Model and MATLAB simulation of the electrical fast transient/burst disturbance in protection and control secondary circuit

Switching in low voltage DC circuit and protection and control secondary circuit results in the electromagnetic disturbance simulated by electrical fast transient/burst described in IEC61000-4(GB/T 17626).The disturbance affects seriously on the microcomputer based protection.The paper researches the mechanism and model of the disturbance and models and simulates the disturbance resulted from the switching of assistant contact of breaker.Based on the simulation,some conclusions are reached.It is beneficial to enhance the EMC simulation at system level of the microcomputer based protection devices and improve the installing and configuration of the corresponding devices and components.