电力系统领域工频干扰原理及试验分析

Principle and Test Analysis of Power Frequency Interference in Power System

一旦变电站接地点分配不合理,接地系统不能通过多点低阻抗接地,事故发生时接地系统会产生大电流,根据公式U=I*R,变电站不同部位对"地"电压将上升。对地阻抗平衡时,装置之间传递信号的缆线会产生相同频率的共模电压,当对地阻抗不平衡时,则会产生相同频率的差模电压。有时候即使没有接地点故障即不存在接地故障电流,信号电缆也会感应具有电源频率的干扰电压。工频抗扰度试验正是为了验证被试装置在额定频率下被干扰并受到短时、传导性的共模和差模工频骚扰时能否正常工作的能力。该文从工频干扰产生机理出发,结合工频干扰数据模型,并设计简易可靠的试验装置对电力装置进行工频抗扰度试验验证,提高电子产品工频抗扰度性能。

Once the distribution of substation grounding points is unreasonable,the grounding system can not be grounded through multi-point low impedance,and the grounding system will produce large current when the accident occurs.According to the formula U=I*R,the voltage of different parts of the substation to the"ground"will rise.When the impedance to ground is balanced,the cables transmitting signals between devices will generate common mode voltage of the same frequency.When the impedance to ground is unbalanced,differential mode voltage of the same frequency will be generated.Sometimes,even if there is no ground fault,that is,there is no ground fault current,the signal cable will also induce interference voltage with power frequency.The purpose of power frequency immunity test is to verify whether the tested device can work normally when it is disturbed at rated frequency and subjected to short-time,conductive common mode and differential mode power frequency disturbance.Based on the generation mechanism of power frequency interference,combined with the data model of power frequency interference,this paper designs a simple and reliable test device to test and verify the power frequency immunity of power devices,so as to improve the power frequency immunity performance of electronic products.