中文摘要：

正确估计电网和用户在公共连接点产生的谐波贡献量，是检测和治理谐波污染的关键。现有的一些方法忽略了由于系统谐波阻抗的变化而引起的用户谐波注入的变化。分析了谐波阻抗变化对公共耦合点（point of common coupling，PCC）处谐波含量的影响；分X/R恒定和X/R变动2种情况，建立了MATLAB/Simulink仿真模型，研究谐波阻抗波动对PCC处谐波电流、谐波电压及谐波功率的影响；利用仿真数据和计算结果绘制曲线，得到谐波阻抗对PCC处供电侧和用户侧谐波贡献量的影响规律。结果有助于当谐波阻抗变化引起系统振荡时用户和供电双方责任的划分。

英文摘要：

The proper estimation for the harmonic contributions of power system and customers on PCC （point of common coupling）is the key of the supervision and management of harmonic pollution.Some of the existing methods ignore the user harmonic injection changes caused by system harmonic impedance change.Therefore,this paper focused on the analysis of the influence of impedance changes on PCC harmonic content.Based on two cases：constant X/R and X/R changing,MATLAB/Simulink simulation model was built to study the effect of impedance fluctuations on the PCC harmonic current,harmonic voltage and harmonic power.The curve was drawn with using the simulation data and calculated result,and the influence law of harmonic impedance on power supply side and user side harmonic contribution at PCC was obtained.The result is helpful to divide responsibilities of users and power supply when harmonic impedance changing causes system oscillation.