DC stack of oil paper insulation under the harmonic voltage local discharge and charge accumulation characteristics research
(Study on Partial Discharge and Charge Accumulation Characteristics of Oil-Pressboard Insulation Under DC SuperMonic Voltage)
1. Study background
Stream -changing transformer Valve side oil paper insulation to withstand the pulse square wave voltage function。The voltage contains a large amount of DC component and high -level harmonic，The existence of harmonic components will make the internal local discharge and charge accumulation characteristics of the changing flow.，It is easier to cause the problem of insulation failure。So，Tests of DC overlay in this article，Research Harmony Frequency、The effect of DC component on the accumulation of local discharge and charge accumulation of oil paper，Explore the interrelated mechanism of the charge of the charge and local discharge。
2. Test platform
The local discharge test platform of DC overlapping harmonic voltage is shown in Figure 1。Test device can simulate the composite voltage under superimposed harmonic。
Figure 1 Local discharge test platform
A spatial charge measurement system based on the electro -sound pulse method is shown in Figure 2，Can meet the measurement requirements of space charges under the superimposed high harmonic electric field。
Figure 2 Space charge measurement system
Set a composite voltage with a harmonic DC ratio of 1: 1，Set different frequencies (50Hz、150Hz、250Hz、300Hz、350Hz) Harmony voltage，Inquiry The effects of DC component Harmony frequency on local discharge and charge distribution characteristics。Another，Set a harmonic DC voltage ratio to 1: 3，As a control。
3. Test results
As shown in Figure 3，Statistics the local discharge feature parameters under different frequency harmonic voltage。You can see when the proportion of the harmonic DC voltage is the same，Maximum discharge、The average discharge and discharge repetition rate increased with the increase of the harmonic frequency。When the superposition harmonic frequency is the same，The characteristics M88 games apkm88 com live casino registerof the characteristics are reduced with the increase of the DC component。This shows that the existence of DC voltage suppresss the promotion effect of high harmonic waves on local discharge。
(A) Maximum discharge (b) Average discharge
(C) Dive repeat rate
Figure 3 DC overlapping local discharge feature parameters under different frequency harmonic voltage
As shown in Figure 4, it is a harmonic DC ratio 1: 1，DC superposition of 50Hz harmonic composite power field at different phases at different phases at different phases of space charging。The charging distribution under the DC composite electric field presents non -symmetry，The distribution of space charges in different phases changes with the change of polarized voltage waveforms outside the outside.。
Figure 4 DC superposition of 50Hz harmonic fields under different phases of space charging waveform
4. Discussion
High -second harmonics have an important impact on the accumulation and dissipation process of residual charge。Inner wall interface of the air gap, charge dissipation, presents index attenuation trends。The higher the outer harmonic voltage frequency，Weakening of charge dissipation effect，The residual charge becomes more，As a result, the residual electric field
bigger。After the voltage polarity is reversed，The residual charge accumulated in the first half of the cycle still has the occurrence of residual electric field to promote reverse discharge。
Statistical DC overlapping different frequencies Harmonic Phase is 270 ° The space charging waveform is shown in Figure 5。With the increase of the superimposed harmonic frequency，The accumulation of the accumulation of positive polarity in the cardboard gradually increases。The DC component in the composite voltage makes the positive polarity charge constantly injected，and make the charge generate directional movement。The increase in harmonic frequency reduces the effective migration distance of the charge，Makes more space in the cardboard accumulation of more charges，The more severe distortion of the field。
Figure 5 DC overlapping space charging under different frequency harmonics
The maximum electric field distortion ΔEMAXshown in Figure 6。From Figure 6, we can know，The same harmonic and DC voltage ratio，The longer the polarization time，ΔEMAXthe bigger. In the same polarization time, the maximum electric field distortion ΔEMAXBig m88 sports bettingincreases with the increase M88 Online Live Casinoin the frequency of the superimposed harmonic voltage。Electric field distortion will exacerbate local discharge，Even leading to insulation breakdown。
Figure 6 The maximum electric field distortion of the harmonic voltage of different frequencies at different times
When the cardboard is undergoing a positive electrode electric field，The process of charge and composite is shown in Figure 7。
Figure 7 The charge and composite process of air space defects in local discharge
5 conclusion
With the rise of the superposition harmonic frequency，The accumulation of the internal charge of the cardboard becomes more，Lead the electric field distortion。Frequent charge injection and extraction is accompanied by increased the number of compounds of charge，A large number of energy release of energy will damage the micro -structure of oil paper insulation，Accelerate its erosion rate，Forming more traps so that the electric field distortion is changed to serious，Then it promoted the generation of local discharge。The existence of DC component establishes a fixed DC reverse electric field，Weakened the strength of the electric field，Added interface injection of potential，Inhibit the local discharge。
Author Chinese name:
Li Yichi，Wang Qiang，He Dongxin，Wang Liangkai，Li Qingquan，Siwen
About the author:
Li Yichi，The first author of this article，Master's degree from the School of Electrical Engineering, Shandong University，Studies mainly engaged in oil paper insulation and deterioration mechanism。
He Dongxin，Associate Professor of the School of Electrical Engineering, Shandong University，Ecclesiated by the 7th Young Talent Project of the 7th China Association for Science and Technology and Future Plan for Young Scholars of Shandong University，Liaison person as a liaison of the Global Energy Internet University Alliance School、Member of the Youth Industry Committee of China Electricity Technology Society and Engineering Electric Specialty Committee。Mainly engaged in the research on the characteristics and failure mechanism of solid insulation charge。Hosted the National Natural Science Foundation of China 3 items、Shandong Province's major innovative project projects and other projects，Published more than 40 high -level journal papers with the first author and communication authors，More than 10 items m88 live casino gamesof authorized invention m88 sports bettingpatents。Winning the Youth Working Committee of the China Electricity and Technology Society of Electricity and Technology in 2020、Excellent Organization Award and Shandong Electrical Engineering Society "May 4th" youth science and technology worker and other honors。
Li Qingquan，Author of communication here，Professor of the School of Electrical Engineering, Shandong University、Doctoral supervisor，Deputy Dean。Director of the Key Laboratory of Extraordinary High -voltage Transmission and Transformer Technology and Equipment of Shandong Province，Member of the High -voltage Special Committee of the China Electrical Engineering Society，Plasma and application of China Electrician Technology Society、Staff of Insulation Materials and Insulation Technology Special Committee。Long -term engaging in the inflammation of the insulation of power equipment、Status assessment、Optimization of insulation and electromagnetic structure、Research and development work in the application of power big data。More than 10 items of vertical topics at the national and provincial and ministerial levels，Live in the State Grid Company、Southern Power Grid Corporation and other more than 40 scientific and technological projects; more than 200 academic papers; participating in the editor -in -chief academic monograph 2，1 masterpiece of monographs; 1 first prize of provincial and ministerial level、2nd prize 2 items，Provincial Education and Teaching Achievements 2 Prize 1 item。As the person in charge of the project is currently undertaking the National Natural Science Foundation of China Smart Grid United Fund (key category)、Shandong Provincial Key R & D Plan-Research on Projects and other projects of major science and technology innovation projects。
Siwen，Dr. High Voltage and Insulation Technology，Lecturer of the School of Information and Electrical Engineering, Shandong University，Deputy Director of Electrical Engineering and its automation professional teaching and research room。The main research direction is the insulation and detection technology of the transformer。undertake Shandong Province Nature Fund、Participate in multiple items such as the National Nature Fund。Published more than ten articles such as SCI and other M88 games apkm88 sports bettinghigh -level academic papers。
The author of this article comes，The team relies on the key laboratory of high -voltage transmission and transformation technology and equipment in Shandong Province、Institute，The main research areas include high voltage insulation diagnosis technology、Electric Equipment Status Online Monitoring、High -pressure testing technology、High -pressure composite insulation and inflammation mechanism and insulation assessment。In the past three years, the team has undertaken the National Natural Fund (including key items、Noodles project、Youth Science Fund Project) More than 10 items，Provincial and ministerial science and technology projects (including provincial key research and development plan, etc.) more than 10 items，More than 50 horizontal topics such as the National Grid Science and Technology Project; the funds for vertical science and technology projects and horizontal scientific research projects exceed 40 million; more than 90 articles have been published at domestic and foreign journals and high -level international conferences，EI include more than 200 papers。
