Circuit breaker control method for simulating fuse fusing characteristic protection and circuit breaker

Abstract

The embodiment of the invention discloses a circuit breaker control method for simulating fuse fusing characteristic protection and a circuit breaker. The method comprises the following steps: S01, acquiring a real-time current value of a line connected with the circuit breaker; s02, calculating a current change rate according to the real-time current value; s03, if the real-time current value exceeds a current preset threshold value and the current change rate exceeds a current change rate preset threshold value, determining that the circuit breaker executes a tripping action, otherwise, executing a step S04; s04, virtual temperature is introduced, and dynamic thermal resistance is calculated according to the virtual temperature and the current change rate; s05, updating the virtual temperature according to the dynamic thermal resistance; and S06, if the updated virtual temperature is greater than or equal to the fusing temperature of the simulated fuse, determining that the circuit breaker executes a tripping action. According to the embodiment of the invention, the error tripping risk of the circuit breaker is reduced, and the circuit breaker is promoted to accurately simulate the fusing protection characteristic of the fuse wire to realize an accurate overcurrent protection effect.

Description

Technical Field

[0001] This invention relates to the field of electrical protection technology, and in particular to a circuit breaker control method and circuit breaker for protection by simulating the fusing characteristics of a fuse. Background Technology

[0002] Traditional fuse racks are mainly deployed in three-phase AC power distribution systems (such as 10kV distribution network branch lines and the incoming side of distribution transformers). Traditional fuse racks use fuses as the core fault-breaking element, and each phase of the three-phase circuit is equipped with a fuse to achieve overcurrent / short-circuit fault protection for each phase. However, they have inherent technical limitations: when a fault occurs, the fuse can only achieve single-phase independent operation. After operation, it will directly cause the distribution circuit to operate with a single phase, which will lead to a chain of problems such as abnormal operation of subsequent equipment or decreased stability of power grid operation.

[0003] The existing patent document CN119725027A discloses an intelligent three-phase contactor that can control the contactor's on / off state by monitoring the three-phase circuit voltage to achieve multiple types of electrical protection. Its overcurrent protection mechanism triggers protection when the load current exceeds the rated value, and disconnects the contactor circuit after passing the I²t inverse time curve to protect the downstream load. However, this solution has the defect of insufficient protection accuracy and cannot equivalently simulate the fusing characteristics of a traditional fuse: when the load current only momentarily exceeds the rated value rather than continuously exceeds the rated value, a traditional fuse will not immediately blow because the current can quickly return to normal, while this contactor solution will directly trigger the disconnection action when it detects the current exceeding the limit, which can easily cause the contactor to trip falsely and make it difficult to achieve the same accurate overcurrent protection effect as a fuse. Summary of the Invention

[0004] This invention provides an integrated circuit breaker and circuit breaking method that simulates the fusing characteristics of a fuse, which solves the problem that existing circuit breaker control methods are prone to false tripping and are difficult to achieve the same accurate overcurrent protection effect as fuses.

[0005] This invention provides a circuit breaker control method for simulating fuse blowing characteristics protection, comprising:

[0006] S01. Obtain the real-time current value of the line connected to the circuit breaker;

[0007] S02. Calculate the current change rate based on the real-time current value;

[0008] S03. If the real-time current value exceeds the current preset threshold and the current change rate exceeds the current change rate preset threshold, then determine that the circuit breaker will perform a tripping action; otherwise, proceed to step S04.

[0009] S04. Introduce a virtual temperature and calculate the dynamic thermal resistance based on the virtual temperature and the rate of change of current.

[0010] S05. Update the virtual temperature based on the dynamic thermal resistance;

[0011] S06. If the updated virtual temperature is greater than or equal to the fusing temperature of the simulated fuse, then the circuit breaker is determined to perform a tripping action to realize the protection of the circuit breaker's simulated fuse fusing characteristics.

[0012] Furthermore, step S04 also includes:

[0013] An aging factor is introduced, the I²t inverse time curve is updated based on the real-time current value, and the aging factor is updated based on the I²t inverse time curve. The dynamic thermal resistance is calculated based on the virtual temperature, the rate of change of current, and the updated aging factor.

[0014] Further, step S01 includes:

[0015] The initial parameters are obtained according to the specifications of the simulated fuse. The initial parameters of the fuse include: initial thermal resistance, initial melting point, melting point, and initial virtual temperature, wherein the initial virtual temperature is less than the melting point.

[0016] The real-time current value of the line connected to the circuit breaker is obtained periodically.

[0017] Step S06 further includes:

[0018] If the updated virtual temperature is less than the melting temperature of the simulated fuse, then proceed to step S07;

[0019] Step S07 includes: repeating steps S02-S06 periodically until it is determined that the circuit breaker will trip.

[0020] Furthermore, step S07 also includes: if the virtual temperature is less than the melting temperature but greater than the warning preset temperature, then it is determined that the circuit breaker will issue a warning action.

[0021] Furthermore, after determining that the circuit breaker has performed a tripping action, the virtual temperature is locked at the tripping value, so that the circuit breaker remains in the tripping state until the virtual temperature is manually reset to the ambient temperature as the initial virtual temperature. At this point, the circuit breaker changes from the open state to the closed state, and steps S01-S07 are executed again. This is used to realize that after the simulated fuse blows, the fuse is manually replaced and then the protection operation is restarted. In this case, the ambient temperature is less than the melting temperature, and the tripping value is greater than or equal to the melting temperature of the simulated fuse.

[0022] Furthermore, the update formula for the aging factor is:

[0023] AF=1+k1*Σ(I²t)+k2*Cycle_Count;

[0024] Wherein, AF is the aging factor; k1 and k2 are determined according to the fuse specifications, and k1 and k2 are constants; Σ(I²t) is the I²t inverse time curve, and Cycle_Count is the number of sampling cycles for the real-time current value.

[0025] Furthermore, the formula for calculating the dynamic thermal resistance is as follows:

[0026] R_th_dynamic(k)=(R_th_base0 / AF)*f(T_virtual(k-1),(I(k)-I(k-1)) / Δt);

[0027] Where R_th_dynamic(k) is the dynamic thermal resistance of the current cycle, R_th_base0 is the initial thermal resistance, AF is the aging factor, T_virtual(k-1) is the virtual temperature of the previous cycle, and I(k)-I(k-1)) / Δt is the rate of change of current between the previous cycle and the current cycle.

[0028] f(T_virtual(k-1),(I(k)-I(k-1)) / Δt) is the correlation function between virtual temperature and the rate of change of current.

[0029] Furthermore, the update formula for the virtual temperature is:

[0030] T_virtual(k) =

[0031] T_virtual(k-1)+Δt*[I(k)²-(T_virtual(k-1)-T_ambient) / R_th_dynamic(k)] / C_th0,

[0032] Where T_virtual(k) represents the virtual temperature of the current cycle, T_virtual(k-1) is the virtual temperature of the previous cycle, Δt is the cycle duration, I(k) is the real-time current value of the current cycle, T_ambient is the ambient temperature, R_th_dynamic(k) is the dynamic thermal resistance of the current cycle, and C_th0 is the initial thermal melting of the fuse.

[0033] This invention also provides a circuit breaker, including a microcontroller and a circuit breaking actuator. The microcontroller includes a current acquisition circuit, a data processing module, and a drive circuit. The first terminal of the current acquisition circuit is used to connect to a three-phase circuit. The second terminal of the current acquisition circuit is connected to the first terminal of the drive circuit through the data processing module. The second terminal of the drive circuit is connected to the circuit breaking actuator.

[0034] The current acquisition circuit is used to acquire the real-time current value of the three-phase circuit;

[0035] The data processing module is used to obtain the real-time current value of the three-phase circuit and execute any of the control methods described above.

[0036] The drive circuit is used to send a tripping action command to the circuit breaker actuator when the data processing module determines that the circuit breaker is to perform a tripping action.

[0037] The circuit breaker mechanism is used to connect to the three-phase circuit and control the three-phase circuit to be synchronously disconnected according to the tripping action command.

[0038] Furthermore, it also includes a power supply component, which includes a capacitor power supply module, a capacitor, and a power conversion module. The first end of the capacitor power supply module is used to connect to one phase of the three-phase circuit through the capacitor. The second end of the capacitor power supply module is connected to the first end of the power conversion module, and the second end of the power conversion module is connected to the controller.

[0039] As can be seen from the above technical solutions, the present invention has the following advantages:

[0040] This embodiment first determines whether the circuit breaker will trip based on the real-time current value and the rate of change of current, based on whether both are greater than a preset threshold. Compared with the prior art, which only uses the I²t inverse time curve to determine the tripping action, this embodiment considers not only whether the real-time current value is greater than the preset threshold, but also whether the rate of change of current is greater than the preset threshold. This avoids tripping immediately when the real-time current value only briefly exceeds the preset threshold. By introducing the judgment of the rate of change of current, it further judges whether the difference between the real-time current value and the past current is too large before determining whether the circuit breaker will trip. This realizes the circuit breaker simulating the situation where the fuse will not immediately blow due to the current quickly returning to normal, reducing the risk of false tripping. At the same time, by judging the rate of change of current, it realizes the simulation of the fuse immediately determining the tripping action of the circuit breaker due to the instantaneous change in the current value, promoting the circuit breaker to accurately simulate the fuse blowing protection characteristics and achieve precise overcurrent protection effect.

[0041] This embodiment further calculates dynamic thermal resistance by introducing virtual temperature combined with current change rate. The virtual temperature is updated based on the dynamic thermal resistance, and the circuit breaker trips based on whether the updated virtual temperature exceeds the fuse's melting point. This simulates a situation where, even when the real-time current value and current change rate are normal, the fuse's heating and cooling become unbalanced, causing heat to accumulate and reach the melting threshold, thus cutting off the circuit. Compared to existing technologies that only use the I²t inverse-time curve to determine the circuit breaker's tripping action, this embodiment's circuit breaker control method further considers the situation where the fuse temperature becomes too high due to abnormal conditions such as overload of the associated circuit, causing it to disconnect the protection circuit. This avoids the risk of the circuit breaker failing to trip when overheated, leading to continued overload operation and protection failure. It promotes accurate simulation of the fuse's melting protection characteristics, achieving precise overcurrent protection. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 A schematic flowchart of a circuit breaker control method for simulating fuse blowing characteristics is provided in an embodiment of the present invention.

[0044] Figure 2 This is a schematic diagram of a circuit breaker system structure provided in an embodiment of the present invention;

[0045] Figure 3 This is a schematic front view of a circuit breaker system provided in an embodiment of the present invention;

[0046] Figure 4 This is a top view schematic diagram of a circuit breaker system provided in an embodiment of the present invention;

[0047] Figure 5 This is a left view schematic diagram of a circuit breaker system provided in an embodiment of the present invention;

[0048] Figure 6 A three-dimensional schematic diagram of a circuit breaker system provided in an embodiment of the present invention;

[0049] Explanation of reference numerals in the attached drawings: 101, Switch mechanism housing; 102, Current sensor coil; 103, Arc extinguishing device; 104, Operating mechanism; 105, Insulated pole power supply side; 106, Capacitor power extraction module; 107, Drive module; 108, DC / DC conversion module; 109, Configuration module; 110, Communication interface; 111, Data processing module; 112, Analog-to-digital conversion module; 113, Current acquisition circuit; 114, Microcontroller; 115, Insulated pole load side. Detailed Implementation

[0050] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0051] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the present application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0052] Please see Figure 1 , Figure 1 This is a flowchart illustrating a circuit breaker control method for simulating fuse blowing characteristics, provided in an embodiment of the present invention.

[0053] This invention provides a circuit breaker control method for simulating fuse blowing characteristics protection, comprising:

[0054] S01. Obtain the real-time current value of the line connected to the circuit breaker;

[0055] S02. Calculate the rate of change of current based on the real-time current value;

[0056] S03. If the real-time current value exceeds the current preset threshold and the current change rate exceeds the current change rate preset threshold, then the circuit breaker is determined to trip; otherwise, proceed to step S04.

[0057] S04. Introduce virtual temperature and calculate dynamic thermal resistance based on virtual temperature and current change rate;

[0058] S05. Update the virtual temperature based on dynamic thermal resistance;

[0059] S06. If the updated virtual temperature is greater than or equal to the fusing temperature of the simulated fuse, then the circuit breaker is determined to trip, thereby realizing the protection of the circuit breaker's simulated fuse fusing characteristics.

[0060] Understandably, in specific implementation, on the one hand, this embodiment first determines whether the real-time current value and the rate of change of current are both greater than a preset threshold based on the real-time current value and the rate of change of current, and then determines that the circuit breaker will perform a tripping action. Compared with the prior art, which only determines the circuit breaker to perform a tripping action based on the I²t inverse time curve, this embodiment not only considers whether the real-time current value is greater than the preset threshold, but also whether the rate of change of current is greater than the preset threshold. This avoids tripping immediately when the real-time current value only briefly exceeds the preset threshold. By introducing the judgment of the rate of change of current, it further judges whether the difference between the real-time current value and the past current is too large before determining whether the circuit breaker will perform a tripping action. This realizes that the circuit breaker simulates the situation where the fuse will not immediately blow due to the current quickly returning to normal, reducing the risk of false tripping of the circuit breaker. At the same time, by judging the rate of change of current, it realizes that the circuit breaker will immediately determine the tripping action when the fuse is simulating a sudden change in the instantaneous current value, promoting the circuit breaker to accurately simulate the fuse blowing protection characteristics and achieve a precise overcurrent protection effect.

[0061] On the other hand, this method further incorporates virtual temperature and current change rate to calculate dynamic thermal resistance. The virtual temperature is updated based on this dynamic thermal resistance, and the circuit breaker trips based on whether the updated virtual temperature exceeds the fuse's melting point. This simulates a scenario where, even when the real-time current value and current change rate are normal, the fuse's heating and cooling become unbalanced, causing heat to accumulate and eventually reach the melting threshold, thus cutting off the circuit. Compared to existing technologies that only use the I²t inverse-time curve to determine the circuit breaker's tripping action, this embodiment further considers the possibility of the fuse overheating due to overload or other abnormal conditions, causing it to disconnect the protection circuit. This avoids the risk of the circuit breaker failing to trip when overheated, leading to continued overload operation and protection failure. It promotes accurate simulation of the fuse's melting protection characteristics, achieving precise overcurrent protection.

[0062] It should be noted that when a real fuse carries a large current, its heat dissipation conditions (thermal resistance) will change drastically due to factors such as electric arc and severe oxidation. Therefore, a virtual temperature and current change rate are introduced to correct the thermal resistance. The virtual temperature is mainly used to reflect the operating temperature of the fuse during the simulation process. Compared with the linear change of the I²t inverse time curve in the existing technology, this embodiment realizes nonlinear dynamic thermal resistance simulation, which simulates the complex physicochemical changes of the fuse under extreme conditions. This promotes the realization of accurate overcurrent protection effect consistent with the circuit breaker and the fuse, and reduces the occurrence of circuit breaker false tripping.

[0063] In a more specific embodiment, step S04 further includes: introducing an aging factor, updating the I²t inverse time curve based on the real-time current value, updating the aging factor based on the I²t inverse time curve, and calculating the dynamic thermal resistance based on the virtual temperature, the rate of change of current, and the updated aging factor.

[0064] Understandably, in specific implementation, this embodiment calculates dynamic thermal resistance by introducing an aging factor, simulating the situation where old fuses will accelerate melting due to overheating due to aging, thus promoting the circuit breaker to accurately simulate the fuse melting protection characteristics and achieve precise overcurrent protection.

[0065] It's important to clarify that digital fuse simulation for circuit breakers doesn't create a completely new protection logic. Instead, it allows the circuit breaker's electronic protection algorithm to accurately replicate the "current-time-breaking" characteristics of traditional fuses. This retains the advantages of fuse protection (such as inverse-time characteristics and low-cost adaptability) while addressing the drawbacks of fuses being disposable and requiring manual replacement. The protective capability of traditional fuses decays with oxidation and aging (e.g., the fusible element thins and its heat resistance decreases). This is an inherent characteristic and a "protection benchmark" that electrical system design must adapt to. If digital protection completely ignores this aging process, it deviates from the core objective of "fuse simulation" and becomes an independent protection scheme disconnected from fuse protection logic, incompatible with the system's original protection design.

[0066] In industrial or civil electrical systems, fuses are often part of a "tiered protection" system (e.g., front-end fuses protect the main circuit, and back-end fuses protect the branch circuits). If the back-end circuit breakers use a digital solution to simulate the fuse but do not consider the aging and degradation of the fuse, a misalignment in the protection logic will occur.

[0067] The actual fusing threshold of an aging fuse will decrease. If the digital protection still trips according to the threshold of a brand new fuse, when an overload occurs, the actual aging fuse at the front end has already blown, but the digital protection at the back end has not taken action, causing the branch equipment to lose protection.

[0068] Conversely, if the front-end fuse is new but the back-end digital protection mistakenly trips the low threshold of an old fuse, it will cause "over-level tripping" and expand the power outage area.

[0069] Therefore, digital protection must simulate the aging of fuses in order to coordinate with the protection characteristics of other fuses in the system and ensure the effectiveness of graded protection.

[0070] It should be further explained that real fuses age and their fusing characteristics change. Therefore, an aging factor AF is introduced, which increases slowly with the "accumulated I²t value" and "energizing cycle". This integrates equipment lifecycle management into the real-time protection algorithm, giving the virtual fuse (circuit breaker) "memory" and "aging" characteristics. Compared with the linear change of the I²t inverse time curve in the existing technology, the introduction of the aging factor to correct the thermal resistance in real time fully considers the oxidation and aging of the fuse. This makes the dynamic thermal resistance-thermal capacity model closer to the physical structure of the fuse, further promoting the realization of accurate overcurrent protection consistent with the fuse, and further reducing the occurrence of circuit breaker false tripping.

[0071] In a more specific embodiment, a circuit breaker control method simulating fuse blowing characteristics includes:

[0072] S01. Obtain the initial parameters according to the specifications of the simulated fuse. The initial parameters of the fuse include: initial thermal resistance, initial melting point, melting point, and initial virtual temperature. The initial virtual temperature is less than the melting point.

[0073] The real-time current value of the line connected to the circuit breaker is obtained periodically.

[0074] S02. Calculate the rate of change of current based on the real-time current value;

[0075] S03. If the real-time current value exceeds the current preset threshold and the current change rate exceeds the current change rate preset threshold, then the circuit breaker is determined to trip; otherwise, proceed to step S04.

[0076] S04. Introduce virtual temperature and aging factor, update the I²t inverse time curve based on real-time current value, update the aging factor based on the I²t inverse time curve, and calculate dynamic thermal resistance based on virtual temperature, current change rate and updated aging factor.

[0077] S05. Update the virtual temperature based on dynamic thermal resistance;

[0078] S06. If the updated virtual temperature is greater than or equal to the fusing temperature of the simulated fuse, then the circuit breaker is determined to trip, thus realizing the protection of the circuit breaker's simulated fuse fusing characteristics; otherwise, proceed to step S07.

[0079] S07: Repeat steps S02-S06 periodically until it is determined that the circuit breaker will trip.

[0080] Understandably, by acquiring the real-time current value of the circuit breaker's connected lines on a periodic basis and performing dynamic thermal resistance and virtual temperature calculations on a periodic basis, the active digital reproduction of the fuse protection mechanism is achieved through periodic monitoring and calculation. Periodic execution ensures the uniformity of data acquisition, ensuring that monitoring and protection can be completed within a fixed time sequence after a fault occurs, and guaranteeing the determinism of the response.

[0081] In a more specific embodiment, after the circuit breaker performs a tripping action, the virtual temperature is locked at the tripping value, so that the circuit breaker remains in the tripping state until the virtual temperature is manually reset to the ambient temperature as the initial virtual temperature. At this time, the circuit breaker changes from the open state to the closed state and steps S01-S07 are executed again to realize that after the simulated fuse blows, the fuse is manually replaced and the protection operation is restarted. Here, the ambient temperature is less than the melting temperature, and the tripping value is greater than or equal to the melting temperature of the simulated fuse.

[0082] Understandably, in practical implementation, the virtual temperature is manually reset to the ambient temperature as the initial virtual temperature. This digitally simulates the core characteristic of a real fuse: "manual replacement is required to restore power after it blows." This is fundamentally different from automatic reset overcurrent protection and is more suitable for the application scenario of circuit breaker benches. When a circuit experiences overload, short circuit, or other faults, the system will not automatically restore power after triggering the protection action. Power can only be restored manually after the fault is checked and safety is confirmed. This design avoids the risk of repeated restarts due to unresolved faults caused by automatic reset, which could lead to secondary damage to equipment or safety accidents.

[0083] It should be noted that after the circuit breaker performs a tripping action, it means that the line remains open after the fuse blows. In this embodiment, the virtual temperature is locked at the tripping value (the tripping value is greater than or equal to the melting temperature of the simulated fuse) to keep the circuit breaker in a tripped state, thus simulating that the line remains open after the fuse blows. In this embodiment, the virtual temperature is manually reset to the ambient temperature as the initial virtual temperature, which is a prerequisite for the circuit breaker to change from an open state to a closed state and re-execute steps S01-S07. That is, it ensures that the simulated fuse can only re-enter the working state after replacement. The ambient temperature must be lower than the melting temperature of the fuse. Using this temperature as the initial virtual temperature can represent the temperature of the new fuse and also meet the simulation requirement that when the fuse is reconnected, the fuse temperature is close to the ambient temperature but lower than the melting temperature, which is in a normal state. Thus, after the virtual temperature is manually reset to the ambient temperature as the initial virtual temperature, the circuit breaker re-executes steps S01-S07. In step S04 of the first cycle, the virtual temperature introduced as the ambient temperature is more consistent with the actual initial temperature state of the new fuse.

[0084] In a more specific embodiment, the current preset value is the short-circuit current value.

[0085] In a more specific embodiment, step S07 further includes: if the virtual temperature is less than the melting temperature but greater than the warning preset temperature, then immediately determine that the circuit breaker will issue a warning action.

[0086] In a more specific embodiment, the formula for updating the aging factor is:

[0087] AF=1+k1*Σ(I²t)+k2*Cycle_Count;

[0088] Wherein, AF is the aging factor; k1 and k2 are determined according to the type of fuse, and k1 and k2 are constants; Σ(I²t) is the I²t inverse time curve, and Cycle_Count is the number of sampling cycles for the real-time current value.

[0089] In a more specific embodiment,

[0090] The formula for calculating dynamic thermal resistance is:

[0091] R_th_dynamic(k)=(R_th_base0 / AF)*f(T_virtual(k-1),(I(k)-I(k-1)) / Δt);

[0092] Where R_th_dynamic(k) is the dynamic thermal resistance of the current cycle, R_th_base0 is the initial thermal resistance, AF is the aging factor, T_virtual(k-1) is the virtual temperature of the previous cycle, and I(k)-I(k-1)) / Δt is the rate of change of current between the previous cycle and the current cycle.

[0093] f(T_virtual(k-1),(I(k)-I(k-1)) / Δt) is the correlation function between virtual temperature and the rate of change of current.

[0094] In a more specific embodiment, the formula for updating the virtual temperature is:

[0095] T_virtual(k) =

[0096] T_virtual(k-1)+Δt*[I(k)²-(T_virtual(k-1)-T_ambient) / R_th_dynamic(k)] / C_th0.

[0097] Where T_virtual(k) represents the virtual temperature of the current cycle, T_virtual(k-1) is the virtual temperature of the previous cycle, Δt is the cycle duration, I(k) is the real-time current value of the current cycle, T_ambient is the ambient temperature, R_th_dynamic(k) is the dynamic thermal resistance of the current cycle, and C_th0 is the initial thermal melting of the fuse.

[0098] It can be understood that, in specific implementation, the I²t inverse time curve is updated based on the real-time current, and the aging factor is updated based on the I²t inverse time curve.

[0099] This invention also provides a circuit breaker, including a microcontroller and a circuit breaking actuator. The microcontroller includes a current acquisition circuit, a data processing module, and a drive circuit. The first terminal of the current acquisition circuit is connected to a three-phase circuit, the second terminal of the current acquisition circuit is connected to the first terminal of the drive circuit through the data processing module, and the second terminal of the drive circuit is connected to the circuit breaking actuator.

[0100] The current acquisition circuit is used to acquire the real-time current value of a three-phase circuit;

[0101] The data processing module is used to acquire the real-time current value of the three-phase circuit and execute the control method of any of the above embodiments;

[0102] The drive circuit is used to send a tripping action command to the circuit breaker actuator when the data processing module determines that the circuit breaker is to perform a tripping action;

[0103] The circuit breaker actuator is connected to the three-phase circuit and is used to control the synchronous circuit breaking of the three-phase circuit according to the tripping action command.

[0104] Understandably, in practice, the problem of phase loss caused by a single fuse blowing is solved by using a microcontroller to drive a controllable mechanical actuator to link three-phase tripping technology.

[0105] It should be noted that the circuit breaker actuator is a three-phase linkage mechanism that can trip repeatedly. By using a microcontroller and the circuit breaker actuator, it can repeatedly switch on and off, solving the problem of needing to replace the fuse after it blows.

[0106] In a more specific embodiment, a power supply component is also included, comprising a capacitor-driven power supply module, a capacitor, and a power conversion module. The first terminal of the capacitor-driven power supply module is connected to one phase of the three-phase circuit via a capacitor, and the second terminal of the capacitor-driven power supply module is connected to the first terminal of the power conversion module. The second terminal of the power conversion module is connected to a microcontroller.

[0107] Understandably, in practice, the microcontroller is powered by a built-in capacitor, which solves the power supply problem of the controller. There is no need for an external power supply PT or additional wiring, and the installation is simple and convenient.

[0108] In a more specific embodiment, the current acquisition module employs a high-precision current sensor.

[0109] In a more specific embodiment, the current acquisition module employs a high-precision current transformer.

[0110] Understandably, in practice, the problem of excessively dispersed fuse blowing is solved by using high-precision current transformers, current acquisition units, and computer chips to achieve precise control. Not only can the trip current setting be refined in segments, but the accuracy of fault tripping is also greatly improved.

[0111] In a more specific embodiment, such as Figures 2-6 As shown, this embodiment of the invention also provides a circuit breaker system.

[0112] It includes a switch mechanism housing 101, which houses a three-phase circuit, a microcontroller 114, and an operating mechanism 104 for three-phase linkage mechanical operation.

[0113] The three-phase circuit is connected to the power supply side 105 and the load side 115 of the insulated pole respectively. A current sensor coil 102 and an arc extinguishing device 103 are provided on each of the three phases of the three-phase circuit.

[0114] The microcontroller includes a current acquisition circuit 113, an analog-to-digital converter module 112, a data processing module 111, a configuration module 109 for configuring current protection parameters, a communication interface 110, a DC / DC converter module 108 for driving the operating mechanism, and a drive module 107.

[0115] The microcontroller's DC / DC conversion module 108 is connected to one phase of the three-phase circuit via the capacitor power supply module 106 and the capacitor, in order to supply power to the microcontroller 114.

[0116] In a more specific embodiment, the installation and use of the circuit breaker includes:

[0117] The microcontroller 114 is integrated and mounted on the switch mechanism housing 101;

[0118] The current sensor coil 102 is built into the pole and provides power to the integrated microcontroller 114; the microcontroller converts the voltage to the operating voltage through the DC / DC converter module 108 and provides it to each module.

[0119] The high-precision circuit sensor is integrated and built into the insulated pole, converting the large current signal into a small current signal and transmitting it to the microcontroller 114.

[0120] Configuration module 109 sets protection parameters, including instantaneous trip and fuse curve settings;

[0121] The reserved communication interface 110 can read out information such as fault records.

[0122] In a more specific embodiment, the working principle of the circuit breaker includes:

[0123] When a fault occurs on the load side, the fault current is converted from a large current to a small current signal through the current sensor coil 102, and then converted into a voltage signal through the current acquisition circuit 113 and transmitted to the analog-to-digital conversion module 112. The analog-to-digital conversion module 112 converts the analog quantity into a digital quantity and transmits it to the data processing module 111.

[0124] The data processing module 111 converts the data into the actual current value. Based on the current set value preset by the configuration module 109, it determines that a fault has occurred and issues an adjustment command to the drive module 107. The drive module 107 drives the circuit to push the three-phase linkage operating mechanism 104. The operating mechanism 104 drives the arc-extinguishing chamber in the three-phase pole to trip and cut off the fault.

[0125] This invention also provides a cloud / main site big data analysis platform (learning center):

[0126] It is used to collect massive amounts of real fuse characteristic data under different currents and aging cycles. A high-precision "dynamic thermal resistance-thermal capacity model" and its parameters are trained using machine learning. It does not directly participate in real-time protection, but is responsible for model training and parameter distribution.

[0127] In a more specific embodiment, the microcontroller connects to the cloud and receives model parameters from the cloud. It does not store complex models; instead, it runs a simplified "real-time state machine" that calculates the cumulative thermal state of the "virtual fuse" based on the input current and the sent parameters, and trips the fuse when a threshold is reached. The microcontroller performs "state computation" rather than a standard I²t integral; its core parameters are injected externally, and the device itself does not possess complete "knowledge" of the algorithm.

[0128] The core algorithm of the microcontroller: the dynamic thermal resistance-thermal capacity model, specifically including:

[0129] An equivalent RC thermal circuit is used to simulate the fuse, but its parameters are dynamic.

[0130] 1) Establishing the basic model:

[0131] The fuse is considered as a system consisting of thermal resistance R_th and thermal capacity C_th.

[0132] Heat (temperature rise) is analogous to voltage, and the square of current (I²) is analogous to a current source.

[0133] The "temperature" state quantity T_virtual of the fuse can be described by the following differential equation:

[0134] C_th*d(T_virtual) / dt+(T_virtual-T_ambient) / R_th=I²,

[0135] Where T_ambient is the ambient temperature, which is obtained or fixed by a temperature sensor.

[0136] 2) Model dynamization:

[0137] a. Voltage-dependent thermal resistance (dynamic R_th):

[0138] When a real fuse carries a large current, its heat dissipation conditions (thermal resistance) change drastically due to factors such as electric arcing and severe oxidation. We introduce a function related to the virtual temperature T_virtual and the rate of change of current di / dt to correct R_th.

[0139] R_th_dynamic=R_th_base*f(T_virtual,di / dt),

[0140] When T_virtual approaches its melting point, the f(.) function causes R_th to increase sharply, simulating the process of heat accumulating and not being able to dissipate; when a large di / dt is detected (indicating a short circuit), R_th is increased instantaneously, causing T_virtual to spike, achieving a rapid "meltdown".

[0141] The standard I²t model is linear, while the nonlinear dynamic thermal resistance here simulates the complex physicochemical changes of the fuse under extreme conditions, which is a non-traditional approach.

[0142] b. Embedding of aging factor (AF):

[0143] Real fuses age, and their fusing characteristics change. We introduce an aging factor AF, which increases slowly with the "cumulative I²t value" and "power-on cycles".

[0144] AF=1+k1*Σ(I²t)+k2*Cycle_Count,

[0145] This AF will directly affect the base thermal resistance R_th_base, causing it to decrease slightly.

[0146] (R_th_base_effective=R_th_base / AF) indicates that aged fuses are more prone to overheating.

[0147] By integrating equipment lifecycle management into real-time protection algorithms, virtual fuses acquire "memory" and "aging" characteristics, which surpasses the protection of fixed curves.

[0148] In a more specific embodiment, the specific execution process of micro-control is as follows:

[0149] 1) Initialization:

[0150] The microcontroller downloads the initial parameters of the selected fuse specification from the cloud: R_th_base0, C_th0, T_melt (fusible temperature), and the coefficients of the function f(.).

[0151] 2) Real-time operation (within each sampling period Δt):

[0152] Step 1: Sample and measure the real-time current I(k);

[0153] Step 2: Calculate dynamic thermal resistance;

[0154] R_th_dynamic(k)=(R_th_base0 / AF)*f(T_virtual(k-1),(I(k)-I(k-1)) / Δt);

[0155] Step 3: Update the virtual temperature and solve the differential equation using the numerical integration method (Euler method):

[0156]

[0157] Step 4: Aging update the accumulated I²t value and calculate the new AF;

[0158] Step 5: Criteria and Execution

[0159] Instantaneous trip simulation: If I(k) exceeds an extremely high threshold (such as short-circuit current) and di / dt is extremely large, then thermal calculation is bypassed and the circuit breaker trips immediately;

[0160] Overload fuse: If T_virtual(k) >= T_melt, a trip signal is issued;

[0161] Warning: If T_virtual(k) exceeds 80% of T_melt, an overload warning will be issued.

[0162] 3) Cooling and Backtracking (Innovation Status Management):

[0163] When the current drops to zero or very low, the model enters a cooling state: T_virtual(k)=T_virtual(k-1)-Δt*(T_virtual(k-1)-T_ambient) / (R_th_dynamic(k)*C_th0)

[0164] Virtual Fuse Status: Once the circuit breaker trips, the device locks T_virtual to an extremely high value (such as "fuse blown") and blocks closing. Maintenance personnel must remotely or locally reset T_virtual to T_ambient using the "Replace Virtual Fuse" command (here referring to manual closing).

[0165] This "state-locked and manual reset" mechanism completely simulates the behavior of a real fuse that "must be replaced after blowing," a stark contrast to overcurrent protection with automatic reset. It is more suitable for the application scenario in this case: a circuit breaker platform. After a fault occurs, manual closing is required to restore power.

[0166] In summary, the circuit breaker control method and circuit breaker for simulating fuse blowing characteristics provided by this invention offer a dynamic thermal resistance-thermal fuse circuit model. Parameters are dynamically adjusted according to temperature and current change rates. An aging factor (AF) is introduced to allow protection characteristics to change with operational history. The model is trained in the cloud, simplifying microcontroller calculations. Based on the virtual fuse blocking state, manual reset is required to simulate fuse replacement. This method exhibits more nonlinear and abrupt characteristics, better simulating the rapid blowing of a fuse at a critical point. The control method and circuit breaker of this embodiment are particularly suitable for applications where traditional fuse protection is path-dependent but requires digital and intelligent upgrades, such as power collection lines in new energy power plants, DC power supply for rail transit, and distribution terminals.

[0167] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A circuit breaker control method simulating the fusing characteristics of a fuse, characterized in that, include: S01. Obtain the real-time current value of the line connected to the circuit breaker; S02. Calculate the current change rate based on the real-time current value; S03. If the real-time current value exceeds the current preset threshold and the current change rate exceeds the current change rate preset threshold, then determine that the circuit breaker will perform a tripping action; otherwise, proceed to step S04. S04. Introduce a virtual temperature and calculate the dynamic thermal resistance based on the virtual temperature and the rate of change of current. S05. Update the virtual temperature based on the dynamic thermal resistance; S06. If the updated virtual temperature is greater than or equal to the fusing temperature of the simulated fuse, then the circuit breaker is determined to perform a tripping action to realize the protection of the circuit breaker's simulated fuse fusing characteristics.

2. The circuit breaker control method for simulating fuse blowing characteristics protection according to claim 1, characterized in that, Step S04 further includes: An aging factor is introduced, the I²t inverse time curve is updated based on the real-time current value, and the aging factor is updated based on the I²t inverse time curve. The dynamic thermal resistance is calculated based on the virtual temperature, the rate of change of current, and the updated aging factor.

3. The circuit breaker control method for simulating fuse blowing characteristics protection according to claim 2, characterized in that, Step S01 includes: The initial parameters are obtained according to the specifications of the simulated fuse. The initial parameters of the fuse include: initial thermal resistance, initial melting point, melting point, and initial virtual temperature, wherein the initial virtual temperature is less than the melting point. The real-time current value of the line connected to the circuit breaker is obtained periodically. Step S06 further includes: If the updated virtual temperature is less than the melting temperature of the simulated fuse, then proceed to step S07; Step S07 includes: repeating steps S02-S06 periodically until it is determined that the circuit breaker will trip.

4. The circuit breaker control method for simulating fuse blowing characteristics protection according to claim 3, characterized in that, Step S07 further includes: if the virtual temperature is less than the melting temperature but greater than the warning preset temperature, then determine that the circuit breaker will issue a warning action.

5. A circuit breaker control method for simulating fuse blowing characteristics protection according to claim 3 or 4, characterized in that, After determining that the circuit breaker has performed a tripping action, the virtual temperature is locked at the tripping value, so that the circuit breaker remains in the tripping state until the virtual temperature is manually reset to the ambient temperature as the initial virtual temperature. At this time, the circuit breaker changes from the open state to the closed state, and steps S01-S07 are executed again. This is used to realize that after the simulated fuse blows, the fuse is manually replaced and then the protection operation is restarted. The ambient temperature is lower than the melting temperature, and the tripping value is greater than or equal to the melting temperature of the simulated fuse.

6. The circuit breaker control method for simulating fuse blowing characteristics protection according to claim 5, characterized in that, The update formula for the aging factor is: AF=1+k1*Σ(I²t)+k2*Cycle_Count; Wherein, AF is the aging factor; k1 and k2 are determined according to the fuse specifications, and k1 and k2 are constants; Σ(I²t) is the I²t inverse time curve, and Cycle_Count is the number of sampling cycles for the real-time current value.

7. The circuit breaker control method for simulating fuse blowing characteristics protection according to claim 6, characterized in that, The formula for calculating the dynamic thermal resistance is: R_th_dynamic(k)=(R_th_base0 / AF)*f(T_virtual(k-1),(I(k)-I(k-1)) / Δt); Where R_th_dynamic(k) is the dynamic thermal resistance of the current cycle, R_th_base0 is the initial thermal resistance, AF is the aging factor, T_virtual(k-1) is the virtual temperature of the previous cycle, and I(k)-I(k-1)) / Δt is the rate of change of current between the previous cycle and the current cycle. f(T_virtual(k-1),(I(k)-I(k-1)) / Δt) is the correlation function between virtual temperature and the rate of change of current.

8. The circuit breaker control method for simulating fuse blowing characteristics protection according to claim 7, characterized in that, The update formula for the virtual temperature is: T_virtual(k)=T_virtual(k-1)+Δt*[I(k)²-(T_virtual(k-1)-T_ambient) / R_th_dynamic(k)] / C_th0, Where T_virtual(k) represents the virtual temperature of the current cycle, T_virtual(k-1) is the virtual temperature of the previous cycle, Δt is the cycle duration, I(k) is the real-time current value of the current cycle, T_ambient is the ambient temperature, R_th_dynamic(k) is the dynamic thermal resistance of the current cycle, and C_th0 is the initial thermal melting of the fuse.

9. A circuit breaker, characterized in that, The device includes a microcontroller and a circuit breaker mechanism. The microcontroller includes a current acquisition circuit, a data processing module, and a drive circuit. The first terminal of the current acquisition circuit is used to connect to a three-phase circuit. The second terminal of the current acquisition circuit is connected to the first terminal of the drive circuit through the data processing module. The second terminal of the drive circuit is connected to the circuit breaker mechanism. The current acquisition circuit is used to acquire the real-time current value of the three-phase circuit; The data processing module is used to obtain the real-time current value of the three-phase circuit and execute the control method according to any one of claims 1-8; The drive circuit is used to send a tripping action command to the circuit breaker actuator when the data processing module determines that the circuit breaker is to perform a tripping action. The circuit breaker mechanism is used to connect to the three-phase circuit and control the three-phase circuit to be synchronously disconnected according to the tripping action command.

10. A circuit breaker according to claim 9, characterized in that, It also includes a power supply component, which includes a capacitor power supply module, a capacitor, and a power conversion module. The first end of the capacitor power supply module is used to connect to one phase of the three-phase circuit through the capacitor. The second end of the capacitor power supply module is connected to the first end of the power conversion module, and the second end of the power conversion module is connected to a controller.

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