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局部放电检测的脉冲电流法具有灵敏度高、信息丰富、抗干扰性较差的特点,通常应用于电力设备的离线试验中。针对脉冲电流法在线应用的技术要求,研制了基于套管屏蔽环的脉冲电流法局部放电在线检测系统。利用开关柜、环网柜中的对接套管提取局部放电脉冲,并设计配套检测阻抗对其进行参数匹配和仿真优化,同时在10 kV开关柜实验平台上验证了所研制检测系统的有效性。仿真与试验结果表明,研制的检测系统能够实现开关柜局部放电的在线脉冲电流法测量及视在放电量校准,同时有效地对局放源进行相位分辨,可以在对输出局放脉冲保持至少10×10^4次/s分辨率与较高幅值的同时对10 kHz及以下低频干扰产生至少40dB的衰减.运行环境下能够有效地进行局放脉冲提取及故障诊断.为开关柜、环网柜的局部放电在线监测提供了一种新思路。 相似文献
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光纤(extrinsic fabry-perot interferometric,EFPI)传感器是基于Fabry-Perot光学干涉原理来检测局放超声信号的一种传感器,具有灵敏度高、抗电磁干扰等优点,广泛应用于电气设备局部放电的检测。该文提出了一种采用内置式光纤EFPI传感器来检测GIS中局放超声信号的方法,利用有限元法对GIS内部SF6中超声信号的传播特性进行了仿真和试验研究。发现当超声信号经过第一个隔板式盆式绝缘子后,衰减度已经达到近90%,当GIS内采用支撑式盆式绝缘子时,局放超声信号的衰减情况则接近于其在单纯SF6气体内传播时的衰减情况。通过光纤EFPI传感器在GIS中距离检测特性的研究,发现不同距离的传感器所测到的局放信号幅值衰减由快到慢,与仿真中的信号衰减规律接近。通过对比光纤EFPI传感器和压电传感器的检测效果,证实光纤EFPI传感器的灵敏度明显高于压电传感器。 相似文献
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为应对常规高频电流脉冲法在测量局部放电时存在干扰信号,而导致影响局部放电判断的问题,本文通过模糊分类理论,取得了区分高频信号中局部放电信号和干扰信号的良好效果。结合局部放电产生机理,分析了不同类型局部放电信号在相位幅值(PRPD)谱图上的分布特征,并应用于脉冲信号的局部放电判断。测量了某抽水蓄能电站多台主变压器在不同工况下接地系统的高频电流脉冲,展示了环境噪声信号、具有固定相位特征的非放电信号等多种信号的PRPD谱图脉冲分布,判断了某台主变压器可能存在外部沿面局部放电情况。 相似文献
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高压开关柜局部放电会在其金属外壳上产生对地电位,称之为暂态对地电压(TEV),是一种有效的局部放电检测手段,成为供电公司开关柜巡检中的重要内容,了解TEV传播特性对改进测量方法,保证测量有效性具有重要意义。采用XFdtd分析软件模拟TEV信号的传播过程,并且搭建了实体开关柜TEV检测模型,通过试验分析了信号强度、测量距离等对于TEV检测的影响,并与仿真结果进行对比,同时对TEV检测的统计谱图与常规脉冲电流法进行了对比,验证其在工程应用中的有效性,研究结果表明:TEV为局部放电引起的时变电磁波在开关柜表面形成的瞬时电位,与波阻抗有关,开关柜金属外壳对TEV信号具有明显的抑制作用,TEV信号是电磁波从壳体不连续的地方泄露而形成的,TEV信号是辐射式传播,并且信号先增强后衰减;TEV信号的上升时间大概在10ns,频率分布在0~100 MHz范围内,放电源越强,TEV信号强度越大,并且近似呈线性关系,TEV检测时,离信号源越近,TEV越强,同时,TEV检测方法在工程应用中有良好的有效性。 相似文献
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为提高气体绝缘组合电器(Gas insulated switchgear,GIS)局部放电类型诊断的精度,提出了一种基于EWT-FE结合IHPO-SVM算法的GIS局部放电诊断方法。为深度挖掘局部放电信号内部特征,利用经验小波变换(Empirical wavelet transform,EWT)结合模糊熵(Fuzzy entropy,FE)算法对信号进行分解,并提取有效特征量;为提高支持向量机(Support vector machine,SVM)算法自适应能力与分类识别精度,提出利用经过余弦衰减计算方法以及指数下降函数改进的猎人猎物优化(Improved hunter-prey optimizer,IHPO)算法对SVM算法参数进行优化选取;搭建GIS局部放电试验模型,建立基于EWT-FE信号分析结合IHPO-SVM的局部放电识别模型,对所提算法有效性进行验证。试验结果表明,所提算法GIS局部放电类型诊断精度均大于95%,优于传统诊断算法。 相似文献
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纳秒脉冲放电可产生非平衡等离子体实现辅助燃烧.通过耦合零维等离子体动力学和燃烧反应动力学,建立了发动机纳秒脉冲放电等离子体助燃甲烷/空气的模型.研究表明:相同放电能量条件下纳秒脉冲放电可在上止点附近成功点燃当量比为0.5的稀混合气,而火花放电只能导致最高温度升高124 K,无法点燃缸内混合气.在纳秒脉冲放电条件下,低温时放电产生的激发态N2(A3Σu+)和O(1D)促进了O原子的生成.放电后期,累积的N2振动激发态在驰豫过程释放出了较多的热量,有利于稀燃条件下的点火.电流密度的增大提高了放电过程中激发态、自由基的浓度,发动机最高燃烧温度升高,点火延迟时间缩短,燃烧相位提前. 相似文献
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当外加电压的时间特性变为非正弦时,固体绝缘材料的导电能力和绝缘性能发生变化。例如,一个额外的应力通过反射电压波出现,这些变化的操作条件导致局部放电(PD)过程和绝缘保护损坏。因此,必须重新考虑低压开关设备的局部放电试验。本文提出了两种基本布置方式,反映了实体保温结构的典型设计实例,这些测试使得在较高的环境温度下计算局部放电起始条件,并且完成局部放电测量结果的比较。交流电压源为局部放电测量提供正弦测试电压,与温度相关的PD特性提供了一个额外的参数进行比较。室温和最高工作温度的升高温度被规定为局部放电的测试条件。通过对局部放电测量结果的解释,提出了低压开关设备的测试程序和测试参数。测试用例的局部放电测量和仿真结果为局部放电特性的极限值提供了假设。因此,一个低压开关设备局部放电测试程序可用于广泛的局部放电测试当中。 相似文献
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《全球能源互联网(英文)》2020,3(5):494-503
Partial discharge (PD) detection is an effective means of discovering insulation faults in gas-insulated switchgear (GIS). One of the most extensively used methods in PD detection has historically been the ultrahigh frequency (UHF) method. This study evaluates the chromatic processing methodology and its key factors for feature extraction of UHF signals in GIS. Three types of artificial defects are installed in the GIS tank at 0°, 90°, and 180°, respectively. The features of the UHF signals are extracted in the chromatic space, and PD discrimination of the defects is achieved. The influences of processors are studied before the feature selections are suggested. The time-stepping method is proposed to determine the rules of UHF signal frequency characteristics that vary with time. Finally, the process and options of the chromatics-inspired methodology are summarized. 相似文献
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Pemen A.J.M. van der Laan P.C.T. Wout de Leeuw 《Energy Conversion, IEEE Transaction on》2006,21(1):155-161
We studied the propagation of partial discharge pulses in a stator winding by means of measurements on a dismantled 35-MW generator and found that a stator winding acts as a transmission line. Therefore, a partial-discharge (PD) signal manifests itself at the generator terminals after a transit time that depends on the location of the discharge. Due to capacitive and inductive couplings in the end-winding region, a second propagation mode is present for higher frequencies. This "fast mode" manifests itself at the terminals without appreciable time delay. The capacitive and inductive couplings also cause crosstalk between the phases. As a consequence, a signal measured in one phase does not necessarily originate from a discharge in that phase. The amplitudes of the fast mode and, to a lesser extent, the slow mode (or transmission-line mode) are heavily damped when the discharge occurs further away from the measuring terminal. The consequence is that only discharges close to the measuring terminal can be observed. The propagation of a PD signal is not only influenced by the construction of the generator but also by its external connections. 相似文献
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随着风力发电装机容量的不断增大,风电在电网中所占比重也越来越高,这就要求并网风电系统应具有低电压穿透能力。在电网电压发生跌落的情况下,为了使风电系统保持并网状态,对电网进行支撑并穿越故障,文章提出一种准确的、快速的电网故障电压检测方法——正序电压检测方法。该方法能在电网电压发生故障下做出快速的、精准的频率自适应响应。该电压检测系统包括正交信号发生器(QSG)、正序分量计算(PSC)和锁相环(PLL)3部分,系统中应用了二阶广义积分正交信号发生器。系统的输入为电网电压,输出为实时的相位角、正序电压分量和故障信号。通过对系统研究和仿真,表明该系统在电网发生故障时可有效地检测到故障信号。 相似文献
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《全球能源互联网(英文)》2018,1(5):568-575
This paper presents a method of tuning governor control parameters of an isolated hydropower generator considering the primary frequency performance and small-signal stability. First, generators that can be operated in isolated state are identified. Second, different schemes are proposed for generator mode switching from on-grid to off-grid state through comparison and mechanism analysis. Third, the time domain model and frequency domain model of the isolated generator governor are constructed to respectively estimate the primary frequency performance and small signal stability. Parameter sets that satisfy the primary frequency performance and small signal stability are acquired as optimal values of governor control parameters. Finally, the measurement-based parameters of the governor are identified and validated using simulations to demonstrate the feasibility and effectiveness of the method. 相似文献
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张俊安 《电网与水力发电进展》2011,27(10):43-47
介绍了电磁耦合法测量XLPE电缆局部放电故障原理以及应用方法,重点比较了基于VHF(甚高频)传感器和UHF(特高频)传感器的检测方法在XLPE电缆局部放电在线监测技术中的应用。结合2种检测方法各自的优点与存在的弊病(VHF:衰减慢,可标定放电量,抗干扰能力差;UHF:抗干扰能力强,衰减快,不可标定放电量),推荐了XLPE电缆附件局部放电的UHF和VHF联合检测方法。 相似文献
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便携式X射线机为保障特种设备的安全发挥巨大作用。是典型的用低压电产生高管电压的检测设备,管电压可高达400kV。控制精度及稳定性至关重要。文中详细分析便携式X射线机管电压、管电流的测量原理,提出基于以上原理的一种便携式X射线机管电压、管电流的计算机测控方法,同时采用可控硅整流实现管电压控制、IGBT变频实现管电流控制。试验数据证明:其管电压、电流控制精度较高,稳定性好,能满足工程需求。该射线机具有良好市场前景。 相似文献
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《Applied Energy》1999,63(3):141-160
The main objective of this project is to realize an integration plan for various renewable-energy systems in remote areas using a geographical-information system (GIS) in order to determine the optimal management and use of energy in these locations. The area studied is Corsica, an island located in the south-east of France. For the remote site considered, four systems supplying electricity are compared: a stand-alone photovoltaic (PV)/batteries system, a hybrid PV/batteries/back-up generator system, an engine generator and an extension of the existing electrical network. The most economic configuration was chosen as the best solution to electrify the remote site. Physical and technical-economical processes are integrated in the GIS. This GIS is used to determine the profitability boundaries for PV systems compared to a grid extension and under four different load profiles, and has led to the elaboration of an integration plan of renewable energies in south Corsica. The study has shown that for 60–90% of remote sites, a PV decentralized electricity system is the most economical means of electrification. 相似文献
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The implementation of condition monitoring and fault diagnosis system (CMFDS) on wind turbine is significant to lower the unscheduled breakdown. Generator is one of the most important components in wind turbine, and generator bearing fault identification always draws lots of attention. However, non-stationary vibration signal of weak fault and compound fault with a large amount of background noise makes this task challenging in many cases. So, effective signal processing method is essential in the accurate diagnosis step of CMFDS. As a novel signal processing method, empirical Wavelet Transform (EWT) is used to extract inherent modulation information by decomposing signal into mono-components under an orthogonal basis, which is seen as a powerful tool for mechanical fault diagnosis. Moreover, in order to avoid the inaccurate identification the internal modes caused by the heavy noise, wavelet spatial neighboring coefficient denoising with data-driven threshold is applied to increase Signal to Noise Ratio (SNR) before EWT. The effectiveness of the proposed technique on weak fault and compound fault diagnosis is first validated by two experimental cases. Finally, the proposed method has been applied to identify fault feature of generator bearing on wind turbine in wind farm successfully. 相似文献