电流互感器暂态饱和特性及差动保护应对措施研究

发布时间：2018-08-09 17:50

【摘要】：随着电力建设的快速推进，电网规模越来越大，结构越来越复杂，暂态过程也变得更加复杂多样，对电流互感器（TA）的暂态性能形成了更大的考验。现场事故分析表明，暂态过程引起的电流互感器铁心饱和是导致电流差动保护误动的一个重要原因。而差动保护通常作为电力设备的主保护，其误动会对设备本身的安全和系统的稳定运行构成非常严重的危害。因此，开展电流互感器暂态饱和特性及差动保护应对策略的研究，对保证电网的运行安全，提高供电可靠性具有非常重要的理论和现实意义。电流互感器暂态饱和特性复杂，受诸多非线性因素的影响。数字仿真和动模试验是进行TA暂态饱和特性研究的基本方法和手段。论文根据TA饱和机理，，对几种典型电流互感器的仿真建模方法进行了对比分析，论证了采用基于J-A理论的TA仿真模型的合理性。根据磁动势等值的原理，提出了一种基于磁链等效原则的电流互感器物理试验模型的构建方法，可将实际电流互感器直接用于动模试验研究。论文介绍了该物理模型的具体实现方法以及动模试验结果。电流互感器暂态饱和是导致差动保护误动的主要原因之一。论文分析了TA铁芯进入饱和之后，二次电流波形的变化特点。在此基础上，归类阐述了目前常用的差动保护抗TA饱和算法，如谐波制动法、时差法、附加制动区法、电流极性比较法以及采样值差动法等的基本原理和实现方法，为差动保护抗TA饱和性能的评估提供参考。在上述研究工作的基础上，针对运行现场变压器空合时，发电机差动保护和线路差动保护发生误动的事故实例，分析了变压器涌流引发TA饱和，进而导致差动保护误动的主要原因，提出了在发电机和线路差动保护中，加强抗TA饱和措施的必要性和可采取的应对策略。针对目前常用的谐波制动方法可能导致区内故障时差动保护动作延时问题，提出了一种基于小矢量的差动保护新方法，并进行了试验验证。文中介绍了该方法的基本原理、实现方法和试验结果。论文最后，对全文工作进行了总结，并对下一步工作进行了展望。
[Abstract]:With the rapid development of power construction, the scale of power network is getting larger and larger, the structure is more and more complex, and the transient process is becoming more complex and diverse, which will test the transient performance of current transformer (TA). Field accident analysis shows that the core saturation of current transformer caused by transient process is an important reason for the maloperation of current differential protection. The differential protection is usually used as the main protection of the power equipment, and its misoperation will cause serious harm to the safety of the equipment itself and the stable operation of the system. Therefore, it is of great theoretical and practical significance to study the transient saturation characteristics of current transformers and the corresponding strategies of differential protection in order to ensure the safety of power network operation and improve the reliability of power supply. The transient saturation characteristics of current transformers are complex and affected by many nonlinear factors. Digital simulation and dynamic simulation test are the basic methods and means to study the transient saturation characteristics of TA. According to TA saturation mechanism, several typical current transformer simulation modeling methods are compared and analyzed, and the rationality of TA simulation model based on J-A theory is demonstrated. According to the principle of magnetodynamic potential equivalence, a method of constructing the physical test model of current transformer based on the principle of magnetic chain equivalence is proposed, which can be directly used in the dynamic model test research of the actual current transformer. The realization method of the physical model and the result of dynamic model test are introduced in this paper. Transient saturation of current transformer is one of the main causes of maloperation of differential protection. The characteristics of the secondary current waveform after the TA core is saturated are analyzed in this paper. On this basis, the basic principles and implementation methods of current differential protection anti-TA saturation algorithms, such as harmonic braking method, moveout method, additional braking zone method, current polarity comparison method and sampled-value differential method, are classified and expounded. It provides a reference for the evaluation of TA saturation resistance of differential protection. Based on the above research work, the TA saturation caused by transformer inrush current is analyzed in view of the maloperation of generator differential protection and line differential protection when the transformer is empty. The main causes of maloperation of differential protection are brought forward. The necessity of strengthening anti-TA saturation measures in differential protection of generator and line and the countermeasures to be taken are put forward. A new differential protection method based on small vectors is proposed to solve the delay problem of differential protection when the current harmonic braking method may lead to the fault in the region. The basic principle, realization method and test results of this method are introduced in this paper. At the end of the paper, the paper summarizes the work of the paper, and looks forward to the next work.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM452

【相似文献】