A method for detecting and positioning partial discharge pulse current of a switch cabinet

Abstract

The application relates to a switch cabinet partial discharge pulse current detection positioning method, a 3D simulation model containing a switch cabinet and a partial discharge pulse current sensor is established, and a switch cabinet simulation circuit diagram is established; different types of partial discharge pulse current sources are sequentially arranged at each position in the switch cabinet, simulated pulse signal waveform amplitudes of each position of multiple measuring points are obtained, and a database is established; time domain waveforms of partial discharge pulse current signals in the switch cabinet are collected on site, time domain waveform amplitudes of multiple measuring points are obtained; the position of partial discharge is determined based on a digital twin simulation waveform amplitude calculation method; the precision of partial discharge positioning can be greatly improved, and the positioning result can be accurate to a certain component in the switch cabinet. Precise positioning can greatly improve the accuracy and work efficiency of equipment insulation defect diagnosis prediction and operation and maintenance, and greatly improve the safety and reliability of the switch cabinet.

Description

Technical Field

[0001] This invention relates to a method for detecting and locating partial discharge pulse current in switchgear, belonging to the field of power distribution network technology. Background Technology

[0002] High-voltage switchgear is a crucial electrical device in power distribution networks. Its main function is to open, close, control, and protect electrical equipment during power generation, transmission, distribution, and energy conversion. The components within a switchgear primarily include circuit breakers, disconnect switches, load switches, operating mechanisms, instrument transformers, and various protective devices.

[0003] During the production, transportation, installation, and maintenance of high-voltage switchgear, defects such as cracks, metal burrs, and scattered metal impurities are unavoidable. With long-term operation, these defects cause the local electric field strength on or inside the insulation surface to exceed the critical electric field strength of the insulation medium itself, thus triggering partial discharge. Furthermore, the persistent partial discharge phenomenon can further degrade the insulation, accelerating insulation failure.

[0004] Partial discharge is accompanied by various physical phenomena such as sound, electricity, light, and heat. Various partial discharge detection methods have developed by monitoring these physical quantities that reflect the discharge phenomena. Currently, commonly used detection methods both domestically and internationally include ultrasonic methods, ultra-high frequency methods, and transient voltage-to-ground methods. These methods generally locate partial discharges by measuring their amplitude. These methods are all external detection methods. Due to the complex propagation process of partial discharge signals and the complexity of on-site interference, these methods suffer from low positioning accuracy and large errors. Even under good detection conditions, these methods can only determine roughly which side of the switchgear the partial discharge is located on, but not which component inside the switchgear it is located on. Inaccurate positioning hinders precise maintenance decision-making.

[0005] Existing partial discharge location technologies for switchgear all employ time-domain location methods, which locate the device based on the amplitude and time delay of the time-domain waveform. However, this method requires extremely high resolution of the measuring instruments, and due to interference, it is very likely to cause misjudgment or omission of information such as the amplitude of the waveform and the arrival time of the first wave, thus reducing the location accuracy. Summary of the Invention

[0006] The purpose of this invention is to provide a method for detecting and locating partial discharge pulse current in switchgear, so as to solve the problems mentioned in the background art.

[0007] The technical solution of the present invention is as follows:

[0008] A method for detecting and locating partial discharge pulse current in switchgear includes the following steps:

[0009] S1. Establish a 3D simulation model including the switch cabinet and the partial discharge pulse current sensor. Obtain the capacitance of each part in the switch cabinet through electric field simulation, and then establish the simulation circuit diagram of the switch cabinet.

[0010] Different types of partial discharge pulse current sources are successively set in various parts of the switch cabinet to obtain the simulated pulse signal waveform amplitudes of various parts at multiple measurement points, and a database is established.

[0011] S2. Conduct partial discharge signal detection on site, collect the time-domain waveform of the partial discharge pulse current signal in the switchgear, and obtain the time-domain waveform amplitude at multiple measurement points;

[0012] S3. Based on the digital twin simulation waveform amplitude calculation method, the amplitude of the actual measured time-domain waveform and the amplitude of the simulated pulse signal waveform are calculated to determine the location of partial discharge.

[0013] Preferably, the database is an n×m matrix, where n represents the number of components inside the switch cabinet and m represents the number of measurement points.

[0014] Preferably, the database is viewed as a set of n vectors, each containing m elements, denoted by M. i Logo:

[0015] M i =(U th1i U th2i …U thmi ), i = 1, 2, ..., n;

[0016] The measured pulse current waveform amplitudes at each measurement point of the switchgear are also considered as vectors, each containing m elements, denoted by S:

[0017] S=(U ts1 U ts2 …U tsm )

[0018] Calculate S and Mi one by one using the following formulas, and use the point with the largest value as the positioning result:

[0019] D i =U th1i ·U ts1 +U th2i ·U ts2 +…+U thmi ·U tsm .

[0020] The present invention has the following beneficial effects:

[0021] This method can significantly improve the accuracy of partial discharge location, with results pinpointing even to a specific component inside the switchgear. Furthermore, it offers greater robustness. Achieving precise location using this method will greatly enhance the accuracy and efficiency of equipment insulation defect diagnosis and prediction, as well as maintenance, thereby significantly improving the safety and reliability of the switchgear. Attached Figure Description

[0022] Figure 1 This is an electrical connection diagram of the switch cabinet of the present invention;

[0023] Figure 2 This is the technical approach of the present invention;

[0024] Figure 3 This is a diagram of the internal structure of the high-voltage switchgear of the present invention;

[0025] Figure 4 This is a simulation circuit diagram of the high-voltage switchgear of the present invention;

[0026] Figure 5 This is a database of waveform parameters for partial discharge pulse current signals in high-voltage switchgear, as described in this invention.

[0027] The reference numerals in the figure are as follows:

[0028] 1. Busbar; 2. Circuit breaker; 3. Current transformer; 4. Surge arrester; 5. Live indicator; 6. Grounding switch; 7. High-voltage cable; 8. Coupling capacitor; 9. Pulse current coupling unit; 10. High-voltage sensor; 11. Disconnecting switch. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0030] The technical principle of this invention is as follows: when a component in the switch cabinet experiences partial discharge, its pulse current signal reaches the detection coupling device, and its transfer function depends on the line in the propagation path and the impedance characteristics of each component; the time-domain waveform amplitude of the signal obtained by the coupling device is directly related to the location of the partial discharge; by using the measured time-domain waveform amplitude of the partial discharge pulse current signal and the simulated waveform amplitude to perform time-domain waveform correlation calculation, the component where the partial discharge is located can be mapped.

[0031] Example:

[0032] The electrical wiring diagrams for the internal components of the high-voltage switchgear are as follows: Figure 1 As shown, the high-voltage switchgear mainly consists of busbar 1, circuit breaker 2, current transformer 3, surge arrester 4, live indicator 5, grounding switch 6, and high-voltage cable 7. To couple partial discharge pulse signals, coupling capacitors 8 and pulse current coupling units 9 are arranged at the phase-connected holes of the switchgear.

[0033] Flowchart as follows Figure 2 As shown:

[0034] First, a 3D simulation model including the switchgear and partial discharge pulse current sensor is established. The capacitance of each component is obtained through electric field simulation. The capacitance parameters can be calculated using two methods: the parallel plate capacitance method and the electrostatic field finite element method. Based on this, a simulation circuit diagram of the switchgear is established, such as... Figure 4 As shown, different types of partial discharge pulse current sources were successively set at the busbar 1, current transformer 3, surge arrester 4 and other parts of the switch cabinet to obtain the simulated time-domain amplitude of each part at multiple measurement points and establish a database.

[0035] Second, partial discharge signal detection was carried out on site, and the time-domain waveform of the partial discharge pulse current signal in the switch cabinet was collected to obtain the signal amplitude at multiple measurement points.

[0036] Third, by performing waveform amplitude correlation calculations between the actual measured waveform and the simulated waveform, the location of the partial discharge can be determined.

[0037] In the simulation, local discharge power supplies were set up for each component of the switchgear (component number i, i = 1, 2, ..., n). Pulse current signals were obtained through simulation, and the amplitude of the pulse signal waveform (U) at each measurement point was extracted. th ) parameters, to establish a signal waveform amplitude database. For example Figure 5 As shown, the database is an n×m matrix.

[0038] Partial discharge signals are measured in the switchgear, and the time-domain waveform amplitude U of the pulse current signal at each measurement point is obtained. ts1 U ts2 …U tsi .

[0039] View the database as a set of n vectors, each containing m elements, and use M... i The identifier, namely:

[0040] Mi=(U th1i U th2i …U thmi ), i = 1, 2, ..., n

[0041] The measured pulse current waveform amplitudes at each measurement point of the switchgear are also considered as vectors, each containing m elements, denoted by S, i.e.:

[0042] S=(U ts1 U ts2 …U tsm )

[0043] S and M are calculated one by one using the amplitude correlation calculation formula. iThe point with the largest correlation is selected as the positioning result. The calculation method for amplitude correlation is as follows:

[0044] D i =U th1i ·U ts1 +U th2i ·U ts2 +…+U thmi ·U tsm .

[0045] This invention will greatly improve the accuracy and efficiency of on-site partial discharge testing and switchgear maintenance, avoid putting equipment into operation with defects, and greatly promote the advancement of electrical equipment testing and inspection technology.

[0046] From an economic perspective, if the core technology of this invention is industrialized and marketed, it will greatly improve the accuracy and efficiency of partial discharge diagnosis of switchgear and reduce the probability of insulation failure in switchgear, resulting in significant direct and indirect economic benefits.

[0047] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for detecting and locating partial discharge pulse current in a switchgear, characterized in that: Includes the following steps: S1. Establish a 3D simulation model including the switch cabinet and the partial discharge pulse current sensor. Obtain the capacitance of each part in the switch cabinet through electric field simulation, and then establish the simulation circuit diagram of the switch cabinet. Different types of partial discharge pulse current sources are successively set in various parts of the switch cabinet to obtain the simulated pulse signal waveform amplitudes of various parts at multiple measurement points, and a database is established. S2. Conduct partial discharge signal detection on site, collect the time-domain waveform of the partial discharge pulse current signal in the switchgear, and obtain the time-domain waveform amplitude at multiple measurement points; S3. Based on the digital twin simulation waveform amplitude calculation method, the amplitude of the actual measured time-domain waveform and the amplitude of the simulated pulse signal waveform are calculated to determine the location of the partial discharge; The database is an n×m matrix, where n represents the number of components inside the switch cabinet and m represents the number of measurement points; View the database as a set of n vectors, each containing m elements, denoted by Mi: M i =( U th1i , U th2i ...U thmi ), i=1, 2……n; The measured pulse current waveform amplitudes at each measurement point of the switchgear are also considered as vectors, each containing m elements, denoted by S: S=(U ts1 ,IN ts2 …IN tsm ) Calculate S and M one by one using the following formulas. i The point with the largest value is used as the location result: 。

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