Method and apparatus for diagnosing mechanical drive of circuit breaker

Abstract

The present disclosure relates to a method for diagnosing a mechanical drive of a circuit breaker, an apparatus for diagnosing a mechanical drive of a circuit breaker, a circuit breaker and a computer-readable storage medium. The method for diagnosing a mechanical drive of a circuit breaker comprises: obtaining an operation voltage and a current curve under the operation voltage; obtaining at least one electrical parameter associated with a current magnitude; and converting the current curve under the operation voltage to a current curve under the normal voltage based on the operation voltage and the at least one electrical parameter.

Description

METHOD AND APPARATUS FOR DIAGNOSINGMECHANICAL DRIVE OF CIRCUIT BREAKERTECHNICAL FIELD

[0001] The present disclosure relates to the technical field of diagnosing a mechanical drive of a circuit breaker, and more specifically, relates to a method for diagnosing a mechanical drive of a circuit breaker, an apparatus for diagnosing a mechanical drive of a circuit breaker, a circuit breaker and a computer-readable storage medium.BACKGROUND

[0002] The status of mechanical drives of high-voltage circuit breakers can be obtained by detecting a variety of electrical and mechanical parameters. The coil current is an important feature that reflects the electromagnetic characteristics and mechanical properties of the mechanical drive of circuit breaker.

[0003] In a report, a set of time and current parameters of different stages are extracted from coil current curve. These parameters are considered as important references for operation status of the circuit breaker. The method of extracting feature parameters is widely used in other coil current analysis and studies. However, in the actual current curve, it may be difficult to obtain some parameters. For example, sometimes the time points of first peak and first valley in current curve is very clear and easy to locate, while these points are hardly to be observed in other cases. Difficulties in parameter extraction make the traditional coil current analysis methods inapplicable.

[0004] Further, if possible magnetic saturation occurs in practice, the coil current curve calculated using the linear model of inductance may be very different from the actual curve. The linear model of inductance cannot be used in coil current analysis when saturation effect occurs.

[0005] Furthermore, the actual operating voltage of the circuit breaker is not constant and fluctuated, which can directly affect coil current and result in deviation between the measured trend and that measured at normal voltages. In order to simply the evaluation of status of mechanical drive, coil current trend should be normalized to that at normal voltage. Unfortunately, there is no compensation method can handle this task.SUMMARY

[0006] In view of the above, the present disclosure aims to propose a method for diagnosing a mechanical drive of a circuit breaker which converts the current curve under the operation voltage to a current curve under the normal voltage.

[0007] To this end, a first aspect of the present disclosure provides a method for diagnosing a mechanical drive of a circuit breaker, comprising: obtaining an operation voltage and a current curve under the operation voltage; obtaining at least one electrical parameter associated with a current magnitude; and converting the current curve under the operation voltage to a current curve under the normal voltage based on the operation voltage and the at least one electrical parameter.

[0008] According to a preferred embodiment of the present disclosure, converting the current curve under the operation voltage to a current curve under the normal voltage based on the operation voltage and the at least one electrical parameter further includes at least one of: dividing the current curve under the operation voltage into four stages including a first stage, a second stage, a third stage and a fourth stage; for the first stage, performing exponential fit to obtain a first current curve under a normal voltage based on the current curve in the first stage under the operation voltage; for the second stage, performing a second order polynomial fit to obtain a second current curve under the normal voltage based on the current curve in the second stage under the operation voltage; for the third stage, calculating LI-I curve to obtain a third current curve under the normal voltage based on the current curve in the third stage under the operation voltage; and for the fourth stage, obtaining a fourth current curve under the normal voltage by putting a horizontal line.

[0009] According to a preferred embodiment of the present disclosure, performing exponential fit to obtain a first current curve under the normal voltage based on the current curve in the first stage under the operation voltage further includes: using the current curve in the first stage under the operation voltage to performexponential fit to obtain a value of k; and using the value of k to obtain the first current curve under the normal voltage.

[0010] According to a preferred embodiment of the present disclosure, performing a second order polynomial fit to obtain a second current curve under the normal voltage based on the current curve in the second stage under the operation voltage further includes: using the current curve in the second stage under the operation voltage to perform second order polynomial fit to obtain the translating value of tn; and using the translating value of tn to obtain the second current curve under the normal voltage.

[0011] According to a preferred embodiment of the present disclosure, calculating LI-I curve to obtain a third current curve under the normal voltage based on the current curve in the third stage under the operation voltage further includes: calculating an inductive curve L curve under the operation voltage based on the current curve in the third stage under the operation voltage; calculating LI-I curve under the operation voltage based on the current curve in the third stage under the operation voltage and the L curve; and obtain a third current curve under the normal voltage based on the normal voltage and the LI-I curve under the operation voltage.

[0012] According to a preferred embodiment of the present disclosure, the method further comprises: combining the first current curve under the normal voltage, the second current curve under the normal voltage, the third current curve under the normal voltage, and the fourth current curve under the normal voltage to obtain a compensated current curve under the normal voltage for diagnosing the mechanical drive of the circuit breaker.

[0013] According to a preferred embodiment of the present disclosure, the at least one electrical parameter associated with a current magnitude includes at least one of: coil current magnitude under normal voltage; coil current magnitude under the operation voltage; or resistance of the circuit.

[0014] According to a preferred embodiment of the present disclosure, the operation voltage is not equal to the normal voltage.

[0015] A second aspect of the present disclosure provides an apparatus for diagnosing a mechanical drive of a circuit breaker, the apparatus comprising: a processor; and a memory used to store instructions, and when the instructions are executed, the processor performs the following operations: obtaining an operation voltage and a current curve under the operation voltage; obtaining at least one electrical parameter associated with a current magnitude; and converting the current curve under the operation voltage to a current curve under the normal voltage based on the operation voltage and the at least one electrical parameter.

[0016] According to a preferred embodiment of the present disclosure, converting the current curve under the operation voltage to a current curve under the normal voltage based on the operation voltage and the at least one electrical parameter further includes at least one of: dividing the current curve under the operation voltage into four stages including a first stage, a second stage, a third stage and a fourth stage; for the first stage, performing exponential fit to obtain a first current curve under a normal voltage based on the current curve in the first stage under the operation voltage; for the second stage, performing a second order polynomial fit to obtain a second current curve under the normal voltage based on the current curve in the second stage under the operation voltage; for the third stage, calculating LI-I curve to obtain a third current curve under the normal voltage based on the current curve in the third stage under the operation voltage; and for the fourth stage, obtaining a fourth current curve under the normal voltage by putting a horizontal line.

[0017] According to a preferred embodiment of the present disclosure, when the instructions are executed, the processor further performs the steps according to the first aspect of the present disclosure.

[0018] A third aspect of the present disclosure provides a circuit breaker, wherein the circuitbreaker comprises the apparatus according to the second aspect of the present disclosure.

[0019] A fourth aspect of the present disclosure provides a computer-readable storage medium having computer-readable program instructions stored thereon, the computer-readable program instructions are used to execute the method for diagnosing a mechanical drive of a circuit breaker according to the first aspect of the present disclosure.

[0020] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a / an / the element, component, device, plant, system, step, etc.” are to be interpreted openly as referring to at least one instance of the element, component, device, plant, system, step, etc., unless explicitly stated otherwise.BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other features and advantages of the present disclosure will be better understood through the following preferred embodiment described in detail with reference to the accompanying drawings, in which a same reference sign indicates a same or similar component.

[0022] Fig. 1 shows a flowchart of a method 100 for diagnosing a mechanical drive of a circuit breaker according to the present disclosure;

[0023] Fig. 2 shows a schematic diagram of an apparatus 200 for diagnosing a mechanical drive of a circuit breaker according to one embodiment of the present disclosure; and

[0024] Fig. 3 shows a schematic diagram of an apparatus 300 for diagnosing a mechanical drive of a circuit breaker according to another embodiment of the present disclosure; and

[0025] Fig. 4 shows current curves before and after using the method for diagnosing a mechanical drive of a circuit breaker according to the present disclosure.

[0026] It should be noted that the drawings not only are used for the explanation and description of the present disclosure, but also are helpful for the definition of the present disclosure when necessary.DETAILED DESCRIPTION

[0027] Various exemplary embodiments of the present disclosure are described in detailbelow with reference to the accompanying drawings. Although the example methods and apparatuses described below include software and / or firmware executed on hardware in other components, it should be noted that these examples are only illustrative and should not be regarded as limited. For example, it can be considered that any or all hardware, software, and firmware components can be implemented exclusively in hardware, exclusively in software, or in any combination of hardware and software. Therefore, although example methods and apparatuses have been described below, those skilled in the art should easily appreciate that the provided examples are not used to limit the ways for implementing these methods and devices.

[0028] In addition, the flowcharts and block diagrams in the accompanying drawings illustrate the possible implemented architecture, functions, and operations of the method and system according to various embodiments of the present disclosure. It should be noted that the functions noted in the blocks may also occur in a different order than the order noted in the drawings. For example, two blocks shown in succession may be executed substantially in parallel, or they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the flowchart and / or block diagrams, and the combination of the blocks in the flowchart and / or block diagrams can be implemented using a dedicated hardware-based system that performs the specified functions or operations, or can be implemented using a combination of dedicated hardware and computer instructions.

[0029] The terms “including”, “comprising” and similar terms used in this disclosure are open-ended terms, i.e., “including / containing, but not limited to” indicating that other elements may also be included. The term “based on” is open-ended. The term “based on” is “based at least in part on”. The term “one embodiment” means “at least one embodiment”; the term “another embodiment” means “at least one additional embodiment” and so on.

[0030] Generally speaking, an electromechanical system model is proposed to describe the electromagnetic effect of mechanical drive. The coil current curve can be divided into several stages. In each stage, based on the motion state of the plunger, a complete circuit breaker mechanical drive workflow can be divided into the following four stages:

[0031] Stage 1 ( t0~t1): The coil is energized, the current is small, the generated electromagnetic force is not sufficient to move the plunger. The coil inductance is a constant.

[0032] Stage 2 (t1~t2): The electromagnetic force makes the plunger move. The coil inductance increases, and the current reaches the first peak and then decreases, until theplunger hits the trigger and stops moving, while current reach the valley.

[0033] Stage 3 (t2~t3): The plunger does not move, and the circuit breaker begins to operate. The current increases again.

[0034] Stage 4 (t3~): The coil current is in approximately steady state. The voltage and loop resistance decide the current magnitude.

[0035] According to the equivalent circuit of operating mechanism and the plunger movement process of the circuit breaker, the equivalent circuit of operating mechanism can be described by the electric equation of this model as follows:

[0037] During the plunger movement, the inductance of the switching mechanism can be calculated using the following equation:

[0038] L(x) = Lo+ “x(2)

[0039] wherein Lois the initial inductance value, A L divided by lcrepresents the change rate of inductance by displacement, and x is the displacement of plunger relative to its initial position.

[0040] This equation indicates that the inductance varies linearly with displacement. According to equation (1) above, the current can be described as:

[0042] In equation (3), if inductance increases linearly during the process, R / L decreases and the current rises slower.

[0043] In some measured curves, the shapes of these curves are similar. The current curve in stage 3 increases slower than in stage 1, which is in a good agreement with the linear inductance assumption above.

[0044] However, this analysis method may not work in other cases, especially for the coil current curve of Blk&Blg circuit breaker. The current curve in stage 3 obviously increases faster than in stage 1, which indicates smaller inductance values in stage 3 and is against linear model of inductance.

[0045] On the other hand, the inductance can be described as the following equation:

[0047] wherein is permeability, N is number of turns, S is cross-sectional area, and le is magnetic circuit length.

[0048] In stage 3, the plunger movement causes a part of the original magnetic circuit to change from air to ferromagnetic material, and the total permeability of the magnetic circuit increases, so inductance increases too. This matches the result when using linear model of inductance.

[0049] In the present case, N, S and le are constants, so the decrease in inductance indicates the decrease in total permeability of magnetic circuit. It is highly likely that this is due to the magnetization curve of the ferromagnetic material entering the saturation region and its permeability decreases.

[0050] In the researching experiment of the inventor, it is found that during the working process of the mechanical drive, its magnetization curve will eventually enter the saturation region. This phenomenon is particularly obvious in Blk&Blg and HMB case. In other coil current analysis methods, the saturation effect of the magnetization curve was rarely mentioned.

[0051] Thus, the inventor of the present disclosure proposes a novel analysis method of coil current mainly based on inductance curve and magnetization curve (also known as B-H curve) of mechanical drive. Based on this method, the magnetic saturation effect can be clearly observed. The magnetization curves of the coil current at different voltages almost overlap in stage 1 and 3, so that the saturated magnetization curve is hardly affected by voltage change. Thus, the extracted B-H curve can be used in condition monitoring of mechanical drive in future. Besides, the coil current curves of the same circuit breaker under different voltages can be converted to the curve that under standard voltage using this B-H trend.

[0052] In general, the present disclosure provides a method for diagnosing a mechanical drive of a circuit breaker. Fig. 1 shows a flowchart of a method 100 for diagnosing a mechanical drive of a circuit breaker according to the present disclosure. As can be seen from Figure 1, the method 100 for diagnosing a mechanical drive of a circuit breaker according to the present disclosure includes at least three steps, namely:

[0053] First, in step 110, an operation voltage and a current curve under the operation voltage are obtained. Then, in step 120, at least one electrical parameter associated with a current magnitude is obtained. In step 130, the current curve under the operation voltage is convertedto a current curve under the normal voltage based on the operation voltage and the at least one electrical parameter. That is to say, before performing the method according to the present disclosure, requirements before the compensation starts are: coil current curve under non-normal voltage, value of operation voltage, and coil current magnitude under normal voltage / coil current magnitude under non-normal voltage / resistance of the loop (steady state).

[0054] In particular, the last method step 130 will be conducted step by step, namely converting the current curve under the operation voltage to a current curve under the normal voltage based on the operation voltage and the at least one electrical parameter further includes at least one of: dividing the current curve under the operation voltage into four stages including a first stage, a second stage, a third stage and a fourth stage; for the first stage, performing exponential fit to obtain a first current curve under a normal voltage based on the current curve in the first stage under the operation voltage; for the second stage, performing a second order polynomial fit to obtain a second current curve under the normal voltage based on the current curve in the second stage under the operation voltage; for the third stage, calculating LI-I curve to obtain a third current curve under the normal voltage based on the current curve in the third stage under the operation voltage; and for the fourth stage, obtaining a fourth current curve under the normal voltage by putting a horizontal line.

[0055] In particular, for the first stage, exponential fit for operation current is done:

[0056] 1 = ^ (1 — e-kt) (5)

[0057] From this exponential fit extract k which is the same value as stage 1 under normal voltage. So, we can use k to simulate stage 1 of current under normal voltage (t0~t1):

[0058] isl= lm(l - e“kt) (6)

[0059] In general, according to a preferred embodiment of the present disclosure, performing exponential fit to obtain a first current curve under the normal voltage based on the current curve in the first stage under the operation voltage further includes: using the current curve in the first stage under the operation voltage to perform exponential fit to obtain a value of k; and using the value of k to obtain the first current curve under the normal voltage.

[0060] Further, in stage 2, B-H trend is affected by both the movement of the plunger and the magnetic saturation. Based on the research of the inventor, the trend of inductance under test voltage in stage 2 can be fitted using 2nd order polynomial fit, namely:

[0061] L(t)(testV) = a(t — b)2+ C (7)

[0062] Translating the test inductance curve by tncan obtain the inductance curve under other voltages (only stage 2 part).

[0063] L(t) = a(t - b + tn)2+ C (8)

[0064] The coil current under other voltage can be calculated as

[0066] Extract feature parameters from current curve under test voltage. Use linear regression to map feature parameters to normal voltage. Do 2nd polynomial fit based on the data.

[0067] Solve equation (9) we can get an expression of current, then combine two expressions to compensate the current in stage 2.

[0068] In general, according to a preferred embodiment of the present disclosure, performing a second order polynomial fit to obtain a second current curve under the normal voltage based on the current curve in the second stage under the operation voltage further includes: using the current curve in the second stage under the operation voltage to perform second order polynomial fit to obtain the translating value of tn; and using the translating value of tn to obtain the second current curve under the normal voltage.

[0069] As widely known that non-linearity between magnetic flux density and magnetic field can be described using one B-H curve.

[0070] According to Ampere circuital theorem:

[0071] $ H dl = 1 (10)

[0072] In annular homogeneous medium:

[0074] As 2TTF and N are constants, magnetic field is linearly depending on current.

[0075] According to the physical definition of magnetic flux density:

[0076] B = 4> / S (12)

[0077] Also, for magnetic flux we have:

[0078] Nd> = LI (13)

[0079] As S and N are constants, magnetic flux density is linearly depending on the product of current and inductance. Now there is a conclusion that magnetic flux and magnetic field arelinearly depending on LI and 1, respectively:

[0080] B~L1 H~1 (14)

[0081] Thus, curve of Ll-I should share the same shape as B-H curve, and trend of Ll-I can be referred as B-H trend for short. Thus, B-H trend under different voltages needs to be overlapped in stage 1, which suggest linearity region for low current situation.

[0082] Thus, according to a preferred embodiment of the present disclosure, calculating LI-I curve to obtain a third current curve under the normal voltage based on the current curve in the third stage under the operation voltage further includes: calculating an inductive curve L curve under the operation voltage based on the current curve in the third stage under the operation voltage; calculating LI-I curve under the operation voltage based on the current curve in the third stage under the operation voltage and the L curve; and obtain a third current curve under the normal voltage based on the normal voltage and the LI-I curve under the operation voltage.

[0083] In stage 3, for Blk&Blg and HMB case, the B-H trend under different voltages is overlapped again. It means that changes in voltage does not have much impact on the magnetization curve (B-H curve) of the circuit breaker.

[0084] Then, polynomial fit can be used to estimate the B-H curve when it enters saturation region, which means coil current has entered stage 3.

[0085] LI = kl + b (15)

[0086] For FSA case, the slope of B-H curve in stage 3 is larger than stage 1, which indicates it has not entered saturation region. The linear model of inductance is still applicable for this case but is not capable of analyzing the other two cases.

[0087] Based on the coil current curve, the inductance L can be reversely calculated using the expression of equivalent circuit:

[0089] According to the above mentioned equations, the inductance at the very beginning should be very close. When the process enters stage 2, significant increase of inductance can be observed. The peak of inductance corresponds to the bottom of valley between stage 2 and stage 3. Thus, in stage 3, Ll-I curve under test voltage is calculated. According to the above listed equation (15), solve the equation and get expression of current in stage 3. Compensatethe coil current until it reaches the max value (steady state in stage 4). In stage 4, current reaches a steady state. Put a horizontal line and combine it to current curve before, we can get whole compensated coil current curve.

[0090] According to a preferred embodiment of the present disclosure, the method further comprises: combining the first current curve under the normal voltage, the second current curve under the normal voltage, the third current curve under the normal voltage, and the fourth current curve under the normal voltage to obtain a compensated current curve under the normal voltage for diagnosing the mechanical drive of the circuit breaker.

[0091] According to a preferred embodiment of the present disclosure, the at least one electrical parameter associated with a current magnitude includes at least one of: coil current magnitude under normal voltage; coil current magnitude under the operation voltage; or resistance of the circuit.

[0092] According to a preferred embodiment of the present disclosure, the operation voltage is not equal to the normal voltage.

[0093] The above mentioned method can also be implemented as an apparatus. Fig. 2 shows a schematic diagram of an apparatus 200 for diagnosing a mechanical drive of a circuit breaker according to one embodiment of the present disclosure. As can be seen from Figure 2, the apparatus 200 for diagnosing a mechanical drive of a circuit breaker includes a processor 210 and a memory 220, wherein the memory is used to store instructions, and when the instructions are executed, the processor performs the following operations: obtaining an operation voltage and a current curve under the operation voltage; obtaining at least one electrical parameter associated with a current magnitude; and converting the current curve under the operation voltage to a current curve under the normal voltage based on the operation voltage and the at least one electrical parameter.

[0094] According to a preferred embodiment of the present disclosure, converting the current curve under the operation voltage to a current curve under the normal voltage based on the operation voltage and the at least one electrical parameter further includes at least one of: dividing the current curve under the operation voltage into four stages including a first stage, a second stage, a third stage and a fourth stage; for the first stage, performing exponential fit to obtain a first current curve under a normalvoltage based on the current curve in the first stage under the operation voltage; for the second stage, performing a second order polynomial fit to obtain a second current curve under the normal voltage based on the current curve in the second stage under the operation voltage; for the third stage, calculating LI-I curve to obtain a third current curve under the normal voltage based on the current curve in the third stage under the operation voltage; and for the fourth stage, obtaining a fourth current curve under the normal voltage by putting a horizontal line.

[0095] According to a preferred embodiment of the present disclosure, when the instructions are executed, the processor further performs the steps according to the first aspect of the present disclosure.

[0096] A third aspect of the present disclosure provides a circuit breaker, wherein the circuit breaker comprises the apparatus according to the second aspect of the present disclosure.

[0097] A fourth aspect of the present disclosure provides a computer-readable storage medium having computer-readable program instructions stored thereon, the computer-readable program instructions are used to execute the method for diagnosing a mechanical drive of a circuit breaker according to the first aspect of the present disclosure.

[0098] This analysis method of the present application is mainly targeted to Blk&Blg, HMB and FSAtype of drives for circuit breakers.

[0099] Applying these methods to diagnostic analysis of circuit breaker, the coil current under different operating voltage can be compensated to coil current under normal voltage. The four stages of coil current can be compensated separately. Then, combine four curves together to get the result.

[0100] In the present application, mapping between coil current and magnetization curve is novel. In other coil current analysis methods, the saturation effect of the magnetization curve was rarely mentioned, while we analyze the experimental data and notice that during the operation of the mechanical drive, its magnetization curve will enter the saturation zone. The magnetization curve in the saturation region is rarely affected by voltage fluctuations and follows linear change. This analysis method provides more possibilities for coil current diagnosis methods and expands the analysis ideas of coil current in circuit breakers.

[0101] Because the magnetization curves at different voltages almost overlap, this analysis method can resist the difficulties caused by voltage fluctuation to some extent. Further, only by calculating the current and inductance data, the LI -I curve can be mapped to the magnetization curve, and thus the complexity of analysis method has been reduced and the efficiency of analysis has been improved. Moreover, this method has been proved to be applicable to three different circuit breaker products. This shows that the method has a certain versatility and is likely to be extended to other different circuit breaker products.

[0102] The present disclosure also provides a computer program product that is tangibly stored on a computer readable storage medium and includes computer executable instructions that, when executed, cause the at least one processor to perform a method for diagnosing a mechanical drive of a circuit breaker according to at least one embodiment of the present disclosure.

[0103] Generally speaking, the various example embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, firmware, logic, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device. When various aspects of the embodiments of the present disclosure are illustrated or described as block diagrams, flowcharts, or using some other graphical representation, it will be appreciated that the blocks, apparatuses, systems, techniques, or methods described herein can be regarded as non-limited examples are implemented in hardware, software, firmware, dedicated circuits or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof.

[0104] Fig. 3 shows a schematic diagram of an apparatus 300 for diagnosing a mechanical drive of a circuit breaker according to yet another embodiment of the present disclosure. It should be appreciated that the apparatus 300 may be implemented to implement the functions of the method 100 in Fig. 1. It can be seen from Fig. 3 that the apparatus 300 includes a processing unit like a central processing unit (CPU) 301 (for example, a processor), which can perform various appropriate actions and processes according to the computer program instructions stored in an integrated circuit like a memory device (such as a read-only memory (ROM, PROM, EPROM) 302 or the computer program instructions loaded from the storage unit 308 to a random access memory (RAM) 303 or a flash memory or other types of memory devices). In the RAM 303, various programs and data required for the operation of theapparatus 300 can also be stored. The CPU 301, the ROM 302, and the RAM 303 are connected to each other via a bus 304. An input / output (I / O) interface 305 is also connected to the bus 304.

[0105] A number of components in the apparatus 300 are connected to the I / O interface 305, including: an input unit 306, such as a keyboard, a mouse, etc.; an output unit 307, such as various types of displays, speakers, etc.; and a storage unit 308, such as a disk, an optical disk, etc.; and a communication unit 309, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 309 allows the apparatus 300 to exchange information / data with other apparatuses through a computer network such as the Internet and / or various telecommunication networks.

[0106] The various methods described above, for example, the method 100 can be executed by the processing unit 301. For example, in some embodiments, the method 100 may be implemented as a computer software program, which is tangibly included in a machine-readable medium, such as the storage unit 308. In some embodiments, part or all of the computer program may be loaded and / or installed on the apparatus 300 via the ROM 302 and / or the communication unit 309. When the computer program is loaded into the RAM 303 and executed by the CPU 301, one or more actions or steps of the method 100 described above can be executed, i.e.:

[0107] obtaining an operation voltage and a current curve under the operation voltage;

[0108] obtaining at least one electrical parameter associated with a current magnitude; and

[0109] converting the current curve under the operation voltage to a current curve under the normal voltage based on the operation voltage and the at least one electrical parameter.

[0110] In one embodiment according to the present disclosure, when the computer program is loaded into the RAM 303 and executed by the CPU 301, the CPU 301 is caused to perform:

[0111] dividing the current curve under the operation voltage into four stages including a first stage, a second stage, a third stage and a fourth stage;

[0112] for the first stage, performing exponential fit to obtain a first current curve under a normal voltage based on the current curve in the first stage under the operation voltage;

[0113] for the second stage, performing a second order polynomial fit to obtain a second current curve under the normal voltage based on the current curve in the second stage underthe operation voltage;

[0114] for the third stage, calculating LI-I curve to obtain a third current curve under the normal voltage based on the current curve in the third stage under the operation voltage; and

[0115] for the fourth stage, obtaining a fourth current curve under the normal voltage by putting a horizontal line.

[0116] In one embodiment according to the present disclosure, when the computer program is loaded into the RAM 303 and executed by the CPU 301, the CPU 301 is caused to perform: using the current curve in the first stage under the operation voltage to perform exponential fit to obtain a value of k; and using the value of k to obtain the first current curve under the normal voltage.

[0117] In one embodiment according to the present disclosure, performing a second order polynomial fit to obtain a second current curve under the normal voltage based on the current curve in the second stage under the operation voltage further includes: using the current curve in the second stage under the operation voltage to perform second order polynomial fit to obtain the translating value of tn; and using the translating value of tn to obtain the second current curve under the normal voltage.

[0118] In one embodiment according to the present disclosure, calculating LI-I curve to obtain a third current curve under the normal voltage based on the current curve in the third stage under the operation voltage further includes: calculating an inductive curve L curve under the operation voltage based on the current curve in the third stage under the operation voltage; calculating LI-I curve under the operation voltage based on the current curve in the third stage under the operation voltage and the L curve; and obtain a third current curve under the normal voltage based on the normal voltage and the LI-I curve under the operation voltage.

[0119] In one embodiment according to the present disclosure, the CPU 301 is caused to combine the first current curve under the normal voltage, the second current curve under the normal voltage, the third current curve under the normal voltage, and the fourth current curveunder the normal voltage to obtain a compensated current curve under the normal voltage for diagnosing the mechanical drive of the circuit breaker.

[0120] In one embodiment according to the present disclosure, the at least one electrical parameter associated with a current magnitude includes at least one of: coil current magnitude under normal voltage; coil current magnitude under the operation voltage; or resistance of the circuit.

[0121] In one embodiment according to the present disclosure, the operation voltage is not equal to the normal voltage.

[0122] In order to show the technical effect of the present disclosure, Fig. 4 shows current curves before and after using the method for diagnosing a mechanical drive of a circuit breaker according to the present disclosure. As shown in Fig. 4, the current curve 401 under the operation voltage is measured by a current sensor or detector. Further, the standard current curve 402 under normal voltage is also shown. After obtaining the measured current curve 401, each stage (namely stage 1, stage 2, stage 3 and stage 4) is compensated or calibrated and then combined to form the compensated current curve 403 under the normal voltage as the compensated result. As illustrated in Fig. 4, the compensated current curve 403 is almost overlapped with the standard current curve 402. That is to say, the method for diagnosing a mechanical drive of a circuit breaker according to the present disclosure can improve the diagnosing accuracy.

[0123] Although it is described above that the various example embodiments of the present disclosure can be implemented in hardware or a dedicated circuit, the above-mentioned device can be implemented in the form of hardware or software, which can be achieved in the form of software, because: in the 1990s, a technological improvement can easily belong to the improvement of the hardware (for example, the improvement of the circuit structure of diodes, transistors, switches, etc.) or the improvement of software ( for example, the improvement of method flow). However, with the continuous development of technology, the improvement of many method processes nowadays can almost be implemented by programming the improved method process into the hardware circuit, in other words, the corresponding hardware circuit structure can be obtained by programming different programs of the hardware circuit, the change of the hardware circuit structure is implemented, that is, the improvement of such amethod flow can also be regarded as a direct improvement of the hardware circuit structure. Therefore, it cannot be considered that the improvement of a method flow cannot be implemented by hardware entity modules. For example, a programmable logic device (PLD) (such as a Field Programmable Gate Array (FPGA)) is an integrated circuit whose logic function is determined by the user's programming of the device. It is programmed by the designer to "integrate" a digital system on a programmable logic device without requiring the chip manufacturer to design and manufacture a dedicated integrated circuit chip. Moreover, instead of manually making integrated circuit chips, this kind of programming is mostly implemented using "logic compiler" software, which is similar to the software compiler used in program development and writing, but the original code must also be written in a specific programming language before compiling, which is called Hardware Description Language (HDL), and HDL is not only one language, but there are many languages, such as ABEL (Advanced Boolean Expression Language), AHDL (Altera Hardware Description Language), Confluence, CUPL (Cornell University Programming Language), HDCal, JHDL (Java Hardware Description Language), Lava, Lola, MyHDL, PALASM, RHDL (Ruby Hardware Description Language), etc., currently the most commonly used is VHDL (Very-High-Speed Integrated Circuit Hardware Description Language) and Verilog. It should also be clear to those skilled in the art that the method flow needs to be logic programmed using the above-mentioned hardware description languages into an integrated circuit, which can easily obtain the hardware circuit that implements the logic method flow.

[0124] The computer readable program instructions or computer program products used to execute various aspects of the disclosure of the present disclosure can also be stored in the cloud. When needed, the user can access the computer-readable program instructions used to execute one aspect of the disclosure of the present disclosure through the mobile Internet, the fixed network or other networks, so as to implement the technical solutions disclosed in each aspect of the disclosure of the present disclosure.

[0125] The foregoing descriptions are only alternative embodiments of the disclosure of the present disclosure, and are not used to limit the embodiments of the present disclosure, for those skilled in the art, the embodiments of the present disclosure may have various modifications and changes. Any modification, equivalent replacement, improvement, etc., made within the spirit and principle of the embodiment of the present disclosure should be included in the protection scope of the embodiment of the present disclosure.

[0126] Although the embodiments of the present disclosure have been described with reference to several specific embodiments, it should be understood that the embodiments of the present disclosure are not limited to the disclosed specific embodiments. The embodiments of the present disclosure are intended to cover various modifications and equivalent arrangements within the spirit and scope of the appended claims. The scope of the claims accords with the broadest interpretation, so as to include all such modifications and equivalent structures and functions.

Claims

CLAIMS1. A method for diagnosing a mechanical drive of a circuit breaker, comprising: obtaining an operation voltage and a current curve under the operation voltage; obtaining at least one electrical parameter associated with a current magnitude; and converting the current curve under the operation voltage to a current curve under the normal voltage based on the operation voltage and the at least one electrical parameter.

2. The method according to claim 1, wherein converting the current curve under the operation voltage to a current curve under the normal voltage based on the operation voltage and the at least one electrical parameter further includes at least one of: dividing the current curve under the operation voltage into four stages including a first stage, a second stage, a third stage and a fourth stage; for the first stage, performing exponential fit to obtain a first current curve under a normal voltage based on the current curve in the first stage under the operation voltage; for the second stage, performing a second order polynomial fit to obtain a second current curve under the normal voltage based on the current curve in the second stage under the operation voltage; for the third stage, calculating LI-I curve to obtain a third current curve under the normal voltage based on the current curve in the third stage under the operation voltage; and for the fourth stage, obtaining a fourth current curve under the normal voltage by putting a horizontal line.

3. The method according to claim 2, wherein performing exponential fit to obtain a first current curve under the normal voltage based on the current curve in the first stage under the operation voltage further includes: using the current curve in the first stage under the operation voltage to perform exponential fit to obtain a value of k; and using the value of k to obtain the first current curve under the normal voltage.

4. The method according to claim 2, wherein performing a second order polynomial fit to obtain a second current curve under the normal voltage based on the current curve in the second stage under the operation voltage further includes: using the current curve in the second stage under the operation voltage to perform second order polynomial fit to obtain the translating value of tn; and using the translating value of tn to obtain the second current curve under the normal voltage.

5. The method according to claim 2, wherein calculating LI-I curve to obtain a third current curve under the normal voltage based on the current curve in the third stage under the operation voltage further includes: calculating an inductive curve L curve under the operation voltage based on the current curve in the third stage under the operation voltage; calculating LI-I curve under the operation voltage based on the current curve in the third stage under the operation voltage and the L curve; and obtain a third current curve under the normal voltage based on the normal voltage and the LI-I curve under the operation voltage.

6. The method according to claim 2, wherein the method further comprises: combining the first current curve under the normal voltage, the second current curve under the normal voltage, the third current curve under the normal voltage, and the fourth current curve under the normal voltage to obtain a compensated current curve under the normal voltage for diagnosing the mechanical drive of the circuit breaker.

7. The method according to claim 1, wherein the at least one electrical parameter associated with a current magnitude includes at least one of: coil current magnitude under normal voltage; coil current magnitude under the operation voltage; orresistance of the circuit.

8. The method according to claim 1, wherein the operation voltage is not equal to the normal voltage.

9. An apparatus for diagnosing a mechanical drive of a circuit breaker, the apparatus comprising: a processor; and a memory used to store instructions, and when the instructions are executed, the processor performs the following operations: obtaining an operation voltage and a current curve under the operation voltage; obtaining at least one electrical parameter associated with a current magnitude; and converting the current curve under the operation voltage to a current curve under the normal voltage based on the operation voltage and the at least one electrical parameter.

10. The apparatus according to claim 9, wherein converting the current curve under the operation voltage to a current curve under the normal voltage based on the operation voltage and the at least one electrical parameter further includes at least one of: dividing the current curve under the operation voltage into four stages including a first stage, a second stage, a third stage and a fourth stage; for the first stage, performing exponential fit to obtain a first current curve under a normal voltage based on the current curve in the first stage under the operation voltage; for the second stage, performing a second order polynomial fit to obtain a second current curve under the normal voltage based on the current curve in the second stage under the operation voltage; for the third stage, calculating LI-I curve to obtain a third current curve under the normal voltage based on the current curve in the third stage under the operation voltage; and for the fourth stage, obtaining a fourth current curve under the normal voltage by puttinga horizontal line.

11. The apparatus according to claim 10, when the instructions are executed, the processor further performs the steps according to any one of claims 3 to 8.

12. A circuit breaker, wherein the circuit breaker comprises the apparatus according to any of claims 9 to 11.

13. A computer-readable storage medium having computer-readable program instructions stored thereon, the computer-readable program instructions are used to execute the method for diagnosing a mechanical drive of a circuit breaker according to any one of claims 1 to 8.

Images