【作者】 彭兵；

【导师】 周建中；

【作者基本信息】 华中科技大学 ， 水利水电工程， 2008， 博士

【摘要】 当前,我国经济高速发展,电力需求十分旺盛,系统供电的可靠性要求越来越高。近三十年来,我国大力开发水电能源,水电装机容量在电力系统中所占的比重逐步提高。同时,随着制造技术的发展,水电机组单机容量越来越大,在系统中的调频、调峰和事故备用功能亦越来越重要。水电机组运行的安全性和可靠性已经成为水电能源学科学术界和工程界研究的热点之一。水电机组是强耦合、非线性的复杂系统,其故障特征分布也具有耦合性和非线性,如果采用单一的、线性的方法,很难对其运行状态做出准确的评价。信息融合能够综合水电机组异源异构信息,全面了解机组状态。带有核函数的支持向量机能够实现输入空间向特征空间的非线性映射,适宜解决非线性问题。这些方法的采用对实施水电机组故障诊断,进而实现水电机组状态检修具有重要的现实意义。现有的故障诊断方法通常在平稳工况下进行,由于开机工况及其过程复杂,信号不容易处理,因此,较少考虑机组启停过程的过渡特性进行故障诊断。实际上,在开机过程中能够获取更多机组故障特征信息,有利于提高故障诊断准确性。同时,结合工程中水电机组振动试验(转速试验、励磁试验和负荷试验)的要求,本文提出了基于多特征信息融合的开机自诊断故障诊断方法。水电机组开机过程包括加速、加励磁和加负荷三个阶段,利用机组开机过程,获取机组频率、时间和空间特征信息,进而对其进行信息融合,这将提高机组故障诊断的准确度。轴心轨迹是水电机组状态信息在数据层时域信息空间的融合结果,其图形特征从另一个角度反映了机组的运行状态。曲线不变矩满足轴心轨迹不封闭的特点,能够表征轴心轨迹的图形特征。但是,离散的曲线不变矩不具有缩放不变性,因此本文在讨论轴心轨迹曲线不变矩不变性的基础上,提出了改进曲线不变矩。实验结果表明,改进后的曲线不变矩具有平移、旋转和缩放不变性。为了有效实现信息输入空间向信息特征空间的非线性映射,本文针对支持向量机中的RBF核函数,研究了其几何特性,采用以黎曼几何为基础的数据依赖性改进方法,以此剔除支持向量机的冗余支持向量,从而显著提高了支持向量机故障诊断的速度和准确度。此外,本文将改进支持向量机应用于水电机组故障诊断。通过理论分析和实验验证,阐明了支持向量机具有较强的泛化推广能力和小样本学习能力,适应于水电机组故障诊断先验知识不足的现实情况。故障实例分析表明,改进支持向量机能够提高机组故障诊断的速度和准确度。针对多元数据融合过程中的“组合爆炸”问题,并在分析证据联合计算复杂度的基础上,提出采用交换律和结合律进行D-S证据信息融合的分解,以降低计算的复杂度。利用相关故障数据进行诊断测试,证实了D-S证据理论交换律和结合律的成立。此外,将信息融合技术应用于水电机组故障诊断,得到了更准确的诊断结论。与单一特征诊断相比,通过水电机组故障信息的频率阶次特征、时间特征和空间特征的融合,故障诊断结论的不确定性更低,而可信度更高。最后,本文设计了一套水电机组稳定性状态监测及故障诊断原型系统。在系统总体设计的框架下,完成了各功能模块的硬件设计和软件设计,建立了故障诊断专家子系统和SVM辅助决策子系统,以满足水电机组稳定性状态监测和故障诊断的实际需要。更多还原

【Abstract】 With high-speeded growth of Chinese economy, demand for electricity increased and requirement for reliable electriciy became stronger. In the past twenty years, water resource and hydropower was exploited widely and capacity of hydro-electricity played a more and more important role in capacity of power system. Development of manufacture technology promoted hugemazation of Hydropower Generating Unit (HGU). Security and reliability of HGU became one of the most attentional objects in research and application of hydropower science.HGU is a complex nonlinear system with strong coupling between partions. It is difficult to comment condition of HGU with single and linear method. By information fusion, all kinds of HGU’s information with different distruction and from different resource are integrated. And Support Vector Machine (SVM) with kernel results HGU’s nonlinear problem with mapping input data into feature space. It is valuable for HGU’s fault diagnosis and condition-based mentanence to apply these methods.Fault diagnosis methods are generally in the condition of stabilization. Vibration signal in starting process is so complex that it is not used to fault diagnosis in starting process. In fact, more fault information could be got in starting process. The idea of fault ditection and analysis in starting process is expounded and the method of fault dignosis by multi-feature information fusion is proposed in this thesis. HGU starting process includes rising-speed phase, rising-excitation phase and rising-load phase, which meets condition of HGU vibration experiments (altering-speed experiment, altering-excitation experiment and altering-load experiment). Frenquency feature, temporal feature and spatial feature of vibration could be gained in HGU starting process. It could raise veracity of fault diagnosis with multi-feature information fusion.Shaft orbit is the result of HGU running information fusion in time domain of data level. It is an open line. Linear moment invarint is a kind of graphics feature of shaft orbit and could reflect condition of running HGU. However, discrete linear moment invariant is change in zoom. Improved linear moment invariant is presented in this thesis. Experiment result shows improved linear moments are invariant in movement, rotation and zoom. In order to map sample from input space to feature sapce effectively, geometry of RBF kernel used in SVM is analyzed and data dependent method based on Riemannian geometry is used in this thesis. Results of analysis and experiments show delecting redandent support vectors is one reason for raising fault diagnosis speed and veracity of SVM. In addition, results of analysis and experiments demonstrate SVM has strong generalization capability and learning capability from little sample set, which meets condition of HGU fault diagnosis with a little prior knownledge. A fault diagnosis example exhibit improved SVM could raise speed and veracity of HGU fault diagnosis.For the problem of combination explosion in inforemation fusion, exchange theorem and conjunction theorem in combination process amonge evidences are researched in this thesis. Results of analysis on calculate complex of combine among evidences show information fusion by D-S theory could be reduced with exchange theorem and conjunction theorem. Results of experiments demonstrate these theorems. In addition, information fusion is applied in HGU fault diagnosis. By fusing frequency featrure information, temporal feature information and spatial feature information, HGU is diagnosed with lower uncertainty and higher reliability.At last, a HGU condition monitoring and fault diagnosis system is designed. Hardware and software design of each module is finished based on general design of the system. At the same time, Fault Diagnosis Expert Subsystem and SVM Assistant Decision Subsystem are built. The system could satisfy many requirements of HGU condition monitoring and fault diagnosis.更多还原