset relationship between the current temperature and the correction coefficient can be a lookup table. Table 2 is a temperature-correction coefficient table that reflects the temperature-correction coefficient mapping relationship. The temperature-correction coefficient table is obtained through empirical estimation or calibration.

[0045] Table 2

[0046] As shown in Table 2, the correction factor is 1 when the current temperature is less than 30 degrees Celsius; 2 when the current temperature is greater than or equal to 30 degrees Celsius and less than 50 degrees Celsius; 5 when the current temperature is greater than or equal to 50 degrees Celsius and less than 70 degrees Celsius; 10 when the current temperature is greater than or equal to 70 degrees Celsius and less than 90 degrees Celsius; and 200 when the current temperature is greater than or equal to 90 degrees Celsius and less than 120 degrees Celsius.

[0047] The final countdown time is equal to the ratio of the initial countdown time to the correction factor corresponding to the current temperature value. For example, when the current current value is greater than or equal to the rated current value but less than 1.2 times the rated current value, and the current temperature value is less than 30 degrees Celsius, the final countdown time is the ratio of the initial countdown time of 3600 seconds to the correction factor 1, which equals 3600 seconds; when the current current value is greater than or equal to the rated current value but less than 1.2 times the rated current value, and the current temperature value is greater than or equal to 30 degrees Celsius but less than 50 degrees Celsius, the final countdown time is the ratio of the initial countdown time of 3600 seconds to the correction factor 2, which equals 1800 seconds; when the current current value is greater than or equal to the rated current value but less than 1.2 times the rated current value, and the current temperature value is greater than or equal to 50 degrees Celsius but less than 70 degrees Celsius... When the current value is greater than or equal to the rated current value but less than 1.2 times the rated current value, and the current temperature value is greater than or equal to 70 degrees Celsius but less than 90 degrees Celsius, the final countdown timer is the ratio of the initial countdown timer of 3600 seconds to the correction factor of 10, which is equal to 360 seconds. When the current value is greater than or equal to the rated current value but less than 1.2 times the rated current value, and the current temperature value is greater than or equal to 90 degrees Celsius but less than 120 degrees Celsius, the final countdown timer is the ratio of the initial countdown timer of 3600 seconds to the correction factor of 200, which is equal to 18 seconds.

[0048] The calculation of the final countdown timer based on the current temperature value, temperature-correction factor table, and preliminary countdown timer is essentially based on a piecewise constant function or lookup table method. It discretizes the continuous temperature variable into several levels and assigns a fixed correction factor to each level to facilitate temperature compensation for the timer.

[0049] Specifically, because the materials (such as insulation layers and coils) of relays and their protective circuits deteriorate at high temperatures, the allowable heat-carrying margin decreases, and the heat generated by overcurrent can be approximated by Joule's law:

[0050] When the ambient temperature is high, the base temperature is high, and the heat dissipation efficiency may decrease, resulting in less additional heat. This could cause it to reach the critical temperature for damage; therefore, to prevent damage, the permissible overcurrent time must be shortened. Therefore, simplifying this continuously changing physical process into several key temperature ranges makes it easier to engineer continuous temperature variables, and facilitates implementation and testing.

[0051] At the same time, since the result of the lookup table is deterministic and predictable, that is, the output correction coefficient is unique for a given temperature range, the behavior of the compensation system is very stable and easy to troubleshoot and verify for safety.

[0052] However, the main drawback of this method is its discontinuity. At the critical point between two temperature levels, such as a jump from 49.9℃ (corresponding to coefficient 2) to 50.0℃ (corresponding to coefficient 5), the countdown speed changes abruptly. This step-like change does not perfectly match the smooth changes in the physical world, which may lead to insufficient precision in the protective action near the critical point.

[0053] Based on this, in another embodiment of this application, the classic Arrhenius equation from materials science and chemical kinetics is introduced to establish a continuous thermal aging rate model, thereby improving the correction coefficient from a piecewise constant to a continuous function that can accurately describe the thermal aging rate of the material. This is because the lifespan (aging) rate of a relay is closely related to temperature, and this relationship is usually exponential, which can be described based on the Arrhenius equation. Specifically, the Arrhenius equation describes the relationship between chemical reaction rate and temperature, and can be used to define the acceleration of a countdown, that is, the countdown speed should be proportional to the risk or rate of thermal damage to the device at the current temperature.

[0054] If the correction factor is And the temperature is Then the model association is represented as:

[0055] in, It is the absolute temperature scale (Kelvin) of the current operating temperature of the relay. The term refers to the pre-factor, which is a constant and can be understood as the maximum reaction rate at infinite temperature. Here it is used as a scaling factor for scaling the overall curve. It is the activation energy, measured in joules per mole (J / mol), representing the energy barrier that triggers material aging. The higher the value, the less sensitive the material is to temperature changes. It is the ideal gas constant, approximately 8.314 J / (mol·K). Among them, the parameter... and These are the inherent physical properties of the key materials used in the relay (such as insulating varnish and plastic housing), which can be found in the manufacturer's material data sheet or obtained by fitting the data through accelerated aging tests on samples. In one example of this application, equal ; equal J / mol.

[0056] Thus, by introducing the aforementioned model correlation, a correction coefficient that changes continuously and smoothly with temperature can be provided. This eliminates abrupt changes at the critical point of gear shifting, resulting in more precise protection actions that perfectly conform to physical laws. Furthermore, because each parameter in the model has a clear physical meaning, the design of the protection strategy is no longer empirical but data-driven based on materials science. In addition, the characteristics of the exponential function associated with this model determine that in the low-temperature region, small temperature changes have a significant impact. The effect is minimal; however, in high-temperature regions, even a small increase in temperature can have a dramatic impact. This value greatly accelerates the countdown, which aligns perfectly with the need for increasingly sensitive protection as temperatures approach danger levels.

[0057] In step S6, the relay is tripped based on the final countdown timer. Specifically, once the relay detects that the current exceeds the rated current value (i.e., enters an overcurrent state), and calculates the current final countdown timer according to S2 to S5, the processor controlling the relay starts a precise timer. This timer starts counting from zero, monitoring the duration of the overcurrent. To ensure the accuracy of the protection, the relay continuously monitors the current value flowing through it and the relay's operating temperature in real time. If the current value changes significantly or the temperature fluctuates greatly during the timing process, the relay dynamically recalculates and updates the final countdown timer based on the new current and temperature values, then updates the timer's target value or adjusts the existing timing process to ensure that the relay always counts down to the latest operating conditions. Once the overcurrent duration recorded by the real-time timer reaches or exceeds the final countdown timer calculated under the current operating conditions, it is determined that the tripping condition has been met, and the relay is tripped. The processor controlling the relay sends instructions to the relay's output module. This output module typically contains one or more highly reliable solid-state relays or mechanical auxiliary relay contacts. These contacts close, outputting an electrical signal (e.g., a DC trip pulse), which is sent directly to the trip coil of the downstream circuit breaker associated with the relay. When the circuit breaker trip coil is energized, it generates a mechanical force that drives the circuit breaker mechanism to operate, causing the main contacts of the circuit breaker to quickly break, thereby isolating the faulty or overloaded circuit from the power system.

[0058] After the first overload protection trips, the relay will resume output after a preset recovery time interval. If the overload protection trips again within the preset trip time interval and locks the relay, the output will not be restored. If the overload protection trips again after the preset trip time interval has elapsed, the output will resume after a preset recovery time interval.

[0059] The preset recovery time interval and preset trip time interval can be set according to actual conditions. For example, if the preset recovery time interval is 200 seconds and the preset trip time interval is 1 hour, after the first overload protection trips, the relay will restore output after a 200-second delay. If the overload protection is activated a second time within 1 hour, the output will be locked and not restored. If the overload protection is activated again after 1 hour, the program will return to the loop after the first overload protection (i.e., the relay will restore output after a preset recovery time interval; if the overload protection trips again within the preset time and the relay is locked, the output will not be restored; if the overload protection trips again after the preset trip time interval, the output will be restored after a preset recovery time interval).

[0060] Accordingly, in one embodiment of this application, the temperature-sensing-based relay control method further includes step S71, in response to the current trip being the first trip, controlling the relay to close after a preset recovery time interval after the control relay trips; or S72, in response to the time interval between the current trip and the previous trip being less than or equal to a preset trip time interval, not controlling the relay to close after the control relay trips; or S73, in response to the time interval between the current trip and the previous trip being greater than a preset time, controlling the relay to close after a preset recovery time interval after the control relay trips.

[0061] It is worth noting that, typically, tripping control is performed solely based on the current fault, ignoring the relay's state prior to the fault. This application proposes that the adverse effects of thermal effects on relays are cumulative. In one embodiment of this application, in the aforementioned... Building upon model correlation, this application introduces the concept of state accumulation, upgrading the protection mechanism from a memoryless, single-event judgment system to a memory-based, full-lifecycle management system that considers the equipment's historical thermal load. In other words, if the current overcurrent event continues, the incremental thermal damage it causes, combined with the accumulated historical thermal damage, will exceed the equipment's safety threshold, necessitating immediate tripping. Therefore, it is necessary to track state variables that describe the equipment's aging level or service life, defined here as the degree of thermal damage, for example, expressed as... .

[0062] First, we need to define the damage rate, that is, at any given time... The cumulative rate of thermal damage to the equipment This rate is not only related to the current temperature It is related to the current that causes the temperature rise. If this is relevant, the model can be simplified by assuming the damage rate is a function of temperature. Based on the Arrhenius formula, we have:

[0063] in, and The damage model constants are determined based on the key materials used in the relay (such as insulating varnish and plastic casing). Is the equipment in The real-time temperature at any given moment. In one example of this application, The value is equal to the pre-exponential factor. The value; B The value is equal to the activation energy. With the ideal gas constant The ratio of .

[0064] The cumulative total damage is expressed as Equal to historical damage The sum of new damage incurred during the current period:

[0065] in This refers to the start time of the current period, such as the beginning time of an overcurrent event (current exceeding the rated current value). In other words, it begins from, for example, the start time of the overcurrent event. up to the current moment The incremental damage caused by this fault event is obtained by integrating the damage rate. Specifically, the integration calculation can be performed by setting... arrive Timing sampling points between And determine the thermal damage accumulation rate for each time-series sampling point. We obtain the result by summing, that is:

[0066] Historical damage It is through the relay during operation. Obtained through calculation.

[0067] In this way, the tripping logic does not have to be based entirely on a countdown, but can be calculated in real time. When it reaches a preset critical damage threshold, representing 100% lifespan loss, it immediately trips. This gives the protective relay a memory function, enabling it to distinguish between healthy equipment that has been operating at low temperatures and light loads for extended periods (capable of withstanding occasional overloads) and sub-healthy equipment that has experienced severe overloads and has not fully cooled down, or that has been operating at high temperatures and heavy loads for a long time (which will trip even under minor overloads). (Higher and faster tripping). In other words, the protection decision is based on the judgment that if the circuit is not cut off at this moment, the accumulated damage will exceed the limit. This is obviously more intelligent than reactive protection, which makes the equipment's design life utilized to the maximum extent while ensuring safety, avoiding wasted life due to overly conservative protection strategies, or premature failure due to ignoring historical loads.

[0068] The critical damage threshold is set according to requirements. In one example of this application, the critical damage threshold is equal to... .

[0069] like Figure 3 As shown, based on the above-mentioned scheme for determining whether to trip based on the accumulation of thermal damage, this application proposes another relay control method based on temperature sensing, which includes the following steps: S1A, acquiring the real-time current and operating temperature of the relay to obtain the real-time current value and operating temperature value; S2A, calculating the degree of thermal damage based on the real-time current value and the operating temperature value; S3A, controlling the relay to trip based on the degree of thermal damage.

[0070] In step S1A, the real-time current and operating temperature of the relay are acquired to obtain real-time current and operating temperature values. Specifically, the real-time current and operating temperature are sampled from the moment the relay starts operating to obtain multiple real-time current values ​​and multiple operating temperature values ​​corresponding to multiple timing sampling points.

[0071] In step S2A, the degree of thermal damage is calculated based on the real-time current value and the operating temperature value. Specifically, according to... and Calculate the degree of thermal damage.

[0072] In step S3A, the relay is controlled to trip based on the degree of thermal damage. Specifically, the relay is controlled to trip when the degree of thermal damage is greater than a critical damage threshold.

[0073] The mechanisms of each step have been explained in the description of the above scheme for determining whether to trip due to accumulated thermal damage, and will not be repeated here.

[0074] In summary, the temperature-sensing-based relay control method provides more precise, reasonable, and efficient overcurrent protection, enhancing the system's adaptability to complex operating environments.

[0075] The present application and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present application. The actual structure is not limited to this. In conclusion, if a person skilled in the art is inspired by this description and designs a similar structure and embodiment without departing from the spirit of the present application, such design should fall within the protection scope of the present application.

Claims

1. A relay control method based on temperature sensing, characterized in that, include: Obtain the current value of the electrical equipment protected by the relay; Obtain the current-time mapping relationship; Determine the initial countdown timer corresponding to the current current value based on the current current value and the current-time mapping relationship; Obtain the current operating temperature of the relay to get the current temperature value; Calculate the final countdown time based on the current temperature value and the initial countdown limit; The relay trips based on the final countdown timer.

2. The relay control method based on temperature sensing according to claim 1, characterized in that, Calculate the final countdown time based on the current temperature value and the initial countdown limit, including: Obtain the correction factor corresponding to the current temperature; The final countdown time is calculated based on the current temperature value, the correction factor, and the initial countdown time. The final countdown time is equal to the ratio of the initial countdown time to the correction factor corresponding to the current temperature value.

3. The relay control method based on temperature sensing according to claim 2, characterized in that, Obtain the correction factor corresponding to the current temperature, including: Look up the correction factor corresponding to the current temperature based on the temperature-correction factor table.

4. The relay control method based on temperature sensing according to claim 2, characterized in that, Obtain the correction factor corresponding to the current temperature, including: The correction factor is calculated based on the function of the correction factor with respect to temperature, corresponding to the current temperature.

5. The relay control method based on temperature sensing according to claim 4, characterized in that, The functional relationship between temperature and correction factor conforms to the Arrhenius equation.

6. The relay control method based on temperature sensing according to claim 2, characterized in that, Based on the current current value and the current-time mapping relationship, determine the initial countdown timer corresponding to the current current value, including: If the current value fluctuates between 1 times or more and less than 1.6 times the rated current value within the current preset time period, the initial countdown time corresponding to the maximum current value within the current preset time period will be used as the initial countdown time corresponding to the current current value.

7. The relay control method based on temperature sensing according to claim 2, characterized in that, Further includes: In response to the current trip being the first trip, the relay is controlled to close after a preset recovery time interval following the control relay trip.

8. The relay control method based on temperature sensing according to claim 2, characterized in that, Further includes: If the time interval between the current trip and the previous trip is less than or equal to the preset trip time interval, the relay will not be controlled to close again after the control relay trips.

9. The relay control method based on temperature sensing according to claim 2, characterized in that, Further includes: In response to the time interval between the current trip and the previous trip being greater than a preset time, the relay is controlled to close after a preset recovery time interval following the control relay trip.

10. A relay control method based on temperature sensing, characterized in that, include: Obtain the real-time current and operating temperature of the relay to get the real-time current value and operating temperature value; The degree of thermal damage is calculated based on the real-time current value and the operating temperature value. The relay trips based on the degree of thermal damage.

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