【作者】 宫政；

【导师】 朱永利；

【作者基本信息】 华北电力大学 ， 计算机应用技术， 2011， 硕士

【摘要】 变压器作为电力系统中的核心设备,它的安全性和可靠性直接关系到电力系统的安全性和可靠性。由于各种内部因素和外部因素的影响,变压器在长期的运行中出现故障或事故的情况是难以避免的。作为变压器的状态检修基础,电力变压器的状态评估显得尤为重要,而作为状态评估的特例,故障诊断技术的研究同样具有非常重要的意义。因此,研究电力变压器的状态评估方法和故障诊断技术,以便及时、准确地检测出变压器的潜伏性故障,在成为电力行业普遍关注的课题的同时,也受到了学术界的广泛关注。在变压器的状态评估方面,鉴于传统的评估方法只考虑了指标的模糊性而忽略了随机性,利用云模型理论在考虑模糊性的同时兼顾随机性的特点,将云模型理论应用其中,建立了新的状态评估模型。同时,结合层次分析法获取各指标的权重信息,利用变权公式对个别关键指标的权重进行均衡性调整,并采用云函数计算出各指标的评判矩阵,最终得到更接近实际的评判向量,从而判断出变压器的状态。通过实例分析,将新的评估模型与传统的评估方法进行对比,得出运用云模型理论对变压器进行状态评估的结果更接近于实际状态。在变压器的故障诊断方面,鉴于物元理论在构建诊断模型时,忽略了分界值的不确定性,使诊断结果偏离了实际情况。利用云模型能合理地解决边界不确定问题,将物元理论与云模型相结合,建立了新的故障诊断模型。同时,结合油中溶解气体分析技术,通过对油中溶解气体的浓度、产气率、总烃含量以及气体间比值的分析,客观、准确地对变压器进行故障诊断。通过与其他诊断技术相比较,并结合案例分析,得出基于物元理论和云模型的变压器故障诊断技术具有更高的正确率。更多还原

【Abstract】 In the power system, the transformer is seen to be the core equipment, so the safety and reliability of the transformer is directly related to the security and reliability of the power system. Due to various internal factors and external factors it is difficult to avoid failure or accident occurred in the transformer’s long run. As the basis of the state of transformer’s maintenance, power transformer condition assessment is particularly important, and as a special case of condition assessment, fault diagnosis technology also has a great significance. Therefore, the study of power transformer condition assessment and fault diagnosis technology for finding incipient faults as early as possible not only become common concern of power industry issues but also received widespread attention in academic.In the study of transformer condition assessment, in view of the traditional fuzzy comprehensive evaluation model only considers fuzziness and ignored randomness of uncertainty, while the cloud model considers fuzziness and randomness of uncertainty at the same time, we establish a new condition assessment model based on cloud model. Besides, we will use sub-indicators of the evaluation object to calculate the evaluation results of objective indicators and get weight information by AHP, using variable weight formula to balance adjustment individual key indicators’weights, and get the actual evaluation vector using cloud formula, then determine the status of the transformer. Through case analysis and compared with the traditional condition assessment, we find that the result based on the new assessment model is closer to the actual state.In the study of transformer fault diagnosis, in view of matter-element theory solving fault diagnosis problems in a simple and effective method, ignoring the uncertainty of boundary values, the result is deviated from the actual situation. Using cloud model theory to consider the uncertainty of the boundary, we combine cloud model theory with matter-element to propose a new model which is based on matter-element theory and cloud model theory. Meanwhile, we combine oil dissolved gas analysis, by analyzing the concentration of dissolved gases, gas production rate, the total hydrocarbon content and the ratio between gas in oil, and establish transformer fault diagnosis model, then determine the transformer fault accurately and objectively. By compared with other techniques, combined with case analysis, we reach the conclusion that the new technique which is based on matter-element theory and cloud model has a higher accuracy.更多还原