【作者】 张涛；

【导师】 蔡金锭；

【作者基本信息】 福州大学 ， 电机与电器， 2010， 博士

【摘要】 基于介质响应理论的回复电压诊断方法是一种快速有效的电气诊断方法。本课题以变压器的绝缘油纸状态为研究对象，深入研究变压器油纸绝缘的回复电压特性及其特征量的变化规律，目的在于能够科学地对变压器油纸绝缘状态进行诊断，提高变压器运行的可靠性，延长其使用寿命。因此，利用回复电压特征量诊断变压器的绝缘状态具有重要的理论研究价值和广泛的实际应用前景。本文研究的主要工作：(1)系统研究了介质响应等值电路建模的方法，分析了各种建模方法的优劣，在此基础上，首次建立了使用初始斜率特征量辨识介质响应等值电路参数的数学优化模型，它不受回复电压采样数据的限制，只需按常规回复电压测量方法就可利用提出的数学模型辨识等值电路的参数值。(2)为准确辨识等值电路参数，采用粒子群优化算法求解含有指数函数的非线性最优化问题；在引入混沌搜索的基础上，将生物灾变理论用于判断粒子群的早熟，将改进后的混合粒子群优化算法用于介质响应等值电路参数辨识，并与遗传算法进行比较，验证改进混合粒子群优化算法的性能。(3)推导了利用电路参数计算等值电路模型回复电压的公式，并用该公式计算回复电压极化谱，与实际测量获得的极化谱进行比较，验证电路模型和数学模型的有效性。(4)研究了绝缘状态引起电路参数变化的规律，在获取实际变压器等值电路参数的基础上，仿真分析了绝缘状态与等值电路参数的关系，提出了利用回复电压方法诊断变压器的绝缘状态新思路和特征量。(5)试验研究了极化电压和充放电时间比对极化谱的影响，推导了主时间常数与弛豫时间之间的关系，建立了固体绝缘的水分含量与20℃主时间常数之间的函数关系式，为定量分析绝缘状态提供依据。(6)试验研究了主时间常数和初始斜率特征量与绝缘状态之间的关系，结合仿真分析结论，首次提出利用主时间常数和峰值初始斜率综合诊断绝缘状态的方法，并通过试验实例进行验证。(7)试验研究了回复电压测量和极化谱的影响因素，提出了现场测量的注意事项和防止干扰的措施。揭示了造成极化谱非标准的机理，并将非标准极化谱按产生机理不同进行分类，提出了诊断非标准极化谱的方法。更多还原

【Abstract】 Return voltage method based on dielectric response theory is still a newnon-intrusive diagnosis method for insulation condition of transformer. Thispaper takes oil-paper insulation condition of transformer as the research object,further researches the characteristics and change law of parameters of returnvoltage, and aims at diagnosing oil-paper insulation condition of transformerscientifically, improving its reliable operation and prolonging its service life. So,the research has not only the important theoretical value, but also a goodextensive practical application prospect.Main contributions of this thesis are listed as following:1．This paper reviews methods for modeling dielectric response equivalentcircuit of insulation systems, and analyses the superiority and inferiority ofthese methods. Based on this analysis, the paper establishes a mathematicalmodel with the data of initial slope of return voltage for solving parameter ofdielectric response equivalent circuit. The model of parameters identification isnot limited by sampled experimental data of return voltage, which can easilyidentify equivalent circuit parameters of dielectric response only through normalreturn voltage measurement.2．To identify equivalent circuit parameters of dielectric response accurately,this paper adopts the Particle Swarm Optimization (PSO) to extract theoptimization problem, and basic PSO algorithm is improved. The chaos search isintroduced into PSO, and bio-disaster theory can be used to evaluate theproblem of premature convergence. The improved hybrid PSO is used to solveequivalent circuit parameters, the obtained results show that the local searchability is improved, and the probability of finding the global optimal value byhybrid PSO is better than that by using modified genetic algorithm.3．The calculation formula of return voltage from the equivalent circuitmodel was deduced. And polarization spectrums of two transformers areobtained according to the formula. By comparing measured and simulatedpolarization spectrum, the results show that the established mathematical modeland obtained circuit parameters are feasible and effective.4．According to identified parameters and calculation formula of returnvoltage, connecting with the practical variation situation of parameters with insulation condition, this paper simulates and analyzes change law ofpolarization spectrum with variation of parameters, which can provide a newidea and characteristic quantity for diagnosis of insulation condition.5．Experimental study is performed on the influences of poling voltage andthe ratio of charging time and discharging time on polarization spectrum. Then,the relationship between relaxation time and dominant time constant isderived. The function relation between moisture in solid insulation anddominant time constant under20℃is established, which can provide evidencefor quantity analysis of insulation condition.6． The correlation between initial slope, dominant time constant andinsulation condition were experimentally studied. On the basis of simulationanalysis and experiments, a synthetic diagnosis method for insulation conditionof transformer with standard polarization spectrum is put forward. This methodcombines dominant time constant and initial slope to determine the synthesizedcondition. A diagnosis example indicates the synthetic method is effective.7．The influences of field test environment on polarization spectrum wereexperimentally studied, and precautions and measures of avoiding interferenceware presented. The generation mechanism of non-standard polarizationspectrum was revealed by dielectric response equivalent circuit, which isclassified by the influence factors. A diagnosis method for insulation conditionof transformer with non-standard polarization spectrum is also proposed. Adiagnosis example testifies the efficiency of the method.更多还原