Method for comprehensively evaluating electrical life of circuit breaker

Abstract

The present invention discloses a method for comprehensively evaluating the electrical life of a circuit breaker, which is specifically carried out according to the following steps: Step 1: Establish a magnetohydrodynamic simulation model according to the designed arc extinguishing chamber structure of the circuit breaker; Step 2: Obtain the spatio-temporal evolution characteristics, arc current, arc voltage, and let-through energy of the arc under different voltages and different current magnitudes through simulation calculations, and establish a database of the simulation results of the circuit breaker; Step 3: Calculate the electrical life of the new circuit breaker product: Calculate the remaining electrical life of the circuit breaker operating online. Thus, the comprehensive evaluation of the electrical life of different circuit breakers is realized. The present invention not only evaluates the electrical life parameters of new circuit breaker products theoretically, but also can evaluate the remaining electrical life times according to the real-time state of the circuit breaker, improving the accuracy of electrical life evaluation while saving costs. This method can be applied to low-voltage circuit breakers and can also be applied to high-voltage gas circuit breakers.

Description

Technical Field

[0001] The present invention belongs to the technical field of arc extinguishing and arc electrical contact of gas circuit breakers, and specifically relates to a method for comprehensively evaluating the electrical life of circuit breakers. Background Art

[0002] Environmental pollution has become a global problem that urgently needs to be solved. Strictly controlling carbon emissions and realizing power generation mainly based on clean energy are important measures. It has been proposed to build a new power system with new energy as the main body, which has pushed the application of new energy to a new level. At the same time, it has brought development opportunities and challenges to the development of fields such as wind power generation, photovoltaic power generation, and energy storage. In the construction of the new power system, the development of the distribution network has also become an important part. In particular, distributed photovoltaics can be directly connected to the distribution network, which puts forward higher requirements for the safety and reliability of the distribution system. As an important power equipment, more performance requirements for low-voltage circuit breakers have been further put forward. Especially with the development of intelligent and digital technologies, the condition detection of circuit breakers has become a new requirement for the performance of circuit breakers.

[0003] In addition to normal breaking capacity, rated voltage, rated current and other parameters, the electrical life of a circuit breaker is also an index that users are very concerned about. Especially for operation and maintenance units, they hope to accurately predict and evaluate the electrical life of the circuit breaker, so as to specify accurate maintenance time and strategies, improve the efficiency of maintenance and operation, and reduce costs. In the past, the electrical life of circuit breakers was that the circuit breaker manufacturers continuously carried out on-off operations under rated current and counted before the products left the factory until the circuit breaker was damaged and could not be switched on or off, and the total number of on-off operations was marked as the electrical life times. However, such a method cannot comprehensively detect each product. On the one hand, this increases the detection cycle and cost. On the other hand, the above tests only measure the parameters under the rated current operation condition, while the circuit breaker often breaks short-circuit current during operation. Under this working condition, the calibrated electrical life data can no longer reflect the true remaining electrical life of the circuit breaker, which leaves a hidden danger for the operation of the circuit breaker. How to evaluate the electrical life parameters of a batch of circuit breakers of the same model through theoretical methods and evaluate the remaining electrical life through the real-time working state of the circuit breaker has become a research hotspot and difficulty. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for comprehensively evaluating the electrical life of circuit breakers, which solves the problem of how to improve the accuracy of electrical life evaluation while saving costs in the evaluation of the electrical life parameters of circuit breaker products.

[0005] The technical solution adopted by the present invention is as follows:

[0006] The method for comprehensively evaluating the electrical life of circuit breakers is specifically carried out according to the following steps:

[0007] Step 1: According to the designed arc extinguishing chamber structure of the circuit breaker, establish a magnetohydrodynamic simulation model;

[0008] Step 2: Through simulation calculations, obtain the spatio-temporal evolution characteristics of the arc, arc current, arc voltage, and let-through energy under different voltages and different currents, and establish a database of circuit breaker simulation results;

[0009] Step 3: Calculate the electrical life of the new circuit breaker product: Based on the database, combined with the contact quality and let-through energy fitting function obtained from the magnetohydrodynamic simulation model, calculate the electrical life times of the new circuit breaker products under different models;

[0010] Calculate the remaining electrical life of the circuit breaker in on-line operation: By comparing the actual arc voltage and arc current curves during the opening process of the circuit breaker collected on-line with the arc voltage and arc current curves in the database, obtain the data with the highest degree of coincidence with the actual curves. According to the data, combined with the contact quality and let-through energy fitting function, calculate the remaining electrical life times of this circuit breaker.

[0011] The features of the present invention also lie in;

[0012] In Step 3, when the magnetohydrodynamic simulation model evaluates the electrical life of different types of circuit breakers, it can only replace the corresponding gas plasma physical property parameters and arc extinguishing chamber structure according to the arc extinguishing gas and arc extinguishing chamber structure; for low-voltage air circuit breakers, select air plasma physical property parameters; for high-voltage SF6 circuit breakers, select SF6 plasma physical property parameters; at the same time, replace different arc extinguishing chamber structures and the boundary conditions corresponding to the arc extinguishing chamber structures one by one, and there is no need to rewrite the program.

[0013] In Step 1, the established magnetohydrodynamic model can not only calculate the dynamic magnetic field generated by the arc itself, but also consider the non-linear B-H curve and eddy current effect in ferromagnetic materials.

[0014] In Step 1, the established magnetohydrodynamic model can also consider the influence of gas-producing materials.

[0015] In Step 2, different voltages are the rated operating voltages of different circuit breakers, and different currents are in the range from the rated current of the circuit breaker to fifteen times the rated current. Among them, the interval value of the simulation calculation current is the rated current.

[0016] In Step 3, when calculating the remaining electrical life of the circuit breaker in on-line operation, the maximum error of the degree of coincidence between the data and the actual curve is <10%.

[0017] The beneficial effects of the present invention are as follows. The method for comprehensively evaluating the electrical life of a circuit breaker can evaluate the electrical life of a new circuit breaker of the same model through this comprehensive evaluation algorithm without the need for experimental testing, saving time and cost and shortening the time for new products to be launched on the market;

[0018] The magnetohydrodynamic model in the method of the present invention is applicable to all gas circuit breakers. When calculating, only the gas plasma parameters and the boundary conditions corresponding to the arc extinguishing chamber structure need to be replaced according to the arc extinguishing medium and the arc extinguishing chamber structure of the circuit breaker, and there is no need to rewrite the program;

[0019] The method of the present invention can accurately predict the remaining electrical life during the movement of the circuit breaker by establishing a database in which the simulation results and the number of electrical life times correspond one by one in advance, without adding complex equipment and prediction algorithms to the circuit breaker, improving the engineering practicability and operability;

[0020] The method of the present invention combines magnetohydrodynamic simulation and the contact ablation life calculation algorithm organically, and is applicable to both the electrical life evaluation of low-voltage circuit breakers and the electrical life evaluation of high-voltage circuit breakers, and has good generality. Brief Description of the Drawings

[0021] Figure 1 is a flowchart for calculating the electrical life of a new circuit breaker product in the method for comprehensively evaluating the electrical life of a circuit breaker of the present invention;

[0022] Figure 2 is a flowchart for calculating the remaining electrical life of an on-line operating circuit breaker in the method for comprehensively evaluating the electrical life of a circuit breaker of the present invention;

[0023] Figure 3 is an arc temperature distribution diagram obtained by magnetohydrodynamic simulation of a molded case circuit breaker in the method for comprehensively evaluating the electrical life of a circuit breaker of the present invention;

[0024] Figure 4 is an arc voltage curve obtained by magnetohydrodynamic simulation of a molded case circuit breaker in the method for comprehensively evaluating the electrical life of a circuit breaker of the present invention;

[0025] Figure 5 is an arc current curve obtained by magnetohydrodynamic simulation of a molded case circuit breaker in the method for comprehensively evaluating the electrical life of a circuit breaker of the present invention. Detailed Embodiments

[0026] The method for comprehensively evaluating the electrical life of a circuit breaker will be described in detail below in conjunction with the drawings and specific embodiments.

[0027] The method for comprehensively evaluating the electrical life of a circuit breaker is specifically carried out according to the following steps:

[0028] Step 1: Establish a magnetohydrodynamic simulation model according to the designed arc extinguishing chamber structure of the circuit breaker;

[0029] Step 2: Obtain the spatio-temporal evolution characteristics of the arc, arc current, arc voltage, and let-through energy under different voltages and different current magnitudes through simulation calculations, and establish a database of the simulation results of the circuit breaker;

[0030] Step 3: Calculate the electrical life of the new circuit breaker product: Based on the database, combined with the contact quality and let-through energy fitting function obtained from the magnetohydrodynamic simulation model, calculate the electrical life times of the new circuit breaker products under different models;

[0031] Calculate the remaining electrical life of the circuit breaker in on-line operation: By comparing the actual arc voltage and arc current curves during the opening process of the circuit breaker collected on-line with the arc voltage and arc current curves in the database, obtain the data with the highest degree of coincidence with the actual curves. According to the data, combined with the contact quality and let-through energy fitting function, calculate the remaining electrical life times of this circuit breaker.

[0032] Regarding the calculation of the electrical life of the new circuit breaker product:

[0033] The flow block diagram is as Figure 1 shown. The present invention provides a method for comprehensively evaluating the electrical life of a circuit breaker. First, according to the arc extinguishing chamber structure of the new circuit breaker product, establish a magnetohydrodynamic simulation model. Through simulation calculations, obtain the spatio-temporal evolution characteristics of the arc, arc current, arc voltage, let-through energy, etc. under different voltages (rated operating voltage of the circuit breaker, 250V, 400V, 690V, 1140V) and different current magnitudes (the current is mainly in the range from the rated current to fifteen times the rated current, and the interval value of the calculated current is the value of the rated current), and establish a database of the simulation results of the circuit breaker of the same model. And according to this calculation result, combined with the contact quality and let-through energy fitting function (obtained from the magnetohydrodynamic simulation model), calculate the electrical life times of this circuit breaker.

[0034] Regarding the calculation of the remaining electrical life of the circuit breaker in on-line operation;

[0035] The flow block diagram is as Figure 2As shown, first, according to the arc extinguishing chamber structure of this circuit breaker product, a magnetohydrodynamic simulation model is established. Through simulation calculations, the spatio-temporal evolution characteristics of the arc, arc current, arc voltage, and let-through energy, etc., are obtained under different voltages (rated operating voltage of the circuit breaker) and different current magnitudes (the current mainly ranges from the rated current to 15 times the rated current, and the calculation current interval is equal to the rated current), and a database of simulation results of circuit breakers of the same model is established. By comparing the actual arc voltage and arc current curves during the opening process of the circuit breaker collected online with the arc voltage and arc current curves in the above-mentioned database obtained through simulation calculations, the data with the highest degree of coincidence with the actual curve (as an example, the maximum error < 10%) is obtained. Based on this data, combined with the contact quality and let-through energy fitting function (obtained through the magnetohydrodynamic simulation model), the electrical life times of this circuit breaker are calculated, which is the remaining electrical life times.

[0036] The method for comprehensively evaluating the electrical life of a circuit breaker according to the present invention will be further described in detail below through specific embodiments.

[0037] Embodiment

[0038] For a certain DC molded case circuit breaker product, the method for comprehensively evaluating the electrical life of a circuit breaker according to the present invention establishes an arc magnetohydrodynamic simulation model of this circuit breaker and calculates to obtain the arc temperature distribution as Figure 3 shown, and the arc voltage and arc current curves are respectively as Figure 4 and Figure 5 shown. According to these arc voltage and arc current curves, combined with the contact ablation calculation model, the electrical life of this circuit breaker is obtained as 2000 times, and according to the experimental results, it is 2006 times. The results are basically consistent, which also verifies the correctness and effectiveness of the method for comprehensively evaluating the electrical life of a circuit breaker according to the present invention.

[0039] The method for comprehensively evaluating the electrical life of a circuit breaker according to the present invention not only theoretically evaluates the electrical life parameters of new circuit breaker products, but also can evaluate the remaining electrical life times according to the real-time state of the circuit breaker, saving costs while improving the accuracy of electrical life evaluation. This method can be applied to low-voltage circuit breakers and can also be applied to high-voltage gas circuit breakers.

Claims

1. A method for comprehensively evaluating the electrical life of a circuit breaker, characterized in that, The specific steps are as follows: Step 1: Establish a magnetohydrodynamic simulation model according to the designed arc extinguishing chamber structure of the circuit breaker; Step 2: Obtain the spatio-temporal evolution characteristics of the arc, arc current, arc voltage, and let-through energy under different voltages and different current magnitudes through simulation calculations, and establish a database of circuit breaker simulation results; Step 3: Calculate the electrical life of the new circuit breaker product: Based on the database, combined with the contact quality and let-through energy fitting function obtained from the magnetohydrodynamic simulation model, calculate the electrical life times of the new circuit breaker products under different models; Calculate the remaining electrical life of the circuit breaker in on-line operation: By comparing the actual arc voltage and arc current curves during the opening process of the circuit breaker collected on-line with the arc voltage and arc current curves in the database, obtain the data with the highest degree of coincidence with the actual curve, and based on the data, combined with the contact quality and let-through energy fitting function, calculate the remaining electrical life times of this circuit breaker.

2. The method for comprehensively evaluating the electrical life of a circuit breaker according to claim 1, characterized in that In Step 3, when the magnetohydrodynamic simulation model evaluates the electrical life of circuit breakers of different models, only according to the arc extinguishing gas and the arc extinguishing chamber structure, replace the corresponding gas plasma physical property parameters and the arc extinguishing chamber structure; for low-voltage air circuit breakers, select air plasma physical property parameters; for high-voltage SF6 circuit breakers, select SF6 plasma physical property parameters; at the same time, just replace different arc extinguishing chamber structures and the boundary conditions corresponding one by one to the arc extinguishing chamber structure, and there is no need to rewrite the program.

3. The method for comprehensively evaluating the electrical life of a circuit breaker according to claim 1, characterized in that, In Step 1, the established magnetohydrodynamic model not only calculates the dynamic magnetic field generated by the arc itself, but also considers the nonlinear B-H curve and eddy current effect in ferromagnetic materials.

4. The method for comprehensively evaluating the electrical life of a circuit breaker according to claim 1, characterized in that, In Step 1, the established magnetohydrodynamic model considers the influence of gas-producing materials.

5. The method for comprehensively evaluating the electrical life of a circuit breaker according to claim 1, characterized in that In Step 2, different voltages are the rated operating voltages of different circuit breakers, and different currents are in the range from the rated current of the circuit breaker to fifteen times the rated current. Among them, the interval value of the simulation calculation current is the rated current.

6. The method for comprehensively evaluating the electrical life of a circuit breaker according to claim 1, characterized in that In Step 3, when calculating the remaining electrical life of the circuit breaker in on-line operation, the maximum error of the degree of coincidence between the data and the actual curve is <10%.

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