Method for evaluating the state of mechanical properties based on current characteristics

Abstract

The application provides a mechanical characteristic state evaluation method based on current characteristics, which comprises the following steps: collecting the opening coil current, closing coil current, energy storage coil current and operating power voltage of a circuit breaker mechanism in real time through a Hall current sensor, and converting them into digital waveform sequences through analog-digital conversion; judging the instantaneous values of the opening coil current, closing coil current and energy storage coil current and the current set values of the starting threshold and the reset threshold in real time, and then extracting key nodes representing the current signal changes according to the digital waveform sequences, so as to further calculate the energy consumed by the mechanism action and judge the operation condition of the circuit breaker.

Description

Technical Field

[0001] This invention relates to the field of power automation technology, and in particular to a method for evaluating the mechanical characteristics based on current characteristics. Background Technology

[0002] With the advancement of urban and rural power distribution network construction, medium-voltage power distribution networks have gradually achieved distribution automation and electrification, aiming to provide reliable power supply. Pole-mounted switches and ring main units in medium-voltage power distribution networks mostly use circuit breakers with spring-loaded operating mechanisms. Mechanical failures in these circuit breakers can cause malfunctions and failures to operate, resulting in damage to other electrical equipment and power outages in the power grid system. Statistical analysis of power distribution network accidents by authoritative institutions shows that approximately 70% of circuit breaker failures occur in the circuit breaker operating mechanism, i.e., due to poor mechanical characteristics. Therefore, monitoring and evaluating the mechanical characteristics of circuit breakers is extremely important.

[0003] The mechanical characteristics monitoring objects of circuit breaker mechanisms mainly include the opening / closing mechanism and the energy storage mechanism. Through online real-time monitoring, the mechanical characteristics and performance of the mechanism can be understood in a timely manner, thereby predicting the lifespan and potential failure points of the circuit breaker in advance, realizing precise operation and maintenance, improving the operational reliability of power equipment, and ensuring the safety of the power grid system.

[0004] Existing methods for monitoring mechanical characteristics mainly include spectrum analysis, infrared analysis, vibration signal analysis, and ultrasonic analysis. These methods mostly monitor the mechanical characteristics of a mechanism by analyzing indirect signals from the mechanism. However, they have disadvantages such as inconvenient installation, limited data, and insufficient early warning capabilities. Summary of the Invention

[0005] In view of the defects and shortcomings of the existing technology, the purpose of this invention is to provide a method for online evaluation of the mechanical characteristics of circuit breakers based on the characteristics of opening and closing and energy storage current.

[0006] The present invention specifically adopts the following technical solution:

[0007] A method for assessing the mechanical characteristics of a circuit breaker based on current features is characterized by: real-time acquisition of the opening coil current, closing coil current, energy storage coil current, and operating power supply voltage of the circuit breaker mechanism using a Hall current sensor, and converting them from analog to digital into a digital waveform sequence; then, by real-time judgment of the instantaneous values ​​of the opening coil current, closing coil current, and energy storage coil current and the current setting values ​​of the start threshold and reset threshold, and then extracting key nodes representing changes in current signals based on the digital waveform sequence to further calculate the energy consumed by the mechanism's actions and determine the operating condition of the circuit breaker.

[0008] Furthermore, it includes the following steps:

[0009] Step S1: The opening coil current, closing coil current, energy storage coil current, and operating power supply voltage of the circuit breaker mechanism are collected in real time by Hall current sensor and converted from analog to digital waveform sequence.

[0010] Step S2: By judging the instantaneous values ​​of the trip coil current, closing coil current and energy storage coil current in real time and the current setting values ​​of the start threshold and reset threshold, the digital waveform sequence is stored as i(k) waveform.

[0011] Step S3: By traversing the i(k) waveform sequence, calculate the change of the i(k) curve vector according to the formula Δi(k)=i(k)-i(k-1), and then find the T0 time when the current appears and the T3 time when the current signal disappears through the trend of Δi(k) change. If i(k) is the opening or closing current, extract the T1 time when the current first appears at its peak value and the T2 time when the current first appears at its valley value.

[0012] Step S4: By following the formula The energy consumed by the calculation mechanism is used to determine the operating condition of the circuit breaker's mechanical characteristics. When the energy J is greater than the set value J... S When this happens, it prompts you to inspect the electrical and mechanical structure of the circuit breaker;

[0013] Step S5: For opening and closing actions, calculate T. Q =T1-T0 is used to determine the change in the internal resistance of the circuit breaker operating coil. When T Q Greater than the set value S Q If this is detected, the operating coil assembly of the maintenance mechanism will be alerted; by calculating T... C =T2-T1 determines the mechanical characteristics of the moving parts of the circuit breaker. When T C Greater than the set value S C If so, it indicates whether the electromagnet core of the maintenance unit is stuck or disengaged;

[0014] Step S6: By following the formula Calculate the similarity between the current operating current curve i(k) and the factory standard operating current curve I(k). If |ρ iI If |<ρset, where ρset is the relevant quantity setting value, it reflects an abnormality in the mechanical characteristics of the circuit breaker operating mechanism, prompting maintenance of the circuit breaker's electrical and mechanical structure.

[0015] This invention and its preferred embodiment enable timely understanding of the mechanical characteristics and performance of the circuit breaker by real-time online monitoring of the opening and closing coil current and energy storage current characteristics. This allows for early prediction of the circuit breaker's lifespan and potential failure points, achieving precise operation and maintenance, improving the operational reliability of power equipment, and ensuring the safety of the power grid system.

[0016] Its beneficial effects include:

[0017] 1. This method only requires monitoring the electrical characteristics of the circuit breaker to evaluate its mechanical characteristics. It only requires installing Hall sensors on the electrical circuit of the circuit breaker, without the need to install sensors that directly detect vibration, displacement, etc., of the circuit breaker mechanism. Therefore, it has the advantages of simple installation and non-intrusive installation.

[0018] 2. This method redundantly evaluates the mechanical characteristics of the circuit breaker mechanism from multiple dimensions, thereby improving the reliability of the evaluation results. Attached Figure Description

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0020] Figure 1 The current waveform diagram is shown for the operating circuit of this invention. Detailed Implementation

[0021] In the following, specific embodiments of this application will be described in detail with reference to the accompanying drawings. Based on these detailed descriptions, those skilled in the art will be able to clearly understand and implement this application. Without departing from the principles of this application, features from various embodiments can be combined to obtain new implementations, or certain features from some embodiments can be substituted to obtain other preferred implementations.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] To make the features and advantages of this patent more apparent and understandable, specific embodiments are provided below for detailed explanation:

[0024] The following is a specific application example to further illustrate the solution of the present invention:

[0025] like Figure 1 As shown, this embodiment of the invention provides an online evaluation method for mechanical properties based on current characteristics, specifically including the following steps:

[0026] Step 1: The opening coil current, closing coil current, energy storage coil current, and operating power supply voltage of the circuit breaker mechanism are collected in real time by Hall current sensor, and the analog-to-digital conversion is performed into a digital waveform sequence. At the same time, the instantaneous values ​​of the opening coil current, closing coil current, and energy storage coil current are calculated in real time.

[0027] Step 2: By judging in real time that the instantaneous values ​​of the trip coil current, closing coil current and energy storage coil current are greater than the set starting current threshold, when the limit is exceeded and the delay setting is met, the waveform recording function is started to store the digital waveform sequence of the trip coil current, closing coil current, energy storage coil current and operating power supply voltage. The trip current object is used to distinguish whether it is a tripping action, a closing action or an energy storage action, and is recorded as i(k).

[0028] Step 3: When the instantaneous values ​​of the trip coil current, closing coil current and energy storage coil current are less than the set reset current threshold, stop the waveform recording function and start the current characteristic analysis function.

[0029] Step 4: Traverse the i(k) waveform sequence and calculate the change of the i(k) curve vector according to the formula Δi(k) = i(k) - i(k-1). Find the times T0 and T3 through the trend of Δi(k) change. If i(k) is the opening or closing current, the times T1 and T2 can also be found. (Refer to the appendix.) Figure 1 .

[0030] Step 5: According to the formula The energy consumed by the mechanism's movement is calculated, where ΔT is the system sampling period, u(k) is the operating power supply voltage waveform sequence, k = 0 represents time T0, and N is the number of sampling points between T3 and T0. The energy J consumed by the mechanism's movement indirectly reflects whether the mechanism's mechanical characteristics are normal. When the energy J is greater than the set value J... S If the circuit breaker's electrical and mechanical structure is not inspected, the system will prompt for maintenance. If i(k) is the energy storage current, the process will proceed to step 7.

[0031] Step 6: Calculate T Q =T1-T0, this time quantity indirectly reflects the change in the internal resistance of the operating coil. When T Q Greater than the set value S Q If this is detected, the operating coil assembly of the maintenance mechanism will be prompted; calculate T. C =T2-T1, this time quantity indirectly reflects the working state of the moving parts of the structure, when T C Greater than the set value S C If so, it will indicate whether the electromagnet core of the maintenance unit is stuck or has tripped.

[0032] Step 7: Perform a similarity assessment between i(k) and the factory standard curve I(k), according to the formula... Calculate the similarity between the current operating current curve and the factory standard operating current curve. If |ρ iI If |<ρset, where ρset is the relevant quantity setting value, it reflects an abnormal operating condition of the circuit breaker operating mechanism, prompting maintenance of the circuit breaker's electrical and mechanical structure.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

[0034] This patent is not limited to the above-described preferred embodiments. Anyone can derive other forms of mechanical characteristic state evaluation methods based on current characteristics under the guidance of this patent. All equivalent changes and modifications made within the scope of this patent application shall fall within the scope of this patent.

Claims

1. A method for evaluating the mechanical property status based on current characteristics, characterized in that: The circuit breaker mechanism's opening coil current, closing coil current, energy storage coil current, and operating power supply voltage are collected in real time using Hall current sensors and converted from analog to digital waveform sequences. Then, by judging the instantaneous values ​​of the trip coil current, closing coil current and energy storage coil current in real time, and the current setting values ​​of the start threshold and reset threshold, the key nodes representing the changes in current signals are extracted according to the digital waveform sequence to further calculate the energy consumed by the mechanism and judge the operating condition of the circuit breaker. Specifically, the following steps are included: Step S1: The opening coil current, closing coil current, energy storage coil current, and operating power supply voltage of the circuit breaker mechanism are collected in real time by Hall current sensor and converted from analog to digital waveform sequence. Step S2: When the instantaneous values ​​of the trip coil current, closing coil current, and energy storage coil current are greater than the set starting current threshold value in real time, and an over-limit occurs while the delay setting is met, the waveform recording function is activated to store the digital waveform sequence of the trip coil current, closing coil current, energy storage coil current, and operating power supply voltage. The over-limit current object is used to distinguish whether it is a tripping action, a closing action, or an energy storage action, denoted as i(k). When the instantaneous values ​​of the trip coil current, closing coil current, and energy storage coil current are less than the set reset current threshold value, the waveform recording function is stopped, and the current characteristic analysis function is activated. Step S3: By traversing the i(k) waveform sequence, according to the formula Calculate the change of the i(k) curve vector, and then through Find the time T0 when the current appears and the time T3 when the current signal disappears by changing the trend. If i(k) is the opening or closing current, then extract the time T1 when the current first reaches its peak and the time T2 when the current first reaches its valley. Step S4: According to the formula The energy consumed by the calculation mechanism is used to determine the operating condition of the circuit breaker's mechanical characteristics. When the energy J is greater than the set value J... S When this occurs, it prompts for inspection of the electrical and mechanical structure of the circuit breaker, where u(k) is the operating power supply voltage waveform sequence; Step S5: For opening and closing actions, calculate T. Q =T1 T0 is used to determine the change in the internal resistance of the circuit breaker operating coil. Q Greater than the set value S Q If this is detected, the operating coil assembly of the maintenance mechanism will be alerted; by calculating T... C =T2 T1 determines the mechanical characteristics of the moving parts of the circuit breaker. When T C Greater than the set value S C If so, it indicates whether the electromagnet core of the maintenance unit is stuck or disengaged; Step S6: According to the formula Calculate the similarity between the current operating current curve i(k) and the factory standard operating current curve I(k). ,in Setting the relevant values ​​will reflect abnormal mechanical characteristics of the circuit breaker operating mechanism, prompting maintenance of the circuit breaker's electrical and mechanical structure.

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