Circuit breaker time characteristic measurement method based on electromagnetic transient signals

Abstract

The invention provides a circuit breaker time characteristic measurement method based on an electromagnetic transient signal, relates to the technical field of circuit breakers of power systems, and solves the problems of complex identification of a rigid opening (closing) point, high realization difficulty and strong dependence on various sensors in the existing method. The method comprises the following steps: collecting electromagnetic transient signals generated in the opening and closing process of the circuit breaker, and analyzing a start-stop mechanism of the electromagnetic transient signals; associating the electromagnetic transient signal with an actual physical motion signal of the moving contact of the circuit breaker to form a corresponding relation, and aligning a travel-time curve of the moving contact of the circuit breaker with a time axis of the electromagnetic transient signal; after the time axes are aligned, feature point time in the electromagnetic transient signals is identified and calibrated, and the feature point time at least comprises a just-open point and / or a just-close point; according to the calibrated feature point time, calculating the just-open time and / or the just-close time of the circuit breaker; according to the invention, the measurement process of the time characteristic of the circuit breaker is simplified, the efficiency is improved, and the high-precision standard is maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit breakers in power systems, and is applied to the process of measuring time characteristics of circuit breakers. In particular, the present invention relates to a method for mining time characteristic points of circuit breaker just opening (closing) based on electromagnetic transient signal characteristics, thereby realizing circuit breaker time characteristic measurement. Background Art

[0002] In the power system, circuit breakers, as important switching devices, play a key role in controlling and protecting circuits. The time characteristics of circuit breakers are an important indicator for evaluating their performance, which is directly related to the safe and stable operation of the power system. Especially in high-voltage or ultra-high-voltage transmission networks, the opening and closing operations of circuit breakers must be completed quickly and accurately to ensure that the fault current can be cut off or power supply can be restored in time, thereby preventing the accident from expanding and reducing the power outage time. Therefore, the accurate identification of the characteristic points of the circuit breaker's opening (closing) time has become one of the keys to measuring the performance of circuit breakers.

[0003] At present, there are some technical applications for measuring the time characteristics of circuit breakers. For example, the vibration signal analysis method determines the action state of the moving contact by monitoring the mechanical vibration generated during the operation of the circuit breaker; the contact acceleration analysis method uses an acceleration sensor installed inside or outside the circuit breaker to capture the acceleration change during the movement of the contact. Although these two methods can reflect the working condition of the circuit breaker to a certain extent, they are difficult to implement because they rely on complex physical phenomena and the mathematical models behind them. In addition, these traditional methods often need to consider the impact of factors such as ambient temperature and humidity on the results, which increases the complexity of data analysis.

[0004] On the other hand, with the development of science and technology, more and more power plants are beginning to use specially designed circuit breaker mechanical time characteristic testers to perform more accurate time characteristic measurements. Such instruments are usually equipped with various types of sensors such as displacement sensors, angular velocity sensors, and even grating sensors to comprehensively record the detailed movement trajectory of the moving contact during the entire opening and closing process. In this way, more accurate and reliable measurement data can indeed be obtained.

[0005] However, this method also has obvious limitations: first, in order to obtain complete motion information, various sensors must be correctly selected and installed, which not only requires technicians to have high professional skills, but also the entire setup process is quite time-consuming and laborious; second, since it involves sensors working on many different principles, how to ensure good coordination between them is also a considerable challenge; finally, considering the possible interference factors in the actual application environment, such as electromagnetic noise, how to improve measurement accuracy has also become a problem that needs to be solved urgently.

[0006] In summary, although the existing circuit breaker time characteristic measurement technology has made some progress, there are still many shortcomings in the identification of the just-opened (closed) point. Finding a new method that is both simple and efficient, which can simplify the measurement process and lower the threshold of use without sacrificing accuracy, has become an important topic in the current research field. Summary of the invention

[0007] Based on the current status of the background technology, the purpose of the present invention is to solve the problems of complex identification of the just-opening (closing) point, great difficulty in implementation, and strong dependence on multiple sensors in the existing circuit breaker time characteristic measurement method, and therefore proposes a circuit breaker time characteristic measurement method based on electromagnetic transient signals. Starting from the electromagnetic transient signal of the circuit breaker opening and closing, the present invention theoretically analyzes the physical characteristics of the circuit breaker opening and closing stroke-time curve and the start and end mechanism of the electromagnetic transient signal, and finally realizes the calibration of the circuit breaker just-opening (closing) point, thereby completing the measurement of the circuit breaker time characteristic.

[0008] The present invention adopts the following technical solutions to achieve the purpose:

[0009] A method for measuring time characteristics of a circuit breaker based on electromagnetic transient signals, the method comprising the following steps:

[0010] S1. Collect the electromagnetic transient signals generated during the opening and closing process of the circuit breaker; analyze the starting and ending mechanism of the electromagnetic transient signals based on the physical characteristics of the circuit breaker opening and closing stroke-time curve;

[0011] S2. During the opening and closing process of the circuit breaker, the electromagnetic transient signal is associated with the actual physical motion signal of the moving contact of the circuit breaker to form a corresponding relationship between the characteristics of the electromagnetic transient signal and the action process of the moving contact of the circuit breaker;

[0012] S3, aligning the travel-time curve of the moving contact of the circuit breaker with the time axis of the electromagnetic transient signal according to the corresponding relationship formed in step S2;

[0013] S4. According to the start and end mechanism of the electromagnetic transient signal, after the time axis is aligned, the characteristic point time in the electromagnetic transient signal is identified and calibrated; the characteristic point at least includes a just-break point and / or a just-close point;

[0014] S5. Calculate the opening time and / or closing time of the circuit breaker based on the calibrated characteristic point time, and complete the circuit breaker time characteristic measurement.

[0015] Specifically, in step S1, based on the vacuum breaker breakdown theory and taking into account the existence of the circuit breaker cutoff value, the start and end mechanism of the electromagnetic transient signal is analyzed.

[0016] Specifically, in step S1, an electric signal sensor is installed in the power system where the circuit breaker is located to collect electromagnetic transient signals generated at the circuit breaker break during the opening and closing of the circuit breaker; the electromagnetic transient signals include transient voltage and transient current.

[0017] Preferably, in step S4, a comprehensive calibration is performed using the characteristic point time of the transient voltage and the transient current, and the transient voltage is used as the primary criterion for characteristic point time calibration, and the transient current is used as the auxiliary criterion for characteristic point time calibration.

[0018] Furthermore, in step S1, the start and end mechanism of the electromagnetic transient signal during the circuit breaker opening process is analyzed as follows:

[0019] The time when the circuit breaker receives the opening command is recorded as T command1 The time when the moving contact of the circuit breaker moves is recorded as T seperate1 ; In the process of circuit breaker opening, the time T required from the circuit breaker opening coil being energized to the circuit breaker moving contact being actuated and starting to separate is opening for:

[0020] T opening =T seperate1 -T command1

[0021] After the moving contact of the circuit breaker is actuated, a diffusion arc is generated. The time from the generation to the extinction of the diffusion arc is recorded as the arcing time T. arcing The extinction time of the diffusion arc is recorded as T end1 , then:

[0022] T arcing =T end1 -T seperate1

[0023] Arcing time T arcing That is, the existence time of the electromagnetic transient signal; based on the theoretical basis that the arcing time of the circuit breaker satisfies the normal distribution, through multiple groups of experiments, the distribution range of the existence time of the electromagnetic transient signal of the same type of circuit breaker during the opening process is measured to complete the start and end mechanism analysis.

[0024] Specifically, during the process from step S2 to step S3, the circuit breaker receives the signal of the opening command, the opening coil of the circuit breaker is energized and drives the iron core to start moving, and the time from the beginning of the separation of the moving contact of the circuit breaker is determined as the time before the electromagnetic transient signal is generated in the power system; the time from the beginning of the separation of the moving contact of the circuit breaker until the arc between the moving contact and the static contact no longer breaks through, that is, the arcing time T arcing, is determined as the time when electromagnetic transient signals exist in the power system; the time from the end of arcing between the moving contact and the static contact of the circuit breaker to the completion of the circuit breaker opening process is determined as the time when the electromagnetic transient signals generated in the power system disappear; thereby completing the correspondence of features and the alignment of the time axis.

[0025] Specifically, in step S4, the electromagnetic transient signal is first filtered, and then the waveform obtained after filtering is slope scanned to determine the corresponding moments when the electromagnetic transient signal just appears and just disappears;

[0026] When the circuit breaker performs the opening operation, the critical point at which the waveform of the electromagnetic transient signal changes from a sine waveform to an irregular waveform is determined as the starting point of the electromagnetic transient signal, and then the critical point at which the waveform of the electromagnetic transient signal changes from an irregular waveform to a sine waveform is determined as the vanishing point of the electromagnetic transient signal, and the vanishing point is determined as the just-opening point of the circuit breaker;

[0027] In step S5, when the circuit breaker performs the opening operation, the corresponding moment when the electromagnetic transient signal just appears is the just-opening point in the time curve of the circuit breaker moving contact, that is, the moment when the circuit breaker moving contact moves T seperate1 , this moment is also the calibration point for calculating the circuit breaker just breaking time;

[0028] The circuit breaker opening time is the time T required from the circuit breaker opening coil being energized to the circuit breaker moving contact being actuated and starting to separate. opening ; Extinction time of diffusion arc T end That is, the corresponding moment when the electromagnetic transient signal just disappears, and then the moment when the circuit breaker receives the opening command is determined by measuring the pulse signal of the opening coil. command1 Therefore, according to the time difference between the corresponding moment when the electromagnetic transient signal just appears and the moment when the circuit breaker receives the opening command, the circuit breaker just-opening time can be calculated, corresponding to T opening value.

[0029] Furthermore, in step S1, the start and end mechanism of the electromagnetic transient signal during the circuit breaker closing process is analyzed as follows:

[0030] The time when the circuit breaker receives the closing command is recorded as T command2 The time when the moving contact of the circuit breaker moves is recorded as T seperate2 ; During the closing process of the circuit breaker, the time required from the energization of the circuit breaker closing coil to the action of the circuit breaker moving contact is recorded as ΔT known After the moving contact of the circuit breaker is actuated, as the moving contact moves, a pre-breakdown phenomenon will occur before the moving contact and the static contact are completely closed, forming a pre-breakdown arc; the time from the generation to the extinction of the pre-breakdown arc is recorded as the arcing time T prestrike The expected extinction time of the punch-through arc is recorded as T e2d2dThe time from the moving contact of the circuit breaker to the expected arc generation is recorded as ΔT stochastic , then the total time of the circuit breaker closing process is T closing As follows:

[0031] T closing =ΔT known +ΔT stochastic +T prestrike

[0032] Arcing time T prestrike That is, the existence time of the electromagnetic transient signal; since the generation time of the expected arc type satisfies the normal distribution, according to the time ΔT stochastic It also meets the theoretical basis of normal distribution. Through multiple groups of experiments, the distribution range of the existence time of electromagnetic transient signals of the same type of circuit breakers during the closing process is measured to complete the start and stop mechanism analysis.

[0033] Specifically, during the process from step S2 to step S3, the circuit breaker receives the signal of the closing command, the closing coil of the circuit breaker is energized and drives the iron core to start moving, and the time corresponding to when the distance between the moving contact and the static contact of the circuit breaker meets the distance for the expected flashover type arc to be generated is determined as the generation time of the electromagnetic transient signal; the time from the expected flashover type arc to the complete closure of the moving contact and the static contact of the circuit breaker is the arcing time T prestrike , is determined as the time when the electromagnetic transient signal exists in the power system; the moment corresponding to when the moving contact and the static contact of the circuit breaker are fully closed is determined as the moment when the electromagnetic transient signal disappears in the power system; thereby completing the correspondence of the features and the alignment of the time axis.

[0034] Specifically, in step S4, the electromagnetic transient signal is first filtered, and then the waveform obtained after filtering is slope scanned to determine the corresponding moments when the electromagnetic transient signal just appears and just disappears;

[0035] When the circuit breaker performs a closing operation, the critical point at which the waveform of the electromagnetic transient signal changes from no waveform to an irregular waveform is determined as the starting point of the electromagnetic transient signal, and then the critical point at which the waveform of the electromagnetic transient signal changes from an irregular waveform to a sine waveform is determined as the vanishing point of the electromagnetic transient signal, and the vanishing point is determined as the rigid closing point of the circuit breaker;

[0036] In step S5, when the circuit breaker performs the closing operation, the corresponding moment when the electromagnetic transient signal just appears is the time when the flashover type arc is expected to be generated, and the corresponding moment when the electromagnetic transient signal just disappears is the just-closing point in the time curve of the circuit breaker moving contact, that is, the extinction time T of the flashover type arc is expected. end2 , this moment is also the calibration point for calculating the circuit breaker just closing time;

[0037] The circuit breaker just closing time is the total time T of the circuit breaker closing process. closing ; Determine the time T when the circuit breaker receives the closing command by measuring the closing coil pulse signal command2 , based on the time difference between the corresponding moment when the electromagnetic transient signal just disappears and the moment when the circuit breaker receives the closing command, the circuit breaker just closing time can be calculated, corresponding to T closing value.

[0038] In summary, due to the adoption of this technical solution, the beneficial effects of the present invention are as follows:

[0039] The method of the present invention directly utilizes the electromagnetic transient electrical signal on the primary side of the circuit breaker to intuitively determine the just-opening (closing) point of the circuit breaker; the method is based on the automatic capture of transient voltage and current characteristic points, and its algorithm is relatively simple and easy to implement, which significantly reduces the complexity and technical threshold faced in identifying the just-opening (closing) point in traditional measurement methods.

[0040] The key to the method of the present invention is to accurately identify the opening (closing) point of the circuit breaker contacts, which is the basis for measuring the opening (closing) time. After effectiveness verification, the method of the present invention can achieve an accuracy level comparable to that of existing mechanical property testers, providing reliable data support for circuit breaker performance analysis. Specifically, the present invention shows through comparative experiments that the average error in the closing time is less than 0.5 milliseconds, and the average error in the opening time is less than 0.6 milliseconds. In addition, the analysis of the results of 200 sets of repeatability tests shows that the degree of agreement between the measurement results of the present invention and the results obtained using the mechanical property tester reached more than 98%, which further proves the high reliability and accuracy of the new method.

[0041] The present invention not only opens up a new perspective in the field of circuit breaker opening (closing) point identification, but also proposes a new solution for the time characteristic measurement of switch elements with similar working principles. More importantly, the present invention also lays the foundation for subsequent research on circuit breaker characteristic analysis related to transient voltage and current, such as three-phase asynchronism and arcing characteristics. Since there is a certain synchronization relationship between transient voltage and current signals and they can be calibrated with each other, even if the characteristics of one signal are not obvious enough, the other signal can still continue to perform effective characteristic point calibration, thereby ensuring the stability and reliability of the entire measurement process. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the overall scheme flow of the method of the present invention;

[0043] Figure 2 A schematic diagram of the timing of the circuit breaker opening process in the present invention;

[0044] Figure 3 It is a schematic diagram of the travel curve of the opening moving contact of the circuit breaker in the present invention;

[0045] Figure 4 A timing diagram of the closing process of the circuit breaker in the present invention;

[0046] Figure 5 It is a schematic diagram of the closing moving contact stroke curve of the circuit breaker in the present invention;

[0047] Figure 6 It is a schematic diagram of the characteristic point calibration of the closing electromagnetic transient signal in the present invention;

[0048] Figure 7 This is a schematic diagram of the calibration of characteristic points of the electromagnetic transient signal of the opening gate in the present invention;

[0049] Figure 8 It is a schematic diagram of the just-closed time error in the present invention;

[0050] Fig. 9 It is a schematic diagram of the time error of the present invention;

[0051] Fig.10 It is a schematic diagram of the error range of the just-opening (closing) time in the present invention. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0053] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] This embodiment provides a circuit breaker time characteristic measurement method based on electromagnetic transient signals. Figure 1 The schematic diagram of the overall process of this method combined with the validity verification can be viewed simultaneously. The steps of this method are summarized as follows:

[0055] S1. Collect the electromagnetic transient signals generated during the opening and closing process of the circuit breaker; analyze the starting and ending mechanism of the electromagnetic transient signals based on the physical characteristics of the circuit breaker opening and closing stroke-time curve;

[0056] S2. During the opening and closing process of the circuit breaker, the electromagnetic transient signal is associated with the actual physical motion signal of the moving contact of the circuit breaker to form a corresponding relationship between the characteristics of the electromagnetic transient signal and the action process of the moving contact of the circuit breaker;

[0057] S3, aligning the travel-time curve of the moving contact of the circuit breaker with the time axis of the electromagnetic transient signal according to the corresponding relationship formed in step S2;

[0058] S4. According to the start and end mechanism of the electromagnetic transient signal, after the time axis is aligned, the characteristic point time in the electromagnetic transient signal is identified and calibrated; the characteristic point at least includes a just-break point and / or a just-close point;

[0059] S5. Calculate the opening time and / or closing time of the circuit breaker based on the calibrated characteristic point time, and complete the circuit breaker time characteristic measurement.

[0060] This embodiment will provide a detailed explanation of the above method process. This embodiment collects the transient voltage and transient current waveforms at the circuit breaker break during the opening and closing operation by installing an electrical signal sensor in the power system where the circuit breaker is located, thereby realizing the collection of electromagnetic transient signals. The acquired transient voltage and current are subjected to characteristic analysis, and the characteristic points of the transient voltage and current waveforms are matched with the time points of the moving contact travel time curve to accurately identify the circuit breaker just opening (closing) point, which is the overall scheme of this embodiment.

[0061] This embodiment first theoretically analyzes the transient voltage, current and moving contact travel time curve model, then performs correlation analysis on the electromagnetic transient signal (voltage, current) waveform and the moving contact travel curve, studies the just-open (close) switch characteristic points and transient voltage and current characteristic points, and establishes a just-open (close) identification method. At the same time, through the multi-group closing test, the error comparison is performed with the data of the mechanical travel tester to verify the effectiveness of the method of this embodiment.

[0062] Firstly, the correlation between electromagnetic transient signal and opening and closing time is analyzed.

[0063] The transient voltage and current during the opening and closing process of the circuit breaker are caused by the arc generated between the moving and static contacts during the opening and closing process. The "arcing" phenomenon occurs when the circuit breaker is opened, and the "pre-breakdown" phenomenon occurs when the circuit breaker is closed. "Arcing" and "pre-breakdown" are essentially the breakdown of the vacuum medium of the break when the moving and static contacts are not fully in contact. According to the classic vacuum break breakdown theory, when the voltage acting on the break exceeds the insulation strength of the gap medium, the break will break down, causing the electromagnetic transient signal to appear.

[0064] Through Paschen's law or Paschen curve, we know that when the voltage intensity of the vacuum circuit breaker is greater than the insulation strength of the vacuum, breakdown will occur and an arc will be generated. When the circuit breaker is opening and closing, the distance between the moving and static contacts will change, so the insulation recovery strength between the moving and static contacts will show dynamic changes. When the voltage intensity between the contacts is greater than the recovery strength of the insulation, the medium will be broken down and an arc will be generated. The generation of the arc is accompanied by transient voltage and current.

[0065] Due to the existence of the cutoff value, the transient current signal generally exists for less time than the transient voltage signal, because when the current flowing through the circuit breaker is less than the cutoff value, the transient current signal disappears. However, at this time, a transient recovery voltage will be generated between the contacts, which is part of the transient voltage existence process. Comprehensive calibration can be performed through transient voltage and current signals. For example, the starting points of transient voltage and transient current correspond to the time point when the arc is generated. In some tests where the transient voltage is not obvious, the transient current can assist in calibrating the characteristic points. It can be seen that there is a close connection between the distance (mechanical stroke) between the moving and static contacts of the circuit breaker, the arc and the electromagnetic transient signal. After the circuit breaker contacts are separated, an arc is generated between the contacts, and the arc is extinguished at the moment when the arc current passes through zero.

[0066] Figure 2 The timing diagram of the circuit breaker opening process is shown here, which can be viewed simultaneously. Figure 2 It can be seen that the circuit breaker is at T command1 After receiving the opening command, it takes a time interval T from the energization of the circuit breaker opening coil to the separation of the circuit breaker contacts. opening ,Right now:

[0067] T opening =T seperate1 -T command1

[0068] T arcing =T end1 -T seperate1

[0069] The time point of contact action is T seperate1 After the contact is actuated, since the contact surface of the circuit breaker cannot be completely flat, the current will always flow through the separated convex point when the moving and static contacts are separated, causing local overheating and melting, and then generating a diffuse arc. The time from the arc generation to the extinction is called the arcing time. Transient voltage and current are also generated with the arcing, and their existence time is T arcing .

[0070] The arcing time is not fixed, but has certain random characteristics. The arcing time of each circuit breaker satisfies the normal distribution law, and the existence time of electromagnetic transient signals (voltage, current) also satisfies certain normal distribution laws. Through multiple groups of experiments, the existence time T of electromagnetic transient signals can be measured. arcing The distribution interval of . Figure 3 It is the transient electrical signal process marked on the moving contact travel-time curve when opening the gate. When opening the gate, it can be mainly divided into the following stages:

[0071] When the circuit breaker receives the opening signal, the opening coil is energized to drive the iron core to start moving until the moving and static contacts of the circuit breaker begin to separate. During this period, no transient voltage and current are generated in the system; the time from the beginning of the separation of the moving and static contacts of the circuit breaker to the end of the arc between the moving and static contacts is the arcing time, during which transient voltage and current are generated in the system; during the period from the end of the arcing of the moving and static contacts of the circuit breaker to the completion of the circuit breaker opening, the transient voltage and current in the system disappear.

[0072] The timing diagram of the circuit breaker closing process is as follows: Figure 4 Similar to the opening operation, after receiving the closing command, it takes a period of time ΔT from the energization of the circuit breaker tripping coil to the start of the circuit breaker contact action. known .

[0073] After the contact moves, as the gap between the fractures continues to decrease, pre-breakdown may occur under certain conditions. The occurrence of pre-breakdown will cause the circuit to be connected in advance before the contacts touch. Combined with the timing diagram of the closing process, the time T of the entire closing process is calculated. closing It is divided into 3 parts, as shown below:

[0074] T closing =ΔT known +ΔT stochastic +T prestrike

[0075] Combination Figure 4 , T command2 is the moment when the circuit breaker receives the closing command, T seperate2 It is the moment when the moving contact starts to move. Pre-breakdown occurs ΔT after the moving contact starts to move stochastic The arcing time after the pre-breakdown occurs is T prestrike , the existence time of the electromagnetic transient signal in the closing process corresponds to its arcing time. Figure 5 It is the transient electrical signal process marked on the moving contact travel-time curve when closing the circuit breaker. When closing the circuit breaker, it can be mainly divided into the following stages:

[0076] When the circuit breaker receives the closing signal, the closing coil is energized, driving the iron core to start moving until the moving and static contacts of the circuit breaker are close to each other, generating transient voltage and current signals; the time from the electromagnetic transient signal generated between the moving and static contacts of the circuit breaker to the beginning of contact between the moving and static contacts of the circuit breaker is the arcing time, and the voltage signal in the system is a transient signal. During the time from the beginning of contact between the moving and static contacts of the circuit breaker to the completion of the circuit breaker closing, the transient voltage and current in the system disappear.

[0077] The following is the process of identifying and calibrating the characteristic points of electromagnetic transient signals in this embodiment. The overall idea of ​​identification is introduced as follows:

[0078] First, the collected transient voltage and current waveforms of opening and closing are filtered to remove the clutter in the power grid.

[0079] Then, by performing a slope scan on the filtered waveform, the moment when the transient voltage and current signals just appear is obtained. When the closing operation is performed, the slope scan voltage and current waveform surges from nothing to something, which is counted as the starting point of the transient electrical signal. The critical point where the slope scan transient electrical signal changes from irregular fluctuations to sinusoidal signals is counted as the transient vanishing point (just closing point); similarly, during the opening operation, the critical point where the voltage and current signals change from sinusoidal waveforms to irregular fluctuations is counted as the starting point of the transient electrical signal, and the slope scan transient electrical signal The critical point from irregular fluctuations to sinusoidal signals is counted as the transient vanishing point (just splitting point). The slope of each subsequent point corresponds to the sine curve one-to-one. When transient voltage and current appear, the slope no longer satisfies the corresponding relationship, so the point where the transient signal appears can be found by slope scanning. Similarly, the point where the transient voltage and current disappear is determined by the sudden change in the slope of the waveform.

[0080] Figure 6 The waveform and time point calibration of the three-phase electromagnetic transient signal of the circuit breaker when closing the circuit breaker are given. According to the principle of characteristic point identification, the moment T1 in the figure is the moment when the electromagnetic transient signal appears, which produces the "pre-breakdown" phenomenon; the moment T2 is the moment when the electromagnetic transient signal disappears, which corresponds to the just-closing point in the moving contact travel time curve, and is also the calibration point for calculating the just-closing time of the circuit breaker. By measuring the closing coil pulse signal, it can be known that the closing signal occurs at the time T command2 , arcing time of closing circuit breaker T prestrike Depends on the existence time of electromagnetic transient signal, then the closing time T closing It depends on the time difference between the disappearance point of the electromagnetic transient signal and the occurrence point of the closing signal, as shown in the following formula:

[0081] T prestrike =T2-T1

[0082] T closing =T2-T command2

[0083] The circuit breaker closing time is calculated accordingly.

[0084] Figure 7 The waveform and time point calibration of the three-phase electromagnetic transient signal of the circuit breaker during opening are given. According to the characteristic point identification principle, the moment T3 in the figure is the moment when the electromagnetic transient signal appears, which corresponds to the just-opening point in the moving contact travel time curve, and is also the calibration point for calculating the circuit breaker opening time; the moment T4 is the moment when the electromagnetic transient signal disappears, and the arcing phenomenon will also disappear at this time. By measuring the pulse signal of the opening coil, it can be known that the time when the opening signal occurs T command1 , arcing time T of opening circuit breaker arcing Depends on the existence time of electromagnetic transient signal, then the time T opening It depends on the time difference between the occurrence point of the electromagnetic transient signal and the occurrence point of the trip signal, as shown in the following formula:

[0085] T arcing =T4-T3

[0086] T opening =T3-T command1

[0087] The above is a detailed introduction to the method process of this embodiment. In order to verify the effectiveness of the calibration method, this embodiment also builds a circuit breaker opening and closing time characteristic test platform that can simulate the actual working conditions of the power plant, and conducts a 10kV spring energy storage circuit breaker opening and closing test. The test platform consists of a circuit breaker, a capacitive voltage transformer, a Rogowski coil, an acquisition card, and a host computer. The electromagnetic transient signals (voltage, current) of the circuit breaker can be collected and analyzed, and the characteristic points of the electromagnetic transient signal waveform can be automatically calibrated by the host computer software, and the automatic calculation of the opening (closing) time can be realized.

[0088] The error analysis of the calculated opening (closing) time is to first use the opening and closing stroke-time curve measured by the circuit breaker mechanical characteristics tester to obtain the opening and closing time of this circuit breaker, which is regarded as the reference value. Then the error is compared with the opening and closing time calibrated by the method of this embodiment. The calibration difference diagram of the two calibration methods is shown in Figure 8 and Fig. 9 The circuit breaker mechanical characteristics tester obtains the circuit breaker just closing time of 44.79ms and just opening time of 29.84ms.

[0089] exist Figure 8 and Fig. 9 In the figure, T6 represents the just-closing time of the circuit breaker mechanical characteristics tester, T5 represents the just-closing time calculated by the method of measuring the opening and closing points by electromagnetic transient signals (voltage, current), T7 represents the just-opening time of the circuit breaker mechanical characteristics tester, and T8 represents the just-opening time calculated by the method of this embodiment.

[0090] When conducting the opening and closing test, the host computer software automatically calibrates the characteristic points of the collected transient voltage and current and calculates the opening (closing) time, and directly outputs the calculation results on the opening and closing time display interface. The opening time of a certain test result is 29.66ms, and the closing time is 45.79ms. By setting an error threshold of 1ms for the opening and closing time, the opening and closing time abnormality can be displayed after exceeding this error. The captured transient voltage and current waveforms are intuitively displayed through the opening and closing time display interface, and the historical transient electrical signal waveforms can be stored. At the same time, if the opening distance length of the circuit breaker is known, the opening and closing speed parameters can be calculated after entering it into the host computer software.

[0091] In order to explore the accuracy of the just-opening (closing) time measured by transient voltage and current, 200 sets of circuit breaker opening and closing operation experiments were carried out in the laboratory to simulate the power plant environment. The just-opening and just-closing time points calibrated by the mechanical properties tester were used as the benchmark, and the errors of the just-opening and just-closing time points calibrated by the electromagnetic transient signal were statistically analyzed. After comprehensive analysis of the 200 sets of experimental data, the average error of the just-closing time of the circuit breaker calibrated with transient voltage and current was 0.43ms. After comprehensive analysis of the 200 sets of experimental data, the average error of the just-opening time of the circuit breaker calibrated with transient voltage was 0.58ms. The measurement results of the just-opening (closing) time are shown in Table 1 below (10 sets of data are taken). The schematic diagram of the error range of the just-opening and just-closing time of 200 sets of closing tests is shown in the figure below. Fig.10 shown.

[0092] Table 1 Schematic diagram of measurement data of the just-opening (closing) time part

[0093]

[0094]

[0095] The measurement results of the circuit breaker opening (closing) time based on transient voltage and current were compared with the test results of the circuit breaker mechanical tester. From the results of 200 sets of closing tests, it can be seen that the method of measuring the circuit breaker opening (closing) time based on electromagnetic transient signals is consistent with the measurement results of the mechanical characteristics tester by more than 98%, the average measurement error of the closing time is less than 0.5ms, and the average measurement error of the opening time is less than 0.6ms.

[0096] In summary, the present invention not only simplifies the measurement process of the circuit breaker time characteristics and improves efficiency, but also maintains high precision standards and is suitable for a wide range of application scenarios, especially for power plant environments where circuit breakers need to be used frequently.

Claims

1. A circuit breaker time characteristic measurement method based on electromagnetic transient signals, characterized in that: The method comprises the following steps: S1. Collect the electromagnetic transient signals generated during the opening and closing process of the circuit breaker; analyze the starting and ending mechanism of the electromagnetic transient signals based on the physical characteristics of the circuit breaker opening and closing stroke-time curve; S2. During the opening and closing process of the circuit breaker, the electromagnetic transient signal is associated with the actual physical motion signal of the moving contact of the circuit breaker to form a corresponding relationship between the characteristics of the electromagnetic transient signal and the action process of the moving contact of the circuit breaker; S3, aligning the travel-time curve of the moving contact of the circuit breaker with the time axis of the electromagnetic transient signal according to the corresponding relationship formed in step S2; S4. According to the start and end mechanism of the electromagnetic transient signal, after the time axis is aligned, the characteristic point time in the electromagnetic transient signal is identified and calibrated; the characteristic point at least includes a just-break point and / or a just-close point; S5. Calculate the opening time and / or closing time of the circuit breaker based on the calibrated characteristic point time, and complete the circuit breaker time characteristic measurement.

2. The circuit breaker time characteristic measurement method according to claim 1, characterized in that: In step S1, based on the vacuum breaker breakdown theory and taking into account the existence of the circuit breaker cutoff value, the start and end mechanism of the electromagnetic transient signal is analyzed.

3. The circuit breaker time characteristic measurement method according to claim 1, characterized in that: In step S1, an electric signal sensor is installed in the power system where the circuit breaker is located to collect electromagnetic transient signals generated at the circuit breaker break during the opening and closing process of the circuit breaker; the electromagnetic transient signals include transient voltage and transient current.

4. The circuit breaker time characteristic measurement method according to claim 3, characterized in that: In step S4, a comprehensive calibration is performed through the characteristic point time of the transient voltage and the transient current, and the transient voltage is used as the primary criterion for the characteristic point time calibration, and the transient current is used as the auxiliary criterion for the characteristic point time.

5. The circuit breaker time characteristic measurement method according to claim 3, characterized in that: In step S1, the analysis of the start and end mechanism of the electromagnetic transient signal during the circuit breaker opening process is as follows: The time when the circuit breaker receives the opening command is recorded as T command1 The time when the moving contact of the circuit breaker moves is recorded as T seperate1 ; In the process of circuit breaker opening, the time T required from the circuit breaker opening coil being energized to the circuit breaker moving contact being actuated and starting to separate is opening for: T opening =T seperate1 -T command1 After the moving contact of the circuit breaker is actuated, a diffusion arc is generated. The time from the generation to the extinction of the diffusion arc is recorded as the arcing time T. arcing The extinction time of the diffusion arc is recorded as T end1 , then: T arcing =T end1 -T seperate1 Arcing time T arcing That is, the existence time of the electromagnetic transient signal; based on the theoretical basis that the arcing time of the circuit breaker satisfies the normal distribution, through multiple groups of experiments, the distribution range of the existence time of the electromagnetic transient signal of the same type of circuit breaker during the opening process is measured to complete the start and end mechanism analysis.

6. The circuit breaker time characteristic measurement method according to claim 5, characterized in that: During the process from step S2 to step S3, the circuit breaker receives the signal of the opening command, the opening coil of the circuit breaker is energized and drives the iron core to start moving, and the time from when the moving contact of the circuit breaker just starts to separate is determined as the time when the electromagnetic transient signal has not yet been generated in the power system; The time from the beginning of separation of the moving contact of the circuit breaker until the arc between the moving contact and the static contact no longer breaks down, that is, the arcing time T arcing , which is determined as the time when electromagnetic transient signals exist in the power system; The time from the end of arc burning between the moving contact and the stationary contact of the circuit breaker to the completion of the circuit breaker opening process is determined as the time when the electromagnetic transient signal generated in the power system disappears; thereby completing the correspondence of the features and the alignment of the time axis.

7. The circuit breaker time characteristic measurement method according to claim 6, characterized in that: In step S4, the electromagnetic transient signal is first filtered, and then the waveform obtained after filtering is slope scanned to determine the corresponding moments when the electromagnetic transient signal just appears and just disappears; When the circuit breaker performs the opening operation, the critical point at which the waveform of the electromagnetic transient signal changes from a sine waveform to an irregular waveform is determined as the starting point of the electromagnetic transient signal, and then the critical point at which the waveform of the electromagnetic transient signal changes from an irregular waveform to a sine waveform is determined as the vanishing point of the electromagnetic transient signal, and the vanishing point is determined as the just-opening point of the circuit breaker; In step S5, when the circuit breaker performs the opening operation, the corresponding moment when the electromagnetic transient signal just appears is the just-opening point in the time curve of the circuit breaker moving contact, that is, the moment when the circuit breaker moving contact moves T seperate1 , this moment is also the calibration point for calculating the circuit breaker just breaking time; The circuit breaker opening time is the time T required from the circuit breaker opening coil being energized to the circuit breaker moving contact being actuated and starting to separate. opening ; Extinction time of diffusion arc T end That is, the corresponding moment when the electromagnetic transient signal just disappears, and then the moment when the circuit breaker receives the opening command is determined by measuring the pulse signal of the opening coil. command1 Therefore, according to the time difference between the corresponding moment when the electromagnetic transient signal just appears and the moment when the circuit breaker receives the opening command, the circuit breaker just-opening time can be calculated, corresponding to T opening value.

8. The circuit breaker time characteristic measurement method according to claim 3, characterized in that: In step S1, the start and end mechanism of the electromagnetic transient signal during the circuit breaker closing process is analyzed as follows: The time when the circuit breaker receives the closing command is recorded as T command2 The time when the moving contact of the circuit breaker moves is recorded as T seperate2 ; During the closing process of the circuit breaker, the time required from the energization of the circuit breaker closing coil to the action of the circuit breaker moving contact is recorded as ΔT known After the moving contact of the circuit breaker is actuated, as the moving contact moves, a pre-breakdown phenomenon will occur before the moving contact and the static contact are completely closed, forming a pre-breakdown arc; the time from the generation to the extinction of the pre-breakdown arc is recorded as the arcing time T prestrike The expected extinction time of the punch-through arc is recorded as T end2 The time from the moving contact of the circuit breaker to the expected arc generation is recorded as ΔT stochastic , then the total time of the circuit breaker closing process is T closing As follows: T closing =ΔT known +ΔT stochastic +T prestrike Arcing time T prestrike That is, the existence time of the electromagnetic transient signal; since the generation time of the expected arc type satisfies the normal distribution, according to the time ΔT stochastic It also meets the theoretical basis of normal distribution. Through multiple groups of experiments, the distribution range of the existence time of electromagnetic transient signals of the same type of circuit breakers during the closing process is measured to complete the start and stop mechanism analysis.

9. The circuit breaker time characteristic measurement method according to claim 8, characterized in that: During the process from step S2 to step S3, the circuit breaker receives the signal of the closing command, the closing coil of the circuit breaker is energized and drives the iron core to start moving, and the time corresponding to when the distance between the moving contact and the static contact of the circuit breaker meets the distance for the expected flashover type arc to be generated is determined as the generation time of the electromagnetic transient signal; the time from the expected flashover type arc to the complete closure of the moving contact and the static contact of the circuit breaker is the arcing time T. prestrike , which is determined as the time when electromagnetic transient signals exist in the power system; The moment corresponding to when the moving contact and the stationary contact of the circuit breaker are fully closed is determined as the moment when the electromagnetic transient signal in the power system disappears; thereby completing the correspondence of the features and the alignment of the time axis.

10. The circuit breaker time characteristic measurement method according to claim 9, characterized in that: In step S4, the electromagnetic transient signal is first filtered, and then the waveform obtained after filtering is slope scanned to determine the corresponding moments when the electromagnetic transient signal just appears and just disappears; When the circuit breaker performs a closing operation, the critical point at which the waveform of the electromagnetic transient signal changes from no waveform to an irregular waveform is determined as the starting point of the electromagnetic transient signal, and then the critical point at which the waveform of the electromagnetic transient signal changes from an irregular waveform to a sine waveform is determined as the vanishing point of the electromagnetic transient signal, and the vanishing point is determined as the rigid closing point of the circuit breaker; In step S5, when the circuit breaker performs the closing operation, the corresponding moment when the electromagnetic transient signal just appears is the time when the flashover type arc is expected to be generated, and the corresponding moment when the electromagnetic transient signal just disappears is the just-closing point in the time curve of the circuit breaker moving contact, that is, the extinction time T of the flashover type arc is expected. end2 , this moment is also the calibration point for calculating the circuit breaker just closing time; The circuit breaker just closing time is the total time T of the circuit breaker closing process. closing ; Determine the time T when the circuit breaker receives the closing command by measuring the closing coil pulse signal command2 , based on the time difference between the corresponding moment when the electromagnetic transient signal just disappears and the moment when the circuit breaker receives the closing command, the circuit breaker just closing time can be calculated, corresponding to T closing value.

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