变压器铁芯剩磁检测与消磁原理的分析、仿真及验证研究

Power transformer is an important part of power system. The main factor affecting the design and service life of the transformer is its electromechanical characteristics. Residual flux does a conspicuous influence on the inrush phenomenon. In fact, such events may result in high levels of transient current, which may affect the transformer mechanical structure and its lifetime. A large number of high harmonics currents lead to waveform distortion of voltage and the current will reduce the quality of the power supply network. Therefore, the principle analysis of the residual flux detection and the design of the residual flux detection and elimination device is the key technical problem that the power grid security needs to be solved urgently. Based on the study of ferromagnetic materials principle of residual flux, this project carries the transient simulation of the residual flux of the power transformer core to determine the effect of the residual flux on the electromechanical characteristics of the power transformer. The establishment of power transformer residual flux simulation analysis platform is proposed, to achieve different types of structural parameters under the size of the power transformer modeling analysis. The method of DC detection of residual flux is proposed, and the mathematical relationship between the magnetization current and residual flux is obtained. The residual flux of the transformer is calculated by measuring the change of current. The design of the demagnetization system is carried out by using the residual flux which has been measured. The residual flux detection and demagnetizing device are configured to achieve the purpose of residual flux detection and elimination. Monitoring real-time changes of the electromechanical characteristics of the different residual fluxes. Then the influence of residual flux on the inrush current and the electromagnetic force of the transformer is analyzed. Finally, the feasibility and reliability of the research work of this project are verified. The results can be commonly used in power transformers and even in the power network, with good direct and indirect benefits.

电力变压器是电力系统的重要组成部分，含有铁芯剩磁的电力变压器在投运时，可能产生较大的励磁涌流，瞬时冲击电流会对电力设备产生危害，使得变压器投运失败，同时产生的大量高次谐波将降低电网供电质量，造成重大经济损失。因此，剩磁检测与消磁原理的分析及剩磁检测消磁装置的设计，是当前电网安全亟需解决的关键技术问题。本项目在研究铁磁材料剩磁产生原理的基础上，进行电力变压器铁芯剩磁的暂态仿真分析，确定剩磁对电力变压器机电特性的影响。提出通过编程建立电力变压器剩磁仿真分析平台，实现不同型号结构尺寸参数下电力变压器的建模分析；提出剩磁的直流检测方法，得到磁化电流变化值与剩磁的数学关系，通过实际测量电流的变化得到待测变压器的剩磁；提出利用已测剩磁进行消磁系统的设计，搭建剩磁检测与消磁装置，试验验证本项目研究工作的可行性及可靠性。项目成果可以在普通电力变压器乃至国网中广泛应用，具有良好的直接和间接效益。

本项目以解决实际电力变压器铁芯剩磁影响下高励磁涌流引起的机电问题为核心，通过对硅钢材料的铁磁特性的实验研究，分析了变压器的机械结构特性与其铁芯材料特性，构建了不同型号电力变压器铁芯仿真模型，进行电力变压器铁芯磁特性的模拟，建立电力变压器剩磁仿真分析平台，实现不同型号结构尺寸参数下电力变压器的建模分析；研究了剩磁测量原理，确定了剩磁与测量电流变化值的计算通式，利用电力变压器剩磁的直流检测方法，通过实际测量电流的变化值得到待测变压器的剩磁；分析电力变压器绕组变形的原理，仿真分析确定了剩磁与绕组电磁力的关系；进行了剩磁消磁原理的分析，研究了剩磁检测、消磁方法，完成了剩磁测量及消磁硬件调试，并通过试验进行了验证。 根据电力科学研究院在电网联网工程中的需求，电力变压器剩磁的评估，可以降低电力变压器运行时涌流的发生机率，防止自动重合闸后跳闸电力变压器无法正常投运情况。随着电网格局的自动智能化发展，在智能变电站变压器自动投退运行前进行剩磁检测与消磁操作，可有效降低变压器涌流和绕组电磁力，避免高励磁涌流对电力变压器机械性能的影响，对延长电力变压器使用寿命有直接的经济效益，是当前电网安全检测系统优化发展的需要，也是电网高效优化运行的需要。