随着供电负荷的密集化，电缆线路的大量应用，中压配电网的对地容性电流越来越大。系统发生单相接地时，由于容性电流增大，系统易发生弧光放电或谐振，影响配电网运行的安全可靠性。为此，系统运行人员需掌握配电网对地容性电流的状态，进而采取一定的措施。文章对电容电流测试原理展开研究。 文章首先对单相金属性直接接地法、中性点外加电容法、三频法、向量法等现有的几种配电网对地电容电流测量方法的测量原理进行了理论分析，并在Matlab\Simulink环境下对上述几种测量方法进行了仿真研究。对上述几种测试方法给出综合评价，确定出向量法为所研制电容电流测试仪器的测试方法。考虑到从实际的配电网PT开口三角形侧采集到的电压信号含有热噪声，以及谐波、间谐波等干扰反馈回的电压信号，为准确测量配电网的对地电容电流，需要对采集的电压信号进行滤波处理。文章基于自适应噪声干扰对消的原理设计了一种自适应陷波滤波器，该自适应陷波滤波器可以准确追踪信号的幅值、频率、相位。最后，对所设计的自适应陷波滤波器在充满噪声的配电网仿真模型中进行滤波性能可行性仿真验证，结果表明该自适应陷波滤波器可以准确提取从PT开口三角形侧反馈回的电压信号，实现向量法准确测量配电网的对地电容电流。

With the densification of power load, and the application of cable line, the capacitive current of the medium voltage distribution network is bigger and bigger.When single-phase grounding fault occurs in the system, due to the increase of the capacitive current, arc discharge or resonance is much more likely to happen in the system, to affect the safety and reliability of operation of the distribution network. Therefore, the system operators need to master the status of the capacitive current, and to take measures. This paper research the testing principle of the capacitive current. First of all, this paper analyzed the measuring principle in theory of several kinds of distribution of capacitance current measurement methods,such as the single-phase grounding method, the neutral and capacitance method, three frequency method, vector method and so on, then simulate and research the above several measurement methods under the environment of Matlab/Simulink.Then this paper gives a comprehensive evaluation about the above several test methods, determines the vector method is the test method of the developed capacitive current test instrument.Considering the voltage signal, collected from the actual distribution network PT openings triangle side,containing voltage signal of feedback interference about thermal noise and harmonic, harmonic and so on,it requires the acquisition of voltage signal filter processing,for the accurate measurement of capacitive current of the distribution network.Based on the principle of adaptive noise cancellation, we designed an adaptive notch filter,which can accurately track the amplitude, frequency and phase of signal.At last,we make the simulation and verification for the adaptive notch filter,results show that the adaptive notch filter can accurately extracted the feedback voltage signal from PT openings triangle side,implement accurate measurement of capacitive current of the distribution network using the vector method.