从一次变压器差动保护误动的联想

The association of a transformer differential protection mal-operation

电力系统运行中继电保护误动的原因很多,其中谐波电流注入到系统中,会给电网运行造成一定的危害,并由此可能引发继电保护误动。在现场,对中频电炉产生的谐波电流进行了测试,对谐波电流造成的保护误动进行了分析。并联电容器对谐波有一定的放大作用,当系统参数符合电流谐振条件时系统将产生谐振,将严重影响继电保护的正确动作。为此,建议在谐波源处增设谐波治理装置或改变系统的LC参数避免谐振的出现,微机继电保护在原理设计上应避免谐波因素的影响。

There are many reasons in the operation of power system relay protection maloperation. Thus harmonic current injects into the system and does harm to the power grid, which may lead to the wrong operation of relay protection. In the field, harmonic current generated by intermediate frequency electric furnace is tested and the protection of harmonic currents caused by wrong operation is analyzed. Shunt capacitors have a certain amplification to harmonic currents. When the system parameters accord with the resonance conditions, the system will produce resonance, which will seriously affect the right action of the relay protection. Harmonic source control device is advised or the system parameters of the LC resonator are altered to avoid resonance. Microcomputer relay protection is designed according to the principles of avoiding the effect of harmonic factors.