电磁式电流互感器饱和特性研究 电网学专业

I题 目 电磁式电流互感器饱和特性研究 摘要电磁式电流互感器是一种以电磁感应原理为基础，具有励磁特性，这种励磁特性是非线性的，能够变换电流并且普遍应用于电力系统中。当出现较大故障电流时，特别是非周期性成分和铁芯的剩余磁性，会导致明显的磁饱和励磁电流增加，从而使得电流互感器性能下降，这是由于继电器针对两次电流畸变而产生的保护作用而导致的。互感器是测量用的变压器，又称仪用变压器，多数是应用在扩大仪表的测量范围，也分为电压互感器和电流互感器两种。测量大电流时，因导线周围产生的磁场会对仪表带来附加影响，故不能采用直接式电流表，用分流器来扩大量限时，分流电阻的功耗颇大，故通常用电流互感器来扩大电流表的测量。电流互感器是工作于低磁感应强度的铁芯变压器。由原、副绕组绕在铁芯上构成，而副绕组匝数很多，所接电流表内电阻很小。所以电流互感器实质上是一个短路运行的升压变压器，是一种将大电流转换为小电流的升压变压器。电流互感器在工作时，由于电磁的影响会对电网工作产生较大的影响。关 键 词：电流互感器 传变特性 饱和特性Abstract Electromagnetic current transformer is a kind of excitation characteristic based on the principle of electromagnetic induction, which is non-linear, can change the current and is widely used in power system. When there is a large fault current, particularly is a periodic components and residual magnetic core, can lead to obvious magnetic saturation excitation current is added, so as to make the current transformer performance degradation, it is the result of the relay in view of the two current distortion of protection. Transformers are measurement transformers, also known as instrument transformers, most of which are used to expand the scope of measurement instruments, also divided into voltage transformers and current transformers. When measuring high current, because of the wire around the magnetic field can influence on additional instrument, therefore cannot use ammeter directly, with shunt IIto expand the amount limit, po...