电力系统中直流接地电阻检测的新原理

A NEW METHOD FOR MEASURING INSULATING RESISTANCE BETWEEN GROUND AND DC POWER SUPPLY IN POWER SYSTEM

提出检测电力系统直流接地电阻的新原理——直流检测法。该方法利用一光控电子开关 ,分别将直流母线的正、负两极通过一限流电阻接地 ,从而分别将直流系统的总电压施加于直流系统的负、正极对地绝缘电阻 (和限流电阻 )上 ,产生一直流电流 ,检测该直流电流的数值 ,根据母线电压值和限流电阻值 ,可计算出直流系统正、负极对地绝缘电阻值。同时 ,在每一个供电支路上 ,分别设置一个霍耳电流传感器 ,让所有支路的正、负两根供电线缆都同时穿过位于该支路的霍耳传感器的原边检测孔 ,和光控开关配合 ,通过这些霍耳传感器的输出可检测出接地故障所在支路。再用一个钳型霍耳传感器 ,可进一步查找到接地故障点的具体位置。和现在普遍采用的交流检测法相比 ,该方法对直流系统无任何不良影响 ;不受系统分布电容影响 ,检测的精度和灵敏度高 ;无需交流信号发生装置 ,显著降低了产品成本。

This paper proposes a new method for measuring insulating resistance between ground and DC power supply. It uses the DC power supply itself to produce current. The positive bus (negative bus) of the DC power supply is linked with a resistor to the ground using a light-controlled MOSFET in order to put the voltage of the DC power supply on the resistor between the negative bus (positive bus) of the DC power supply and ground. By measuring the current from DC power supply to ground, the value of resistor between the negative bus (positive bus) of DC power supply and ground can be obtained. With one Hall sensor in each branch and one pincer-like Hall sensor, the location of fault grounding point can be detected. The method has many advantages over the method used before, such as high accuracy, high precision, simplicity in measuring circuit design, low cost and so on.