基于PDC分析的时频混合绝缘诊断方法研究

发布时间：2019-03-15 07:10

【摘要】：介电谱绝缘诊断中老化弛豫特征参数的提取是理论研究的基础问题，通过时域极化去极化电流（PDC）检测数据数值计算介电响应频域特性和恢复电压，以及线性高压放大器的级联方法是介电谱诊断技术中的关键测试问题。论文首先分析阶跃激励下介质的全电流响应，给出基于多指数函数拟合的PDC参数表征方法，该方法可用来求解德拜模型中的各支路电阻与支路电容。仿真研究油纸绝缘结构中不同松弛时间支路、电导率参数对复介电常数与损耗因数时域、频域特性的影响，并与文献中的实验结果进行对比，取得一致的规律，为研究介电谱绝缘诊断提供理论分析方法。文中设计用于PDC分析的微电流检测电路，为解决高阻值电阻误差过大问题，文中采用T型电阻网络实现50倍的高阻值电阻，通过油纸绝缘PDC特性测试验证所设计微电流检测电路的合理性和有效性。针对高阻抗介质材料的恢复电压无法测试问题，本文根据电介质的极化去极化电流测试数据，通过理论计算得到其恢复电压特性，提出根据极化去极化电流计算恢复电压的数值变换算法，推导出恢复电压递推公式，仿真与实验证明该公式的有效性。论文结合PDC参数拟合所得的德拜等值电路模型各元件参数，给出复介电常数与损耗因数的频域计算公式。由于存在传统时频域变换哈蒙近似公式的局限性和频域法在低频段测量介电参数需要时间较长的问题，论文给出基于时域PDC分析的连续傅里叶变换与快速傅里叶变换的时频域变换方法，，仿真得到油纸绝缘FDS特性，数值变换与试验测试结果取得一致。论文针对基于PDC分析的时频混合绝缘诊断方法进行大量的实验研究，实验验证根据绝缘纸板的极化去极化电流通过傅里叶变换获得其频域复电容和损耗因数特性的正确性，设计并搭建变压器绝缘油测试系统平台，模拟现场实际情况对变压器油进行实验室加速电热联合老化实验，分析油中不同含水量、经过不同方法处理的油样和老化因素对FDS曲线的影响，测得的FDS曲线与理论分析取得一致。针对交联聚乙烯介电谱绝缘诊断，开展老化时间与老化温度影响的实验研究，实验得到在热、氧和铜催化加速热老化作用下，对于不同老化程度的交联聚乙烯试样，在相同老化时间、不同温度下损耗因数最小值基本恒定，该最小值随老化程度增加而增大，可以用损耗因数频域最小值作为交联聚乙烯绝缘老化程度的评估判据。高压线性放大器是介电谱绝缘诊断测试技术关键环节，由于传统高压电源技术无法实现介电谱绝缘诊断的宽频范围，现有的线性高压放大器输出电压范围有限，因此本文提出一种高压线性放大电路的串级级联式结构，文中利用双运放差分输出解决高压电源供电问题，给出单元电路与级联结构，单元电路可以实现40倍线性放大范围，n级级联可以实现40n倍线性高压放大，应用频率范围在10-3~104Hz，单级电压转换率达40V/μs，论文实际测试所研制的2级串级式高压线性放大器幅频、相频等性能，结果验证这一电路设计的合理性和有效性。由于传统介电谱绝缘诊断基于介电参数时域、频域测试曲线变化规律的比较，很难确定准确的绝缘评价指标问题，本文在系统研究介电谱绝缘时频混合诊断技术理论与实验基础上，提出介质松弛时间分布特征参数提取的多变量非线性最小二乘拟合方法。根据测量的介质PDC全电流数据，通过多指数拟合分析得出德拜模型各支路参数，依据频域分析中的复介电常数与损耗因数计算公式得到介电参数频域特性，进一步给出以Cole-Cole修正模型为基础的复介电常数经验公式，提出多变量函数非线性最小二乘拟合方法，用于介质松弛时间分布特征参数的提取。文中通过变压器油热老化FDS实验数据验证该方法的有效性，提取加速老化50h~200h不同老化时段的变压器油松弛时间分布特征参数，结果表明随着老化时间增加，特征参数值显著变化，可以用于绝缘老化状态评估。论文提出介质松弛时间分布特征参数提取的多变量非线性最小二乘拟合方法，可以为电介质绝缘老化定量判据的确定奠定理论基础。用快速傅里叶变换方法将时域测量的极化去极化电流值变到频域，从而得到频域谱低频段值，代替直接用频域法进行测量，此方法很大程度上减少测量时间。提出的PDC电流测试数据直接计算出RVM测试波形的数值算法，可以解决高阻抗绝缘恢复电压测试难题，拓宽传统PDC测试的应用范围。此外，论文提出交联聚乙烯绝缘损耗因数频域最小值的绝缘老化判据，提出高压线性放大电路的串级级联式结构，使得本文研究对介电谱绝缘诊断相关理论与实验研究具有一定理论与应用价值。
[Abstract]:the extraction of the aging relaxation characteristic parameters in the dielectric spectrum insulation diagnosis is the basic problem of the theoretical study, and the dielectric response frequency domain characteristic and the recovery voltage are calculated by the time domain polarization depolarized current (pdc) detection data value, And the cascade method of the linear high-voltage amplifier is a key test problem in the dielectric spectrum diagnosis technology. In this paper, the full-current response of the medium under the step excitation is first analyzed, and the method for characterization of the PDC parameter based on the multi-exponential function fitting is presented. The method can be used to solve the branch resistance and the branch electrical resistance of each branch in the Debye model. In this paper, the effects of different relaxation time branches and conductivity parameters on the time domain and frequency domain of the dielectric constant and the loss factor of the oil paper insulation structure are simulated, and the results of the experiments are compared with the experimental results in the literature to obtain a uniform rule, and the theoretical analysis is provided for the study of the insulation diagnosis of the dielectric spectrum. In this paper, a micro-current detection circuit for PDC analysis is designed. In order to solve the problem of high resistance error of high resistance, a resistance of 50 times is realized by using a T-type resistor network, and the rationality of the design of the micro-current detection circuit is verified by the performance test of the oil-paper-insulated PDC. The recovery voltage of the high-impedance dielectric material cannot be tested. According to the measurement data of the polarization depolarized current of the dielectric, the recovery voltage characteristic of the dielectric is calculated by the theory, and the number of the recovery voltage is calculated according to the polarization depolarized current. In this paper, the recursive formula of the recovery voltage is derived, and the simulation and the experiment prove the same. The validity of the formula is presented in this paper. The parameters of each element of the Debye equivalent circuit model obtained by fitting the PDC parameter are given, and the complex dielectric constant and the loss factor are given. Due to the limitation of the traditional time-domain transformation Hammond approximation formula and the problem that the frequency-domain method needs a long time to measure the dielectric parameters in the low-frequency section, the paper gives the continuous Fourier transform and the fast Fourier transform based on the time-domain PDC analysis. in that time-domain transformation method, the characteristic of the oil-paper insulation FDS, the numerical transformation and the test measure are obtained by the simulation, In this paper, a large number of experimental researches are carried out for the time-frequency hybrid insulation diagnosis method based on PDC analysis, and the frequency domain complex capacitance and loss of the insulation board are obtained by Fourier transform according to the polarization depolarization current of the insulating paper board. The correctness of the consumption factor characteristics, the design and construction of the transformer insulating oil test system platform, the simulation of the actual situation on the transformer oil, the laboratory accelerated electric heating combined aging experiment, the analysis of the different water content in the oil, the oil sample and the aging factor treated by different methods FDS curve measured by the effect on the FDS curve An experimental study on the effect of aging time and aging temperature on the insulation diagnosis of cross-linked polyethylene dielectric spectrum is carried out, and the cross-linked polyethylene test with different aging degree is obtained under the action of heat, oxygen and copper to accelerate the thermal aging. For example, at the same aging time, the minimum value of the loss factor at different temperatures is substantially constant, and the minimum value increases with the increase of the aging degree, and the minimum value of the loss factor frequency domain can be used as the cross-linked polyethylene insulation The high-voltage linear amplifier is the key part of the dielectric spectrum insulation diagnosis and test, and because the traditional high-voltage power supply technology can not realize the wide frequency range of the dielectric spectrum insulation diagnosis, the existing linear high voltage The output voltage range of the amplifier is limited, so this paper presents a cascade cascade structure of a high-voltage linear amplification circuit. In this paper, a double-op amp differential output is used to solve the problem of power supply of the high-voltage power supply, and the unit circuit and the cascade structure are given. The unit circuit can The 40-time linear amplification range is realized, the n-stage cascade can realize 40n-times linear high-voltage amplification, the application frequency range is 10-3-104Hz, the single-stage voltage conversion rate is 40 V/. mu.s, and the two-stage series-stage high-voltage linear amplifier amplitude-frequency, phase-frequency and other performances developed by the actual test of the paper are verified, The rationality and effectiveness of the circuit design are reasonable and effective. Because the traditional dielectric spectrum insulation diagnosis is based on the comparison of the dielectric parameter time domain and the frequency domain test curve, it is difficult to determine the accurate insulation evaluation index problem. In this paper, the dielectric spectrum insulation time-frequency mixing is studied in this paper. On the basis of the theory and experiment of the combined diagnosis, it is proposed that the characteristic parameters of the relaxation time distribution of the medium are extracted According to the measured medium PDC full current data, the parameters of each branch of the Debye model are obtained through the multi-index fitting analysis, and the complex dielectric constant and the loss due to the frequency domain analysis are counted In this paper, the frequency-domain characteristics of the dielectric parameters are obtained, and the complex dielectric constant empirical formula based on the Cole-Cole correction model is given. The nonlinear least-square fitting method of the multi-variable function is proposed, which is used in the medium. The characteristic parameters of the relaxation time distribution are extracted. The effectiveness of the method is verified by the experimental data of the oil-heat aging FDS of the transformer. The characteristic parameters of the relaxation time of the transformer oil in different aging periods are extracted and accelerated for 50-200 h. The results show that with the aging, There is an increase in the characteristic parameter value. The method can be used for evaluating the insulation aging state. The method of multi-variable nonlinear least square fitting for extracting the characteristic parameters of the relaxation time distribution of the medium can be used as a dielectric insulation. The method of fast Fourier transform is used to change the polarization depolarized current value of the time-domain measurement to the frequency domain, so as to obtain the low-frequency segment value of the frequency-domain spectrum instead of the direct-use frequency-domain method. The method can reduce the measurement time to a great extent. The proposed PDC current test data directly calculates the numerical algorithm of the RVM test waveform, and can solve the problem of high-impedance insulation recovery voltage test. The application range of the traditional PDC test is widened. In addition, the insulation aging criterion of the minimum value of the frequency-domain minimum of the cross-linked polyethylene insulation loss factor is put forward, and the cascade cascade structure of the high-voltage linear amplification circuit is put forward, so that the theory and the theory of the insulation diagnosis of the dielectric spectrum are studied in this paper.
【学位授予单位】：哈尔滨理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM855

【共引文献】