大气条件下纳秒脉冲放电及其声特性分析(英文)

There was no well-resolved mechanism of audible noise caused by corona discharge on UHV transmission lines. Hence we measured the sound pressure of pulsed discharges between needle-plane electrodes under different discharge conditions in air, for revealing the intrinsic relationship between discharge and its audible noise(AN). The relationship between discharge parameters and audio characte- ristics was drawn from the analysis of the electric and sound signals obtained in experiments. Experiment results showed that nanosecond pulsed discharges produce the sound pressure with a microsecond pulse lagging behind the discharge pulse in their waveforms. The peak value of the sound pulse decreases and its high frequency component gradually attenuates, when the measuring distance from discharges increases. The sound pulses correlate with the discharge current and voltage significantly, especially the current. The audible noise produced by repetitive pulsed discharge increases with the strength, duration, and pulse repetition rate of discharge.     

大气压针板介质阻挡放电中微流注、电晕和辉光放电相互转换研究（英文）

To discuss the modes of dielectric barrier discharge(DBD) between needle-to-plane electrodes in air,DBD is generated and observed on a needle-to-plane device at atmospheric pressure air.Fast images of the DBD are taken by using a charge couple device(CCD) cinema with a macro lens,while the electrical and photo-electricity waveforms of the DBD are recorded.The current waveforms show that under an applied voltage of 3 kV,there are numerous short current pulses in both positive and negative half-periods of discharges.However,under 6 kV,there are still the numerous short current pulses in the positive half-periods,but only one wide current pulse in each negative half-period.This difference is also found in the photoelectric signals.The streamer,corona and glow discharges are observed from the images of the discharges at different applied voltages.The structure of glow discharge in the negative period is exactly the same as that of the low pressure glow discharge.However,in the positive period of discharge there is always a streamer.In the negative period of discharge,while the applied voltage increases,the transition from corona to glow discharge is observed.The progress of a transition between streamer and glow discharge at 6 kV during one period is analyzed.The glow discharge appearance is determined by two factors: the discharge current is limited to a certain extent by the dielectric layer; the charges deposited on the dielectric layer during the last half period enhance the intensity of the electric field.At an insufficient applied voltage,the cathode drop leads to no glow discharge,but Trichel pulses.     

电晕放电脉冲电流波形和相位分布的测量、分析与仿真(英文)

Partial discharge(PD) is one of the most important phenomenon in high voltage insulations.In most cases, the appearance of partial discharges is related to insulation defects.Understanding partial discharges is important for diagnosis on insulation condition.Corona discharges appear when extremely high electric field appears on the conductor surface exceeding the electric field strength of the gas.The high electric field may occur at around protrusion with very sharp tip.This paper reported a holistic approach of corona discharge investigation.The needle-plane electrode system was used.The medium between the electrodes was air.The needle was made from steel with radius of curvature of 3μm(Ogura needle).Sinusoidal as well as triangular applied voltages were used.The waveform of the corona discharges was measured using a digital oscilloscope.The corona discharge pulses were measured using a phase-resolved PD measurement system.The system was able to measure the magnitude(q) and phase angle position(φ) of each PD pulses,as well as the number of discharge pulses(n).The role of applied voltage was investigated using phase-resolved analysis of corona discharge pulses through pulse sequence,pulse magnitude and pulse number analysis. Experimental results indicated that corona discharge current waveform was an impulse with rise time of about several ns and the impulse width of about 100 ns.The Fast Fourier Transform analysis indicated that the corona discharge current waveform had several spectrum peaks at frequency of 7.8 MHz,85.9 MHz,109.4 MHz and 195.3 MHz.The experimental results also showed that discharge pulses were concentrated around the peak of applied voltage for both sinusoidal and triangular voltages.The discharge magnitude,as well as its probability of occurrence,was strongly dependent on the instantaneous applied voltage.The shape ofφ-n,as well asφ-q-n PD patterns,were strongly reflected by the shape of applied voltage.In order to get deep understanding of the corona discharge,by utilizing results of the phase-resolved analysis,electrical equivalent circuits of corona discharges were proposed.The electrical equivalent circuit contained capacitances and a spark gap.For deeply understanding of PD phenomenon,computer simulation was done by using the proposed electrical equivalent circuits.The similarity of the measured and simulated PD patterns was assessed by comparing measured and simulated theφ-q-n andφ-n PD patterns.The results indicated that simulated PD patterns similar to those obtained from experiment.     

氦气与D2O混合气中阻挡放电灯工作的物理过程（英文）

This paper presents both results of a numerical modeling and an experimental study of the influence of various parameters on the radiation characteristics of barrier discharge lamp working in He/D2O mixture.It is obtained that the intensity of ultraviolet radiation is a non-monotonic function of both the water and the helium pressures.The experimental results also show that the increase of both the discharge voltage and the discharge pulse frequency leads to the increase of radiation intensity.The comparison between the experimentally obtained data and the results of numerical modeling allows us to define the mechanism controlling the ultraviolet radiation in He/D2O mixture at various parameters.     

直流局部放电检测系统研制与应用(英文)

Direct current (DC) partial discharge (PD) test has drawn extensive attention from world-wide electric power research institutes in recent years. However, presently, no DC PD detection device on the market has the statistical function. Thus, we developed a test system for PD detection under DC voltage, which is characterized by strong anti-jamming capability, continuous high-speed real-time data acquisi- tion and effective, complete detection of DC PD signals. The DC PD mechanism, as well as the measuring principles, software system, and hardware design of the test equipment were introduced. Adopting typical electrode pairs, we tested the statistical spectrum of PD under DC voltage. The main difference in statistical spectrums between parallel plate electrodes and needle-plate electrodes was that the time interval between two consecutive discharges for needle-plate electrodes has obviously larger variation range than that for parallel plate electrodes, which could be the convincing proof for distinguishing the type of electrodes under DC PD. Practical results indicate that the proposed sys- tem can measure time domain signals of DC PD of oil-paper insulation effectively and promptly, and it can be used to determine and detect defects in DC power transmission equipment.     

A Forecasting Method of Pollution Flashover Voltage of Insulators Based on Robust Regression

In view of the limitations in the prediction of pollution flashover voltage by least squares regression, a method to predict pollution flashover voltage by robust regression is proposed. According to testing voltage and the data of salt deposit density (ρSDD ) and non-soluble deposit density (ρNSDD ), the regression coefficient is solved by a complex weighting least square iteration algorithm. In iterative calculations, the weight function is adopted, in which the weight coefficient is the function of the residual error of last iteration to weaken the influence of singular values on the regression coefficient. The characteristic exponent denoting ρSDD influence and characteristic exponent denoting ρNSDD influence are mapped by the regression coefficient, and thus the pollution flashover voltage of insulators can be predicted. Through the comparison of test results, robust regression results and least squares regression results, the effectiveness of the proposed robust regression-based forecasting method is verified.     

大气压氦气与氩气等离子体射流形成机理的对比研究(英文)

To compare the formation mechanisms of He and Ar atmospheric pressure plasma jets(APPJs),an intensified charge-coupled device(ICCD)are utilized to observe the dynamic process of APPJ.The experimental results show that,He APPJ is first ignited,which is independent of the dielectric barrier discharge(DBD)between the two wrapped electrodes when the high voltage placed at the downstream.The intensity and APPJ length under positive discharge pulses are bigger than that under negative discharge pulses due to the space charge effect.The He APPJ is formed by the DBD development when the high-voltage electrode placed at the upstream side of tube.However,the plasma plume in Ar APPJ is formed by the propagation of DBD whatever the high-voltage electrode is arranged on upstream or downstream side of ground electrode.The difference in formation mechanism between He and Ar APPJs is mainly caused by the gas properties.Moreover,during the discharges,Ar tends to lead to thermal instability and electron Maxwellian instability.     

气压对发电机定子线棒端部电晕放电特性的影响(英文)

According to the mechanism of corona discharge at the end of the generator stator bar,a model of stator bar end corona discharge is presented.In a closed corona cage at low atmospheric pressure,the corona discharge characteristics of the stator bar end model were observed using an ultraviolet imaging instrument and an oscilloscope.The influence of atmospheric pressure on the corona inception voltage and discharge intensity was analyzed.The results show that the corona inception voltage is lower under lower atmospheric pressure;the discharge intensity is stronger under lower atmospheric pressure.The particles swarm-optimized support vector machine was employed to analyze the impacts of air pressure and humidity on the corona inception voltage.Error between the calculated value of the established model and the experimental value is less than 5%.The established model can be used to calculate the corona inception voltage of the stator bar end model.     

方波脉冲电压下聚酰亚胺薄膜降解机理(英文)

Partial discharge (PD) under a sequence of high-repetition-rate square pulses is one of the key factors leading to premature failure of insulation systems of inverter-fed motors. Polyimide (PI) film is an important type of insulating material used in the inverter-fed motors. In this paper, micro-morphology and structure change of PI film aged by bipolar continuous square impulse voltage (BCSIV) with ampli- tude above partial discharge inception voltage (PDIV) are investigated by scanning electron microscope (SEM). The chemical bonds of PI chain are analyzed through Fourier transform infrared spectroscopy (FTIR). The results show that the degradation mechanism of PI film is the fracturing of chemical bonds caused by the erosion from PDs. Three layers are displayed in both 100 HN film and 100 CR film. The de- gradation path of PI film is initiated from surface and then gradually extends to the interior with continuous aging. Nano-fillers can retard the degradation of PI film and prolong its lifetime.     

交直流复合电压下电晕放电实验研究(英文)

Converter transformers are one of the most important electrical apparatuses in the ultra high voltage(UHV) DC transmission systems.The valve side and the low voltage(LV) bushing are stressed by long-term AC and DC composite voltage leading to significant partial discharge(PD) and posing great danger to the insulation system.In this paper AC and DC composite voltage is applied on a metal needle-plate model to produce PD signal sequences,and then the pulse waveshape and frequency spectrum are analyzed and compared with PD signals under conventional AC or DC voltage.In the end,the phase-resolved distribution is analyzed to depict the new characteristics of PD under this composite voltage.     

组合电器局部放电特高频检测的气压影响分析

特高频检测法以其高灵敏度和抗干扰能力,广泛应用于组合电器绝缘状态的现场检测。为研究局部放电特高频信号与视在放电量之间的关系,文中建立了基于特高频和脉冲电流法的局部放电联合检测系统,分别采集0.3~0.5 MPa气压下金属突出物缺陷模型的放电数据,提取UHF信号累积能量,并与视在放电量进行了相关分析。研究结果表明,各个气压下的UHF信号累积能量与放电量平方始终呈现线性函数关系,其线性斜率与气体压力相对应,这为特高频信号标定研究奠定了基础。     

GIS中典型局放缺陷的UHF信号与放电量的相关分析

超高频(UHF)信号与放电量的关系是局部放电UHF检测研究的难点问题,为了解GIS局部放电UHF法的检测结果与脉冲电流法的参量之间的关系,通过4种典型缺陷的局部放电模型的实验研究,比较了UHF信号的能量、二次积分、峰值电压、峰峰值、波面积等参量与放电量及放电量平方之间的联系。研究表明,UHF信号能量与其放电量平方的线性关系均具有最高的可决系数,即UHF信号能量与放电量平方之间存在线性关系;得到了UHF信号能量与其放电量之间的最佳回归曲线。研究结果对用超高频法定量检测电力设备局部放电具有重要的参考价值和指导作用。     

针-板电极局部放电光测法信号一次积分值与放电量的关系

为解决电气设备局部放电(PD)光测法定量检测的问题,在深入分析PD光测法信号一次积分值物理意义的基础上,推导出信号一次积分值与视在放电量成线性关系。实验结果表明:针-板电极空气间隙在不同极性、不同距离下的PD光测法信号一次积分值与视在放电量均成线性关系,斜率大小是正针负板大于负针正板,且针-板电极间隙距离越大斜率越大。另外,随着施加电压升高,PD脉冲重复率增大,信号一次积分值和视在放电量分布区间均变宽,且分布区间的最大值和最小值均变大。因此,可以用光测法信号获取PD视在放电量,但需对不同极性和不同间隙距离进行一定的校正。     

局部放电特高频检测校准影响因素研究

局部放电特高频(UHF)法广泛应用于电气设备在线监测,由于UHF信号传递函数的影响因素相当繁复,至今未能实现定量校准。为研究UHF检测技术定量校准的影响因素,分析了典型局部放电源的放电机理,通过试验研究了UHF信号的传播规律以及天线测量特性。研究表明,基于特征参量放电量的UHF检测校准可靠性与放电源有较大关联,电晕放电与悬浮放电的校准曲线更能准确表征设备绝缘缺陷的严重程度,内部气隙放电与沿面放电的准确性则相对较差。UHF信号能量衰减至平稳期所需距离随频率增高而变小,而UHF信号频率变化时不影响传感器在不同角度测量的信号能量衰减变化规律。因此,UHF信号校准必须综合考量具体的放电类型与测量条件。研究结果可为构建UHF校准体系的进一步研究提供参考,对推进UHF法在电力设备故障诊断和绝缘状态评估中的应用具有重要意义。     

连续方波脉冲下的局部放电测量分析系统

本文对连续脉冲电压下局部放电的测量分析系统进行研究.分析了不同铁芯材料传感器的响应特性,并用小波包对高低频干扰信号的提取方法进行了研究.在此基础上,通过对脉冲电压下局部放电分析,进一步研究各种统计参量的统计方法和特征,并对样本老化时间和统计参量的关系也进行了验证.通过这些研究,表明该系统对脉冲电压下局部放电的提取和统计是有效的.上述工作的开展,为更深入地研究脉冲电压下绝缘老化机理打下了坚实的基础.     

方波脉冲电压频率对变频牵引电机绞线对绝缘特性的影响

测试了不同频率方波脉冲电压下牵引电机绞线对的电热联合老化寿命、介质损耗因数（tanδ）及局部放电平均放电量,测试结果表明：方波脉冲电压频率升高,使局部放电平均放电量增大,局部放电对绞线对绝缘的破坏作用加强,使绞线对的老化寿命缩短;方波脉冲电压频率升高,使绞线对老化程度加深,陷阱密度增大,降低了自由载流子浓度,使局部放电起始放电电压（PDIV）增大,从而使介质损耗因数曲线转折点电压升高.     

高压脉冲电容器的直流局部放电绝缘检测

高压脉冲电容器的绝缘性能直接关系到其在放电单元中工作的可靠性,直流局部放电测试能够为评估高压脉冲电容器绝缘性能状况提供有效信息。在分析油浸膜—纸绝缘电容器的绝缘特性的基础上,利用所研制的直流局部放电测试系统在一般屏蔽实验室条件下应用平衡法对油浸膜—纸绝缘电容器进行了直流局部放电实验研究,结果表明,可以用放电量—局部放电次数来表征电容器的绝缘状况。通过一批同型号、同批次电容器的直流局部放电试验研究,证明电容器绝缘劣化严重时,其局部放电水平随电压增加而剧烈变化。     

基于超高频法的典型GIS局部放电检测

GIS局部放电检测是GIS绝缘状态监测的一种科学有效的方法。笔者构建了GIS实验模型以及基于超高频法的局部放电在线检测系统,对GIS中典型的几种局部放电特征进行了研究,采用基于相位的分析模式详细分析了不同放电类型在不同电压条件下的放电特征,并结合常规局部放电测试仪,对UHF信号的放电量进行估计,为进一步进行放电类型的智能模式识别及研究超高频信号与放电量关系提供了试验依据,以提高UHF局部放电检测的工程实用性。     

基于EEMD与边际谱能量的电缆局部放电定位方法

振荡波局部放电试验在电缆绝缘缺陷检测中得到了越来越多的研究和应用,但背景噪声干扰和放电脉冲匹配的问题会影响局部放电定位的准确度。为实现振荡波电压下电缆绝缘缺陷的准确定位,提出一种基于集合经验模态分解与Hilbert边际谱能量的局部放电定位方法。首先采用移动窗口阈值法提取出局部放电脉冲信号,采用集合经验模态分解算法对信号进行分解,对得到的各分量进行Hilbert变换获得其边际谱能量值;然后选择不同本征模态函数分量在原始信号边际谱能量值的占比作为特征量,计算信号相似度进行入射脉冲信号和反射脉冲信号的匹配,最终采用时域反射法进行局部放电定位;最后对35 kV电缆进行振荡波耐压试验,对检测到的局部放电信号进行定位计算。结果表明,提出的方法可以在高斯白噪声较强的情况下实现电缆绝缘缺陷定位,定位平均误差可以达到1.15%。     

基于多小波的多态性局部放电信号提取算法

受放电机理、传播路径等因素的影响，局部放电信号往往呈现出多种形态，基于单一小波基函数的小波分析难以处理这样多态性的问题。为此，文中引入了具有多个小波基函数的多小波。针对不同形态的局部放电信号，分别进行了大量的仿真分析，以均方误差为衡量指标，研究多小波在不同局部放电模型下的消噪效果，并寻求最佳的消噪参数。在此基础上，将多小波用于提取多态性的局部放电信号，并与已有的文献进行比较。仿真和实测信号的处理结果表明，选择合适的参数，在提取多态性局放信号时，多小波具有明显优于最优小波及小波集合的性能。