电网中各母线的谐波电压是所有谐波源共同作用的效果,因此准确区分各主要谐波源在特定母线上的谐波贡献对划分谐波污染责任有着重要意义。首先分析并指出区分各谐波源谐波贡献的关键在于准确计算谐波源节点与所关注母线间的谐波互/自阻抗,在此基础上提出一种“非干预式”的谐波贡献划分方法。该方法以各谐波源注入谐波电流中的快速变化分量为工具,根据独立随机矢量的统计特性,抽取出各谐波源节点与关注母线间的谐波互/自阻抗,最后根据计算所得阻抗值分别计算出各谐波源对关注母线的矢量贡献和标量贡献。对IEEE 14节点的系统进行仿真,结果表明该方法可很好地区分各谐波源在特定母线上的谐波贡献,大大抑制了其他谐波源的波动对谐波贡献划分的不利影响,同时也为谐波污染的责任划分提供了新的依据。
Harmonic voltages at each bus of a power grid are the combinations of voltage contributions of each harmonic source located in the same grid. Distinguishing the contributions of each main harmonic source to the harmonic voltages of particular buses is very significant for responsibility partition of harmonic pollution. This paper first analyzes and points out that the critical process in harmonic contribution distinguishing is to calculate the harmonic mutual/self impedance between harmonic source buses and the concerned buses accurately. Then a novel “non-invasive” method for harmonic contribution distinguishing is put forward. With the fast components of harmonic current injected by harmonic sources as the tool, this method extracts the mutual/self impedance between the main harmonic source buses and the concerned buses according to the statistical property of independent random vectors; finally, harmonic vector contributions and scalar contributions of each harmonic source to all concerned buses can be obtained according to the calculated mutual/self impedance. A case study based on the IEEE 14-bus test system was conducted, it shows that the proposed approach is effective to distinguish the harmonic contributions due to all main harmonic sources to the concerned buses, and can largely eliminates the negative effect caused by the harmonic fluctuation of other harmonic sources in contribution distinguishing; moreover, it also provides a new basis for responsibility partition of harmonic pollution.