基于MATLAB的电压互感器铁磁谐振数字仿真

Digital Simulation Analysis on Ferroresonance of Electromagnetic Potential Transformer Based on MATLAB

应用MATLAB软件的PSB和Simulink仿真工具 ,建立仿真模型 ,研究了中性点不接地系统中的铁磁谐振规律。研究表明 ,TV励磁特性决定谐振的频率 ,即相间差别较大时易于发生 1/ 3分频谐振 ,反之则易于发生 1/ 2分频谐振。中性点不接地系统防止TV谐振工作中应选用励磁特性好的TV ,减少同一系统中TV接地的数量 ;尽可能地使系统三相对地电容相同 ,否则不宜采用二次侧消谐 ;在采用高压绕组中性点经非线性电阻接地消谐时应注意绝缘配合问题 ,因单相接地情况下中性点处存在较高电压。

Through the application of Power System block-Set and Simulink based on MATLAB software, the saturation of electromagnetic potential transformers is simulated by VCCS and then ferromagnetic resonance of a group of TV in an isolated neutral system are studied. Ferromagnetic resonance frequency depends on the difference among magnetization characteristics of potential transformers in a group, that is, bigger difference leads more easily to 1/3 power frequency resonance, otherwise 1/2 power frequency resonance. When eliminating resonance methods are used, the following attentions should be paid to. First, selecting TV with good magnetization characteristic and reducing the number of grounded TV are strongly suggested. Secondly, keeping phase-to-ground capacitances in the system equilibrium or microcomputer resonance eliminator connected in the tertiary winding had better not to be used. In the end, when using nonlinear resistance between primary neutral point of TV and ground, insulation coordination problem must be highlighted for the high voltage during single phase grounding.