谐波对电容式电压互感器运行特性的影响研究

Research on the influence of harmonic on the operation characteristics of capacitor voltage transformers

针对电容式电压互感器(Capacitor Voltage Transformers,CVT)在谐波干扰下二次侧产生畸变的问题,阐述了CVT的结构特性和工作原理,从系统传递函数角度分析了杂散电容和耦合电容对CVT高频特性的影响以及谐波干扰使CVT的测量误差发生的变化。为了进一步了解谐波对CVT运行特性的影响,运用仿真软件Matlab搭建包含杂散电容和耦合电容的CVT高频等效电路模型对其进行仿真试验,以获得CVT的幅频特性曲线。仿真结果表明,电网中的谐波电压会使CVT的测量误差产生变化,并不适宜直接用来测量谐波电压。

Aiming at the distortion of CVT at the secondary side, this paper expounds the structure characteristics and working principle of CVT, analyzes the influence of stray capacitance and coupling capacitance on the high fre- quency of CVT from the aspect of system transfer function and the change of measurement difference caused by har- monic disturbance. In order to further understand the influence of harmonic on the operation characteristics of CVT, this paper establishes the model of CVT high frequency equivalent circuit including stray capacitance and coupling capacitance by Matlab to acquire the amplitude-frequency curve of CVT. The simulation result shows that the harmonic voltage in power grid, which will changes the measurement difference of CVT, is not suitable for di- rectly measuring harmonic voltage.