| Recently, the power electronic devices are the main source of harmonics. At the same time, they are effective in improving power supply reliability and assuring sine waveform of voltages and currents for customers. Thus harmonics become a long-term and important issue for investigation, and it is a challenging problem for power system researchers.The paper first introduces the basic knowledge of power system harmonics, and points out the importance of studying harmonics. It discusses the models of system components for harmonic analysis, as well as the applicability, advantages and shortcoming of the models. It also uses PCFLOH to analysis power system harmonics in frequency domain.The paper illustrates the model for harmonic analysis in two main categories. One is the typical power system components, such as generator, transformer and transmission lines. The other is new equipment, such as power electronic device, and it becomes the main source of harmonics as power electronic technique develops. Based on the analysis and recognization of the characteristics of the devices, the paper emphasizes the necessity of using current-source to stand for the devices, and represent their frequency characteristics.Part three of the paper introduces the standards and guidelines designed by international organizations and many countries for limiting power system harmonics and power equipment harmonics. The paper introduces the national standard for harmonics of our country according to the situations of china.Part four of the paper uses PCFLOH to analysis a 18-node distribution power system, and provides the results of waveform distortion. According to the analysis result, it discusses the influence of different models for harmonic analysis, and discusses how to select the models for different condition and accuracy requirements. |
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