Non-contact insulation monitoring method and system for circuit breaker based on array spatial electric field

Abstract

A non-contact insulation monitoring method and system for circuit breakers based on array spatial electric fields includes: constructing a spatial electric field measurement model for a single monitoring point of the circuit breaker, correcting the measurement results of the spatial electric field measurement model based on environmental factors to obtain the spatial electric field of the monitoring point array of the circuit breaker; using gray correlation theory to obtain a monitoring point array from the spatial electric field of the circuit breaker's monitoring point array whose correlation with the defect-free spatial electric field does not exceed a first correlation threshold, as the optimal monitoring point array; based on the optimal monitoring point array, using gray correlation theory, when the measurement results of the circuit breaker's spatial electric field measurement model have a correlation with the degraded spatial electric field that is not less than a second correlation threshold, issuing a circuit breaker insulation defect warning based on the degradation type corresponding to the degraded spatial electric field. The present invention monitors insulation degradation of high-voltage circuit breakers in real time and accurately in a non-contact manner.

Description

Technical Field

[0001] The present invention belongs to the field of high voltage and insulation technology, and in particular relates to a non-contact insulation monitoring method and system for circuit breakers based on array spatial electric field. Background Art

[0002] As the core switchgear of power systems, high-voltage circuit breakers are responsible for interrupting the normal operating current of the power system and quickly clearing the fault current of short-circuit fault lamps, playing a dual role of control and protection. During long-term operation, high-voltage circuit breakers are subjected to harsh electromagnetic, thermal, and mechanical factors, which will inevitably lead to problems such as internal insulation degradation and contact heating and ablation. In severe cases, these problems may cause the circuit breaker operating mechanism to refuse to operate or malfunction, switches and porcelain sleeves to explode, contacts to have poor contact and severe heating, metal melting to cause ground short circuits or porcelain bottle explosions, and other accidents. Therefore, the status monitoring and evaluation of high-voltage circuit breakers is of great importance and is of great significance to the safe and stable operation of power systems.

[0003] Internal insulation degradation in high-voltage circuit breakers typically manifests as electrolytes such as trace amounts of water in SF6, damage to switch contacts, and moisture along the surfaces or seals. These degradation phenomena can alter the overall dielectric and conductive properties, thereby affecting the spatial electric field distribution. Existing methods for assessing the condition of high-voltage circuit breakers rely on three main approaches. The first involves regular preventive testing, including insulation resistance and leakage current measurements. These methods are labor-intensive, cumbersome on-site operations, and may even require power outages. Furthermore, they fail to detect potential problems in a timely manner. The second method involves on-site live testing, primarily using ultraviolet and infrared imaging, but these methods are unable to detect problems such as internal insulation degradation and contact failure. The third method is to use sound, light, heat, electromagnetic and other sensors to directly or indirectly obtain signals to evaluate and determine the operating status of the circuit breaker. The main monitoring methods that can currently identify the insulation status of circuit breakers, such as opening and closing current monitoring, use invasive measurement methods. Generally, it is necessary to connect the current sensor in series with the current loop, which will change the electrical circuit. Therefore, this method generally requires power outage construction, and the installation and wiring workload is large. In addition, if it is damaged, the subsequent maintenance will be troublesome. Summary of the Invention

[0004] To address the deficiencies in the prior art, the present invention provides a method and system for non-contact insulation monitoring of circuit breakers based on an array spatial electric field. The electric field monitoring device is magnetically mounted on the outside of the casing flange or the transmission mechanism housing of the circuit breaker. By monitoring the amplitude of the power frequency electric field near the housing of the three-phase operating mechanism, the insulation degradation of the high-voltage circuit breaker is accurately and in real time in a non-contact manner. Upon identifying an obvious internal insulation fault, the terminal user is promptly informed, alerting the substation operation and maintenance personnel to promptly eliminate the equipment defect.

[0005] The present invention adopts the following technical solutions.

[0006] A non-contact insulation monitoring method for a circuit breaker based on an array spatial electric field, comprising:

[0007] Step 1: construct a spatial electric field measurement model for a single monitoring point of a circuit breaker, and correct the measurement results of the spatial electric field measurement model according to environmental factors to obtain the spatial electric field of the monitoring point array of the circuit breaker;

[0008] Step 2: Using grey correlation theory, a monitoring point array whose correlation with the defect-free spatial electric field of the monitoring point array of the circuit breaker does not exceed a first correlation threshold is obtained as the optimal monitoring point array;

[0009] Step 3: Based on the optimal monitoring point array and using the grey correlation theory, when the correlation between the measurement result of the spatial electric field measurement model of the circuit breaker and the degraded spatial electric field is not less than the second correlation threshold, an insulation defect warning of the circuit breaker is performed according to the degradation type corresponding to the degraded spatial electric field.

[0010] The spatial electric field measurement model includes: D-dot electric field probe, amplification and filtering module, Lora communication module, MCU module, lithium battery, battery voltage acquisition module and charging protection module.

[0011] In the d-dot electric field probe, the capacitance C is measured M Voltage across both ends It is proportional to the electric field strength at the monitoring point; where Ω is the environmental factor, and the environmental factor Ω is a vector with a dimension not greater than 11;

[0012] The induced voltage correction value is as follows:

[0013]

[0014] Where,

[0015] is the induced voltage correction value at time t,

[0016] is the voltage across the measuring capacitor at time t under the influence of environmental factors,

[0017] γ is the correction coefficient for environmental factors.

[0018] The environmental factor correction factor is as follows:

[0019]

[0020] Where,

[0021] α i is the velocity parameter of the i-th dimension,

[0022] M x is the mean of a dimension indicator x,

[0023] Δ i is the deviation limit of the i-th dimension.

[0024] Step 2 includes:

[0025] Step 2.1: For a circuit breaker with qualified insulation, the monitoring point array obtained by executing step 1 and the non-defective spatial electric field constitute a first reference sequence Y, where Y = {y(k) | k = 1, 2, ..., n}, where n is the number of monitoring points; for a circuit breaker with degraded insulation, the monitoring point array obtained by executing step 1 and the defective spatial electric field constitute a comparison sequence X j , X j ={x j (k)|k=1,2,…,n}, j=1,2,…,m, where m is the number of types of monitoring point arrays to be evaluated;

[0026] Step 2.2: For the j-th monitoring point array to be evaluated, calculate the quantitative characteristic correlation coefficient between each element in the first reference sequence and each element in the comparison sequence, as follows:

[0027]

[0028] Where,

[0029] ξ j (k) is the element x in the comparison sequence under the j-th monitoring point array to be evaluated. j The quantitative characteristic correlation coefficient between (k) and the element y(k) in the first reference sequence,

[0030] ρ is the resolution coefficient, ρ∈(0,1);

[0031] Step 2.3: For the j-th monitoring point array to be evaluated, the first correlation degree between the comparison sequence and the first reference sequence is determined based on the average value method using the quantity characteristic correlation coefficient, as follows:

[0032]

[0033] Where,

[0034] r j is the first correlation degree between the comparison sequence and the first reference sequence under the j-th monitoring point array to be evaluated;

[0035] Step 2.4: Take the monitoring point array to be evaluated whose correlation does not exceed the first correlation threshold as the optimal monitoring point array of the circuit breaker.

[0036] Preferably, step 2.1 further comprises: normalizing the original data of the spatial electric field of the monitoring point array of the circuit breaker.

[0037] The value of the first correlation threshold is 0.2.

[0038] Step 3 includes:

[0039] Step 3.1: For circuit breakers with different insulation degradation types, based on the optimal monitoring point array, execute step 1 to obtain the optimal monitoring point array degradation spatial electric field constituting a second reference sequence. The spatial electric field measured data of the circuit breaker under the optimal monitoring point array obtained using the spatial electric field measurement model constitutes a monitoring sequence.

[0040] Step 3.2, calculating a second correlation degree between the second reference sequence and the monitoring sequence according to steps 2.2 to 2.3;

[0041] Step 3.3: When the correlation between the monitoring sequence and the second reference sequence is not less than the second correlation threshold, the insulation degradation type corresponding to the second reference sequence is used as the insulation defect of the monitoring sequence, and an early warning is issued.

[0042] The value of the second correlation threshold is 0.9.

[0043] A non-contact insulation monitoring system for circuit breakers based on array space electric field, comprising: a space electric field measurement model module, an optimal monitoring point array module, and an insulation defect early warning module;

[0044] The spatial electric field measurement model module is used to construct a spatial electric field measurement model for a single monitoring point of a circuit breaker, and to correct the measurement results of the spatial electric field measurement model according to environmental factors to obtain the spatial electric field of the monitoring point array of the circuit breaker;

[0045] An optimal monitoring point array module is used to use grey correlation theory to obtain, from the monitoring point array spatial electric field of the circuit breaker, a monitoring point array whose correlation with the defect-free spatial electric field does not exceed a first correlation threshold, as the optimal monitoring point array;

[0046] The insulation defect early warning module is used to issue an insulation defect early warning for the circuit breaker based on the optimal monitoring point array and the grey correlation theory. When the correlation between the measurement results of the spatial electric field measurement model of the circuit breaker and the degraded spatial electric field is not less than the second correlation threshold, the module is used to issue an insulation defect early warning for the circuit breaker according to the degradation type corresponding to the degraded spatial electric field.

[0047] The beneficial effect of the present invention is that, compared with the existing technology, the non-contact insulation monitoring method based on the multi-point array spatial electric field is used to identify and evaluate the degradation status of the high-voltage circuit breaker, which can not only make up for the shortcomings of the existing monitoring means and fill the gap in the non-contact insulation monitoring technology of the high-voltage circuit breaker, but also effectively monitor the degradation of the high-voltage circuit breaker in real time, and timely discover potential fault defects, further ensuring the safe and stable operation of the power system within the jurisdiction. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a flow chart of the non-contact insulation monitoring method for circuit breakers based on array spatial electric field proposed by the present invention;

[0049] Figure 2 Schematic diagram of a D-dot electric field probe according to an embodiment of the present invention;

[0050] Figure 3 A flow chart of a strategy for establishing a spatial electric field monitoring point array in an embodiment of the present invention;

[0051] Figure 4 This is a flow chart of insulation degradation identification in an embodiment of the present invention;

[0052] Figure 5 Schematic diagram of calculation results of the second correlation degree in an embodiment of the present invention. DETAILED DESCRIPTION

[0053] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0054] The present invention provides a non-contact insulation monitoring method for circuit breakers based on array space electric field, such as Figure 1 As shown, including:

[0055] Step 1: construct a spatial electric field measurement model for a single monitoring point of a circuit breaker, and modify the measurement results of the spatial electric field measurement model according to environmental factors to obtain the spatial electric field of the monitoring point array of the circuit breaker.

[0056] Specifically, at any moment, the electric field at a single monitoring point is measured; through continuous measurement, a sequence of electric fields at the monitoring points is obtained within a period of time.

[0057] In a non-limiting preferred embodiment, the spatial electric field measurement model includes: a D-dot (differential capacitive voltage divider) electric field probe, an amplification and filtering module, a Lora communication module, an MCU module, a lithium battery, a battery voltage acquisition module and a charging protection module.

[0058] The principle of D-dot electric field probe is as follows Figure 2 As shown. A hollow metal spherical shell is divided into upper and lower parts. The upper and lower hemispheres after separation are the two electrodes of the space electric field sensor, and they are bonded together by insulating material. A measuring capacitor C is used inside the space electric field sensor. M Connected to the upper and lower hemispheres, if the space electric field sensor is placed perpendicular to the electric field E of the two hemispheres of the space electric field sensor O (t), the two hemispherical electrodes will induce charges, and then measure the capacitance C M An induced voltage U is generated at both ends of M (t), induced voltage U M (t) is the measurement signal of the electric field in space.

[0059] Measuring capacitance C M Voltage across both ends It is directly proportional to the electric field strength at the monitoring point, where Ω is the environmental factor. However, the environmental factors on site change dramatically, resulting in a large gap between the on-site environmental conditions and the theoretical conditions, which leads to a large error in the measured value of the electric field strength at the monitoring point. Therefore, it is necessary to measure the capacitance C. M The induced voltage U M (t) Make corrections.

[0060] Based on the multi-dimensional differentiated correction method, the environmental factor data and the corresponding correction method are used to obtain the measurement signal results of the positive environmental factors.

[0061] Without loss of generality, it is assumed that the environmental factor Ω is a vector with no more than 11 dimensions, including but not limited to temperature, humidity, atmospheric pressure, dew point, magnetic field strength and other dimensional indicators; in this case, the induced voltage correction value satisfies formula (1):

[0062]

[0063] Where,

[0064] is the induced voltage correction value,

[0065] is the voltage across the measuring capacitor under the influence of environmental factors,

[0066] γ is the environmental factor correction coefficient, which satisfies formula (2):

[0067]

[0068] Where,

[0069] α i is the velocity parameter of the i-th dimension,

[0070] M x is the mean of a dimension indicator x,

[0071] Δ i is the deviation limit of the i-th dimension.

[0072] In a non-limiting preferred embodiment, the influence of temperature dimension is taken as an example to introduce Δ i The calculation method is as follows: assuming the standard temperature is t b , one-year statistics are {t1, t 2， …, t 8736}, t represents temperature, the subscript indicates one measurement point per hour, and a year is calculated as 365 days.

[0073] Calculate the mean of the temperature dimension for one year: M t =Mean{t1, t2, ..., t 8736};

[0074] Calculate the variance of the temperature dimension for one year: SD t =SD{t1, t2, ..., t 8736};

[0075] Δ i Take the 3σ point of statistical data for each dimension deviation limit, and the temperature dimension deviation limit Δ t Satisfying formula (3):

[0076] Δ t =3SD t (3)

[0077] Furthermore, if the difference between the on-site environmental conditions and the theoretical conditions is very small, γ is close to 1, and the induced voltage correction value satisfies formula (4):

[0078]

[0079] Therefore, as long as the measured capacitance C is obtained by measurement M The voltage at both ends is measured and the environmental factors are corrected to obtain the induced voltage correction value. Then we can get a more accurate electric field E O (t).

[0080] In addition, whether in a uniform electric field or a non-uniform electric field, the D-dot electric field probe used in the present invention is a spherical spatial electric field sensor that can measure any type of industrial frequency electric field. The measured voltage is proportional to the electric field strength at the monitoring point. Therefore, by measuring and correcting the induced voltage, accurate electric field measurement values ​​can be obtained, which is beneficial to improving the accuracy and reliability of insulation monitoring.

[0081] Step 2: Using grey correlation theory, obtain a monitoring point array whose correlation with the defect-free spatial electric field does not exceed a first correlation threshold from the monitoring point array spatial electric field of the circuit breaker as the optimal monitoring point array.

[0082] Specifically, if Figure 3 As shown, step 2 includes:

[0083] Step 2.1: For a circuit breaker with qualified insulation, the monitoring point array obtained by executing step 1 and the non-defective spatial electric field constitute a first reference sequence Y, where Y = {y(k) | k = 1, 2, ..., n}, where n is the number of monitoring points; for a circuit breaker with degraded insulation, the monitoring point array obtained by executing step 1 and the defective spatial electric field constitute a comparison sequence X j , X j ={x j (k)|k=1,2,…,n}, j=1,2,…,m, where m is the number of types of monitoring point arrays to be evaluated.

[0084] Furthermore, n is also the number of spatial electric field measurement models used for monitoring.

[0085] Preferably, the original data of the spatial electric field of the monitoring point array of the circuit breaker is normalized.

[0086] In a non-limiting preferred embodiment, electric field parameter data at different spatial positions need to be collected. Although the units of the electric field parameter data are consistent, the numerical values ​​vary greatly. Therefore, it is necessary to eliminate the influence of the data magnitude, that is, to normalize the original data to satisfy formula (5):

[0087]

[0088] Where,

[0089] W l [] min is the minimum value in the lattice space electric field data array of the circuit breaker,

[0090] W l [] max is the maximum value in the lattice space electric field data array of the circuit breaker,

[0091] W l[t] is the data to be processed in the lattice space electric field data array of the circuit breaker,

[0092] W l '[t] is the data after normalization.

[0093] Step 2.2: For the j-th monitoring point array to be evaluated, calculate the quantitative characteristic correlation coefficient between each element in the first reference sequence and each element in the comparison sequence, satisfying formula (6):

[0094]

[0095] Where,

[0096] ξ j (k) is the element X in the comparison sequence under the j-th monitoring point array to be evaluated. j The quantitative characteristic correlation coefficient between (k) and the element Y(k) in the first reference sequence,

[0097] ρ is the resolution coefficient, ρ∈(0,1). The smaller ρ is, the greater the resolution. The specific value depends on the situation. When ρ≤0.5463, the resolution is the best, and ρ=0.5 is usually used.

[0098] Step 2.3: For the j-th monitoring point array to be evaluated, the first correlation degree between the comparison sequence and the first reference sequence is determined based on the average value method using the quantity characteristic correlation coefficient, satisfying formula (7):

[0099]

[0100] Where,

[0101] r j is the first correlation degree between the comparison number sequence and the first reference number sequence under the j-th monitoring point array to be evaluated.

[0102] Specifically, the first correlation r j The correlation between the defect electric field and the defect-free electric field corresponding to the j-th monitoring point array to be evaluated is characterized.

[0103] Step 2.4: select the monitoring point array to be evaluated whose correlation does not exceed a first correlation threshold as the optimal monitoring point array for the circuit breaker. The first correlation threshold is set to 0.2.

[0104] Step 3: Based on the optimal monitoring point array and using the grey correlation theory, when the correlation between the measurement result of the spatial electric field measurement model of the circuit breaker and the degraded spatial electric field is not less than the second correlation threshold, an insulation defect warning of the circuit breaker is performed according to the degradation type corresponding to the degraded spatial electric field.

[0105] Specifically, if Figure 4As shown, step 3 includes:

[0106] Step 3.1: For circuit breakers with different insulation degradation types, based on the optimal monitoring point array, execute step 1 to obtain the optimal monitoring point array degradation spatial electric field constituting a second reference sequence, and the spatial electric field measured data of the circuit breaker under the optimal monitoring point array obtained by the spatial electric field measurement model constitutes a monitoring sequence.

[0107] Specifically, the spatial electric field measurement model obtains the measured data of the spatial electric field of the circuit breaker under the optimal monitoring point array through a D-dot electric field probe.

[0108] Step 3.2: Calculate the second correlation degree between the second reference sequence and the monitoring sequence according to steps 2.2 to 2.3.

[0109] Specifically, the second correlation degree represents the correlation degree between the insulation condition of the circuit breaker in the operating state and the insulation defect sample. The greater the correlation degree, the higher the possibility of insulation degradation.

[0110] Step 3.3: When the correlation between the monitoring sequence and the second reference sequence is not less than the second correlation threshold, the insulation degradation type corresponding to the second reference sequence is used as the insulation defect of the monitoring sequence, and an early warning is issued.

[0111] It is worth noting that in the embodiment of the present invention, selecting the monitoring sequence corresponding to the second correlation threshold value of not less than 0.9 for alarm is a non-restrictive and preferred choice. Those skilled in the art can select different second correlation threshold values ​​according to actual project needs and equipment safety requirements.

[0112] Furthermore, for insulation defect samples, the defect levels of different types of insulation defect samples are divided into three categories. When an early warning is issued, not only the insulation fault type can be warned, but the insulation fault level can also be judged to correspond to different levels of fault handling methods.

[0113] The present invention employs grey correlation theory twice. The first use of grey correlation theory in step 2 is used as a strategy for determining the optimal array of monitoring points, which is the array of D-dot electric field probes. The second use of grey correlation theory in step 3 implements an insulation evaluation method for insulation monitoring.

[0114] Taking the degradation monitoring of a phase of a 220kV oil-poor circuit breaker at a substation as an example, a mild degradation alarm was issued at 10:00 am on October 13. In this implementation case, three types of defects (contact damage, insulation damage, and insulation moisture) were selected and three levels of early warning (1 mild, 2 moderate, 3 severe) were issued. The monitoring results at the time of the alarm are as follows: Figure 5 As shown, it shows the insulation moisture level 1 warning.

[0115] The present invention uses a non-contact high-voltage circuit breaker insulation monitoring method based on a multi-point array spatial electric field to identify and evaluate its degradation state. This method can not only make up for the shortcomings of existing monitoring means and fill the gap in non-contact online monitoring technology for high-voltage circuit breakers, but also effectively monitor the degradation of high-voltage circuit breakers in real time, and promptly discover potential fault defects, further ensuring the safe and stable operation of the power system within the jurisdiction.

[0116] The present invention also provides a non-contact insulation monitoring system for circuit breakers based on array space electric field, comprising: a space electric field measurement model module, an optimal monitoring point array module, and an insulation defect early warning module;

[0117] The spatial electric field measurement model module is used to construct a spatial electric field measurement model for a single monitoring point of a circuit breaker, and to correct the measurement results of the spatial electric field measurement model according to environmental factors to obtain the spatial electric field of the monitoring point array of the circuit breaker;

[0118] An optimal monitoring point array module is used to use grey correlation theory to obtain, from the monitoring point array spatial electric field of the circuit breaker, a monitoring point array whose correlation with the defect-free spatial electric field does not exceed a first correlation threshold, as the optimal monitoring point array;

[0119] The insulation defect early warning module is used to issue an insulation defect early warning for the circuit breaker based on the optimal monitoring point array and the grey correlation theory. When the correlation between the measurement results of the spatial electric field measurement model of the circuit breaker and the degraded spatial electric field is not less than the second correlation threshold, the module is used to issue an insulation defect early warning for the circuit breaker according to the degradation type corresponding to the degraded spatial electric field.

[0120] The present disclosure may be a system, method and / or computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0121] A computer-readable storage medium can be a tangible device that can hold and store instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination thereof. As used herein, a computer-readable storage medium is not to be construed as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through an electrical wire.

[0122] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions to be stored in the computer-readable storage medium in each computing / processing device.

[0123] The computer program instructions for performing the operations of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, and conventional procedural programming languages ​​such as "C" language or similar programming languages. Computer-readable program instructions may be executed entirely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., utilizing an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be personalized by utilizing the state information of the computer-readable program instructions. The electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A non-contact insulation monitoring method for circuit breakers based on array space electric field, characterized in that: include: Step 1: construct a spatial electric field measurement model for a single monitoring point of a circuit breaker, and correct the measurement results of the spatial electric field measurement model according to environmental factors to obtain the spatial electric field of the monitoring point array of the circuit breaker; Step 2, using grey correlation theory, obtains a monitoring point array whose correlation with the defect-free spatial electric field does not exceed a first correlation threshold from the spatial electric field of the monitoring point array of the circuit breaker as the optimal monitoring point array; including: Step 2.1: For a circuit breaker with qualified insulation, the electric field of the monitoring point array obtained by executing step 1 constitutes the first reference sequence. , ,in is the number of monitoring points; for the circuit breaker with insulation degradation, the monitoring point array obtained by executing step 1 has a defective spatial electric field forming a comparison series , , , is the number of types of monitoring point arrays to be evaluated; Step 2.2, the first The quantitative characteristic correlation coefficient between each element in the first reference sequence and each element in the comparison sequence is calculated as follows: Where, This is the first Compare the elements in the sequence under the monitoring point array With the element in the first reference sequence The quantitative characteristic correlation coefficient between is the resolution coefficient, ; Step 2.3, the first A monitoring point array is used, and a first correlation degree between a comparison sequence and a first reference sequence is determined based on an average value method using a quantity characteristic correlation coefficient, as shown in the following formula: Where, This is the first a first correlation degree between the comparison number sequence and the first reference number sequence under the monitoring point array; Step 2.4, taking the monitoring point array to be evaluated whose correlation does not exceed the first correlation threshold as the optimal monitoring point array of the circuit breaker; Step 3: Based on the optimal monitoring point array and using the grey correlation theory, when the correlation between the measurement result of the spatial electric field measurement model of the circuit breaker and the degraded spatial electric field is not less than the second correlation threshold, an insulation defect warning of the circuit breaker is performed according to the degradation type corresponding to the degraded spatial electric field.

2. The method for non-contact insulation monitoring of circuit breakers based on array space electric field according to claim 1, characterized in that: The spatial electric field measurement model includes: d-dot electric field probe; In the D-dot electric field probe, capacitance is measured Voltage across both ends It is proportional to the electric field strength at the monitoring point; Environmental factors is a vector with no more than 11 dimensions; The induced voltage correction value is as follows: Where, For the moment The induced voltage correction value, Moments influenced by environmental factors The voltage across the measuring capacitor, is the correction factor for environmental factors.

3. The non-contact insulation monitoring method for circuit breakers based on array space electric field according to claim 2, characterized in that: The environmental factor correction factor is as follows: Where, For the The velocity parameter of the dimension, For a dimension indicator The mean of For the Dimensions deviate from the limit.

4. The method for non-contact insulation monitoring of circuit breakers based on array space electric field according to claim 1, characterized in that: Step 2.1 also includes: normalizing the original data of the spatial electric field of the monitoring point array of the circuit breaker.

5. The non-contact insulation monitoring method for circuit breakers based on array space electric field according to claim 1, characterized in that: The value of the first correlation threshold is 0.

2.

6. The method for non-contact insulation monitoring of circuit breakers based on array space electric field according to claim 1, characterized in that: Step 3 includes: Step 3.1: For circuit breakers with different insulation degradation types, based on the optimal monitoring point array, execute step 1 to obtain the optimal monitoring point array degradation spatial electric field constituting a second reference sequence. The spatial electric field measured data of the circuit breaker under the optimal monitoring point array obtained using the spatial electric field measurement model constitutes a monitoring sequence. Step 3.2, calculating a second correlation degree between the second reference sequence and the monitoring sequence according to steps 2.2 to 2.3; Step 3.3: When the correlation between the monitoring sequence and the second reference sequence is not less than the second correlation threshold, the insulation degradation type corresponding to the second reference sequence is used as the insulation defect of the monitoring sequence, and an early warning is issued.

7. The method for non-contact insulation monitoring of circuit breakers based on array space electric field according to claim 6, characterized in that: The value of the second correlation threshold is 0.

9.

8. A circuit breaker non-contact insulation monitoring system based on array spatial electric field, used to implement the method according to any one of claims 1 to 7, characterized in that: include : Space electric field measurement model module, optimal monitoring point array module, insulation defect early warning module; The spatial electric field measurement model module is used to construct a spatial electric field measurement model for a single monitoring point of a circuit breaker, and to correct the measurement results of the spatial electric field measurement model according to environmental factors to obtain the spatial electric field of the monitoring point array of the circuit breaker; The optimal monitoring point array module is used to use the grey correlation theory to obtain a monitoring point array whose correlation with the defect-free spatial electric field of the monitoring point array of the circuit breaker does not exceed a first correlation threshold from the spatial electric field of the monitoring point array of the circuit breaker as the optimal monitoring point array; wherein, for the circuit breaker with qualified insulation, the defect-free spatial electric field of the monitoring point array obtained by executing step 1 constitutes a first reference sequence , ,in is the number of monitoring points; for the circuit breaker with insulation degradation, the monitoring point array obtained by executing step 1 has a defective spatial electric field forming a comparison series , , , is the number of types of monitoring point arrays to be evaluated; The quantitative characteristic correlation coefficient between each element in the first reference sequence and each element in the comparison sequence is calculated as follows: Where, This is the first Compare the elements in the sequence under the monitoring point array With the element in the first reference sequence The quantitative characteristic correlation coefficient between is the resolution coefficient, ; To be evaluated A monitoring point array is used, and a first correlation degree between a comparison sequence and a first reference sequence is determined based on an average value method using a quantity characteristic correlation coefficient, as shown in the following formula: Where, This is the first a first correlation degree between the comparison number sequence and the first reference number sequence under the monitoring point array; Taking the monitoring point array to be evaluated whose correlation does not exceed the first correlation threshold as the optimal monitoring point array of the circuit breaker; The insulation defect early warning module is used to issue an insulation defect early warning for the circuit breaker based on the optimal monitoring point array and the grey correlation theory. When the correlation between the measurement results of the spatial electric field measurement model of the circuit breaker and the degraded spatial electric field is not less than the second correlation threshold, the module is used to issue an insulation defect early warning for the circuit breaker according to the degradation type corresponding to the degraded spatial electric field.

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