基于动态谐波域的饱和变压器建模与励磁涌流特性分析

Study on Modeling of Saturated Transformer and Analysis of Excitation Inrush Current Based on Dynamic Harmonic Domain

变压器是链接不同电压等级电路以保证电能高效传输的必不可缺的一环,在空载合闸时,时常因为铁芯饱和而产生较大的励磁涌流,导致继电保护装置误动作、引起过电压而损坏设备的绝缘等不良后果,现有的研究仅通过电磁暂态仿真等时域方法对励磁涌流波形进行观察,缺乏对励磁涌流特性影响因素的深入分析。基于此,利用动态谐波域理论建立了实际工程中常见类型饱和变压器的动态谐波域模型,准确再现了与时域仿真一致的励磁涌流现象;通过进一步地将变压器动态谐波域模型线性化,建立谐波转移矩阵模型,以谐波的视角分析不同因素对励磁涌流特性的影响。结果显示,相较于一次侧Y接法的变压器,Yg的级联方式将产生更大的励磁涌流,但二次侧D接法将会降低励磁涌流。

Transformers are an essential part of linking circuits of different voltage levels to ensure efficient transmission of electrical energy.However,when the transformer is in no-load closing,there is often a large excitation inrush current because of the saturation of the core,which leads to the malfunction of the relay protection device,causing overvoltage and damage to the insulation of the equipment.The current research only observes the inrush current waveform through time domain methods such as electromagnetic transient simulation,and lacks in-depth analysis of the factors affecting the excitation inrush current characteristics.Based on this,dynamic harmonic domain theory is adopted to establish the dynamic harmonic domain model of common types of saturated transformers in practical engineering,and the excitation inrush current phenomenon is accurately reproduced,which is consistent with the time domain simulation.Furthermore,the dynamic harmonic domain model of transformer is linearized and the harmonic transfer matrix model is established to analyze the influence of different factors on the inrush current characteristics from the perspective of harmonics.The results show that,compared with the primary side Y connection of the transformer,the cascade system of Yg will produce a larger excitation inrush current,but the secondary D connection will reduce the inrush current.