Insulator surface charge cleaning method based on plasma discharge

Abstract

According to the insulator surface charge cleaning method based on plasma discharge provided by the invention, the surface charge of the insulator can be actively, quickly and safely neutralized and cleaned through a composite discharge mode of pulse + direct current bias under the condition that equipment is not disassembled; the method comprises the following steps; equipment connection; setting and generating parameters of a composite waveform; high-voltage amplification; the plasma discharges to sweep charges; the discharge plasma device generates a high-pulse voltage electric field to reach gas breakdown field strength, a violent ionization reaction occurs, a large number of charged particles are further generated, and when superposed voltage acts during a pulse interval, the charged particles generated during the pulse interval migrate to the surface of the insulator under the action of the electric field generated during the pulse interval, so that the charged particles are formed. When residual charges in the discharge space are swept, migrated charges are used for neutralizing charges on the surface of the insulator, so that the charges on the surface of the insulator are swept; and cleaning is finished.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of insulator cleaning, in particular to an insulator surface charge cleaning method based on plasma discharge. BACKGROUND

[0002] Gas insulated switchgear is the core equipment of modern power system, and its reliability is directly related to the safe and stable operation of the entire power grid. As a key insulating component in GIS, the surface charge accumulation problem of the basin-type insulator has been a serious technical challenge for a long time. A large amount of charge will accumulate under long-term operation, and a large amount of dust will be electrostatically attracted during power-off maintenance. Long-term surface charge accumulation of the insulator leads to electric field distortion, reduction of insulation strength and potential flashover failure, so it is necessary to effectively eliminate the surface charge periodically.

[0003] Currently, the commonly used methods for accelerating charge dissipation include applying a reverse electric field or heating, but the efficiency is low, and the insulating material itself may be damaged by heat or electrical aging, which is not ideal.

[0004] Based on the above background, it is necessary to quickly and actively restore the insulator to the initial state of "zero charge" during equipment maintenance, in order to prepare for subsequent withstand voltage tests and long-term stable operation. Low-temperature plasma is favored by scholars in the field of charge cleaning due to its unique physical and chemical properties, so a "non-contact" technology is developed, which does not require the discharge electrode to directly contact the surface of the insulator, avoiding the risk of physical damage. By innovatively using a composite voltage waveform of "pulse particle generation + direct current migration guidance", an advanced process is realized, which can actively, quickly and safely neutralize and remove the surface charge without disassembling the equipment. This technology is an important technical breakthrough in improving the reliability of GIS operation, realizing intelligent operation and maintenance, and promoting the development of environmentally friendly power grid equipment. SUMMARY

[0005] The present application aims to overcome the technical defects of the prior art and provides an insulator surface charge cleaning method based on plasma discharge, which can actively, quickly and safely neutralize and remove the surface charge of the insulator without disassembling the equipment through a composite discharge mode of "pulse + direct current bias".

[0006] The present application provides the following technical solution: an insulator surface charge cleaning method based on plasma discharge, comprising the following steps:

[0007] Step 1: Equipment connection; connect the output end of the voltage waveform generation device to the discharge plasma device, and place the insulator to be cleaned in the discharge gap of the discharge plasma device; the voltage waveform generation device comprises a high-voltage amplifier and a function generator;

[0008] Step 2, parameter setting and generation of composite waveform; set pulse parameters, DC voltage parameters, waveform type and DC bias parameters in the function generator, and generate voltage waveform and send to the high-voltage amplifier;

[0009] Step 3, high-voltage amplification; the high-voltage amplifier raises the voltage waveform of the function generator and applies it to the discharge plasma device;

[0010] Step 4, plasma discharge charge cleaning; the discharge plasma device generates a high pulse voltage electric field to reach the gas breakdown field strength, causing a violent ionization reaction, and then generating a large number of charged particles. When there is a superimposed voltage during the pulse interval, the charged particles generated during the pulse interval will migrate to the surface of the insulator under the action of the electric field generated during the pulse interval. While cleaning the residual charge in the discharge space, the migrated charge is used to neutralize the surface charge of the insulator, achieving the cleaning of the surface charge of the insulator;

[0011] Step 5, cleaning is completed; when the surface charge of the insulator is reduced to the target level, first turn off the voltage waveform generation device, then turn off the discharge plasma device, and finally use the bleed rod to ground to discharge the charge at the output end of the discharge plasma device and the high-voltage amplifier. The bleed rod contacts the high-voltage end of the discharge plasma device and the output end of the high-voltage amplifier.

[0012] Further,

[0013] When the voltage waveform generation device drives the discharge process of the discharge plasma device, any one of pulse, square wave, sine wave, triangular wave, and sawtooth wave is used as the voltage waveform. The voltage waveform generation device superimposes the same polarity voltage during the voltage interval.

[0014] Further,

[0015] In step 2, the function generator sets pulse parameters, DC voltage parameters, waveform type and DC bias parameters. The pulse voltage polarity and the bias voltage polarity are set to be the same, the voltage polarity is positive or negative, the bias voltage waveform is set to be DC or a certain fluctuation ripple voltage, and the bias voltage exists for 1%~100% of the overall voltage interval.

[0016] Further,

[0017] It is characterized in that, in step 2, the parameter setting and generation of the composite waveform, the function generator generates the composite waveform using the following mathematical formula:

[0018] wherein, is the output voltage, is the pulse voltage amplitude, is the pulse width, is the duration of the DC voltage, is the duration of the DC voltage, is the time of the pulse and DC intersection, t is the time variable, is the rectangular window function, which defines the timing position of the pulse and DC, wherein, = 10 ns, is the guard interval to prevent the pulse and DC from overlapping; the required voltage waveform is obtained by adjusting the input function of the function generator.

[0019] Further,

[0020] The step 3 further comprises waveform calibration, by calving the high-voltage amplifier, inputting a 1V sine wave, adjusting the high-voltage amplifier gain to output 2kV, inputting a pulse width of 1000ns, verifying whether the output high-voltage pulse voltage pulse width is 1000ns, connecting a 1kΩ resistor in series at the output end of the high-voltage amplifier, using a high-voltage differential probe to capture the output voltage waveform, and confirming that there is no distortion and that THD < 5%.

[0021] Further,

[0022] The discharge plasma device comprises an electrode structure, the electrode structure adopts any one of a single needle-plate electrode, a multi-needle-plate electrode, a needle-needle electrode structure, and a plate-plate electrode structure, the electrode structure comprises a high-voltage end and a grounding end, the high-voltage end is connected to the output end of the high-voltage amplifier, and the grounding end is grounded.

[0023] Further,

[0024] The discharge gap spacing between the high-voltage end and the grounding end is 10-150mm.

[0025] Further,

[0026] The position of the needle electrode in the multi-needle-plate electrode is any one of a straight line, a circle, a triangle, a quadrilateral, a pentagon, a hexagon, a heptagon, and an octagon.

[0027] Further,

[0028] In the step 5, the surface charge of the insulator is scanned and detected by using an electrostatic probe to scan the surface charge density on the surface of the insulator, and the potential formed by the surface charge density satisfies a target value ≤ 150V.

[0029] Further,

[0030] The electrode material of the electrode structure adopts any one of stainless steel, copper, iron, aluminum, and nickel.

[0031] Compared with the prior art, the beneficial effects of the present application are:

[0032] The method realizes efficient and lossless cleaning by non-contact plasma discharge, uses precisely controllable complex waveforms to drive charged particles to actively neutralize the surface charge of insulators, effectively solves the problem of surface charge accumulation of insulators that cannot be handled by traditional methods, and significantly improves the insulation reliability and operation efficiency of equipment.

[0033] 1. Efficient active cleaning:

[0034] The method uses high-amplitude pulses to establish a strong electric field in a very short time (nanoseconds / microseconds), efficiently breaks down the gas, generates high-density plasma, and generates a large number of positive and negative charged particles as "cleaning media" to actively neutralize the charge on the surface of the insulator, achieving rapid and active removal. It cleverly uses the synergistic effect of "pulse ionization" and "direct current migration", generates high-density charged particles during the pulse phase, and guides the charged particles with a specific polarity generated during the pulse phase to migrate directionally to the surface of the insulator during the direct current bias phase, achieving efficient charge transfer and neutralization, and being able to reduce the surface charge to a very low target level. This process not only cleans the surface charge of the insulator, but also removes residual charge in the discharge space, creating a clean environment for the next pulse discharge and avoiding secondary accumulation, fundamentally eliminating the problem of charge accumulation on the surface of the insulator.

[0035] 2. Non-contact operation, lossless and safe:

[0036] During the entire cleaning process, the discharge electrode has no direct physical contact with the surface of the insulator, completely avoiding scratches, wear and tear or contamination that may be caused by traditional physical wiping, which is crucial for precise and expensive GIS pot-type insulators. By precisely controlling discharge parameters such as pulse width, frequency, it can ensure that the plasma is in a low-temperature non-equilibrium state, i.e. high electron temperature and low gas temperature. This can not only ensure effective ionization, but also prevent high temperature from causing thermal aging, decomposition or carbonization of organic insulating materials such as epoxy resin;

[0037] 3. Precise control:

[0038] The amplitude, frequency, pulse width and DC bias size and polarity of the pulse can be flexibly set by the function generator. This allows the method to adapt to different types of insulators, different pollution (charge) conditions and different gas environments; for example, the polarity of the direct current bias can be adjusted according to the polarity of the surface charge to drive ions of the opposite polarity to neutralize precisely; when the charge is reduced to the "target level", it can be stopped to avoid over-cleaning or insufficient cleaning. BRIEF DESCRIPTION OF DRAWINGS

[0039] Fig. 1 Connection diagram of voltage waveform generation device and discharge plasma device of the present application;

[0040] Fig. 2 Figure 1 is a diagram showing the effect of cleaning space positive charges by a direct current voltage obtained by numerical simulation of a positive pulse superimposed on a positive direct current according to the present application.

[0041] Explanation of reference signs:

[0042] 1. High-voltage amplifier; 2. Function generator; 3. High-voltage terminal; 4. Ground terminal. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor fall within the scope of the present application.

[0044] As shown in Fig. 1, which shows a specific embodiment of the present application: Figs. 1-2

[0045] The insulator surface charge cleaning method based on plasma discharge comprises the following steps:

[0046] Step 1. Device connection: connecting the output end of a voltage waveform generating device to a discharge plasma device, and placing the insulator to be cleaned in the discharge gap of the discharge plasma device; the voltage waveform generating device comprises a high-voltage amplifier 1 and a function generator 2.

[0047] Step 2. Parameter setting and generation of complex waveform: setting pulse parameters, direct current voltage parameters, and waveform type direct current bias parameters in the function generator 2, and generating a voltage waveform and sending it to the high-voltage amplifier 1.

[0048] Step 3. High-voltage amplification: the high-voltage amplifier 1 raises the voltage waveform of the function generator 2 and applies it to the discharge plasma device.

[0049] Step 4. Plasma discharge cleaning of charges: the discharge plasma device generates a high pulse voltage electric field reaching the gas breakdown field strength, causing a violent ionization reaction and generating a large number of charged particles. When there is a superimposed voltage during the pulse interval, the charged particles generated during the pulse interval will migrate to the surface of the insulator under the action of the electric field generated during the pulse interval, thereby cleaning the residual charges in the discharge space and neutralizing the surface charges of the insulator, achieving cleaning of the surface charges of the insulator.

[0050] Step 5. Cleaning is completed: when the surface charge of the insulator decreases to the target level, first turn off the voltage waveform generating device, then turn off the discharge plasma device, and finally use a bleeder rod to ground to discharge the charges at the output end of the discharge plasma device and the high-voltage amplifier 1. The bleeder rod contacts the high-voltage terminal 3 of the discharge plasma device and the output end of the high-voltage amplifier 1. ​

[0051] For example, in the function generator set the parameters of the pulse, such as frequency 10 kHz, pulse width 50 ns, amplitude 5 V (amplified target for 10 kV); and the parameters of the DC voltage, such as amplitude 0.5 V (amplified target for 1000 V), waveform type DC bias, start DC output after the pulse falling edge, DC duration is during the pulse interval.

[0052] As shown in Fig. 2 The difference between the contrast and the non-superimposed DC voltage and DC different size, the charge cleaning effect.

[0053] Fig. 2 The numerical simulation of the positive pulse superimposed positive DC case obtained by the DC voltage cleaning space positive charge effect diagram, from the results can be known when the superimposed DC to a certain extent, can effectively sweep the discharge space of the positive charge left, DC voltage from 800 V to 1200 V, the number of positive charge cleaning increased by more than 1 times, at the same time with the increase of the number of pulse, the number of charge cleaning also increases, for subsequent improve the pulse discharge energy provides favorable environment.

[0054] Specifically,

[0055] The voltage waveform generating device drives the discharge process of the discharge plasma device, adopts any one of pulse, square wave, sine wave, triangular wave, sawtooth wave voltage waveform, and the voltage waveform generating device superimposes the voltage with the same polarity during the voltage interval.

[0056] The method can use various waveforms (pulse, square wave, etc.) to drive discharge. In the voltage interval of the basic waveform, i.e. zero potential period, a direct current bias voltage of the same polarity is superimposed to realize directional migration. Taking the pulse wave as an example, in a pulse cycle, the voltage rises from 0 to high voltage instantaneously, and then falls back to 0. During the pulse period (high voltage stage), the gas is broken down to produce various charged particles including electrons, positive ions and negative ions. When the voltage falls back to 0, the residual charged particles in the discharge space begin to diffuse freely, part of which is combined and disappears, and part of which moves randomly. Although some particles will reach the surface of the insulator, this process is random and inefficient, and is not a controlled directional migration. The method cleverly solves the above problems by "superimposing the same polarity voltage during the voltage interval". Taking the superposition of positive pulse wave and positive direct current bias as an example, during the pulse interval period (directional migration stage), the pulse high voltage disappears, but does not fall to 0, but maintains a lower positive direct current bias voltage (for example, +1kV). This voltage itself is usually not enough to directly break down the gas, but it maintains a continuous and constant (positive polarity) weak electric field. The positive electric field will immediately push and absorb the electrons with light mass and high mobility to the anode (ground electrode), thereby quickly removing the electrons from the discharge space. The positive ions with heavy mass and low mobility will make directional and continuous drift motion to the cathode (i.e. the surface of the insulator) under the drive of the positive electric field. These positive ions guided by the electric field will eventually bombard the surface of the insulator with negative charge (or need to be neutralized), achieving efficient charge neutralization. At the same time, this process also cleans the positive ions in the discharge space, creating a "clean" starting point for the next pulse cycle.

[0057] Among them, pulse wave and square wave are the most typical and effective. The high level and low level (after superimposing bias) are clearly distinguished, and the ionization stage and migration stage are completely separated in time, with the highest control accuracy.

[0058] Regardless of the change of the basic waveform, the "same polarity bias voltage superimposed during the interval period" plays the role of an "electric field baton", ensuring that there is a continuous and one-way force to guide the charged particles to do useful work (migration neutralization) between two high-energy ionization pulses, rather than wasting them. The originally disordered and inefficient random diffusion process is transformed into a highly ordered, efficient and controllable directional transport process, thereby greatly improving the efficiency and reliability of surface charge cleaning.

[0059] Specifically,

[0060] The function generator 2 in step 2 sets pulse parameters, DC voltage parameters, waveform type DC bias parameters, sets the pulse voltage polarity and the same polarity as the bias voltage, the voltage polarity is positive or negative, sets the bias voltage waveform to be DC or a certain fluctuation ripple voltage, and sets the bias voltage existing time to be 1%~100% of the overall voltage interval time.

[0061] The setting of the same polarity of the pulse voltage and the bias voltage ensures the correctness of the cleaning direction and the efficiency of the process. The bias waveform (DC / ripple) provides a control dimension for the migration driving force. Appropriate fluctuations sometimes help to prevent ions from "accumulating" or forming space charge blockage in the migration path, which may be beneficial to maintain the smoothness of the migration channel. However, as long as the valley value of the ripple can effectively maintain a directional electric field, the overall effect is similar to that of DC bias.

[0062] The bias time ratio is a fine adjustment of the rhythm of the two core links of "ionization" and "migration" on the time axis, allowing the operator to optimize the entire work cycle according to the specific discharge geometry, gas type and insulator state.

[0063] Specifically,

[0064] It is characterized in that the parameter setting and generation of the composite waveform in step 2, the function generator 2 uses the following mathematical formula to generate the composite waveform:

[0065] wherein, is the output voltage, is the pulse voltage amplitude, is the pulse width, is the DC voltage amplitude, is the duration of the DC voltage, is the time of pulse and DC intersection, t is the time variable, is a rectangular window function that defines the timing position of pulse and DC, wherein, =10ns, is a guard interval to prevent pulse and DC from overlapping; by adjusting the input function of the function generator 2, the required voltage waveform is obtained.

[0066] As Fig. 1As shown, the specific embodiment includes a high-voltage amplifier 1 and a function generator 2 composite voltage waveform generating device and a multi-needle-plate electrode discharge plasma device, the output end of the function generator 2 is connected to the input port of the high-voltage amplifier through a 50Ω coaxial cable, the output end of the high-voltage amplifier is connected to the needle electrode through a high-voltage cable, the plate electrode is grounded, the high-voltage end 3 is a multi-needle electrode, the ground end 4 is a plate electrode, the pulse amplitude, frequency, pulse width range, DC voltage amplitude range, duration, etc. output by the function generator 2 are all adjustable; the pulse amplitude range output is 1V~10V (before amplification); the pulse frequency range output is 1kHz~1MHz, the resolution is 1Hz; the pulse width range output is 10ns~100ns, the rise time is less than 5ns; the DC voltage duration output is 0.1μs~100μs, the accuracy is ±1%; the DC voltage amplitude range output is 0.1V~5V (before amplification); the timing error of the generated pulse superimposed with DC is less than 1ns;

[0067] By adjusting the input function of the function generator, the required voltage waveform is obtained, such as Fig. 2 As shown, the voltage during the pulse interval is changed from the common 0V to 400V, 800V and 1200V, and the space charge sweeping effect diagram is obtained. When the pulse voltage produces discharge, during the common 0V pulse interval voltage, the 0V voltage during the interval cannot form an applied electric field, and cannot effectively migrate the residual charges in the space, so that the charges still accumulate in the space, inhibiting the subsequent pulse discharge. When there is an applied voltage during the pulse interval, the electric field generated by the voltage applied during the pulse interval can be used to migrate the residual charges in the discharge space under the action of the electric field, so as to achieve the purpose of sweeping the space charges, so that the subsequent pulse discharge is enhanced, and the charges can produce directional migration effect.

[0068] In the application of sweeping the surface charges of insulators, during power outage maintenance, the insulator is placed in the discharge gap of the multi-needle-plate electrode, and the excitation voltage generated by the function generator and the high-voltage amplifier acts on the multi-needle electrode, and the high pulse voltage makes the electric field reach the gas breakdown field strength, and then a large number of charged particles are generated. When there is a voltage during the pulse interval, the charged particles generated during the pulse interval will migrate to the surface of the insulator under the action of the electric field generated during the pulse interval, and at the same time, the migrated charges are used to neutralize the surface charges of the insulator, so as to finally achieve the purpose of sweeping the surface charges of the insulator.

[0069] The input voltage and output voltage of the high-voltage amplifier 1 are adjustable; the input voltage range is 0V-10V, and the impedance is 50Ω; the output voltage range is 0V-20kV, and the gain G=2000; the bandwidth is 100MHz, so as to ensure that the nanosecond pulse waveform is not distorted.

[0070] Specifically,

[0071] Waveform calibration is also included in step 3. By calibrating the high-voltage amplifier 1, input a 1V sine wave, adjust the high-voltage amplifier 1 gain to output 2kV, input pulse width of 1000ns, verify whether the output high-voltage pulse voltage pulse width is 1000ns, the output end of the high-voltage amplifier 1 is connected in series with a 1kΩ resistor, and the output voltage waveform is captured using a high-voltage differential probe, confirming that there is no distortion and the THD is less than 5%.

[0072] The calibration step ensures that the voltage waveform applied to the discharge plasma device is highly consistent with the ideal waveform set by the function generator, thereby ensuring the effectiveness and safety of the cleaning charge.

[0073] 1. Gain calibration (verify amplification factor)

[0074] "Input a 1V sine wave, adjust the high-voltage amplifier gain to output 2kV", ensures that the amplifier's amplification factor (gain) is accurate and accurate, which is the basis of all waveform amplification. The sine wave is a basic continuous waveform, easy to measure and calculate gain (gain = output voltage peak / input voltage peak). The target set in this embodiment is a gain of 2000 times (2000V / 1V).

[0075] Input a standard 1V peak sine wave and observe the output. By adjusting the gain control knob or internal settings on the amplifier, make the output peak stable at 2kV. This ensures that for any input signal, the amplifier can amplify it with a linear relationship of 2000 times.

[0076] 2. Transient response verification (verify pulse fidelity)

[0077] "Input a pulse width of 1000ns, verify whether the output high-voltage pulse voltage pulse width is 1000ns", test the high-voltage amplifier's response to extremely fast changing signals. The generation of pulsed plasma relies on the rapid rise of voltage. If the rise time of the high-voltage amplifier is too slow, a 1000ns fast input pulse will be "rounded", becoming slow. This cannot establish a strong electric field in a short time to break down the gas, resulting in insufficient ionization or no ionization at all. The requirement that the output rise time be less than 500ns is to ensure that the high-voltage amplifier can be used to generate nanosecond-level fast pulses for plasma.

[0078] 3. Waveform fidelity verification (verify distortionless output)

[0079] The output end of the high-voltage amplifier 1 is connected in series with a 1kΩ resistor, and a high-voltage differential probe is used to capture the output voltage waveform, and it is confirmed that there is no distortion and THD < 5%, which ensures that when the amplifier drives the load, the output waveform has no obvious distortion, overshoot or oscillation. The 1kΩ resistor acts as a minimum and stable dummy load, which simulates the working condition when the plasma is not broken down (i.e. the discharge gap corresponds to a high resistance state). It helps to damp the high-frequency oscillation that may occur.

[0080] In high-frequency circuits, the inductance and parasitic capacitance of the cable can form a resonant circuit, causing the output waveform to ring at the edges. Connecting a small resistor in series can effectively suppress this phenomenon and make the waveform cleaner. A high-voltage differential probe is used, and a normal oscilloscope probe cannot withstand kV-level high voltage, so a special high-voltage differential probe must be used for accurate and safe measurement.

[0081] The total harmonic distortion THD < 5% represents the ratio of the total energy of all harmonic components to the energy of the base signal.

[0082] The output waveform is required to have only extremely small distortion, ensuring that the applied electric field is precisely controllable and eliminating interference factors caused by waveform distortion.

[0083] Specifically,

[0084] The discharge plasma device includes an electrode structure, which adopts any one of a single needle-plate electrode, a multi-needle-plate electrode, a needle-needle electrode structure, and a plate-plate electrode structure. The electrode structure includes a high-voltage end 3 and a ground end 4. The high-voltage end 3 is connected to the output end of the high-voltage amplifier 1, and the ground end 4 is grounded.

[0085] In this embodiment, a multi-needle-plate electrode structure is selected, which can generate a large area of relatively uniform plasma at a lower voltage, and has the characteristics of perfect coordination with the "pulse-bias" driving waveform, and is suitable for the application of insulator surface charge cleaning. It arranges multiple needle electrodes as high-voltage ends and a common plate electrode as a ground end according to a certain array. Each needle tip is a strong field emission point, forming the superposition of multiple non-uniform electric fields, and each needle tip generates a discharge at the same time. These independent discharge areas can be fused to form a relatively uniform and diffuse low-temperature plasma area, which is an ideal choice for cleaning the surface of GIS basin-type insulators. By optimizing the array arrangement, spacing and needle tip curvature of the needles, uniform coverage of the insulator surface can be achieved. Combining the low breakdown voltage advantage of the needle electrode and the wide area characteristic of the plate electrode, the efficiency and uniformity are balanced.

[0086] Specifically,

[0087] The discharge gap spacing between the high-voltage end 3 and the ground end 4 is 10-150 mm.

[0088] In the application on different types of insulators, according to its voltage grade and specific type setting discharge gap spacing, such as power outage maintenance cleaning insulator surface charge, at 550kV, the diameter of the post insulator is 120 mm, and the discharge gap spacing of 150 mm is selected, the thickness of the basin type insulator is 60 mm, and the discharge gap spacing of 90 mm is selected, the thickness of the 126kV disc type insulator is 50 mm, and the discharge gap spacing of 80 mm is selected.

[0089] Specifically,

[0090] The position of the needle electrode in the multi-needle-plate electrode is any one of a linear shape, a circular shape, a triangular shape, a quadrilateral shape, a pentagonal shape, a hexagonal shape, a heptagonal shape, and an octagonal shape.

[0091] In the multi-needle-plate electrode structure, the geometric arrangement of the needle electrode directly determines the uniformity of the plasma region and the synergy of the electric field distribution, thereby ultimately affecting the uniformity and efficiency of the insulator surface charge cleaning.

[0092] The arrangement of the needle electrode is to form a plasma layer as uniform and full as possible above the insulator surface. Different arrangement modes are suitable for different insulator shapes and cleaning requirements.

[0093] The circular insulator (such as a GIS basin type insulator): the circular arrangement is preferred, or a high-order symmetric polygon such as a hexagonal or octagonal shape.

[0094] Rectangular / strip-shaped insulator: the linear or rectangular arrangement is preferred.

[0095] For the most common circular GIS basin type insulator in the power industry, the circular electrode array with a center needle or the hexagonal array is the optimal choice, which can generate a concentric and symmetric plasma ring or surface with the insulator, ensuring that the insulator surface can be uniformly and effectively cleaned from the center to the edge, thereby maximizing the recovery of its insulating performance.

[0096] Specifically,

[0097] In step 5, the insulator surface charge is scanned and detected by an electrostatic probe on the insulator surface to obtain the surface charge density, and the potential formed by the surface charge density satisfies the target value ≤ 150V.

[0098] The scanning detection moves the probe on the surface of the insulator according to a certain path to obtain the charge / potential distribution map of the whole surface. The whole surface of the insulator is ensured to be effectively treated, not only most areas, and the target value ≤ 150V is set, which represents the maximum residual potential allowed to exist on the surface of the insulator after cleaning. 150V is an extremely low value, indicating that the surface charge has been neutralized extremely thoroughly, meaning that the charge has been effectively controlled in an absolutely safe range.

[0099] The working voltage and overvoltage in GIS are as high as tens to hundreds of kilovolts. The electric field generated by the residual potential of 150V can be completely ignored compared with the working electric field. This means that the electric field distribution of the cleaned insulator almost returns to the "factory state", greatly eliminating the risk of electric field distortion and flashover caused by charge accumulation.

[0100] This standard makes the whole cleaning process form a complete "monitoring-control-feedback" closed loop, ensuring that the electrical performance of the cleaned insulator is substantially restored, and ensuring the absolute safety of the subsequent operation of the GIS equipment.

[0101] Specifically,

[0102] The electrode material of the electrode structure is any one of stainless steel, copper, iron, aluminum, and nickel.

[0103] In this embodiment, the needle-plate electrode discharge plasma device includes a multi-needle electrode and a plate electrode, a discharge gap spacing is arranged, the needle electrode material is tungsten-copper alloy, the tip curvature radius is 50μs, the handle diameter is 2mm, and the length is 30mm. The plate electrode material is 316L stainless steel, and the adjustable range of the discharge gap spacing is 10mm~150mm.

[0104] The preferred embodiments of the application are described in detail above in combination with the drawings, but the application is not limited to the above-mentioned embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the application, which involves related technologies well known to those skilled in the art, and all fall within the protection scope of the patent of the application.

[0105] Many other changes and modifications can be made without departing from the concept and scope of the application. It should be understood that the application is not limited to the specific embodiments, and the scope of the application is defined by the appended claims.

Claims

1. A method for cleaning surface charge of an insulator based on plasma discharge, characterized by, It comprises the following steps: Step 1, device connection; the output end of the voltage waveform generating device is connected to the discharge plasma device, and the insulator to be cleaned is placed in the discharge gap of the discharge plasma device; the voltage waveform generating device comprises a high-voltage amplifier (1) and a function generator (2); Step 2, parameter setting and generation of the composite waveform; in the function generator (2), the pulse parameters, the parameters of the direct current voltage, the waveform type direct current bias parameters are set, and the voltage waveform is generated and sent to the high-voltage amplifier (1); Step 3, high-voltage amplification; the high-voltage amplifier (1) raises the voltage waveform of the function generator (2) and applies it to the discharge plasma device; Step 4, plasma discharge charge cleaning; the discharge plasma device generates a high pulse voltage electric field reaching the gas breakdown field strength, and a violent ionization reaction occurs, thereby generating a large number of charged particles; when there is a superimposed voltage during the pulse interval, the charged particles generated during the pulse interval will migrate to the surface of the insulator under the action of the electric field generated during the pulse interval, thereby cleaning the residual charge in the discharge space and neutralizing the surface charge of the insulator, so as to clean the surface charge of the insulator; Step 5, cleaning end; when the surface charge of the insulator is reduced to the target level, the voltage waveform generating device is turned off first, then the discharge plasma device is turned off, and finally the output end of the discharge plasma device and the high-voltage amplifier (1) is discharged by grounding the discharge rod, and the discharge rod contacts the high-voltage end (3) of the discharge plasma device and the output end of the high-voltage amplifier (1).

2. The method of claim 1, wherein the method is a method of sweeping surface charge of an insulator based on a plasma discharge. When the voltage waveform generating device drives the discharge process of the discharge plasma device, any one of pulse, square wave, sine wave, triangular wave and sawtooth wave is used as the voltage waveform, and the voltage waveform generating device superimposes the same polarity voltage during the voltage interval.

3. The method of claim 2, wherein the method is performed by a plasma discharge based surface charge sweeper. In step 2, the function generator (2) sets the pulse parameters, the parameters of the direct current voltage, the waveform type direct current bias parameters, sets the pulse voltage polarity and the bias voltage polarity to be the same, the voltage polarity is positive or negative, sets the bias voltage waveform to be direct current or a certain fluctuation ripple voltage, and sets the bias voltage existing time to be 1%~100% of the time ratio during the whole voltage interval.

4. The method according to any one of claims 1 to 3, wherein In step 2, the function generator (2) uses the following mathematical formula to generate the composite waveform: where, Vout is the output voltage, Vp is the pulse voltage amplitude, Tp is the pulse width, Vd is the DC voltage amplitude, Td is the duration of the DC voltage, t is the time variable, W(t) is a rectangular window function defining the timing position of the pulse and the DC, where, = 10 ns is a guard interval preventing the overlap of the pulse and the DC; by adjusting the input function of the function generator (2), the desired voltage waveform is obtained.

5. The method of claim 4, wherein the method is performed by a plasma discharge based surface charge sweeper. In step 3, waveform calibration is also included, 1V sine wave is input through calibration of the high-voltage amplifier (1), the gain of the high-voltage amplifier (1) is adjusted to 2kV, the input pulse width is 1000ns, and it is verified whether the output high-voltage pulse voltage pulse width is 1000ns, the output end of the high-voltage amplifier (1) is connected in series with a 1kΩ resistor, a high-voltage differential probe is used to capture the output voltage waveform, and it is confirmed that there is no distortion and the THD is less than 5%.

6. The method of claim 1, wherein the method is a method of clearing surface charge from an insulator based on a plasma discharge. The discharge plasma device comprises an electrode structure, which adopts any one of single needle-plate electrode, multiple needle-plate electrode, needle-needle electrode structure and plate-plate electrode structure, and the electrode structure comprises a high-voltage end (3) and a grounding end (4), the high-voltage end (3) is connected to the output end of the high-voltage amplifier (1), and the grounding end (4) is grounded.

7. The method of claim 6, wherein the method is a method of clearing surface charge from an insulator based on a plasma discharge. The discharge gap spacing between the high-voltage end (3) and the grounding end (4) is 10-150 mm.

8. The method of claim 6, wherein the method is a method of clearing surface charge from an insulator based on a plasma discharge. The position of the needle electrode in the multiple needle-plate electrode is any one of linear, circular, triangular, quadrilateral, pentagonal, hexagonal, heptagonal and octagonal polygonal structure.

9. The method of claim 1, wherein the method is a method of clearing surface charge from an insulator based on a plasma discharge. In step 5, the surface charge of the insulator is scanned and detected by an electrostatic probe to obtain the surface charge density, and the potential formed by the surface charge density satisfies the target value ≤ 150 V.

10. The method of claim 6, wherein the method is a method of clearing surface charge from an insulator based on a plasma discharge. The electrode material of the electrode structure adopts any one of stainless steel, copper, iron, aluminum and nickel.

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